This document summarizes observations from the Hubble Space Telescope in November and December 2012 that detected statistically significant surpluses of hydrogen and oxygen emissions above Europa's southern hemisphere. This suggests the presence of two plumes of water vapor extending 200 km high with column densities of about 1020 m-2. Previous observations in 1999 and November 2012 did not detect these plumes, indicating the plume activity varies and may depend on Europa's changing orbital phases and tidal stresses. Models of the observations are consistent with intermittent vapor plumes erupting from fractures on Europa's surface near its south pole.
Transient Water Vapor at Europa’s South PoleCarlos Bella
1) Hubble Space Telescope images from November and December 2012 of Europa's atmosphere detected statistically significant surpluses of hydrogen Lyman-α and oxygen OI130.4 nm emissions above Europa's southern hemisphere in December 2012.
2) These emissions were observed in the same region over a period of ~7 hours, suggesting an inhomogeneous atmosphere, consistent with two 200-km-high plumes of water vapor with column densities of about 1020 m−2.
3) No plumes were detected in November 2012 images or previous 1999 images, indicating variable plume activity possibly related to Europa's changing orbital phases and surface stresses. The December 2012 plume was seen when Europa was near apocenter.
Observed glacier and volatile distribution on Pluto from atmosphere–topograph...Sérgio Sacani
Pluto has a variety of surface frosts and landforms as well as a
complex atmosphere1. There is ongoing geological activity related
to the massive Sputnik Planum glacier, mostly made of nitrogen (N2)
ice mixed with solid carbon monoxide and methane2, covering the
4-kilometre-deep, 1,000-kilometre-wide basin of Sputnik Planum1,3
near the anti-Charon point. The glacier has been suggested to arise
from a source region connected to the deep interior, or from a sink
collecting the volatiles released planetwide1. Thin deposits of N2
frost, however, were also detected at mid-northern latitudes and
methane ice was observed to cover most of Pluto except for the
darker, frost-free equatorial regions2. Here we report numerical
simulations of the evolution of N2, methane and carbon monoxide
on Pluto over thousands of years. The model predicts N2 ice
accumulation in the deepest low-latitude basin and the threefold
increase in atmospheric pressure that has been observed to occur
since 19884–6. This points to atmospheric–topographic processes as
the origin of Sputnik Planum’s N2 glacier. The same simulations also
reproduce the observed quantities of volatiles in the atmosphere and
show frosts of methane, and sometimes N2, that seasonally cover the
mid- and high latitudes, explaining the bright northern polar cap
reported in the 1990s7,8 and the observed ice distribution in 20152.
The model also predicts that most of these seasonal frosts should
disappear in the next decade.
First results from_the_hubble_opal_program_jupiter_in_2015Sérgio Sacani
Os cientistas usando o Telescópio Espacial Hubble da NASA/ESA produziram novos mapas de Júpiter, que mostram as contínuas mudanças que ocorrem com a famosa Grande Mancha Vermelha. As imagens também revelam uma rara estrutura em forma de onda na atmosfera do planeta que não tinha sido vista por décadas. A nova imagem é a primeira de uma série de retratos anuais dos planetas externos do Sistema Solar, que nos darão um novo olhar desses mundos remotos, e ajudarão os cientistas a estudarem como eles mudam com o passar do tempo.
Nessa nova imagem de Júpiter, uma grande quantidade de feições foi capturada incluindo ventos, nuvens e tempestades. Os cientistas por trás dessas novas imagens, as obtiveram usando a Wide Field Camera 3 do Hubble, num período de observação de mais de 10 horas e produziram assim dois mapas completos do planeta, a partir das suas observações. Esses mapas fizeram com que fosse possível determinar a velocidade dos ventos em Júpiter, com a finalidade de identificar diferentes fenômenos na sua atmosfera além de traquear as suas feições mais famosas.
As novas imagens confirmam que a grande tempestade que tem existido na superfície de nuvens de Júpiter por no mínimo 300 anos, continua a encolher, mas mesmo que desapareça, ela irá morrer lutando. A tempestade, conhecida como Grande Mancha Vermelha, é vista aqui fazendo seus movimentos em espiral no centro da imagem do planeta. Ela tem diminuído de tamanho de maneira muito rápida de ano em ano. Mas agora, a taxa de encolhimento parece ter reduzido novamente, mesmo apesar da mancha ser cerca de 240 quilômetros menor do que era em 2014.
Detection of hydrogen sulfide above the clouds in Uranus’s atmosphereSérgio Sacani
Visible-to-near-infrared observations indicate that the cloud top of the main cloud deck on Uranus lies at a pressure level of
between 1.2 bar and 3 bar. However, its composition has never been unambiguously identified, although it is widely assumed
to be composed primarily of either ammonia or hydrogen sulfide (H2S) ice. Here, we present evidence of a clear detection of
gaseous H2S above this cloud deck in the wavelength region 1.57–1.59 μm with a mole fraction of 0.4–0.8 ppm at the cloud top.
Its detection constrains the deep bulk sulfur/nitrogen abundance to exceed unity (>4.4–5.0 times the solar value) in Uranus’s
bulk atmosphere, and places a lower limit on the mole fraction of H2S below the observed cloud of (1.0 2.5) × 10 5 − − . The detection
of gaseous H2S at these pressure levels adds to the weight of evidence that the principal constituent of 1.2–3-bar cloud is
likely to be H2S ice.
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
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.
Isotopic evidence of long-lived volcanism on IoSérgio Sacani
Jupiter’s moon Io hosts extensive volcanism, driven by tidal heating. The isotopic composition of Io's inventory of volatile chemical elements, including sulfur and chlorine, reflects its outgassing and mass loss history, and thus records information about its evolution. We used millimeter observations of Io’s atmosphere to measure sulfur isotopes in gaseous SO2 and SO, and chlorine isotopes in gaseous NaCl and KCl. We find 34S/32S = 0.0595 ± 0.0038 (equivalent to δ34S = +347 ± 86‰), which is highly enriched compared to average Solar System values and indicates that Io has lost 94 to 99% of its available sulfur. Our measurement of 37Cl/35Cl = 0.403 ± 0.028 (δ37Cl = +263 ± 88‰) shows that chlorine is similarly enriched. These results indicate that Io has been volcanically active for most (or all) of its history, with potentially higher outgassing and mass-loss rates at earlier times.
This document summarizes the discovery of two planetary companions orbiting the metal-poor star HIP 11952 based on radial velocity measurements. The star HIP 11952 was observed over a period of 16 months using the FEROS spectrograph. Analysis of the spectra revealed periodic radial velocity variations of 6.95 days and 290 days, indicating the presence of two planets with minimum masses of 0.78 MJup and 2.93 MJup orbiting at 0.07 AU and 0.81 AU, respectively. HIP 11952 is a metal-poor star with [Fe/H] of -1.95, making it one of the few known systems with planets orbiting a star with such low metallicity
Transient Water Vapor at Europa’s South PoleCarlos Bella
1) Hubble Space Telescope images from November and December 2012 of Europa's atmosphere detected statistically significant surpluses of hydrogen Lyman-α and oxygen OI130.4 nm emissions above Europa's southern hemisphere in December 2012.
2) These emissions were observed in the same region over a period of ~7 hours, suggesting an inhomogeneous atmosphere, consistent with two 200-km-high plumes of water vapor with column densities of about 1020 m−2.
3) No plumes were detected in November 2012 images or previous 1999 images, indicating variable plume activity possibly related to Europa's changing orbital phases and surface stresses. The December 2012 plume was seen when Europa was near apocenter.
