Meridional brightness temperatures were measured on the surface of Titan during the 2004–2014 portion of the
Cassini mission by the Composite Infrared Spectrometer. Temperatures mapped from pole to pole during five twoyear
periods show a marked seasonal dependence. The surface temperature near the south pole over this time
decreased by 2 K from 91.7±0.3 to 89.7±0.5 K while at the north pole the temperature increased by 1 K from
90.7±0.5 to 91.5±0.2 K. The latitude of maximum temperature moved from 19 S to 16 N, tracking the subsolar
latitude. As the latitude changed, the maximum temperature remained constant at 93.65±0.15 K. In 2010
our temperatures repeated the north–south symmetry seen by Voyager one Titan year earlier in 1980. Early in the
mission, temperatures at all latitudes had agreed with GCM predictions, but by 2014 temperatures in the north were
lower than modeled by 1 K. The temperature rise in the north may be delayed by cooling of sea surfaces and moist
ground brought on by seasonal methane precipitation and evaporation.
Плутон светится в рентгеновском диапазонеAnatol Alizar
Chandra detected X-rays from Pluto in 2014 and 2015 observations, finding 8 photons in the 0.31-0.60 keV band. No photons were detected from 0.60-1.0 keV. Allowing for background, there was a statistically significant detection of X-rays from Pluto. Charge exchange between solar wind ions and Pluto's atmosphere can produce X-rays and may explain the detection, but the observed rate is higher than expected given New Horizons measurements of Pluto's atmosphere and solar wind conditions. The solar wind may be focused within 60,000 km of Pluto to produce the detected X-ray emission.
The document summarizes research from images taken by the New Horizons spacecraft of Charon, Pluto's largest moon. The images reveal Charon has a reddish polar cap at its north pole. Thermal models show the pole experiences long periods of extreme cold temperatures due to Charon's high obliquity and long seasons. The researchers hypothesize that methane and other volatiles escaping from Pluto's atmosphere become cold-trapped at Charon's winter pole, where they are processed by radiation into non-volatile organic compounds that remain on the surface to form the red cap. Spectral and compositional evidence supports this mechanism of seasonal accumulation of photolyzed volatiles to explain Charon's unique polar color
Атмосфера Земли медленно теряет кислородAnatol Alizar
This document summarizes research on reconstructing past atmospheric oxygen (O2) levels over the past 800,000 years using O2/N2 ratios measured from ancient air bubbles trapped in ice cores from Greenland and Antarctica. The main findings are:
1) O2/N2 ratios from multiple ice cores show a consistent decline of 8.4‰ per million years over the past 800,000 years, equivalent to a 0.7% decline in atmospheric O2 levels.
2) This decline is unlikely to be explained by changes in air bubble formation processes or other non-atmospheric factors, as argon/nitrogen ratios from the same ice cores show an inconsistent increasing trend over the same
1) Spectra from the Mars Global Surveyor's Thermal Emission Spectrometer were used to monitor the abundance and distribution of water vapor on Mars over one full Mars year.
2) A maximum in water vapor abundance was observed at high latitudes during local summer in both hemispheres, reaching up to 100 pr-mm in the north and 50 pr-mm in the south.
3) There were large differences between the hemispheres and seasons, suggesting cross-equatorial transport of water from north to south after northern summer but not after southern summer.
Climatic consequences of regional nuclear conflicts27Nav
This study uses a climate model to simulate the climatic effects of a regional nuclear war between two countries using 100 Hiroshima-sized nuclear weapons on cities in the subtropics. The model finds that the smoke produced by urban fires would cause significant global cooling and reductions in precipitation lasting over a decade. The climate effects are more long-lasting than previous studies due to the smoke being lofted higher into the stratosphere where removal is slower. Reductions in surface sunlight, temperatures, and precipitation of up to 15 W/m^2, 1°C, and 9% respectively are found for several years globally following the conflict.
Water vapor mapping on mars using omega mars expressAwad Albalwi
A systematic mapping of water vapor on Mars has been achieved using the imaging spectrometer OMEGA aboard the Mars Express
spacecraft, using the depth of the 2.6 mm (n1, n3) band of H2O. We report results obtained during two periods: (1) Ls ¼ 330–401
(January–June 2004), before and after the equinox, and (2) Ls ¼ 90–1251, which correspond to early northern summer
This document summarizes observations of the gas cloud G2 as it passes near the supermassive black hole at the center of the Milky Way galaxy. New observations in 2013 with the NACO and SINFONI instruments on the VLT show that G2 continues to be stretched out along its orbit due to tidal forces. The head of G2 is now stretched over 15,000 Schwarzschild radii. Some gas has passed the pericenter of the orbit and is seen blueshifted. The luminosity and line ratios of G2 remain constant, showing no evidence of heating as it interacts with ambient gas. The pericenter passage will occur over about a year as G2 is stretched out along its orbit.
1) The document discusses observations of mesospheric gravity waves over the Andes Mountains from both ground-based and satellite instruments.
2) Ground-based observations have been made at the Andes Lidar Observatory in Cerro Pachon, Chile since 2009, measuring gravity wave activity in the mesosphere through OH layer measurements.
3) Complementary satellite observations have been made by the SABER instrument on the TIMED satellite, which has measured increased temperature variance in the mesosphere over the Andes during winter months that indicates stronger gravity wave activity.
Плутон светится в рентгеновском диапазонеAnatol Alizar
Chandra detected X-rays from Pluto in 2014 and 2015 observations, finding 8 photons in the 0.31-0.60 keV band. No photons were detected from 0.60-1.0 keV. Allowing for background, there was a statistically significant detection of X-rays from Pluto. Charge exchange between solar wind ions and Pluto's atmosphere can produce X-rays and may explain the detection, but the observed rate is higher than expected given New Horizons measurements of Pluto's atmosphere and solar wind conditions. The solar wind may be focused within 60,000 km of Pluto to produce the detected X-ray emission.
The document summarizes research from images taken by the New Horizons spacecraft of Charon, Pluto's largest moon. The images reveal Charon has a reddish polar cap at its north pole. Thermal models show the pole experiences long periods of extreme cold temperatures due to Charon's high obliquity and long seasons. The researchers hypothesize that methane and other volatiles escaping from Pluto's atmosphere become cold-trapped at Charon's winter pole, where they are processed by radiation into non-volatile organic compounds that remain on the surface to form the red cap. Spectral and compositional evidence supports this mechanism of seasonal accumulation of photolyzed volatiles to explain Charon's unique polar color
Атмосфера Земли медленно теряет кислородAnatol Alizar
This document summarizes research on reconstructing past atmospheric oxygen (O2) levels over the past 800,000 years using O2/N2 ratios measured from ancient air bubbles trapped in ice cores from Greenland and Antarctica. The main findings are:
1) O2/N2 ratios from multiple ice cores show a consistent decline of 8.4‰ per million years over the past 800,000 years, equivalent to a 0.7% decline in atmospheric O2 levels.
2) This decline is unlikely to be explained by changes in air bubble formation processes or other non-atmospheric factors, as argon/nitrogen ratios from the same ice cores show an inconsistent increasing trend over the same
1) Spectra from the Mars Global Surveyor's Thermal Emission Spectrometer were used to monitor the abundance and distribution of water vapor on Mars over one full Mars year.
2) A maximum in water vapor abundance was observed at high latitudes during local summer in both hemispheres, reaching up to 100 pr-mm in the north and 50 pr-mm in the south.
3) There were large differences between the hemispheres and seasons, suggesting cross-equatorial transport of water from north to south after northern summer but not after southern summer.
Climatic consequences of regional nuclear conflicts27Nav
This study uses a climate model to simulate the climatic effects of a regional nuclear war between two countries using 100 Hiroshima-sized nuclear weapons on cities in the subtropics. The model finds that the smoke produced by urban fires would cause significant global cooling and reductions in precipitation lasting over a decade. The climate effects are more long-lasting than previous studies due to the smoke being lofted higher into the stratosphere where removal is slower. Reductions in surface sunlight, temperatures, and precipitation of up to 15 W/m^2, 1°C, and 9% respectively are found for several years globally following the conflict.
Water vapor mapping on mars using omega mars expressAwad Albalwi
A systematic mapping of water vapor on Mars has been achieved using the imaging spectrometer OMEGA aboard the Mars Express
spacecraft, using the depth of the 2.6 mm (n1, n3) band of H2O. We report results obtained during two periods: (1) Ls ¼ 330–401
(January–June 2004), before and after the equinox, and (2) Ls ¼ 90–1251, which correspond to early northern summer
This document summarizes observations of the gas cloud G2 as it passes near the supermassive black hole at the center of the Milky Way galaxy. New observations in 2013 with the NACO and SINFONI instruments on the VLT show that G2 continues to be stretched out along its orbit due to tidal forces. The head of G2 is now stretched over 15,000 Schwarzschild radii. Some gas has passed the pericenter of the orbit and is seen blueshifted. The luminosity and line ratios of G2 remain constant, showing no evidence of heating as it interacts with ambient gas. The pericenter passage will occur over about a year as G2 is stretched out along its orbit.
1) The document discusses observations of mesospheric gravity waves over the Andes Mountains from both ground-based and satellite instruments.
2) Ground-based observations have been made at the Andes Lidar Observatory in Cerro Pachon, Chile since 2009, measuring gravity wave activity in the mesosphere through OH layer measurements.
3) Complementary satellite observations have been made by the SABER instrument on the TIMED satellite, which has measured increased temperature variance in the mesosphere over the Andes during winter months that indicates stronger gravity wave activity.
The document summarizes the discovery and characterization of exoplanet atmospheres over time. It discusses key observational highlights including the identification of molecules, day-night temperature variations, and variability in some atmospheres. Modeling techniques are also described that aim to constrain atmospheric properties by fitting millions of models to data. The summary outlines progress made but also future directions, such as direct imaging of young planets and the potential for characterizing small planets around M stars.
This document compares in situ wind speed observations from Wave Glider deployments in the Southern Ocean to several satellite-derived and reanalysis wind products. The study finds that the ECMWF reanalysis product best represents the temporal variability of winds compared to in situ data. However, the NCEP/NCAR Reanalysis II product matches observed trends in deviation from the mean wind speed and best depicts the mean wind state, especially during high wind periods. Overall, the high-resolution ECMWF product performs best during lower wind conditions with lower wind speed biases across categories.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
T he effect_of_orbital_configuration)_on_the_possible_climates_and_habitabili...Sérgio Sacani
This research article explores how the orbital configuration of Kepler-62f, a potentially habitable exoplanet in a five-planet system, could affect its climate and habitability. N-body simulations were used to determine the stable range of orbital eccentricities for Kepler-62f. Climate simulations using two global climate models then examined the planet's surface habitability across this range of eccentricities and for different atmospheric compositions. The simulations found multiple combinations of orbital and atmospheric parameters that could allow for surface liquid water on Kepler-62f, including higher orbital eccentricities coupled with high planetary obliquity or atmospheric CO2 levels above 3 bars.