Observed glacier and volatile distribution on Pluto from atmosphere–topograph...Sérgio Sacani
Pluto has a variety of surface frosts and landforms as well as a
complex atmosphere1. There is ongoing geological activity related
to the massive Sputnik Planum glacier, mostly made of nitrogen (N2)
ice mixed with solid carbon monoxide and methane2, covering the
4-kilometre-deep, 1,000-kilometre-wide basin of Sputnik Planum1,3
near the anti-Charon point. The glacier has been suggested to arise
from a source region connected to the deep interior, or from a sink
collecting the volatiles released planetwide1. Thin deposits of N2
frost, however, were also detected at mid-northern latitudes and
methane ice was observed to cover most of Pluto except for the
darker, frost-free equatorial regions2. Here we report numerical
simulations of the evolution of N2, methane and carbon monoxide
on Pluto over thousands of years. The model predicts N2 ice
accumulation in the deepest low-latitude basin and the threefold
increase in atmospheric pressure that has been observed to occur
since 19884–6. This points to atmospheric–topographic processes as
the origin of Sputnik Planum’s N2 glacier. The same simulations also
reproduce the observed quantities of volatiles in the atmosphere and
show frosts of methane, and sometimes N2, that seasonally cover the
mid- and high latitudes, explaining the bright northern polar cap
reported in the 1990s7,8 and the observed ice distribution in 20152.
The model also predicts that most of these seasonal frosts should
disappear in the next decade.
First results from_the_hubble_opal_program_jupiter_in_2015Sérgio Sacani
Os cientistas usando o Telescópio Espacial Hubble da NASA/ESA produziram novos mapas de Júpiter, que mostram as contínuas mudanças que ocorrem com a famosa Grande Mancha Vermelha. As imagens também revelam uma rara estrutura em forma de onda na atmosfera do planeta que não tinha sido vista por décadas. A nova imagem é a primeira de uma série de retratos anuais dos planetas externos do Sistema Solar, que nos darão um novo olhar desses mundos remotos, e ajudarão os cientistas a estudarem como eles mudam com o passar do tempo.
Nessa nova imagem de Júpiter, uma grande quantidade de feições foi capturada incluindo ventos, nuvens e tempestades. Os cientistas por trás dessas novas imagens, as obtiveram usando a Wide Field Camera 3 do Hubble, num período de observação de mais de 10 horas e produziram assim dois mapas completos do planeta, a partir das suas observações. Esses mapas fizeram com que fosse possível determinar a velocidade dos ventos em Júpiter, com a finalidade de identificar diferentes fenômenos na sua atmosfera além de traquear as suas feições mais famosas.
As novas imagens confirmam que a grande tempestade que tem existido na superfície de nuvens de Júpiter por no mínimo 300 anos, continua a encolher, mas mesmo que desapareça, ela irá morrer lutando. A tempestade, conhecida como Grande Mancha Vermelha, é vista aqui fazendo seus movimentos em espiral no centro da imagem do planeta. Ela tem diminuído de tamanho de maneira muito rápida de ano em ano. Mas agora, a taxa de encolhimento parece ter reduzido novamente, mesmo apesar da mancha ser cerca de 240 quilômetros menor do que era em 2014.
Detection of hydrogen sulfide above the clouds in Uranus’s atmosphereSérgio Sacani
Visible-to-near-infrared observations indicate that the cloud top of the main cloud deck on Uranus lies at a pressure level of
between 1.2 bar and 3 bar. However, its composition has never been unambiguously identified, although it is widely assumed
to be composed primarily of either ammonia or hydrogen sulfide (H2S) ice. Here, we present evidence of a clear detection of
gaseous H2S above this cloud deck in the wavelength region 1.57–1.59 μm with a mole fraction of 0.4–0.8 ppm at the cloud top.
Its detection constrains the deep bulk sulfur/nitrogen abundance to exceed unity (>4.4–5.0 times the solar value) in Uranus’s
bulk atmosphere, and places a lower limit on the mole fraction of H2S below the observed cloud of (1.0 2.5) × 10 5 − − . The detection
of gaseous H2S at these pressure levels adds to the weight of evidence that the principal constituent of 1.2–3-bar cloud is
likely to be H2S ice.
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
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.
Isotopic evidence of long-lived volcanism on IoSérgio Sacani
Jupiter’s moon Io hosts extensive volcanism, driven by tidal heating. The isotopic composition of Io's inventory of volatile chemical elements, including sulfur and chlorine, reflects its outgassing and mass loss history, and thus records information about its evolution. We used millimeter observations of Io’s atmosphere to measure sulfur isotopes in gaseous SO2 and SO, and chlorine isotopes in gaseous NaCl and KCl. We find 34S/32S = 0.0595 ± 0.0038 (equivalent to δ34S = +347 ± 86‰), which is highly enriched compared to average Solar System values and indicates that Io has lost 94 to 99% of its available sulfur. Our measurement of 37Cl/35Cl = 0.403 ± 0.028 (δ37Cl = +263 ± 88‰) shows that chlorine is similarly enriched. These results indicate that Io has been volcanically active for most (or all) of its history, with potentially higher outgassing and mass-loss rates at earlier times.
This document summarizes the discovery of two planetary companions orbiting the metal-poor star HIP 11952 based on radial velocity measurements. The star HIP 11952 was observed over a period of 16 months using the FEROS spectrograph. Analysis of the spectra revealed periodic radial velocity variations of 6.95 days and 290 days, indicating the presence of two planets with minimum masses of 0.78 MJup and 2.93 MJup orbiting at 0.07 AU and 0.81 AU, respectively. HIP 11952 is a metal-poor star with [Fe/H] of -1.95, making it one of the few known systems with planets orbiting a star with such low metallicity
The shadow _of_the_flying_saucer_a_very_low_temperature_for_large_dust_grainsSérgio Sacani
Os astrónomos usaram o ALMA e os telescópios do IRAM para fazer a primeira medição direta da temperatura dos grãos de poeira grandes situados nas regiões periféricas de um disco de formação planetária que se encontra em torno de uma estrela jovem. Ao observar de forma inovadora um objeto cujo nome informal é Disco Voador, os astrónomos descobriram que os grãos de poeira são muito mais frios do que o esperado: -266º Celsius. Este resultado surpreendente sugere que os modelos teóricos destes discos precisam de ser revistos.
Uma equipa internacional liderada por Stephane Guilloteau do Laboratoire d´Astrophysique de Bordeaux, França, mediu a temperatura de enormes grãos de poeira que se encontram em torno da jovem estrela 2MASS J16281370-2431391 na região de formação estelar Rho Ophiuchi, a cerca de 400 anos-luz de distância da Terra.
Esta estrela encontra-se rodeada por um disco de gás e poeira — chamado disco protoplanetário, uma vez que se encontra na fase inicial da formação de um sistema planetário. Este disco é visto de perfil quando observado a partir da Terra e a sua aparência em imagens no visível levou a que se lhe desse o nome informal de Disco Voador.
Os astrónomos utilizaram o ALMA para observar o brilho emitido pelas moléculas de monóxido de carbono no disco da 2MASS J16281370-2431391. As imagens revelaram-se extremamente nítidas e descobriu-se algo estranho — em alguns casos o sinal recebido era negativo. Normalmente um sinal negativo é fisicamente impossível, mas neste caso existe uma explicação, que leva a uma conclusão surpreendente.