On the possibility of through passage of asteroid bodies across the Earth’s a...Sérgio Sacani
We have studied the conditions of through passage of asteroids with diameters 200, 100, and
50 m, consisting of three types of materials – iron, stone, and water ice, across the Earth’s
atmosphere with a minimum trajectory altitude in the range 10–15 km. The conditions of this
passage with a subsequent exit into outer space with the preservation of a substantial fraction
of the initial mass have been found. The results obtained support our idea explaining one of the
long-standing problems of astronomy – the Tunguska phenomenon, which has not received
reasonable and comprehensive interpretations to date. We argue that the Tunguska event was
caused by an iron asteroid body, which passed through the Earth’s atmosphere and continued
to the near-solar orbit.
Arctic climate Change: observed and modelled temperature and sea-ice variabilitySimoneBoccuccia
1) Two pronounced warming events are seen in observed Arctic temperatures in the early 20th century and from 1980 onwards. The early warming was confined to north of 60°N while the recent warming encompasses the whole Earth but is amplified in the Arctic.
2) The spatial patterns of temperature trends during the early 20th century warming and subsequent cooling periods were similar, suggesting natural climate variability, while the recent warming trend has a distinctively different pattern.
3) Modeling studies suggest the early 20th century warming was likely due to natural processes within the climate system, while no models have been able to produce the recent global warming without including anthropogenic forcing from greenhouse gases.
Artigo descreve como os cientistas utilizaram o Telescópio Espacial Hubble para descobrir a estratosfera num exoplaneta classificado como um Júpiter quente. Descoberta essa que pode ajudar a descobrir como os exoplanetas se formam e qual a composição de suas atmosferas.
Study of Average Hourly Variations of Radio Refractivity Variations across So...iosrjce
The results of the diurnal variation of refractivity based on measurement of atmospheric pressure,
temperature and relative humidity made across some selected locations within Nigeria, Yola (90
11' N, 120
30'
E), Anyigba (70
45' N, 60
45' E), Lagos (60
27' N, 50
12' E), and Port-Harcourt (40
48'N, 70E), is presented in this
study. The study utilized three years of meteorological data measured from January 2010 to December 2013
using Vantage Pro 2 automatic weather station installed at each location. The average hourly variations of
refractivity in the dry season is largely as a result of the variations of the wet component (humidity) while the
average daily variations of surface radio refractivity in the rainy season is as a result of both the variations of
the dry (pressure) and wet (humidity) component of surface radio refractivity. It also observed that the values of
surface radio refractivity showed seasonal variations with high value during rainy season and low values
during dry season with an increase in the value of surface radio refractivity from minimum value of about
242N-units at Anyigba station to maximum value of about 384-N units at Lagos station. The diurnal variation of
refractivity of the troposphere is a function of local meteorology as observed from results obtained from the
study.
A precise water_abundance_measurement_for_the_hot_jupiter_wasp_43bSérgio Sacani
This document presents a precise measurement of the water abundance in the atmosphere of the exoplanet WASP-43b using transmission and thermal emission spectroscopy from the Hubble Space Telescope. The key findings are:
1) The water content of WASP-43b's atmosphere is consistent with solar composition at planetary temperatures, ranging from 0.4 to 3.5 times the solar water abundance.
2) This metallicity measurement extends the trend seen in the solar system of lower metal enrichment for higher mass planets.
3) Measuring a planet's water content constrains its formation location in the protoplanetary disk and provides insight into planetary formation models.
Satellite passive microwave measurements of the climate crisisChelle Gentemann
Invited presentation at the NASEM Committee on Radio Frequencies 2021 Fall Meeting. An overview of how passive microwave measurements are used to understand climate change.
A hexagon in Saturn’s northern stratosphere surrounding the emerging summerti...Sérgio Sacani
Saturn’s polar stratosphere exhibits the seasonal growth and dissipation of broad, warm
vortices poleward of ~75° latitude, which are strongest in the summer and absent in winter.
The longevity of the exploration of the Saturn system by Cassini allows the use of infrared
spectroscopy to trace the formation of the North Polar Stratospheric Vortex (NPSV), a region
of enhanced temperatures and elevated hydrocarbon abundances at millibar pressures. We
constrain the timescales of stratospheric vortex formation and dissipation in both hemispheres.
Although the NPSV formed during late northern spring, by the end of Cassini’s
reconnaissance (shortly after northern summer solstice), it still did not display the contrasts
in temperature and composition that were evident at the south pole during southern summer.
The newly formed NPSV was bounded by a strengthening stratospheric thermal gradient near
78°N. The emergent boundary was hexagonal, suggesting that the Rossby wave responsible
for Saturn’s long-lived polar hexagon—which was previously expected to be trapped in the
troposphere—can influence the stratospheric temperatures some 300 km above Saturn’s
clouds.
The document provides background information on the COPE field campaign and the goals and instrumentation of the COPE-MED research project. The COPE campaign studied convective storms in southwest England through aircraft and ground-based radar observations. COPE-MED aims to investigate microphysical pathways and entrainment effects on precipitation formation. Key goals are to analyze cloud liquid water content and droplet number concentration measurements from the campaign and examine droplet spectral characteristics during non-precipitating cloud penetrations.
1) Satellite measurements from the SABER instrument on the TIMED satellite and temperature measurements from the MTM instrument on Cerro Pachon, Chile were used to analyze gravity wave activity in the mesosphere over a 13 year period.
2) Both datasets show enhanced gravity wave potential energy and temperature variance during the winter months, with a peak in activity during 2008-2009.
3) The potential energy was calculated using temperature perturbation and buoyancy frequency profiles from SABER. This revealed an annual pattern of increased wave activity in the winter months over the Andes region.
Dark side of_comet_67_p_churyumov_gerasiemnko_in_august_october_2014Sérgio Sacani
Usando o instrumento Microwave Instrument for Rosetta Orbiter (MIRO), os cientistas estão estudando a região polar sul do cometa no final de sua longa estação de inverno. Os dados sugerem que essas regiões frias e escuras abrigam gelo nas suas primeiras dezenas de centímetros abaixo da superfície em quantidades muito maiores do que as encontradas em outras áreas do cometa.
Desde a sua chegada no Cometa 67P/Churyumov-Gerasimenko, a Rosetta tem pesquisado a superfície e o ambiente desse corpo de forma curiosa. Mas por um longo período de tempo, uma porção do núcleo, as regiões frias e escuras ao redor do polo sul do cometa, permaneceram inacessíveis para quase todos os instrumentos a bordo da sonda.
Devido a uma combinação de sua forma em lobo duplo e a inclinação do seu eixo de rotação, o cometa da Rosetta, tem um padrão sazonal muito peculiar durante a sua órbita de 6.5 anos. As estações estão distribuídas de maneira muito assimétrica entre os dois hemisférios, cada um deles compreende parte tanto dos lobos como do pescoço do cometa.
Na maior parte da órbita do cometa, o hemisfério norte experimenta um verão muito longo, durando cerca de 5.5 anos, e o hemisfério sul passa por um longo, frio e escuro inverno. Contudo, poucos meses antes do cometa passar pelo seu periélio, o ponto na sua órbita, mais próximo do Sol, a situação muda, e o hemisfério sul passa por um breve porém quente verão.
A uranian trojan_and_the_frequency_of_temporary_giant_planet_co_orbitalsSérgio Sacani
1) Researchers detected a 60 km diameter object called 2011 QF99 that orbits the Sun in a 1:1 resonance with Uranus, never straying far from Uranus' Lagrangian point 60 degrees ahead of it (L4).
2) Numerical simulations show 2011 QF99 oscillating around the L4 point for over 70,000 years before transitioning to other co-orbital behavior and eventually becoming unstable within 1 million years.
3) Based on these simulations and estimates of supply from the trans-Neptunian region, the researchers calculate that temporarily around 0.4% of Centaurs should be Uranian co-orbitals and 2.8% should be Neptun
Very regular high-frequency pulsation modes in young intermediate-mass starsSérgio Sacani
Asteroseismology probes the internal structures of stars by using their natural
pulsation frequencies1. It relies on identifying sequences of pulsation modes that can
be compared with theoretical models, which has been done successfully for many
classes of pulsators, including low-mass solar-type stars2, red giants3, high-mass stars4
and white dwarfs5. However, a large group of pulsating stars of intermediate mass—the
so-called δ Scuti stars—have rich pulsation spectra for which systematic mode
identification has not hitherto been possible6,7. This arises because only a seemingly
random subset of possible modes are excited and because rapid rotation tends to
spoil regular patterns8–10. Here we report the detection of remarkably regular
sequences of high-frequency pulsation modes in 60 intermediate-mass
main-sequence stars, which enables definitive mode identification. The space
motions of some of these stars indicate that they are members of known associations
of young stars, as confirmed by modelling of their pulsation spectra.
- Astrônomos descobriram que uma pequena estrela, do tamanho de Júpiter, possui uma tempestade muito parecida com a Grande Mancha Vermelha e que está ali, persistente por dois anos.
- Enquanto nos planetas, esse tipo de característica é normal, em estrelas essa é a melhor evidência encontrada até hoje.
- A estrela é chamada de W1906+40 e pertence a uma classe de objetos frios chamados de Anãs-L.
- Elas são consideradas estrelas pois fundem átomos e geram luz, como o Sol faz, enquanto que as anãs marrons são conhecidas como estrelas que falharam, pois elas não possuem o processo de fusão atômica em seu interior.
- Nesse novo estudo os astrônomos foram capazes de verificar as mudanças na atmosfera da estrela por dois anos. A técnica usada foi semelhante à de detecção de exoplanetas, analisando a curva de luz da estrela, que apresentava quedas, mas que não era por questão de planetas.
- Os astrônomos usaram o Spitzer e estudaram a luz infravermelha da estrela, que revelou uma gigantesca mancha escura que não era uma mancha magnética estelar, mas sim uma tempestade com um diâmetro equivalente ao de 3 Terras. O spitzer foi capaz de estudar camadas diferentes da atmosfera da estrela e esses dados junto com os dados do Kepler, revelaram com clareza a tempestade estelar.
- Futuras observações serão realizadas usando os dois equipamentos para tentar identificar esse tipo de tempestade em anãs marrons, por exemplo, e tentar descobrir se esse tipo de fenômeno é muito comum, ou é raro no universo.
This document summarizes a study that used the Surface Energy Balance System (SEBS) model with MODIS satellite data and NCEP reanalysis data to estimate sensible heat flux in the Arou region of China from May to September 2011. The SEBS-estimated sensible heat fluxes showed good agreement with in-situ measurements from a Large Aperture Scintillometer, especially from July to September when vegetation cover was densest. A sensitivity analysis found that sensible heat flux was most sensitive to temperature difference between surface and reference height and surface roughness length.
Multi-phase volcanic resurfacing at Loki Patera on IoSérgio Sacani
The Jovian moon Io hosts the most powerful persistently active
volcano in the Solar System, Loki Patera1,2. The interior of this
volcanic, caldera-like feature is composed of a warm, dark floor
covering 21,500 square kilometres3 surrounding a much cooler
central ‘island’4. The temperature gradient seen across areas of
the patera indicates a systematic resurfacing process4–9, which
has been seen to occur typically every one to three years since the
1980s5,10. Analysis of past data has indicated that the resurfacing
progressed around the patera in an anti-clockwise direction at a
rate of one to two kilometres per day, and that it is caused either
by episodic eruptions that emplace voluminous lava flows or by a
cyclically overturning lava lake contained within the patera5,8,9,11.
However, spacecraft and telescope observations have been unable to
map the emission from the entire patera floor at sufficient spatial
resolution to establish the physical processes at play. Here we report
temperature and lava cooling age maps of the entire patera floor at
a spatial sampling of about two kilometres, derived from groundbased
interferometric imaging of thermal emission from Loki Patera
obtained on 8 March 2015 ut as the limb of Europa occulted Io.
Our results indicate that Loki Patera is resurfaced by a multi-phase
process in which two waves propagate and converge around the
central island. The different velocities and start times of the waves
indicate a non-uniformity in the lava gas content and/or crust bulk
density across the patera.
This document provides an overview of geophysics, including what geophysics is, examples of different types of geophysics (such as solid earth geophysics, exploration geophysics, engineering geophysics), and examples of specific geophysical methods like gravity, magnetics, seismic, ground penetrating radar, and resistivity. It also discusses aspects of planning and conducting geophysical surveys, such as spatial aliasing, sources of noise, data processing, and displaying data.
Titan’s aerosol and stratospheric ice opacities between 18 and 500 μm vertic...Sérgio Sacani
This document is an accepted manuscript for publication in Icarus that summarizes research analyzing data from the Cassini CIRS instrument to characterize Titan's stratospheric aerosols and ices between 18-500 μm. The research finds that aerosols are well-mixed from the surface to 300 km altitude, while nitrile ice clouds (likely HCN and HC3N) appear centered around 90 km. There is also evidence of an ice cloud layer at 60 km that may be C2H6 ice. Volume extinction coefficients derived from CIRS data are compared to those from DISR, finding particle size ratios consistent with sub-micron aerosols and ice particle effective radii of only a few microns.
First Observation of the Earth’s Permanent FreeOscillation s on Ocean Bottom ...Sérgio Sacani
The Earth’s hum is the permanent free oscillations of the Earth recorded in the absence ofearthquakes, at periods above 30 s. We present the first observations of its fundamental spheroidaleigenmodes on broadband ocean bottom seismometers (OBSs) in the Indian Ocean. At the ocean bottom,the effects of ocean infragravity waves (compliance) and seafloor currents (tilt) overshadow the hum. In ourexperiment, data are also affected by electronic glitches. We remove these signals from the seismic traceby subtracting average glitch signals; performing a linear regression; and using frequency-dependentresponse functions between pressure, horizontal, and vertical seismic components. This reduces the longperiod noise on the OBS to the level of a good land station. Finally, by windowing the autocorrelation toinclude only the direct arrival, the first and second orbits around the Earth, and by calculating its Fouriertransform, we clearly observe the eigenmodes at the ocean bottom.
The document summarizes the discovery and characterization of exoplanet atmospheres over time. It discusses key observational highlights including the identification of molecules, day-night temperature variations, and variability in some atmospheres. Modeling techniques are also described that aim to constrain atmospheric properties by fitting millions of models to data. The summary outlines progress made but also future directions, such as direct imaging of young planets and the potential for characterizing small planets around M stars.
This document compares in situ wind speed observations from Wave Glider deployments in the Southern Ocean to several satellite-derived and reanalysis wind products. The study finds that the ECMWF reanalysis product best represents the temporal variability of winds compared to in situ data. However, the NCEP/NCAR Reanalysis II product matches observed trends in deviation from the mean wind speed and best depicts the mean wind state, especially during high wind periods. Overall, the high-resolution ECMWF product performs best during lower wind conditions with lower wind speed biases across categories.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
T he effect_of_orbital_configuration)_on_the_possible_climates_and_habitabili...Sérgio Sacani
This research article explores how the orbital configuration of Kepler-62f, a potentially habitable exoplanet in a five-planet system, could affect its climate and habitability. N-body simulations were used to determine the stable range of orbital eccentricities for Kepler-62f. Climate simulations using two global climate models then examined the planet's surface habitability across this range of eccentricities and for different atmospheric compositions. The simulations found multiple combinations of orbital and atmospheric parameters that could allow for surface liquid water on Kepler-62f, including higher orbital eccentricities coupled with high planetary obliquity or atmospheric CO2 levels above 3 bars.
On the possibility of through passage of asteroid bodies across the Earth’s a...Sérgio Sacani
We have studied the conditions of through passage of asteroids with diameters 200, 100, and
50 m, consisting of three types of materials – iron, stone, and water ice, across the Earth’s
atmosphere with a minimum trajectory altitude in the range 10–15 km. The conditions of this
passage with a subsequent exit into outer space with the preservation of a substantial fraction
of the initial mass have been found. The results obtained support our idea explaining one of the
long-standing problems of astronomy – the Tunguska phenomenon, which has not received
reasonable and comprehensive interpretations to date. We argue that the Tunguska event was
caused by an iron asteroid body, which passed through the Earth’s atmosphere and continued
to the near-solar orbit.
Arctic climate Change: observed and modelled temperature and sea-ice variabilitySimoneBoccuccia
1) Two pronounced warming events are seen in observed Arctic temperatures in the early 20th century and from 1980 onwards. The early warming was confined to north of 60°N while the recent warming encompasses the whole Earth but is amplified in the Arctic.
2) The spatial patterns of temperature trends during the early 20th century warming and subsequent cooling periods were similar, suggesting natural climate variability, while the recent warming trend has a distinctively different pattern.
3) Modeling studies suggest the early 20th century warming was likely due to natural processes within the climate system, while no models have been able to produce the recent global warming without including anthropogenic forcing from greenhouse gases.
Artigo descreve como os cientistas utilizaram o Telescópio Espacial Hubble para descobrir a estratosfera num exoplaneta classificado como um Júpiter quente. Descoberta essa que pode ajudar a descobrir como os exoplanetas se formam e qual a composição de suas atmosferas.
Study of Average Hourly Variations of Radio Refractivity Variations across So...iosrjce
The results of the diurnal variation of refractivity based on measurement of atmospheric pressure,
temperature and relative humidity made across some selected locations within Nigeria, Yola (90
11' N, 120
30'
E), Anyigba (70
45' N, 60
45' E), Lagos (60
27' N, 50
12' E), and Port-Harcourt (40
48'N, 70E), is presented in this
study. The study utilized three years of meteorological data measured from January 2010 to December 2013
using Vantage Pro 2 automatic weather station installed at each location. The average hourly variations of
refractivity in the dry season is largely as a result of the variations of the wet component (humidity) while the
average daily variations of surface radio refractivity in the rainy season is as a result of both the variations of
the dry (pressure) and wet (humidity) component of surface radio refractivity. It also observed that the values of
surface radio refractivity showed seasonal variations with high value during rainy season and low values
during dry season with an increase in the value of surface radio refractivity from minimum value of about
242N-units at Anyigba station to maximum value of about 384-N units at Lagos station. The diurnal variation of
refractivity of the troposphere is a function of local meteorology as observed from results obtained from the
study.
A precise water_abundance_measurement_for_the_hot_jupiter_wasp_43bSérgio Sacani
This document presents a precise measurement of the water abundance in the atmosphere of the exoplanet WASP-43b using transmission and thermal emission spectroscopy from the Hubble Space Telescope. The key findings are:
1) The water content of WASP-43b's atmosphere is consistent with solar composition at planetary temperatures, ranging from 0.4 to 3.5 times the solar water abundance.
2) This metallicity measurement extends the trend seen in the solar system of lower metal enrichment for higher mass planets.
3) Measuring a planet's water content constrains its formation location in the protoplanetary disk and provides insight into planetary formation models.
Satellite passive microwave measurements of the climate crisisChelle Gentemann
Invited presentation at the NASEM Committee on Radio Frequencies 2021 Fall Meeting. An overview of how passive microwave measurements are used to understand climate change.
A hexagon in Saturn’s northern stratosphere surrounding the emerging summerti...Sérgio Sacani
Saturn’s polar stratosphere exhibits the seasonal growth and dissipation of broad, warm
vortices poleward of ~75° latitude, which are strongest in the summer and absent in winter.
The longevity of the exploration of the Saturn system by Cassini allows the use of infrared
spectroscopy to trace the formation of the North Polar Stratospheric Vortex (NPSV), a region
of enhanced temperatures and elevated hydrocarbon abundances at millibar pressures. We
constrain the timescales of stratospheric vortex formation and dissipation in both hemispheres.
Although the NPSV formed during late northern spring, by the end of Cassini’s
reconnaissance (shortly after northern summer solstice), it still did not display the contrasts
in temperature and composition that were evident at the south pole during southern summer.
The newly formed NPSV was bounded by a strengthening stratospheric thermal gradient near
78°N. The emergent boundary was hexagonal, suggesting that the Rossby wave responsible
for Saturn’s long-lived polar hexagon—which was previously expected to be trapped in the
troposphere—can influence the stratospheric temperatures some 300 km above Saturn’s
clouds.
The document provides background information on the COPE field campaign and the goals and instrumentation of the COPE-MED research project. The COPE campaign studied convective storms in southwest England through aircraft and ground-based radar observations. COPE-MED aims to investigate microphysical pathways and entrainment effects on precipitation formation. Key goals are to analyze cloud liquid water content and droplet number concentration measurements from the campaign and examine droplet spectral characteristics during non-precipitating cloud penetrations.
1) Satellite measurements from the SABER instrument on the TIMED satellite and temperature measurements from the MTM instrument on Cerro Pachon, Chile were used to analyze gravity wave activity in the mesosphere over a 13 year period.
2) Both datasets show enhanced gravity wave potential energy and temperature variance during the winter months, with a peak in activity during 2008-2009.
3) The potential energy was calculated using temperature perturbation and buoyancy frequency profiles from SABER. This revealed an annual pattern of increased wave activity in the winter months over the Andes region.
Dark side of_comet_67_p_churyumov_gerasiemnko_in_august_october_2014Sérgio Sacani
Usando o instrumento Microwave Instrument for Rosetta Orbiter (MIRO), os cientistas estão estudando a região polar sul do cometa no final de sua longa estação de inverno. Os dados sugerem que essas regiões frias e escuras abrigam gelo nas suas primeiras dezenas de centímetros abaixo da superfície em quantidades muito maiores do que as encontradas em outras áreas do cometa.
Desde a sua chegada no Cometa 67P/Churyumov-Gerasimenko, a Rosetta tem pesquisado a superfície e o ambiente desse corpo de forma curiosa. Mas por um longo período de tempo, uma porção do núcleo, as regiões frias e escuras ao redor do polo sul do cometa, permaneceram inacessíveis para quase todos os instrumentos a bordo da sonda.
Devido a uma combinação de sua forma em lobo duplo e a inclinação do seu eixo de rotação, o cometa da Rosetta, tem um padrão sazonal muito peculiar durante a sua órbita de 6.5 anos. As estações estão distribuídas de maneira muito assimétrica entre os dois hemisférios, cada um deles compreende parte tanto dos lobos como do pescoço do cometa.
Na maior parte da órbita do cometa, o hemisfério norte experimenta um verão muito longo, durando cerca de 5.5 anos, e o hemisfério sul passa por um longo, frio e escuro inverno. Contudo, poucos meses antes do cometa passar pelo seu periélio, o ponto na sua órbita, mais próximo do Sol, a situação muda, e o hemisfério sul passa por um breve porém quente verão.