Herschel far infrared_spectroscopy_of_the_galactic_centerSérgio Sacani
The document summarizes observations from the Herschel Space Observatory of the Galactic Center region, focusing on a spectral scan toward Sagittarius A*. Key findings include:
1) Strong emission from atomic fine structure lines and rotationally excited lines of molecules like CO, H2O and HCO+ are detected.
2) The excitation of the CO ladder is consistent with either a hot isothermal gas component at 103.1 K and 104 cm-3, or a distribution of warmer gas at higher densities, with most CO at 300 K.
3) The detected molecular features suggest heating is from a combination of UV irradiation and shocks in the gas, rather than very enhanced X-ray or cosmic
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.
Beyond the disk: EUV coronagraphic observations of the Extreme Ultraviolet Im...Sérgio Sacani
Most observations of the solar corona beyond 2 R consist of broadband visible light imagery carried out with coronagraphs.
The associated diagnostics mainly consist of kinematics and derivations of the electron number density. While the measurement of the
properties of emission lines can provide crucial additional diagnostics of the coronal plasma (temperatures, velocities, abundances,
etc.), these types of observations are comparatively rare. In visible wavelengths, observations at these heights are limited to total
eclipses. In the ultraviolet (UV) to extreme UV (EUV) range, very few additional observations have been achieved since the pioneering
results of the Ultraviolet Coronagraph Spectrometer (UVCS).
Aims. One of the objectives of the Full Sun Imager (FSI) channel of the Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter
mission has been to provide very wide field-of-view EUV diagnostics of the morphology and dynamics of the solar atmosphere in
temperature regimes that are typical of the lower transition region and of the corona.
Methods. FSI carries out observations in two narrowbands of the EUV spectrum centered on 17.4 nm and 30.4 nm that are dominated,
respectively, by lines of Fe ix/x (formed in the corona around 1 MK) and by the resonance line of He ii (formed around 80 kK in the
lower transition region). Unlike previous EUV imagers, FSI includes a moveable occulting disk that can be inserted in the optical path
to reduce the amount of instrumental stray light to a minimum.
Results. FSI detects signals at 17.4 nm up to the edge of its field of view (7 R), which is about twice further than was previously
possible. Operation at 30.4 nm are for the moment compromised by an as-yet unidentified source of stray light. Comparisons with
observations by the LASCO and Metis coronagraphs confirm the presence of morphological similarities and differences between the
broadband visible light and EUV emissions, as documented on the basis of prior eclipse and space-based observations.
Conclusions. The very-wide-field observations of FSI out to about 3 and 7 R, without and with the occulting disk, respectively, are
paving the way for future dedicated instruments.
- ALMA observations of the young triple star system GGTau-A reveal CO gas fragments within the central cavity separating the inner and outer circumstellar disks.
- The CO gas appears in streamer-like structures as predicted by simulations, with warmer gas at the interface with the inner disks able to sustain accretion.
- The dust ring surrounding the central stars is well resolved, and modeling constrains the dust temperature profile, finding temperatures below the CO freeze-out point of 17K in the midplane.
Planet formation in the young, low-mass multiple stellar system GG Tau-AGOASA
This document summarizes observations of the young multiple star system GGTau-A using the Atacama Large Millimeter/submillimeter Array (ALMA). ALMA observations resolved cold dust and CO gas within the central cavity between the inner and outer circumbinary disks. The observations detected CO gas fragments in the cavity that appear capable of replenishing the inner circumstellar disk around GGTau-Aa beyond its accretion lifetime, allowing more time for planet formation. The observations also characterized the physical properties of the outer circumbinary dust ring, determining its dust temperature profile. Finally, the observations detected excess CO emission near the inner edge of the outer ring that may be a signature of a forming sub-stellar companion.
Measurements of the_near_nucleus_coma_of_comet_67_p_churyumov_gerasimenko_wit...Sérgio Sacani
Artigo descreve descoberta feita pelo instrumento Alice da sonda Rosetta no cometa 67P/Churyumov-Gerasimenko, das moléculas de água e dióxido de carbono quebradas que pairam pela atmosfera do cometa.
Gas physical conditions_and_kinematics_of_the_giant_outflow_ou4Sérgio Sacani
This document discusses observations of the giant outflow Ou4, located near the HII region Sh 2-129. Spectroscopic observations of Ou4 reveal shock-excited gas consistent with a fast collimated outflow. Mid-infrared images show a bubble of hot dust emission inside Ou4 that corresponds to [OIII] features. The distance and properties of Ou4 are consistent with it being launched about 90,000 years ago from the young massive star cluster HR 8119, located at the center of Sh 2-129. However, the possibility that Ou4 is a planetary nebula or resulted from an eruptive event on a massive asymptotic giant branch star cannot be ruled out.
The wonderful complexity_of_the_mira_ab_systemSérgio Sacani
The ALMA observations of the Mira AB binary system reveal an amazingly complex circumstellar environment shaped by multiple dynamical processes. In the blue wing of the CO emission line, opposing large arcs form a bubble structure around Mira A, possibly created by the wind from Mira B blowing into Mira A's expanding envelope. In the main line component, spiral arcs are seen around Mira A that appear relatively flat and oriented in the orbital plane. An accretion wake is also visible trailing Mira B. The companion is marginally resolved with a separation of 0.487 arcseconds from Mira A.
This document discusses the need for a reconciled ozone dataset for trend analysis. It outlines several goals for the dataset including assessing the state of the ozone layer, evaluating trends in ozone-depleting substances, and analyzing interactions between tropospheric and stratospheric ozone. The document also describes challenges with combining ozone profile records from different satellite instruments and the need for a workshop to develop a work plan for creating the reconciled ozone dataset.
This document summarizes research on determining temperatures, luminosities, and masses of the coldest known brown dwarfs. The key findings are:
1) Precise distances were measured for a sample of late-T and Y dwarfs using Spitzer Space Telescope astrometry, allowing accurate calculation of absolute fluxes, luminosities, and temperatures.
2) Y0 dwarfs were found to have temperatures of 400-450 K, significantly warmer than previous estimates, and masses of 5-20 times Jupiter's mass.
3) While having similar temperatures, Y dwarfs showed diverse spectral energy distributions, suggesting temperature alone does not determine spectra. Physical properties like gravity, clouds and chemistry also influence spectra.
The document analyzes Spitzer Infrared Spectrograph (IRS) observations of warm molecular hydrogen (H2) gas in M51. It finds that the six H2 lines observed have distinct emission distributions across the galaxy. Lower J lines like H2 S(0) peak in the spiral arms, while higher J lines like H2 S(3) peak at the nucleus. The observations are used to model the H2 excitation temperature and mass in a warm (100-300 K) and hot (400-1000 K) phase. The warm gas peaks at 11 M_sun/pc^2 in the spiral arms, while the hot gas peaks at 0.24 M_sun/pc^2 at the
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
Evidence of a plume on Europa from Galileo magnetic and plasma wave signaturesSérgio Sacani
The icy surface of Jupiter’s moon, Europa, is thought to lie
on top of a global ocean1–4. Signatures in some Hubble Space
Telescope images have been associated with putative water
plumes rising above Europa’s surface5,6, providing support for
the ocean theory. However, all telescopic detections reported
were made at the limit of sensitivity of the data5–7
, thereby calling
for a search for plume signatures in in-situ measurements.