A uranian trojan_and_the_frequency_of_temporary_giant_planet_co_orbitalsSérgio Sacani
1) Researchers detected a 60 km diameter object called 2011 QF99 that orbits the Sun in a 1:1 resonance with Uranus, never straying far from Uranus' Lagrangian point 60 degrees ahead of it (L4).
2) Numerical simulations show 2011 QF99 oscillating around the L4 point for over 70,000 years before transitioning to other co-orbital behavior and eventually becoming unstable within 1 million years.
3) Based on these simulations and estimates of supply from the trans-Neptunian region, the researchers calculate that temporarily around 0.4% of Centaurs should be Uranian co-orbitals and 2.8% should be Neptun
Very regular high-frequency pulsation modes in young intermediate-mass starsSérgio Sacani
Asteroseismology probes the internal structures of stars by using their natural
pulsation frequencies1. It relies on identifying sequences of pulsation modes that can
be compared with theoretical models, which has been done successfully for many
classes of pulsators, including low-mass solar-type stars2, red giants3, high-mass stars4
and white dwarfs5. However, a large group of pulsating stars of intermediate mass—the
so-called δ Scuti stars—have rich pulsation spectra for which systematic mode
identification has not hitherto been possible6,7. This arises because only a seemingly
random subset of possible modes are excited and because rapid rotation tends to
spoil regular patterns8–10. Here we report the detection of remarkably regular
sequences of high-frequency pulsation modes in 60 intermediate-mass
main-sequence stars, which enables definitive mode identification. The space
motions of some of these stars indicate that they are members of known associations
of young stars, as confirmed by modelling of their pulsation spectra.
- Astrônomos descobriram que uma pequena estrela, do tamanho de Júpiter, possui uma tempestade muito parecida com a Grande Mancha Vermelha e que está ali, persistente por dois anos.
- Enquanto nos planetas, esse tipo de característica é normal, em estrelas essa é a melhor evidência encontrada até hoje.
- A estrela é chamada de W1906+40 e pertence a uma classe de objetos frios chamados de Anãs-L.
- Elas são consideradas estrelas pois fundem átomos e geram luz, como o Sol faz, enquanto que as anãs marrons são conhecidas como estrelas que falharam, pois elas não possuem o processo de fusão atômica em seu interior.
- Nesse novo estudo os astrônomos foram capazes de verificar as mudanças na atmosfera da estrela por dois anos. A técnica usada foi semelhante à de detecção de exoplanetas, analisando a curva de luz da estrela, que apresentava quedas, mas que não era por questão de planetas.
- Os astrônomos usaram o Spitzer e estudaram a luz infravermelha da estrela, que revelou uma gigantesca mancha escura que não era uma mancha magnética estelar, mas sim uma tempestade com um diâmetro equivalente ao de 3 Terras. O spitzer foi capaz de estudar camadas diferentes da atmosfera da estrela e esses dados junto com os dados do Kepler, revelaram com clareza a tempestade estelar.
- Futuras observações serão realizadas usando os dois equipamentos para tentar identificar esse tipo de tempestade em anãs marrons, por exemplo, e tentar descobrir se esse tipo de fenômeno é muito comum, ou é raro no universo.
This document summarizes a study that used the Surface Energy Balance System (SEBS) model with MODIS satellite data and NCEP reanalysis data to estimate sensible heat flux in the Arou region of China from May to September 2011. The SEBS-estimated sensible heat fluxes showed good agreement with in-situ measurements from a Large Aperture Scintillometer, especially from July to September when vegetation cover was densest. A sensitivity analysis found that sensible heat flux was most sensitive to temperature difference between surface and reference height and surface roughness length.
Multi-phase volcanic resurfacing at Loki Patera on IoSérgio Sacani
The Jovian moon Io hosts the most powerful persistently active
volcano in the Solar System, Loki Patera1,2. The interior of this
volcanic, caldera-like feature is composed of a warm, dark floor
covering 21,500 square kilometres3 surrounding a much cooler
central ‘island’4. The temperature gradient seen across areas of
the patera indicates a systematic resurfacing process4–9, which
has been seen to occur typically every one to three years since the
1980s5,10. Analysis of past data has indicated that the resurfacing
progressed around the patera in an anti-clockwise direction at a
rate of one to two kilometres per day, and that it is caused either
by episodic eruptions that emplace voluminous lava flows or by a
cyclically overturning lava lake contained within the patera5,8,9,11.
However, spacecraft and telescope observations have been unable to
map the emission from the entire patera floor at sufficient spatial
resolution to establish the physical processes at play. Here we report
temperature and lava cooling age maps of the entire patera floor at
a spatial sampling of about two kilometres, derived from groundbased
interferometric imaging of thermal emission from Loki Patera
obtained on 8 March 2015 ut as the limb of Europa occulted Io.
Our results indicate that Loki Patera is resurfaced by a multi-phase
process in which two waves propagate and converge around the
central island. The different velocities and start times of the waves
indicate a non-uniformity in the lava gas content and/or crust bulk
density across the patera.
This document provides an overview of geophysics, including what geophysics is, examples of different types of geophysics (such as solid earth geophysics, exploration geophysics, engineering geophysics), and examples of specific geophysical methods like gravity, magnetics, seismic, ground penetrating radar, and resistivity. It also discusses aspects of planning and conducting geophysical surveys, such as spatial aliasing, sources of noise, data processing, and displaying data.
Titan’s aerosol and stratospheric ice opacities between 18 and 500 μm vertic...Sérgio Sacani
This document is an accepted manuscript for publication in Icarus that summarizes research analyzing data from the Cassini CIRS instrument to characterize Titan's stratospheric aerosols and ices between 18-500 μm. The research finds that aerosols are well-mixed from the surface to 300 km altitude, while nitrile ice clouds (likely HCN and HC3N) appear centered around 90 km. There is also evidence of an ice cloud layer at 60 km that may be C2H6 ice. Volume extinction coefficients derived from CIRS data are compared to those from DISR, finding particle size ratios consistent with sub-micron aerosols and ice particle effective radii of only a few microns.
First Observation of the Earth’s Permanent FreeOscillation s on Ocean Bottom ...Sérgio Sacani
The Earth’s hum is the permanent free oscillations of the Earth recorded in the absence ofearthquakes, at periods above 30 s. We present the first observations of its fundamental spheroidaleigenmodes on broadband ocean bottom seismometers (OBSs) in the Indian Ocean. At the ocean bottom,the effects of ocean infragravity waves (compliance) and seafloor currents (tilt) overshadow the hum. In ourexperiment, data are also affected by electronic glitches. We remove these signals from the seismic traceby subtracting average glitch signals; performing a linear regression; and using frequency-dependentresponse functions between pressure, horizontal, and vertical seismic components. This reduces the longperiod noise on the OBS to the level of a good land station. Finally, by windowing the autocorrelation toinclude only the direct arrival, the first and second orbits around the Earth, and by calculating its Fouriertransform, we clearly observe the eigenmodes at the ocean bottom.
This document summarizes data from multiple scientific organizations on trends in global surface air temperatures and atmospheric greenhouse gas levels. The key points are:
1) Six independent scientific groups find that average global land and sea surface temperatures have steadily increased over the past century, with the most rapid rise occurring over the past 50 years.
2) Regional temperature changes are often larger than global averages, with greater warming at northern high latitudes and Arctic regions.
3) Satellite and weather balloon data also indicate warming of the lower troposphere and cooling of the lower stratosphere.
4) Atmospheric levels of greenhouse gases like carbon dioxide and methane have risen substantially since the industrial revolution due to human activities like fossil fuel burning
X-Ray Properties of NGC 253ʼs Starburst-driven OutflowSérgio Sacani
We analyze image and spectral data from ≈365 ks of observations from the Chandra X-ray Observatory of the
nearby, edge-on starburst galaxy NGC 253 to constrain properties of the hot phase of the outflow. We focus our
analysis on the −1.1 to +0.63 kpc region of the outflow and define several regions for spectral extraction where we
determine best-fit temperatures and metal abundances. We find that the temperatures and electron densities peak in
the central ∼250 pc region of the outflow and decrease with distance. These temperature and density profiles are in
disagreement with an adiabatic spherically expanding starburst wind model and suggest the presence of additional
physics such as mass loading and nonspherical outflow geometry. Our derived temperatures and densities yield
cooling times in the nuclear region of a few million years, which may imply that the hot gas can undergo bulk
radiative cooling as it escapes along the minor axis. Our metal abundances of O, Ne, Mg, Si, S, and Fe all peak in
the central region and decrease with distance along the outflow, with the exception of Ne, which maintains a flat
distribution. The metal abundances indicate significant dilution outside of the starburst region. We also find
estimates of the mass outflow rates, which are 2.8 Me yr−1 in the northern outflow and 3.2 Me yr−1 in the southern
outflow. Additionally, we detect emission from charge exchange and find it makes a significant contribution (20%–
42%) to the total broadband (0.5–7 keV) X-ray emission in the central and southern regions of the outflow.
The formation of Charon’s red poles from seasonally cold-trapped volatilesSérgio Sacani
A unique feature of Pluto’s large satellite Charon is its dark red
northern polar cap1. Similar colours on Pluto’s surface have been
attributed2 to tholin-like organic macromolecules produced by
energetic radiation processing of hydrocarbons. The polar location
on Charon implicates the temperature extremes that result from
Charon’s high obliquity and long seasons in the production of this
material. The escape of Pluto’s atmosphere provides a potential
feedstock for a complex chemistry3,4. Gas from Pluto that is
transiently cold-trapped and processed at Charon’s winter pole was
proposed1,2 as an explanation for the dark coloration on the basis
of an image of Charon’s northern hemisphere, but not modelled
quantitatively. Here we report images of the southern hemisphere
illuminated by Pluto-shine and also images taken during the
approach phase that show the northern polar cap over a range of
longitudes. We model the surface thermal environment on Charon
and the supply and temporary cold-trapping of material escaping
from Pluto, as well as the photolytic processing of this material
into more complex and less volatile molecules while cold-trapped.
The model results are consistent with the proposed mechanism for
producing the observed colour pattern on Charon.
The pristine nature of SMSS 1605−1443 revealed by ESPRESSOSérgio Sacani
SMSS J160540.18−144323.1 is the carbon-enhanced metal-poor (CEMP) star with the lowest iron abundance ever measured, [Fe/H] =
−6.2, which was first reported with the SkyMapper telescope. The carbon abundance is A(C) ≈ 6.1 in the low-C band, as the majority of the stars
in this metallicity range. Yet, constraining the isotopic ratio of key species, such as carbon, sheds light on the properties and origin of these elusive
stars.
Aims. We performed high-resolution observations of SMSS 1605−1443 with the ESPRESSO spectrograph to look for variations in the radial
velocity (vrad) with time. These data have been combined with older MIKE and UVES archival observations to enlarge the temporal baseline. The
12C/
13C isotopic ratio is also studied to explore the possibility of mass transfer from a binary companion.
Methods. A cross-correlation function against a natural template was applied to detect vrad variability and a spectral synthesis technique was used
to derive 12C/
13C in the stellar atmosphere.
Results. We confirm previous indications of binarity in SMSS 1605−1443 and measured a lower limit 12C/
13C > 60 at more than a 3σ confidence
level, proving that this system is chemically unmixed and that no mass transfer from the unseen companion has happened so far. Thus, we confirm
the CEMP-no nature of SMSS 1605−1443 and show that the pristine chemical composition of the cloud from which it formed is currently imprinted
in its stellar atmosphere free of contamination.
Historical and Contemporary Trends in the Size, Drift, and Color of Jupiterʼs...Sérgio Sacani
The Great Red Spot on Jupiter has been shrinking over the past 150+ years based on historical records and spacecraft observations. Recent data from 1979-2017 show the Spot shrinking longitudinally at a rate of 0.194 degrees per year and latitudinally at 0.048 degrees per year. Its westward drift has also been accelerating, increasing about 0.002 degrees per day each year. High resolution images allow analysis of changes in the Spot's color, winds, and internal structure over this time period.
This document summarizes data on changes in Earth's surface temperature and atmospheric greenhouse gases. It presents data from 6 independent scientific organizations that show global surface temperatures have been steadily increasing over the past century, with land warming more than oceans and the Northern Hemisphere warming more than the Southern. Regional and seasonal data also show uneven impacts. Satellite, temperature probe, and borehole data corroborate surface warming. Atmospheric levels of greenhouse gases like CO2, methane, and nitrous oxide have also increased due to human activities and contribute to rising temperatures.
The extremely high albedo of LTT 9779 b revealed by CHEOPSSérgio Sacani
Optical secondary eclipse measurements of small planets can provide a wealth of information about the reflective properties
of these worlds, but the measurements are particularly challenging to attain because of their relatively shallow depth. If such signals
can be detected and modeled, however, they can provide planetary albedos, thermal characteristics, and information on absorbers in
the upper atmosphere.
Aims. We aim to detect and characterize the optical secondary eclipse of the planet LTT 9779 b using the CHaracterising ExOPlanet
Satellite (CHEOPS) to measure the planetary albedo and search for the signature of atmospheric condensates.
Methods. We observed ten secondary eclipses of the planet with CHEOPS. We carefully analyzed and detrended the light curves using
three independent methods to perform the final astrophysical detrending and eclipse model fitting of the individual and combined light
curves.
Results. Each of our analysis methods yielded statistically similar results, providing a robust detection of the eclipse of LTT 9779 b
with a depth of 115±24 ppm. This surprisingly large depth provides a geometric albedo for the planet of 0.80+0.10
−0.17, consistent with
estimates of radiative-convective models. This value is similar to that of Venus in our own Solar System. When combining the eclipse
from CHEOPS with the measurements from TESS and Spitzer, our global climate models indicate that LTT 9779 b likely has a super
metal-rich atmosphere, with a lower limit of 400× solar being found, and the presence of silicate clouds. The observations also reveal
hints of optical eclipse depth variability, but these have yet to be confirmed.
Conclusions. The results found here in the optical when combined with those in the near-infrared provide the first steps toward
understanding the atmospheric structure and physical processes of ultrahot Neptune worlds that inhabit the Neptune desert.
diurnal temperature range trend over North Carolina and the associated mechan...Sayem Zaman, Ph.D, PE.
This study seeks to investigate the variability and presence of trends in the diurnal surface air temperature range
(DTR) over North Carolina (NC) for the period 1950–2009. The significance trend test and the magnitude of trends were determined using the non-parametric Mann–Kendall test and the Theil–Sen approach, respectively.
Statewide significant trends (p b 0.05) of decreasing DTR were found in all seasons and annually during the analysis period. The highest (lowest) temporal DTR trends of magnitude −0.19 (−0.031) °C/decade were found in summer (winter). Potential mechanisms for the presence/absence of trends in DTR have been highlighted. Historical
data sets of the three main moisture components (precipitation, total cloud cover (TCC), and soil moisture) and
the two major atmospheric circulation modes (North Atlantic Oscillation and Southern Oscillation) were used for
correlation analysis. The DTRs were found to be negatively correlated with the precipitation, TCC, and soil moisture across the state for all the seasons and annual basis. It appears that the moisture components related better to the DTR than to the atmospheric circulation modes.
This document summarizes evidence for the past and present distribution of water on Mars in its three phases - solid, liquid, and vapor. It discusses the theoretical and observational evidence for each phase, including calculations of the depth of the Martian cryosphere based on thermal modeling, constitutive relations for ice deformation, comparisons of Martian and terrestrial rock glaciers, and analysis of slope asymmetry in polar layered deposits indicating differential sublimation erosion of ice-rich material. Spatial and temporal variations in atmospheric water vapor from early telescopic observations through recent TES data are also summarized.
One tenth solar_abundances_along_the_body_of-the_streamSérgio Sacani
This document summarizes a study that analyzed spectra from four background quasars to measure the chemical abundances along the Magellanic Stream. Two key findings are:
1) The sightlines toward RBS 144 and NGC 7714 yielded metallicities of around 0.1 times the solar value, indicating a uniform low abundance along the main body of the Stream. This supports models where the Stream was stripped from the SMC around 1-2.5 billion years ago when the SMC had a metallicity of around 0.1 solar.
2) A higher metallicity of around 0.5 solar was found in the inner Stream toward Fairall 9, sampling a filament traced to the LMC. This shows the bifurc
Magnetic field and_wind_of_kappa_ceti_towards_the_planetary_habitability_of_t...Sérgio Sacani
We report magnetic field measurements for κ
1 Cet, a proxy of the young Sun when life arose on Earth. We carry out an analysis
of the magnetic properties determined from spectropolarimetric observations and reconstruct its large-scale surface magnetic
field to derive the magnetic environment, stellar winds and particle flux permeating the interplanetary medium around κ
1 Cet.
Our results show a closer magnetosphere and mass-loss rate of M˙ = 9.7 × 10−13 M yr−1
, i.e., a factor 50 times larger than the
current solar wind mass-loss rate, resulting in a larger interaction via space weather disturbances between the stellar wind and
a hypothetical young-Earth analogue, potentially affecting the planet’s habitability. Interaction of the wind from the young Sun
with the planetary ancient magnetic field may have affected the young Earth and its life conditions.
A Pinatubo Climate Modeling InvestigationJody Sullivan
The document summarizes a comprehensive investigation into the climate effects of the 1991 eruption of Mount Pinatubo. Key points:
- Pinatubo produced the largest climate forcing of any 20th century volcano due to its large output of aerosols. This allows for a more quantitative analysis of climate sensitivity to a transient forcing event.
- Observations show a maximum global cooling of around 0.25°C 1-3 years after eruptions of similar size, though models typically predict around 0.5°C of cooling. Pinatubo provides an opportunity to test understanding of the climate response.
- Early predictions using a climate model matched observations reasonably well, showing peak stratospheric
The deep blue_color_of_hd189733b_albedo_measurements_with_hst_stis_at_visible...Sérgio Sacani
The document summarizes a study that measured the geometric albedo of the exoplanet HD 189733b across visible wavelengths using Hubble Space Telescope observations. It found an albedo of 0.40 ± 0.12 at 290-450 nm that decreased to below 0.12 at 450-570 nm, suggesting optically thick clouds reflecting light at shorter wavelengths and sodium absorption suppressing reflection beyond 450 nm. This wavelength-dependent albedo implies HD 189733b would appear deep blue in color at visible wavelengths.
Large-scale Volcanism and the Heat Death of Terrestrial WorldsSérgio Sacani
This document discusses the potential for large igneous provinces (LIPs) to cause the "heat death" of terrestrial planets through massive volcanic eruptions that overwhelm the climate system. It examines the timing of LIP events on Earth to estimate the likelihood of nearly simultaneous eruptions. Statistical analysis of Earth's LIP record finds that eruptions within 0.1-1 million years of each other are likely. Simultaneous LIPs could have driven Venus into a runaway greenhouse effect like its current state. The timing of LIP events on Earth provides insight into potential past LIP activity on Venus that may have ended its hypothesized earlier temperate climate.
The document discusses satellite radar altimeter measurements of elevation changes in the Larsen Ice Shelf between 1992 and 2001. It finds that the ice shelf lowered by up to 0.27 meters per year on average. This thinning is explained by increased summer meltwater and loss of basal ice through melting. Enhanced ocean-driven melting may provide a link between regional climate warming and the successive breakup of sections of the Larsen Ice Shelf. Testing rules out other potential causes of thinning like changes in sea level, ocean density, or surface accumulation. The long-term thinning observed suggests meltwater production alone does not account for the lowering, indicating additional thinning mechanisms are also involved.
Characterization of Antarctic micrometeorites by thermoluminescenceFatemeh Sedaghatpour
This document characterizes four Antarctic micrometeorites using thermoluminescence (TL). TL measurements found the micrometeorites have sensitivities ranging from 0.017 to 0.087 and similar TL peak temperatures and widths. Heating experiments on meteorite fragments showed the TL properties were not significantly affected by atmospheric passage. The TL properties of the micrometeorites closely resemble the CM chondrite MAC 87300 and terrestrial forsterites, suggesting they contain forsterite but do not match any known meteorite class. Scanning electron images and analyses found the micrometeorites consist of olivine, pyroxene, and iron oxides.
Two temperate Earth-mass planets orbiting the nearby star GJ 1002Sérgio Sacani
We report the discovery and characterisation of two Earth-mass planets orbiting in the habitable zone of the nearby M-dwarf GJ 1002 based on
the analysis of the radial-velocity (RV) time series from the ESPRESSO and CARMENES spectrographs. The host star is the quiet M5.5 V star
GJ 1002 (relatively faint in the optical, V ∼ 13.8 mag, but brighter in the infrared, J ∼ 8.3 mag), located at 4.84 pc from the Sun.
We analyse 139 spectroscopic observations taken between 2017 and 2021. We performed a joint analysis of the time series of the RV and full-width
half maximum (FWHM) of the cross-correlation function (CCF) to model the planetary and stellar signals present in the data, applying Gaussian
process regression to deal with the stellar activity.
We detect the signal of two planets orbiting GJ 1002. GJ 1002 b is a planet with a minimum mass mp sin i of 1.08 ± 0.13 M⊕ with an orbital period
of 10.3465 ± 0.0027 days at a distance of 0.0457 ± 0.0013 au from its parent star, receiving an estimated stellar flux of 0.67 F⊕. GJ 1002 c is a
planet with a minimum mass mp sin i of 1.36 ± 0.17 M⊕ with an orbital period of 20.202 ± 0.013 days at a distance of 0.0738 ± 0.0021 au from
its parent star, receiving an estimated stellar flux of 0.257 F⊕. We also detect the rotation signature of the star, with a period of 126 ± 15 days. We
find that there is a correlation between the temperature of certain optical elements in the spectrographs and changes in the instrumental profile that
can affect the scientific data, showing a seasonal behaviour that creates spurious signals at periods longer than ∼ 200 days.
GJ 1002 is one of the few known nearby systems with planets that could potentially host habitable environments. The closeness of the host star
to the Sun makes the angular sizes of the orbits of both planets (∼ 9.7 mas and ∼ 15.7 mas, respectively) large enough for their atmosphere to be
studied via high-contrast high-resolution spectroscopy with instruments such as the future spectrograph ANDES for the ELT or the LIFE mission.