Here, we report in-situ evidence of a plume on Europa from
the magnetic field and plasma wave observations acquired on
Galileo’s closest encounter with the moon. During this flyby,
which dropped below 400 km altitude, the magnetometer8
recorded an approximately 1,000-kilometre-scale field rotation
and a decrease of over 200 nT in field magnitude, and
the Plasma Wave Spectrometer9 registered intense localized
wave emissions indicative of a brief but substantial increase
in plasma density. We show that the location, duration and
variations of the magnetic field and plasma wave measurements
are consistent with the interaction of Jupiter’s corotating
plasma with Europa if a plume with characteristics inferred
from Hubble images were erupting from the region of Europa’s
thermal anomalies. These results provide strong independent
evidence of the presence of plumes at Europa.
Variations in the amount of water ice on Ceres’ surface suggest a seasonal wa...Sérgio Sacani
The dwarf planet Ceres is known to host a considerable amount of water in its interior, and areas of water ice were
detected by the Dawn spacecraft on its surface. Moreover, sporadic water and hydroxyl emissions have been observed
from space telescopes. We report the detection of water ice in a mid-latitude crater and its unexpected variation
with time. The Dawn spectrometer data show a change of water ice signatures over a period of 6 months,
which is well modeled as ~2-km2 increase of water ice. The observed increase, coupled with Ceres’ orbital parameters,
points to an ongoing process that seems correlated with solar flux. The reported variation on Ceres’ surface
indicates that this body is chemically and physically active at the present time.
A brightening of Jupiter’s auroral 7.8-μm CH4 emission during a solar-wind co...Sérgio Sacani
Enhanced mid-infrared emission from CH4 and other stratospheric hydrocarbons has been observed coincident with
Jupiter’s ultraviolet auroral emission1–3
. This suggests that
auroral processes and the neutral stratosphere of Jupiter
are coupled; however, the exact nature of this coupling is
unknown. Here we present a time series of Subaru-COMICS
images of Jupiter measured at a wavelength of 7.80 μm on
11–14 January, 4–5 February and 17–20 May 2017. These data
show that both the morphology and magnitude of the auroral
CH4 emission vary on daily timescales in relation to external
solar-wind conditions. The southern auroral CH4 emission
increased in brightness temperature by about 3.8 K between
15:50 ut, 11 January and 12:57 ut, 12 January, during a predicted solar-wind compression. During the same compression, the northern auroral emission exhibited a duskside
brightening, which mimics the morphology observed in the
ultraviolet auroral emission during periods of enhanced solarwind pressure4,5
. These results suggest that changes in external solar-wind conditions perturb the Jovian magnetosphere
in such a way that energetic particles are accelerated into the
planet’s atmosphere, deposit their energy as deep as the neutral stratosphere, and modify the thermal structure, the abundance of CH4 or the population of energy states of CH4. We
also find that the northern and southern auroral CH4 emission
evolved independently between the January, February and
May images, as has been observed at X-ray wavelengths over
shorter timescales6 and at mid-infrared wavelengths over longer timescales7
.
Observations of gas_flows_inside_a_protoplanetary_gapSérgio Sacani
1) ALMA observations of the protoplanetary disk around HD 142527 reveal diffuse CO gas and denser HCO+ filaments inside the dust gap.
2) The HCO+ filaments extend from the outer disk towards the inner disk and star, indicating gas flowing across the gap.
3) Estimates of the gas flow rate through the filaments are sufficient to sustain the observed rate of accretion onto the star, supporting the interpretation that the filaments are planet-induced gap-crossing accretion streams.
MUSE sneaks a peek at extreme ram-pressure stripping events. I. A kinematic s...Sérgio Sacani
- MUSE observations of the galaxy ESO137-001 reveal an extended gaseous tail over 30 kpc long traced by H-alpha emission, providing evidence of an extreme ram pressure stripping event as the galaxy falls into the massive Norma galaxy cluster.
- Analysis of the H-alpha kinematics and stellar velocity field show that ram pressure has removed the interstellar medium from the outer disk while the primary tail is still fed by gas from the galaxy center, with gravitational interactions not appearing to be the main mechanism of gas removal.
- The stripped gas retains evidence of the disk's rotational velocity out to around 20 kpc downstream, indicating the galaxy is moving radially along the plane of the sky, while
This document describes observations of the galaxy ESO137-001 using the MUSE instrument on the VLT. The key points are:
1) MUSE observations reveal an extended gas tail stretching over 30 kpc from the galaxy, tracing ongoing ram pressure stripping as it falls into the Norma galaxy cluster.
2) Analysis of the gas kinematics and stellar velocity field show that ram pressure has removed the interstellar medium from the outer disk while the primary tail is still fed by gas from the galaxy center.
3) The stripped gas retains evidence of the disk's rotational velocity out to 20 kpc downstream, indicating the galaxy is moving radially through the cluster. Beyond this the gas shows greater turbulence,
Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...Sérgio Sacani
We present the JWST discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS
+
53.13485
−
27.82088
with a host spectroscopic redshift of
2.903
±
0.007
. The transient was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic followup with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (
�
(
�
−
�
)
∼
0.9
) despite a host galaxy with low-extinction and has a high Ca II velocity (
19
,
000
±
2
,
000
km/s) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-
�
Ca-rich population. Although such an object is too red for any low-
�
cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement (
≲
1
�
) with
Λ
CDM. Therefore unlike low-
�
Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high-
�
truly diverge from their low-
�
counterparts, and to confirm that standardized luminosities nevertheless remain constant with redshift.
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...Sérgio Sacani
Wereport the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in the blazar OJ287. In the binary black hole model, it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our multifrequency observing campaign was set up to search for such a signature of the impact based on a prediction made 8 yr earlier. The first I-band results of the flare have already been reported by Kishore et al. (2024). Here we combine these data with our monitoring in the R-band. There is a big change in the R–I spectral index by 1.0 ±0.1 between the normal background and the flare, suggesting a new component of radiation. The polarization variation during the rise of the flare suggests the same. The limits on the source size place it most reasonably in the jet of the secondary BH. We then ask why we have not seen this phenomenon before. We show that OJ287 was never before observed with sufficient sensitivity on the night when the flare should have happened according to the binary model. We also study the probability that this flare is just an oversized example of intraday variability using the Krakow data set of intense monitoring between 2015 and 2023. We find that the occurrence of a flare of this size and rapidity is unlikely. In machine-readable Tables 1 and 2, we give the full orbit-linked historical light curve of OJ287 as well as the dense monitoring sample of Krakow.
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Most observations of the solar corona beyond 2 R consist of broadband visible light imagery carried out with coronagraphs.
The associated diagnostics mainly consist of kinematics and derivations of the electron number density. While the measurement of the
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Water vapor mapping on mars using omega mars expressAwad Albalwi
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The icy surface of Jupiter’s moon, Europa, is thought to lie
on top of a global ocean1–4. Signatures in some Hubble Space
Telescope images have been associated with putative water
plumes rising above Europa’s surface5,6, providing support for
the ocean theory. However, all telescopic detections reported
were made at the limit of sensitivity of the data5–7
, thereby calling
for a search for plume signatures in in-situ measurements.
Here, we report in-situ evidence of a plume on Europa from
the magnetic field and plasma wave observations acquired on
Galileo’s closest encounter with the moon. During this flyby,
which dropped below 400 km altitude, the magnetometer8
recorded an approximately 1,000-kilometre-scale field rotation
and a decrease of over 200 nT in field magnitude, and
the Plasma Wave Spectrometer9 registered intense localized
wave emissions indicative of a brief but substantial increase
in plasma density. We show that the location, duration and
variations of the magnetic field and plasma wave measurements
are consistent with the interaction of Jupiter’s corotating
plasma with Europa if a plume with characteristics inferred
from Hubble images were erupting from the region of Europa’s
thermal anomalies. These results provide strong independent
evidence of the presence of plumes at Europa.
Variations in the amount of water ice on Ceres’ surface suggest a seasonal wa...Sérgio Sacani
The dwarf planet Ceres is known to host a considerable amount of water in its interior, and areas of water ice were
detected by the Dawn spacecraft on its surface. Moreover, sporadic water and hydroxyl emissions have been observed
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with time. The Dawn spectrometer data show a change of water ice signatures over a period of 6 months,
which is well modeled as ~2-km2 increase of water ice. The observed increase, coupled with Ceres’ orbital parameters,
points to an ongoing process that seems correlated with solar flux. The reported variation on Ceres’ surface
indicates that this body is chemically and physically active at the present time.
A brightening of Jupiter’s auroral 7.8-μm CH4 emission during a solar-wind co...Sérgio Sacani
Enhanced mid-infrared emission from CH4 and other stratospheric hydrocarbons has been observed coincident with
Jupiter’s ultraviolet auroral emission1–3
. This suggests that
auroral processes and the neutral stratosphere of Jupiter
are coupled; however, the exact nature of this coupling is
unknown. Here we present a time series of Subaru-COMICS
images of Jupiter measured at a wavelength of 7.80 μm on
11–14 January, 4–5 February and 17–20 May 2017. These data
show that both the morphology and magnitude of the auroral
CH4 emission vary on daily timescales in relation to external
solar-wind conditions. The southern auroral CH4 emission
increased in brightness temperature by about 3.8 K between
15:50 ut, 11 January and 12:57 ut, 12 January, during a predicted solar-wind compression. During the same compression, the northern auroral emission exhibited a duskside
brightening, which mimics the morphology observed in the
ultraviolet auroral emission during periods of enhanced solarwind pressure4,5
. These results suggest that changes in external solar-wind conditions perturb the Jovian magnetosphere
in such a way that energetic particles are accelerated into the
planet’s atmosphere, deposit their energy as deep as the neutral stratosphere, and modify the thermal structure, the abundance of CH4 or the population of energy states of CH4. We
also find that the northern and southern auroral CH4 emission
evolved independently between the January, February and
May images, as has been observed at X-ray wavelengths over
shorter timescales6 and at mid-infrared wavelengths over longer timescales7
.
Observations of gas_flows_inside_a_protoplanetary_gapSérgio Sacani
1) ALMA observations of the protoplanetary disk around HD 142527 reveal diffuse CO gas and denser HCO+ filaments inside the dust gap.
2) The HCO+ filaments extend from the outer disk towards the inner disk and star, indicating gas flowing across the gap.
3) Estimates of the gas flow rate through the filaments are sufficient to sustain the observed rate of accretion onto the star, supporting the interpretation that the filaments are planet-induced gap-crossing accretion streams.
MUSE sneaks a peek at extreme ram-pressure stripping events. I. A kinematic s...Sérgio Sacani
- MUSE observations of the galaxy ESO137-001 reveal an extended gaseous tail over 30 kpc long traced by H-alpha emission, providing evidence of an extreme ram pressure stripping event as the galaxy falls into the massive Norma galaxy cluster.
- Analysis of the H-alpha kinematics and stellar velocity field show that ram pressure has removed the interstellar medium from the outer disk while the primary tail is still fed by gas from the galaxy center, with gravitational interactions not appearing to be the main mechanism of gas removal.
- The stripped gas retains evidence of the disk's rotational velocity out to around 20 kpc downstream, indicating the galaxy is moving radially along the plane of the sky, while
This document describes observations of the galaxy ESO137-001 using the MUSE instrument on the VLT. The key points are:
1) MUSE observations reveal an extended gas tail stretching over 30 kpc from the galaxy, tracing ongoing ram pressure stripping as it falls into the Norma galaxy cluster.
2) Analysis of the gas kinematics and stellar velocity field show that ram pressure has removed the interstellar medium from the outer disk while the primary tail is still fed by gas from the galaxy center.
3) The stripped gas retains evidence of the disk's rotational velocity out to 20 kpc downstream, indicating the galaxy is moving radially through the cluster. Beyond this the gas shows greater turbulence,
Similar to Transient water vapour_at_europas_south_pole (20)
Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...Sérgio Sacani
We present the JWST discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS
+
53.13485
−
27.82088
with a host spectroscopic redshift of
2.903
±
0.007
. The transient was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic followup with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (
�
(
�
−
�
)
∼
0.9
) despite a host galaxy with low-extinction and has a high Ca II velocity (
19
,
000
±
2
,
000
km/s) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-
�
Ca-rich population. Although such an object is too red for any low-
�
cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement (
≲
1
�
) with
Λ
CDM. Therefore unlike low-
�
Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high-
�
truly diverge from their low-
�
counterparts, and to confirm that standardized luminosities nevertheless remain constant with redshift.
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...Sérgio Sacani
Wereport the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in the blazar OJ287. In the binary black hole model, it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our multifrequency observing campaign was set up to search for such a signature of the impact based on a prediction made 8 yr earlier. The first I-band results of the flare have already been reported by Kishore et al. (2024). Here we combine these data with our monitoring in the R-band. There is a big change in the R–I spectral index by 1.0 ±0.1 between the normal background and the flare, suggesting a new component of radiation. The polarization variation during the rise of the flare suggests the same. The limits on the source size place it most reasonably in the jet of the secondary BH. We then ask why we have not seen this phenomenon before. We show that OJ287 was never before observed with sufficient sensitivity on the night when the flare should have happened according to the binary model. We also study the probability that this flare is just an oversized example of intraday variability using the Krakow data set of intense monitoring between 2015 and 2023. We find that the occurrence of a flare of this size and rapidity is unlikely. In machine-readable Tables 1 and 2, we give the full orbit-linked historical light curve of OJ287 as well as the dense monitoring sample of Krakow.