Similar to Surface temperatures on_titan_during_northern_winter_and_spring (20)
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Sérgio Sacani
Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the
atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets
receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric
composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet
transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (Porb) of 12.76 days.
The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous Porb from TESS data. We
confirmed the transit signal and Porb using ground-based photometry with MuSCAT2 and MuSCAT3, and
validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as
well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope
and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host
star is inactive, with an X-ray-to-bolometric luminosity ratio of log 5.7 L L X bol » - . Joint analysis of the light
curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R⊕,a3σ mass upper limit of
3.9 M⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric
(TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small
list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.
Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TES...Sérgio Sacani
We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a
bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the
lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors
42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations
with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory,
as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of
12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent
future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar
compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool
stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
The importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox
(1) by adding two additional terms to the Drake Equation: foc
(the fraction of habitable exoplanets
with significant continents and oceans) and fpt
(the fraction of habitable exoplanets with significant
continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by
demonstrating that the product of foc
and fpt
is very small (< 0.00003–0.002). We propose that the lack
of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on
exoplanets with primitive life.
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. Itremains enigmatic how subduction could be initiated so soon after the presumably Moon‐forming giant impact(MGI). Earlier studies found an increase in Earth's core‐mantle boundary (CMB) temperature due to theaccumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, withsome of the impactor's mantle potentially surviving as the large low‐shear velocity provinces (LLSVPs). Here,we show that a hot post‐impact CMB drives the initiation of strong mantle plumes that can induce subductioninitiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMBtemperature is the primary factor triggering early subduction, with enrichment of heat‐producing elements inLLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications forunderstanding the diverse tectonic regimes of rocky planets.
Climate extremes likely to drive land mammal extinction during next supercont...Sérgio Sacani
Mammals have dominated Earth for approximately 55 Myr thanks to their
adaptations and resilience to warming and cooling during the Cenozoic. All
life will eventually perish in a runaway greenhouse once absorbed solar
radiation exceeds the emission of thermal radiation in several billions of
years. However, conditions rendering the Earth naturally inhospitable to
mammals may develop sooner because of long-term processes linked to
plate tectonics (short-term perturbations are not considered here). In
~250 Myr, all continents will converge to form Earth’s next supercontinent,
Pangea Ultima. A natural consequence of the creation and decay of Pangea
Ultima will be extremes in pCO2 due to changes in volcanic rifting and
outgassing. Here we show that increased pCO2, solar energy (F⨀;
approximately +2.5% W m−2 greater than today) and continentality (larger
range in temperatures away from the ocean) lead to increasing warming
hostile to mammalian life. We assess their impact on mammalian
physiological limits (dry bulb, wet bulb and Humidex heat stress indicators)
as well as a planetary habitability index. Given mammals’ continued survival,
predicted background pCO2 levels of 410–816 ppm combined with increased
F⨀ will probably lead to a climate tipping point and their mass extinction.
The results also highlight how global landmass configuration, pCO2 and F⨀
play a critical role in planetary habitability.
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Sérgio Sacani
The recently reported observation of VFTS 243 is the first example of a massive black-hole binary
system with negligible binary interaction following black-hole formation. The black-hole mass (≈10M⊙)
and near-circular orbit (e ≈ 0.02) of VFTS 243 suggest that the progenitor star experienced complete
collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to
constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence
level, the natal kick velocity (mass decrement) is ≲10 km=s (≲1.0M⊙), with a full probability distribution
that peaks when ≈0.3M⊙ were ejected, presumably in neutrinos, and the black hole experienced a natal
kick of 4 km=s. The neutrino-emission asymmetry is ≲4%, with best fit values of ∼0–0.2%. Such a small
neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions.
Detectability of Solar Panels as a TechnosignatureSérgio Sacani
In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like
exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the
UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept
like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide
the 2022 human energy needs with a land cover of ∼ 2.4%, and projecting the future energy demand
assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope.
Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the
ultraviolet-to-visible (0.34 − 0.52 µm), we find that several 100s of hours of observation time is needed
to reach a SNR of 5 for an Earth-like planet around a Sun-like star at 10pc, even with a solar panel
coverage of ∼ 23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev
Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even
with much larger populations than today, the total energy use of human civilization would be orders of
magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev
Type I civilization. Any extraterrrestrial civilization that likewise achieves sustainable population
levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization
as imagined in the Fermi paradox may not exist.
Jet reorientation in central galaxies of clusters and groups: insights from V...Sérgio Sacani
Recent observations of galaxy clusters and groups with misalignments between their central AGN jets
and X-ray cavities, or with multiple misaligned cavities, have raised concerns about the jet – bubble
connection in cooling cores, and the processes responsible for jet realignment. To investigate the
frequency and causes of such misalignments, we construct a sample of 16 cool core galaxy clusters and
groups. Using VLBA radio data we measure the parsec-scale position angle of the jets, and compare
it with the position angle of the X-ray cavities detected in Chandra data. Using the overall sample
and selected subsets, we consistently find that there is a 30% – 38% chance to find a misalignment
larger than ∆Ψ = 45◦ when observing a cluster/group with a detected jet and at least one cavity. We
determine that projection may account for an apparently large ∆Ψ only in a fraction of objects (∼35%),
and given that gas dynamical disturbances (as sloshing) are found in both aligned and misaligned
systems, we exclude environmental perturbation as the main driver of cavity – jet misalignment.
Moreover, we find that large misalignments (up to ∼ 90◦
) are favored over smaller ones (45◦ ≤ ∆Ψ ≤
70◦
), and that the change in jet direction can occur on timescales between one and a few tens of Myr.
We conclude that misalignments are more likely related to actual reorientation of the jet axis, and we
discuss several engine-based mechanisms that may cause these dramatic changes.
The solar dynamo begins near the surfaceSérgio Sacani
The magnetic dynamo cycle of the Sun features a distinct pattern: a propagating
region of sunspot emergence appears around 30° latitude and vanishes near the
equator every 11 years (ref. 1). Moreover, longitudinal flows called torsional oscillations
closely shadow sunspot migration, undoubtedly sharing a common cause2. Contrary
to theories suggesting deep origins of these phenomena, helioseismology pinpoints
low-latitude torsional oscillations to the outer 5–10% of the Sun, the near-surface
shear layer3,4. Within this zone, inwardly increasing differential rotation coupled with
a poloidal magnetic field strongly implicates the magneto-rotational instability5,6,
prominent in accretion-disk theory and observed in laboratory experiments7.
Together, these two facts prompt the general question: whether the solar dynamo is
possibly a near-surface instability. Here we report strong affirmative evidence in stark
contrast to traditional models8 focusing on the deeper tachocline. Simple analytic
estimates show that the near-surface magneto-rotational instability better explains
the spatiotemporal scales of the torsional oscillations and inferred subsurface
magnetic field amplitudes9. State-of-the-art numerical simulations corroborate these
estimates and reproduce hemispherical magnetic current helicity laws10. The dynamo
resulting from a well-understood near-surface phenomenon improves prospects
for accurate predictions of full magnetic cycles and space weather, affecting the
electromagnetic infrastructure of Earth.
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...Sérgio Sacani
In the Nice model of solar system formation, Uranus and Neptune undergo an orbital upheaval,
sweeping through a planetesimal disk. The region of the disk from which material is accreted by
the ice giants during this phase of their evolution has not previously been identified. We perform
direct N-body orbital simulations of the four giant planets to determine the amount and origin of solid
accretion during this orbital upheaval. We find that the ice giants undergo an extreme bombardment
event, with collision rates as much as ∼3 per hour assuming km-sized planetesimals, increasing the
total planet mass by up to ∼0.35%. In all cases, the initially outermost ice giant experiences the
largest total enhancement. We determine that for some plausible planetesimal properties, the resulting
atmospheric enrichment could potentially produce sufficient latent heat to alter the planetary cooling
timescale according to existing models. Our findings suggest that substantial accretion during this
phase of planetary evolution may have been sufficient to impact the atmospheric composition and
thermal evolution of the ice giants, motivating future work on the fate of deposited solid material.
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...Sérgio Sacani
The highest priority recommendation of the Astro2020 Decadal Survey for space-based astronomy
was the construction of an observatory capable of characterizing habitable worlds. In this paper series
we explore the detectability of and interference from exomoons and exorings serendipitously observed
with the proposed Habitable Worlds Observatory (HWO) as it seeks to characterize exoplanets, starting
in this manuscript with Earth-Moon analog mutual events. Unlike transits, which only occur in systems
viewed near edge-on, shadow (i.e., solar eclipse) and lunar eclipse mutual events occur in almost every
star-planet-moon system. The cadence of these events can vary widely from ∼yearly to multiple events
per day, as was the case in our younger Earth-Moon system. Leveraging previous space-based (EPOXI)
lightcurves of a Moon transit and performance predictions from the LUVOIR-B concept, we derive
the detectability of Moon analogs with HWO. We determine that Earth-Moon analogs are detectable
with observation of ∼2-20 mutual events for systems within 10 pc, and larger moons should remain
detectable out to 20 pc. We explore the extent to which exomoon mutual events can mimic planet
features and weather. We find that HWO wavelength coverage in the near-IR, specifically in the 1.4 µm
water band where large moons can outshine their host planet, will aid in differentiating exomoon signals
from exoplanet variability. Finally, we predict that exomoons formed through collision processes akin
to our Moon are more likely to be detected in younger systems, where shorter orbital periods and
favorable geometry enhance the probability and frequency of mutual events.
Emergent ribozyme behaviors in oxychlorine brines indicate a unique niche for...Sérgio Sacani
Mars is a particularly attractive candidate among known astronomical objects
to potentially host life. Results from space exploration missions have provided
insights into Martian geochemistry that indicate oxychlorine species, particularly perchlorate, are ubiquitous features of the Martian geochemical landscape. Perchlorate presents potential obstacles for known forms of life due to
its toxicity. However, it can also provide potential benefits, such as producing
brines by deliquescence, like those thought to exist on present-day Mars. Here
we show perchlorate brines support folding and catalysis of functional RNAs,
while inactivating representative protein enzymes. Additionally, we show
perchlorate and other oxychlorine species enable ribozyme functions,
including homeostasis-like regulatory behavior and ribozyme-catalyzed
chlorination of organic molecules. We suggest nucleic acids are uniquely wellsuited to hypersaline Martian environments. Furthermore, Martian near- or
subsurface oxychlorine brines, and brines found in potential lifeforms, could
provide a unique niche for biomolecular evolution.