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...Sérgio Sacani
Context. The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact Doppler-shifted Brγ emission. The ionized hydrogen in combination with the observation of mid-infrared L-band continuum emission suggests that most of these sources are embedded in a dusty envelope. These embedded sources are part of the S-cluster, and their relationship to the S-stars is still under debate. To date, the question of the origin of these two populations has been vague, although all explanations favor migration processes for the individual cluster members. Aims. This work revisits the S-cluster and its dusty members orbiting the supermassive black hole SgrA* on bound Keplerian orbits from a kinematic perspective. The aim is to explore the Keplerian parameters for patterns that might imply a nonrandom distribution of the sample. Additionally, various analytical aspects are considered to address the nature of the dusty sources. Methods. Based on the photometric analysis, we estimated the individual H−K and K−L colors for the source sample and compared the results to known cluster members. The classification revealed a noticeable contrast between the S-stars and the dusty sources. To fit the flux-density distribution, we utilized the radiative transfer code HYPERION and implemented a young stellar object Class I model. We obtained the position angle from the Keplerian fit results; additionally, we analyzed the distribution of the inclinations and the longitudes of the ascending node. Results. The colors of the dusty sources suggest a stellar nature consistent with the spectral energy distribution in the near and midinfrared domains. Furthermore, the evaporation timescales of dusty and gaseous clumps in the vicinity of SgrA* are much shorter ( 2yr) than the epochs covered by the observations (≈15yr). In addition to the strong evidence for the stellar classification of the D-sources, we also find a clear disk-like pattern following the arrangements of S-stars proposed in the literature. Furthermore, we find a global intrinsic inclination for all dusty sources of 60 ± 20◦, implying a common formation process. Conclusions. The pattern of the dusty sources manifested in the distribution of the position angles, inclinations, and longitudes of the ascending node strongly suggests two different scenarios: the main-sequence stars and the dusty stellar S-cluster sources share a common formation history or migrated with a similar formation channel in the vicinity of SgrA*. Alternatively, the gravitational influence of SgrA* in combination with a massive perturber, such as a putative intermediate mass black hole in the IRS 13 cluster, forces the dusty objects and S-stars to follow a particular orbital arrangement. Key words. stars: black holes– stars: formation– Galaxy: center– galaxies: star formation
JAMES WEBB STUDY THE MASSIVE BLACK HOLE SEEDSSérgio Sacani
The pathway(s) to seeding the massive black holes (MBHs) that exist at the heart of galaxies in the present and distant Universe remains an unsolved problem. Here we categorise, describe and quantitatively discuss the formation pathways of both light and heavy seeds. We emphasise that the most recent computational models suggest that rather than a bimodal-like mass spectrum between light and heavy seeds with light at one end and heavy at the other that instead a continuum exists. Light seeds being more ubiquitous and the heavier seeds becoming less and less abundant due the rarer environmental conditions required for their formation. We therefore examine the different mechanisms that give rise to different seed mass spectrums. We show how and why the mechanisms that produce the heaviest seeds are also among the rarest events in the Universe and are hence extremely unlikely to be the seeds for the vast majority of the MBH population. We quantify, within the limits of the current large uncertainties in the seeding processes, the expected number densities of the seed mass spectrum. We argue that light seeds must be at least 103 to 105 times more numerous than heavy seeds to explain the MBH population as a whole. Based on our current understanding of the seed population this makes heavy seeds (Mseed > 103 M⊙) a significantly more likely pathway given that heavy seeds have an abundance pattern than is close to and likely in excess of 10−4 compared to light seeds. Finally, we examine the current state-of-the-art in numerical calculations and recent observations and plot a path forward for near-future advances in both domains.
Anti-Universe And Emergent Gravity and the Dark UniverseSérgio Sacani
Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. Using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. Due to the competition between area and volume law entanglement the microscopic de Sitter states do not thermalise at sub-Hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. The emergent laws of gravity contain an additional ‘dark’ gravitational force describing the ‘elastic’ response due to the entropy displacement. We derive an estimate of the strength of this extra force in terms of the baryonic mass, Newton’s constant and the Hubble acceleration scale a0 = cH0, and provide evidence for the fact that this additional ‘dark gravity force’ explains the observed phenomena in galaxies and clusters currently attributed to dark matter.
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.
Salesforce Integration for Bonterra Impact Management (fka Social Solutions A...Jeffrey Haguewood
Sidekick Solutions uses Bonterra Impact Management (fka Social Solutions Apricot) and automation solutions to integrate data for business workflows.
We believe integration and automation are essential to user experience and the promise of efficient work through technology. Automation is the critical ingredient to realizing that full vision. We develop integration products and services for Bonterra Case Management software to support the deployment of automations for a variety of use cases.
This video focuses on integration of Salesforce with Bonterra Impact Management.
Interested in deploying an integration with Salesforce for Bonterra Impact Management? Contact us at sales@sidekicksolutionsllc.com to discuss next steps.
HCL Notes und Domino Lizenzkostenreduzierung in der Welt von DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-und-domino-lizenzkostenreduzierung-in-der-welt-von-dlau/
DLAU und die Lizenzen nach dem CCB- und CCX-Modell sind für viele in der HCL-Community seit letztem Jahr ein heißes Thema. Als Notes- oder Domino-Kunde haben Sie vielleicht mit unerwartet hohen Benutzerzahlen und Lizenzgebühren zu kämpfen. Sie fragen sich vielleicht, wie diese neue Art der Lizenzierung funktioniert und welchen Nutzen sie Ihnen bringt. Vor allem wollen Sie sicherlich Ihr Budget einhalten und Kosten sparen, wo immer möglich. Das verstehen wir und wir möchten Ihnen dabei helfen!
Wir erklären Ihnen, wie Sie häufige Konfigurationsprobleme lösen können, die dazu führen können, dass mehr Benutzer gezählt werden als nötig, und wie Sie überflüssige oder ungenutzte Konten identifizieren und entfernen können, um Geld zu sparen. Es gibt auch einige Ansätze, die zu unnötigen Ausgaben führen können, z. B. wenn ein Personendokument anstelle eines Mail-Ins für geteilte Mailboxen verwendet wird. Wir zeigen Ihnen solche Fälle und deren Lösungen. Und natürlich erklären wir Ihnen das neue Lizenzmodell.
Nehmen Sie an diesem Webinar teil, bei dem HCL-Ambassador Marc Thomas und Gastredner Franz Walder Ihnen diese neue Welt näherbringen. Es vermittelt Ihnen die Tools und das Know-how, um den Überblick zu bewahren. Sie werden in der Lage sein, Ihre Kosten durch eine optimierte Domino-Konfiguration zu reduzieren und auch in Zukunft gering zu halten.
Diese Themen werden behandelt
- Reduzierung der Lizenzkosten durch Auffinden und Beheben von Fehlkonfigurationen und überflüssigen Konten
- Wie funktionieren CCB- und CCX-Lizenzen wirklich?
- Verstehen des DLAU-Tools und wie man es am besten nutzt
- Tipps für häufige Problembereiche, wie z. B. Team-Postfächer, Funktions-/Testbenutzer usw.
- Praxisbeispiele und Best Practices zum sofortigen Umsetzen
How to Interpret Trends in the Kalyan Rajdhani Mix Chart.pdfChart Kalyan
A Mix Chart displays historical data of numbers in a graphical or tabular form. The Kalyan Rajdhani Mix Chart specifically shows the results of a sequence of numbers over different periods.
Digital Marketing Trends in 2024 | Guide for Staying AheadWask
https://www.wask.co/ebooks/digital-marketing-trends-in-2024
Feeling lost in the digital marketing whirlwind of 2024? Technology is changing, consumer habits are evolving, and staying ahead of the curve feels like a never-ending pursuit. This e-book is your compass. Dive into actionable insights to handle the complexities of modern marketing. From hyper-personalization to the power of user-generated content, learn how to build long-term relationships with your audience and unlock the secrets to success in the ever-shifting digital landscape.
Trusted Execution Environment for Decentralized Process MiningLucaBarbaro3
Presentation of the paper "Trusted Execution Environment for Decentralized Process Mining" given during the CAiSE 2024 Conference in Cyprus on June 7, 2024.
Ocean lotus Threat actors project by John Sitima 2024 (1).pptxSitimaJohn
Ocean Lotus cyber threat actors represent a sophisticated, persistent, and politically motivated group that poses a significant risk to organizations and individuals in the Southeast Asian region. Their continuous evolution and adaptability underscore the need for robust cybersecurity measures and international cooperation to identify and mitigate the threats posed by such advanced persistent threat groups.
Building Production Ready Search Pipelines with Spark and MilvusZilliz
Spark is the widely used ETL tool for processing, indexing and ingesting data to serving stack for search. Milvus is the production-ready open-source vector database. In this talk we will show how to use Spark to process unstructured data to extract vector representations, and push the vectors to Milvus vector database for search serving.