Continuum emission from within the plunging region of black hole discsSérgio Sacani
The thermal continuum emission observed from accreting black holes across X-ray bands has the potential to be leveraged as a
powerful probe of the mass and spin of the central black hole. The vast majority of existing ‘continuum fitting’ models neglect
emission sourced at and within the innermost stable circular orbit (ISCO) of the black hole. Numerical simulations, however,
find non-zero emission sourced from these regions. In this work, we extend existing techniques by including the emission
sourced from within the plunging region, utilizing new analytical models that reproduce the properties of numerical accretion
simulations. We show that in general the neglected intra-ISCO emission produces a hot-and-small quasi-blackbody component,
but can also produce a weak power-law tail for more extreme parameter regions. A similar hot-and-small blackbody component
has been added in by hand in an ad hoc manner to previous analyses of X-ray binary spectra. We show that the X-ray spectrum
of MAXI J1820+070 in a soft-state outburst is extremely well described by a full Kerr black hole disc, while conventional
models that neglect intra-ISCO emission are unable to reproduce the data. We believe this represents the first robust detection of
intra-ISCO emission in the literature, and allows additional constraints to be placed on the MAXI J1820 + 070 black hole spin
which must be low a• < 0.5 to allow a detectable intra-ISCO region. Emission from within the ISCO is the dominant emission
component in the MAXI J1820 + 070 spectrum between 6 and 10 keV, highlighting the necessity of including this region. Our
continuum fitting model is made publicly available.
Nucleophilic Addition of carbonyl compounds.pptxSSR02
Nucleophilic addition is the most important reaction of carbonyls. Not just aldehydes and ketones, but also carboxylic acid derivatives in general.
Carbonyls undergo addition reactions with a large range of nucleophiles.
Comparing the relative basicity of the nucleophile and the product is extremely helpful in determining how reversible the addition reaction is. Reactions with Grignards and hydrides are irreversible. Reactions with weak bases like halides and carboxylates generally don’t happen.
Electronic effects (inductive effects, electron donation) have a large impact on reactivity.
Large groups adjacent to the carbonyl will slow the rate of reaction.
Neutral nucleophiles can also add to carbonyls, although their additions are generally slower and more reversible. Acid catalysis is sometimes employed to increase the rate of addition.
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
BREEDING METHODS FOR DISEASE RESISTANCE.pptxRASHMI M G
Plant breeding for disease resistance is a strategy to reduce crop losses caused by disease. Plants have an innate immune system that allows them to recognize pathogens and provide resistance. However, breeding for long-lasting resistance often involves combining multiple resistance genes
hematic appreciation test is a psychological assessment tool used to measure an individual's appreciation and understanding of specific themes or topics. This test helps to evaluate an individual's ability to connect different ideas and concepts within a given theme, as well as their overall comprehension and interpretation skills. The results of the test can provide valuable insights into an individual's cognitive abilities, creativity, and critical thinking skills
ESR spectroscopy in liquid food and beverages.pptxPRIYANKA PATEL
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
When I was asked to give a companion lecture in support of ‘The Philosophy of Science’ (https://shorturl.at/4pUXz) I decided not to walk through the detail of the many methodologies in order of use. Instead, I chose to employ a long standing, and ongoing, scientific development as an exemplar. And so, I chose the ever evolving story of Thermodynamics as a scientific investigation at its best.
Conducted over a period of >200 years, Thermodynamics R&D, and application, benefitted from the highest levels of professionalism, collaboration, and technical thoroughness. New layers of application, methodology, and practice were made possible by the progressive advance of technology. In turn, this has seen measurement and modelling accuracy continually improved at a micro and macro level.
Perhaps most importantly, Thermodynamics rapidly became a primary tool in the advance of applied science/engineering/technology, spanning micro-tech, to aerospace and cosmology. I can think of no better a story to illustrate the breadth of scientific methodologies and applications at their best.
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
and analysis methods, numerous infrastructure platforms have been developed for phenotyping.
Unlocking the mysteries of reproduction: Exploring fecundity and gonadosomati...AbdullaAlAsif1
The pygmy halfbeak Dermogenys colletei, is known for its viviparous nature, this presents an intriguing case of relatively low fecundity, raising questions about potential compensatory reproductive strategies employed by this species. Our study delves into the examination of fecundity and the Gonadosomatic Index (GSI) in the Pygmy Halfbeak, D. colletei (Meisner, 2001), an intriguing viviparous fish indigenous to Sarawak, Borneo. We hypothesize that the Pygmy halfbeak, D. colletei, may exhibit unique reproductive adaptations to offset its low fecundity, thus enhancing its survival and fitness. To address this, we conducted a comprehensive study utilizing 28 mature female specimens of D. colletei, carefully measuring fecundity and GSI to shed light on the reproductive adaptations of this species. Our findings reveal that D. colletei indeed exhibits low fecundity, with a mean of 16.76 ± 2.01, and a mean GSI of 12.83 ± 1.27, providing crucial insights into the reproductive mechanisms at play in this species. These results underscore the existence of unique reproductive strategies in D. colletei, enabling its adaptation and persistence in Borneo's diverse aquatic ecosystems, and call for further ecological research to elucidate these mechanisms. This study lends to a better understanding of viviparous fish in Borneo and contributes to the broader field of aquatic ecology, enhancing our knowledge of species adaptations to unique ecological challenges.
Current Ms word generated power point presentation covers major details about the micronuclei test. It's significance and assays to conduct it. It is used to detect the micronuclei formation inside the cells of nearly every multicellular organism. It's formation takes place during chromosomal sepration at metaphase.
ESPP presentation to EU Waste Water Network, 4th June 2024 “EU policies driving nutrient removal and recycling
and the revised UWWTD (Urban Waste Water Treatment Directive)”
2. observation at 90 S, recorded on 2005 June 6 at a distance of
436,000 km from Titan. For that observation the field of view
(FOV) covered 77–90 S.
Spectra within each period were zonally averaged in 10°
latitude bins from 90 S to 90 N to create meridional maps. To
maintain good sensitivity we only used averages with more
than 100 spectra in a bin. The number of spectra in a bin ranged
from 117 to 8858 with an average of 1958. To keep the FOV,
smaller than about 8° in latitude on the surface, the range from
the spacecraft to the target point was limited to less than
140,000 km. The FOV was restricted to be entirely on Titanʼs
disk and emission angles were limited to 0°–50° to avoid the
need for large atmospheric corrections. We used spectra from
the far-infrared spectral channel of CIRS that covers
10–600 cm−1
. Most of the spectra were recorded at 15 cm−1
resolution, but some were taken from higher resolution data
sets and smoothed to 15 cm−1
. We used a single 15 cm−1
resolution element centered at 530 cm−1
for measuring the
surface radiance. At 530 cm−1
the opacity of the atmosphere
reaches a minimum in the collisional opacities of CH4–N2 and
H2–N2 (Courtin et al. 1995; Samuelson et al. 1997). Molecular
emissions below 520 cm−1
(Kunde et al. 1981; Coustenis et al.
2008) were avoided. Making our measurements at 530 cm−1
permits direct comparison with previous works (Flasar et al.
1981, Jennings et al. 2009, 2011). The CIRS spectra were
calibrated using the method described by Flasar et al. (2004).
3. DATA ANALYSIS
The surface brightness temperatures were corrected for
atmospheric opacity using a model similar to that described by
Jennings et al. (2011). The model was adjusted for the central
date of each of our five sample periods. The model is based on
the temperature profile measured in situ at 0–147 km altitude
by the Huygens Atmospheric Structure Instrument (HASI) on
the Huygens descent probe (Fulchignoni et al. 2005). Mod-
ifications were applied to the HASI profile to account for
latitude dependences and seasonal variations in temperature
found by CIRS and Cassini radio occultations (Coustenis et al.
2007, 2010, 2013, 2015; Achterberg et al. 2008, 2011;
Schinder et al. 2011, 2012; Bampasidis et al. 2012). At
latitudes greater than about 60° the stratospheric temperature
had a minimum in winter near 120 km. In the model this
minimum in the north weakened toward equinox and after
equinox began forming in the south. We also included the very
low temperatures seen in the atmosphere near the south pole
during 2012–2014 (Achterberg et al. 2014; Coustenis et al.
2015; Jennings et al. 2015). The lowest 10 km of the
troposphere was transitioned to the surface temperature.
Surface relief, local and global, was not treated in the model,
but since the temperatures in the lowest 1 km are forced to be
close to the surface temperature, the effect of altitude variations
is minimal and well within the model approximation. Haze
opacity was constant up to 80 km and increased above that with
a scale height of 65 km (de Kok et al. 2007; Cottini et al. 2012).
The haze opacity increased by 50% from south to north
(following Figure 7 in Cottini et al. 2012). The model used a
CH4–N2 opacity based on the CH4 altitude profile of Niemann
et al. (2010). Absorption coefficients for CH4–N2 were taken
from Borysow & Tang (1993) and were increased by 50%
following de Kok et al. (2010). We adopted an H2–N2 opacity
based on a 0.001 mole fraction of H2 (Courtin et al. 1995;
Jennings et al. 2009; Niemann et al. 2010) using H2–N2
absorption coefficients from Courtin (1988) and Dore et al.
(1986). Corrections for the atmosphere were all less than 0.2 K,
except for the 70–80 S and 80–90 S bins in 2013–2014
(Ls = 53°) which, because of the very low atmospheric
temperatures at the south pole, required a correction of 0.4 K.
Figure 1. Measured surface brightness temperatures (blue) on Titan compared
with GCM predictions, for five approximately two-year periods during the
Cassini mission. The error bars are two standard deviations, calculated from the
average that produced each data point. Variation in the size of the error bars is
due primarily to differences in the number of spectra averaged. The two GCM
curves (Tokano 2005) correspond to low thermal inertia (red) and high thermal
inertia (green). Two of the periods, Ls = 313° and 28°, did not have sufficient
data to completely map the high latitudes. The single data point at 90 S for
Ls = 313°, added here to extend the coverage to the south pole, was from 2005
June 6.
2
The Astrophysical Journal Letters, 816:L17 (4pp), 2016 January 1 Jennings et al.
3. Between 0° and 50° emission angle 80%–70% of the detected
radiance originates at Titanʼs surface. We assumed unit
emissivity for Titanʼs surface at 530 cm−1
(Jennings
et al. 2011).
4. RESULTS AND DISCUSSION
Figure 1 shows our measurements in the five time periods. It
is clear that between early and late in the Cassini mission the
warmest latitudes shifted from south to north of the equator. As
they moved northward, the highest temperatures in each period
remained about the same. From averages within±20° of the
peak in each period, we found the peak temperatures to be
steady at 93.65±0.15 K. At the poles, however, the changes
were large. Averages at high latitudes (70°–90°) showed that
between 2006 and 2013 (Ls = 335–53), temperatures near the
north pole increased by 1 K from 90.7±0.5 to 91.5±0.2 K,
while temperatures near the south pole decreased by 2 K from
91.7±0.3 to 89.7±0.5 K. We note that in the stratosphere
(1–0.1 mbar) between 2010 and 2014 the temperature in the
south dropped by about 40 K, whereas in the north it increased
by only 6 K (Bampasidis et al. 2012; Coustenis et al. 2015).
Our measurements are compared in Figure 1 with predictions
from Tokano (2005). That study used a three-dimensional
general circulation model (GCM) of the surface and lower
atmosphere to derive surface temperatures as a function of
latitude over a Titan year. We take two cases in that study to
represent surfaces with low and high thermal inertia: “porous
icy regolith” and “rock-ice mixture,” respectively, with thermal
inertias 335 and 2711 J m−2
/ s/K. Predictions for these two
cases are plotted for each of our five time periods. As can be
seen from the figure, in the south the temperatures have more
closely tracked the low thermal inertia case. In the north, on the
other hand, the temperatures have not followed either case.
Early in the mission the northern temperatures were aligned
with the high thermal inertia case, while most recently
(Ls = 53°) they have fallen below both cases. The model
forecasts 92.7 K near the pole for 2013–2014, but the measured
temperature is 91.5 K. The lagging temperatures may be an
effect of the seas at northern latitudes. Seas account for 10%
the surface area at 55–90 N (Hayes et al. 2011). Le Gall et al.
(2015), from 2.18 cm radiometry, report a slower than expected
rise in temperature in Ligeia Mare in 2014–2015, possibly
revealing the cooling effect of the northern seas. Cooling due to
methane evaporation, which may be stronger in the spring as
precipitation enhances methane concentrations, will depress
sea surface temperatures during early spring (Tokano &
Lorenz 2015b). Even without the extra cooling from evapora-
tion, seas have higher thermal inertia than dry land and can be
expected to warm more slowly (Tokano 2009). It is not
surprising, therefore, that our zonal averages covering both
land and seas show temperatures increasing more slowly than
land alone.
If the seas are cooled more than the land, however, we would
expect to be able to measure a temperature contrast between
them. We checked for differences in temperature between land
and seas in two ways. First, for the period 2013 April to 2014
September, we looked in the latitude interval 77–83 N both on
Legeia Mare (230–260 W) and on land (50–80 W). We found
that the land and sea temperatures were the same within the
measurement uncertainty, 91.7±0.8 K. Second, for 2012
January to 2015 September, we averaged temperatures over the
whole sea district (70–90 N, 230–340 W) and compared this
with an average of land temperatures at the same latitudes
(50–200 W). Again they were the same within the uncertainty,
91.4±0.3 K. We interpret these measurements to mean that in
the north the land is behaving thermally like the sea surfaces
and is therefore probably moist (Lora et al. 2015). Evaporation
of methane, possibly boosted by spring precipitation, may be
cooling the land surface in the same way the sea surfaces are
cooled (Tokano & Lorenz 2015b). The temperatures at 46 N
and 55 N in our latest period (2013–2014, Ls = 53°) appear to
be particularly low, possibly also a consequence of cooling at
those latitudes. In the south the apparent correspondence of the
temperatures to the low thermal inertia case might mean that
the land there is drier (Lora & Mitchell 2015). Also, the slower
than expected warming in the north may, in part, result from
exotic behavior of surface liquids on Titan contemplated by
Tan et al. (2015). As the season progresses through late spring
and the land dries, temperatures may begin to rise more rapidly.
The conditions for ethane and methane condensation have
changed markedly at the poles over the Cassini mission
(Jennings et al. 2009, 2011). Saturation vapor pressure is
strongly dependent on temperature for both species. At the
north pole, where temperatures have increased by 1 K, the
methane saturation vapor pressure will have increased by 14%
and ethane by 25%. At the south pole, where temperatures have
decreased by 2 K, the saturation vapor pressure will have
decreased by 30% for methane and 40% for ethane. Major
changes in condensation are likely to be taking place on the
surface at both poles. Both ethane and methane have triple
points (90.6 K for methane and 89.9 K for ethane) near the
90 K temperature we most recently measured at 70–90 S.
Huygens HASI measured the surface temperature at 10 S
latitude on 2005 January 14 (Fulchignoni et al. 2005). That
result, 93.65±0.25 K, agrees within the error with our
measurements in 2004–2006 (Ls = 313°). Between 2005 and
2013 the temperature at the Huygens touchdown latitude had
decreased by about 1 K. Our measurements also agree with
near-surface temperatures reported by Schinder et al. (2011,
2012) from Cassini radio occultations. Their 10 reported
ingress and egress surface temperatures, near the same latitudes
and dates, were on average 0.25 K lower than CIRS with a
standard deviation of 0.45 K.
In previous reports (Jennings et al. 2009; Tan et al. 2015) we
presented an analytic formula to describe the latitudinal and
seasonal dependence of the surface temperatures. We have
updated that formula to include the measurements recorded
since those earlier studies. The data in each period were fitted
with a cosine latitude profile, which we have found provides a
useful match to the shape of the latitude map for each period.
The seasonal changes in the temperatures were described by
allowing the cosine to vary over time. All measurements from
the five periods were fitted at once, with each measurement
weighted by its number of spectra. Because the peak
temperatures near the equator did not change over the mission
we set the amplitude of the cosine to our measured peak value,
93.65 K. The recent depressed temperatures in the north were
accounted for by letting the width of the cosine narrow with
time. We minimized the standard deviation by adjusting the
linear variation of the width and peak latitude. Our result,
describing the evolution of surface temperature over
2004–2014 (and not strictly valid outside those years), is given
3
The Astrophysical Journal Letters, 816:L17 (4pp), 2016 January 1 Jennings et al.
4. by the formula
1
T L Y Y93.65 cos 4.2 2.8 0.000082 0.003 .
( )
[( ( )) ( )]= - - ´ +
Here L is the latitude and Y is the number of years since
equinox (2009 August 11). The standard deviation of this
formula from the data is 0.4 K. From this formula we see that
the peak in the temperature distribution moved from 19 S to
16 N during the mission, roughly tracking the sub-solar
latitude. The formula gives the seasonal lag, i.e., the interval
following equinox to when the temperature distribution was
closest to symmetric about the equator: ΔY ∼ 0.7 yr, or
ΔLs ∼ 8°. This is consistent with the lag reported by Janssen
et al. (2015) and Jennings et al. (2011). The date corresponding
to the seasonal lag was 2010 April, one Titan year after
Voyager 1 found a similar north–south symmetry in surface
temperatures (Flasar et al. 1981).
CIRS will add another two-year measurement interval in the
remaining portion of the Cassini mission leading up to northern
summer solstice. By then we anticipate seeing additional
changes in the meridional surface temperatures.
The authors acknowledge support from NASAʼs Cassini
mission and Cassini Data Analysis Program. T. T. was
supported by DFG Grant TO269/4-1. We also thank A. Le
Gall and M. Janssen for stimulating discussions and for making
available preprints of their work.
REFERENCES
Achterberg, R. K., Conrath, B. J., Gierasch, P. J., Flasar, F. M., & Nixon, C. A.
2008, Icar, 194, 263
Achterberg, R. K., Gierasch, P. J., Conrath, B. J., Flasar, F. M., & Nixon, C. A.
2011, Icar, 211, 686
Achterberg, R. K., Gierasch, P. J., Conrath, B. J., et al. 2014, BAAS, 46,
102.07
Bampasidis, G., Coustenis, A., Achterberg, R. K., et al. 2012, ApJ, 760, 144
Borysow, A., & Tang, C. 1993, Icar, 105, 175
Cottini, V., Nixon, C. A., Jennings, D. E., et al. 2012, P&SS, 60, 62
Courtin, R. 1988, Icar, 75, 245
Courtin, R., Gautier, D., & McKay, C. P. 1995, Icar, 114, 144
Courtin, R., & Kim, S. J. 2002, P&SS, 50, 309
Coustenis, A., Achterberg, R. K., Conrath, B. J., et al. 2007, Icar, 189, 35
Coustenis, A., Bampasidis, G., Achterberg, R. K., et al. 2013, ApJ, 779, 177
Coustenis, A., Jennings, D. E., Achterberg, R. K., et al. 2015, Icar, in press
Coustenis, A., Jennings, D. E., Jolly, A., et al. 2008, Icar, 197, 539
Coustenis, A., Nixon, C. A., Jennings, D. E., et al. 2010, Icar, 207, 461
de Kok, R., Irwin, P. G. J., & Teanby, N. A. 2010, Icar, 209, 854
de Kok, R., Irwin, P. G. J., Teanby, N. A., et al. 2007, Icar, 191, 223
Dore, P., Borysow, A., & Frommhold, L. 1986, JChPh, 84, 5211
Flasar, F. M., Kunde, V. G., Abbas, M. M., et al. 2004, SSRv, 115, 169
Flasar, F. M., Samuelson, R. E., & Conrath, B. J. 1981, Natur, 292, 693
Fulchignoni, M., Ferri, F., Angrilli, F., et al. 2005, Natur, 438, 785
Hayes, A. G., Aharonson, O., Lunine, J. I., et al. 2011, Icar, 211, 655
Janssen, M. A., Le Gall, A., Lopes, R. M., et al. 2015, Icar, in press
Janssen, M. A., Lorenz, R. D., West, R., et al. 2009, Icar, 200, 222
Jennings, D. E., Achterberg, R. K., Cottini, V., et al. 2015, ApJL, 804, L34
Jennings, D. E., Cottini, V., Nixon, C. A., et al. 2011, ApJL, 737, L15
Jennings, D. E., Flasar, F. M., Kunde, V. G., et al. 2009, ApJL, 691, L103
Kunde, V. G., Aikin, A. C., Hanel, R. A., et al. 1981, Natur, 292, 686
Le Gall, A., Malaska, M. J., Lorenz, R. D., et al. 2015, JGRE, submitted
Lora, J. M., Lunine, J. I., & Russell, J. L. 2015, Icar, 250, 516
Lora, J. M., & Mitchell, J. L. 2015, GeoRL, 42, 6213
Lorenz, R. D., Newman, C. E., Tokano, T., et al. 2012, P&SS, 70, 73
Lucas, A., Rodriguez, S., Narteau, C., et al. 2014, GeoRL, 41, 6093
Mitchell, J. L., Pierrehumbert, R. T., Frierson, D. M. W., & Caballero, R. 2009,
Icar, 203, 250
Niemann, H. B., Atreya, S. K., Demick, J. E., et al. 2010, JGR, 115, E12006
Rodriguez, S., Le Mouélic, S., Rannou, P., et al. 2011, Icar, 216, 89
Samuelson, R. E., Hanel, R. A., Kunde, V. G., & Maguire, W. C. 1981, Natur,
292, 688
Samuelson, R. E., Nath, N. R., & Borysow, A. 1997, P&SS, 45, 959
Schinder, P. J., Flasar, F. M., Essam, A. M., et al. 2012, Icar, 221, 1020
Schinder, P. J., Flasar, F. M., Marouf, E. A., et al. 2011, Icar, 215, 460
Tan, S. P., Kargel, J. S., Jennings, D. E., et al. 2015, Icar, 250, 64
Teanby, N. A., Irwin, P. G. J., Nixon, C. A., et al. 2012, Natur, 491, 732
Tokano, T. 2005, Icar, 173, 222
Tokano, T. 2008, Icar, 194, 243
Tokano, T. 2009, Icar, 204, 619
Tokano, T., & Lorenz, R. D. 2015a, JGRE, 120, 20
Tokano, T., & Lorenz, R. D. 2015b, Icar, in press
Vinatier, S., Bézard, B., Lebonnois, S., et al. 2015, Icar, 250, 95
West, R. A., Balloch, J., Dumont, P., et al. 2011, GeoRL, 38, L06204
West, R. A., Del Genio, A. D., Barbara, J. M., et al. 2015, Icar, in press
4
The Astrophysical Journal Letters, 816:L17 (4pp), 2016 January 1 Jennings et al.