Nunit vs XUnit vs MSTest Differences Between These Unit Testing Frameworks.pdfflufftailshop
When it comes to unit testing in the .NET ecosystem, developers have a wide range of options available. Among the most popular choices are NUnit, XUnit, and MSTest. These unit testing frameworks provide essential tools and features to help ensure the quality and reliability of code. However, understanding the differences between these frameworks is crucial for selecting the most suitable one for your projects.
Unlock the Future of Search with MongoDB Atlas_ Vector Search Unleashed.pdfMalak Abu Hammad
Discover how MongoDB Atlas and vector search technology can revolutionize your application's search capabilities. This comprehensive presentation covers:
* What is Vector Search?
* Importance and benefits of vector search
* Practical use cases across various industries
* Step-by-step implementation guide
* Live demos with code snippets
* Enhancing LLM capabilities with vector search
* Best practices and optimization strategies
Perfect for developers, AI enthusiasts, and tech leaders. Learn how to leverage MongoDB Atlas to deliver highly relevant, context-aware search results, transforming your data retrieval process. Stay ahead in tech innovation and maximize the potential of your applications.
#MongoDB #VectorSearch #AI #SemanticSearch #TechInnovation #DataScience #LLM #MachineLearning #SearchTechnology
Dive into the realm of operating systems (OS) with Pravash Chandra Das, a seasoned Digital Forensic Analyst, as your guide. 🚀 This comprehensive presentation illuminates the core concepts, types, and evolution of OS, essential for understanding modern computing landscapes.
Beginning with the foundational definition, Das clarifies the pivotal role of OS as system software orchestrating hardware resources, software applications, and user interactions. Through succinct descriptions, he delineates the diverse types of OS, from single-user, single-task environments like early MS-DOS iterations, to multi-user, multi-tasking systems exemplified by modern Linux distributions.
Crucial components like the kernel and shell are dissected, highlighting their indispensable functions in resource management and user interface interaction. Das elucidates how the kernel acts as the central nervous system, orchestrating process scheduling, memory allocation, and device management. Meanwhile, the shell serves as the gateway for user commands, bridging the gap between human input and machine execution. 💻
The narrative then shifts to a captivating exploration of prominent desktop OSs, Windows, macOS, and Linux. Windows, with its globally ubiquitous presence and user-friendly interface, emerges as a cornerstone in personal computing history. macOS, lauded for its sleek design and seamless integration with Apple's ecosystem, stands as a beacon of stability and creativity. Linux, an open-source marvel, offers unparalleled flexibility and security, revolutionizing the computing landscape. 🖥️
Moving to the realm of mobile devices, Das unravels the dominance of Android and iOS. Android's open-source ethos fosters a vibrant ecosystem of customization and innovation, while iOS boasts a seamless user experience and robust security infrastructure. Meanwhile, discontinued platforms like Symbian and Palm OS evoke nostalgia for their pioneering roles in the smartphone revolution.
The journey concludes with a reflection on the ever-evolving landscape of OS, underscored by the emergence of real-time operating systems (RTOS) and the persistent quest for innovation and efficiency. As technology continues to shape our world, understanding the foundations and evolution of operating systems remains paramount. Join Pravash Chandra Das on this illuminating journey through the heart of computing. 🌟
In the rapidly evolving landscape of technologies, XML continues to play a vital role in structuring, storing, and transporting data across diverse systems. The recent advancements in artificial intelligence (AI) present new methodologies for enhancing XML development workflows, introducing efficiency, automation, and intelligent capabilities. This presentation will outline the scope and perspective of utilizing AI in XML development. The potential benefits and the possible pitfalls will be highlighted, providing a balanced view of the subject.
We will explore the capabilities of AI in understanding XML markup languages and autonomously creating structured XML content. Additionally, we will examine the capacity of AI to enrich plain text with appropriate XML markup. Practical examples and methodological guidelines will be provided to elucidate how AI can be effectively prompted to interpret and generate accurate XML markup.
Further emphasis will be placed on the role of AI in developing XSLT, or schemas such as XSD and Schematron. We will address the techniques and strategies adopted to create prompts for generating code, explaining code, or refactoring the code, and the results achieved.
The discussion will extend to how AI can be used to transform XML content. In particular, the focus will be on the use of AI XPath extension functions in XSLT, Schematron, Schematron Quick Fixes, or for XML content refactoring.
The presentation aims to deliver a comprehensive overview of AI usage in XML development, providing attendees with the necessary knowledge to make informed decisions. Whether you’re at the early stages of adopting AI or considering integrating it in advanced XML development, this presentation will cover all levels of expertise.
By highlighting the potential advantages and challenges of integrating AI with XML development tools and languages, the presentation seeks to inspire thoughtful conversation around the future of XML development. We’ll not only delve into the technical aspects of AI-powered XML development but also discuss practical implications and possible future directions.
5th LF Energy Power Grid Model Meet-up SlidesDanBrown980551
5th Power Grid Model Meet-up
It is with great pleasure that we extend to you an invitation to the 5th Power Grid Model Meet-up, scheduled for 6th June 2024. This event will adopt a hybrid format, allowing participants to join us either through an online Mircosoft Teams session or in person at TU/e located at Den Dolech 2, Eindhoven, Netherlands. The meet-up will be hosted by Eindhoven University of Technology (TU/e), a research university specializing in engineering science & technology.
Power Grid Model
The global energy transition is placing new and unprecedented demands on Distribution System Operators (DSOs). Alongside upgrades to grid capacity, processes such as digitization, capacity optimization, and congestion management are becoming vital for delivering reliable services.
Power Grid Model is an open source project from Linux Foundation Energy and provides a calculation engine that is increasingly essential for DSOs. It offers a standards-based foundation enabling real-time power systems analysis, simulations of electrical power grids, and sophisticated what-if analysis. In addition, it enables in-depth studies and analysis of the electrical power grid’s behavior and performance. This comprehensive model incorporates essential factors such as power generation capacity, electrical losses, voltage levels, power flows, and system stability.
Power Grid Model is currently being applied in a wide variety of use cases, including grid planning, expansion, reliability, and congestion studies. It can also help in analyzing the impact of renewable energy integration, assessing the effects of disturbances or faults, and developing strategies for grid control and optimization.
What to expect
For the upcoming meetup we are organizing, we have an exciting lineup of activities planned:
-Insightful presentations covering two practical applications of the Power Grid Model.
-An update on the latest advancements in Power Grid -Model technology during the first and second quarters of 2024.
-An interactive brainstorming session to discuss and propose new feature requests.
-An opportunity to connect with fellow Power Grid Model enthusiasts and users.
Letter and Document Automation for Bonterra Impact Management (fka Social Sol...Jeffrey Haguewood
Sidekick Solutions uses Bonterra Impact Management (fka Social Solutions Apricot) and automation solutions to integrate data for business workflows.
We believe integration and automation are essential to user experience and the promise of efficient work through technology. Automation is the critical ingredient to realizing that full vision. We develop integration products and services for Bonterra Case Management software to support the deployment of automations for a variety of use cases.
This video focuses on automated letter generation for Bonterra Impact Management using Google Workspace or Microsoft 365.
Interested in deploying letter generation automations for Bonterra Impact Management? Contact us at sales@sidekicksolutionsllc.com to discuss next steps.
A Comprehensive Guide to DeFi Development Services in 2024Intelisync
DeFi represents a paradigm shift in the financial industry. Instead of relying on traditional, centralized institutions like banks, DeFi leverages blockchain technology to create a decentralized network of financial services. This means that financial transactions can occur directly between parties, without intermediaries, using smart contracts on platforms like Ethereum.
In 2024, we are witnessing an explosion of new DeFi projects and protocols, each pushing the boundaries of what’s possible in finance.
In summary, DeFi in 2024 is not just a trend; it’s a revolution that democratizes finance, enhances security and transparency, and fosters continuous innovation. As we proceed through this presentation, we'll explore the various components and services of DeFi in detail, shedding light on how they are transforming the financial landscape.
At Intelisync, we specialize in providing comprehensive DeFi development services tailored to meet the unique needs of our clients. From smart contract development to dApp creation and security audits, we ensure that your DeFi project is built with innovation, security, and scalability in mind. Trust Intelisync to guide you through the intricate landscape of decentralized finance and unlock the full potential of blockchain technology.
Ready to take your DeFi project to the next level? Partner with Intelisync for expert DeFi development services today!
Let's Integrate MuleSoft RPA, COMPOSER, APM with AWS IDP along with Slackshyamraj55
Discover the seamless integration of RPA (Robotic Process Automation), COMPOSER, and APM with AWS IDP enhanced with Slack notifications. Explore how these technologies converge to streamline workflows, optimize performance, and ensure secure access, all while leveraging the power of AWS IDP and real-time communication via Slack notifications.
1. Revised Manuscript: Confidential
26 November 2013
Title: Transient Water Vapor at Europa’s South Pole
Authors: Lorenz Roth1,2*†, Joachim Saur2†, Kurt D. Retherford1, Darrell F. Strobel3,4, Paul D.
Feldman4, Melissa A. McGrath5, Francis Nimmo6
Affiliations:
1
Southwest Research Institute, San Antonio, TX, USA;
2
Institute of Geophysics and Meteorology, University of Cologne, Germany;
3
Department of Earth and Planetary Science, The Johns Hopkins University, Baltimore, MD,
USA;
4
Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD, USA;
5
NASA Marshall Space Flight Center, Huntsville, AL, USA;
6
Department of Earth and Planetary Sciences, University of California Santa Cruz, CA, USA.
* Correspondence to: lorenz.roth@swri.edu
† These authors contributed equally to this work
Abstract: In November and December 2012 the Hubble Space Telescope (HST) imaged
Europa’s ultraviolet emissions in the search for vapor plume activity. We report statistically
significant coincident surpluses of hydrogen Lyman-α and oxygen OI130.4 nm emissions above
the southern hemisphere in December 2012. These emissions are persistently found in the same
area over ~7 hours, suggesting atmospheric inhomogeneity; they are consistent with two 200
km high plumes of water vapor with line-of-sight column densities of about 1020 m-2. Nondetection in November and in previous HST images from 1999 suggests varying plume activity
that might depend on changing surface stresses based on Europa’s orbital phases. The plume is
present when Europa was near apocenter, and not detected close to its pericenter in agreement
with tidal modeling predictions.
Main Text: Europa’s exceptional surface morphology suggests the existence of a layer of liquid
water under the icy crust (1,2), which has been confirmed independently by magnetometer
measurements (3). Despite signs of active resurfacing in chaos terrains (4) and the existence of a
subsurface ocean, current geologic activity has not been observed directly in Voyager and
Galileo observations (2,5,6) or in any other data. Europa also possesses a tenuous atmosphere
generated by sputtering and radiolysis (7-9) that was detected in 1995 through HST ultraviolet
(UV) observations of oxygen emissions at 130.4 nm and 135.6 nm (10,11). Spatially revolved
images of these atmospheric emissions obtained by the HST Space Telescope Imaging
Spectrograph (STIS) revealed an irregular emission pattern at the two oxygen multiplets, which
originates from an inhomogeneous neutral gas abundance across the surface (12,13) or Europa’s
highly variable plasma environment, or both. An enhanced emission near 90° west longitude
when Europa was near its apocenter detected by the HST Advanced Camera for Surveys (ACS)
was associated with a possible existence of plumes in a region where high shear stresses are
expected, but an unambiguous correlation was not possible due to low data quality (14).
We report STIS spectral images of Europa’s trailing/anti-Jovian hemisphere and leading
hemisphere obtained in November and December 2012, respectively. Previous observations, in
2. 1999, targeted Europa’s trailing hemisphere (Table 1). The observations in 2012 were timed to
coincide with the maximum variation of the Jupiter’s magnetic field orientation at Europa. With
this configuration, spatially inhomogeneous yet time-variable emissions originating from the
periodically changing magnetospheric conditions can be separated from time-stationary emission
inhomogeneities due to atmospheric anomalies.
Fig. 1: Visible images of the observed hemispheres (A-C) with sub-observer longitudes listed
and combined STIS images of the hydrogen and oxygen emissions (D-O) (Table 1). The Lymanα morphology (D-F) reveals an anti-correlation with the brightness in the visible (15). (G-O):
Same Lyman-α images, and OI130.4 nm and OI]135.6 nm images with solar disk-reflectance
subtracted. 3×3 pixels are binned and the STIS images are smoothed to enhance visibility of the
significant features. The dotted light blue circles indicate the multiplet lines (15). The color scale
is normalized to the respective brightness and the scale maximum (corresponding to 1.0 on the
2
3. scale) is listed in each image. Oversaturated pixels with intensities above maximum are white.
The contours show signal-to-noise (SNR) ratios of the binned pixels (and contours for SNR=1
are omitted here in (D-F) and (M-O)).
After correction of the images for instrumental and background noise (15), the remaining
emission sources are: solar reflectance from Europa’s surface, solar resonance scattering by
atmospheric H and O atoms (negligible for OI135.6 nm), and electron impact (dissociative)
excitation of atmospheric species, such as O2, O and H2O. To subtract the light reflected from the
surface, we generated model spectral images by convolving normalized inverted visible images
with a solar UV spectrum (15). Whereas the surface reflectance corrected Lyman-α brightness is
mostly consistent with a zero signal for the 1999 and November 2012 observations, a
pronounced 400-600 R (16) region is found above the limb near the south pole in the residual
Lyman-α emission in the December 2012 image (Fig. 1I).
The residual atmospheric oxygen emissions at 130.4 nm and 135.6 nm in contrast cover most of
Europa’s disk (Fig. 1J-O). The 135.6/130.4 ratios of 1.6±0.1 (both 1999 and November 2012)
and 2.1±0.2 (December 2012) are consistent with previous measurements and an O2 atmosphere
with a low mixing ratio of O (10,11). The oxygen aurora morphologies undergo considerable
variations during the ~7 hours of all observations (Figs. 2,S1,S2). Bright OI]135.6 nm patches
are found close to the poles, which appear to rock towards and away from Jupiter in correlation
with the varying magnetic field orientation at Europa. The OI130.4 nm aurora pattern roughly
resembles the OI]135.6 nm pattern (cf. I and N in Figs. S1 and S2, respectively) as expected if
both OI multiplets originate from electron-impact dissociated O2. Apparent deviations of the
OI130.4 nm morphology from the OI]135.6 emission can be attributed in part to the
inhomogeneity of the higher surface reflectance at 130.4 nm. This becomes most apparent in the
combined images (Fig. 1J-L), because the time-variable atmospheric contributions are smoothed
through the superposition. The generally patchy OI130.4 nm morphology is additionally affected
by the low signal-to-noise ratio of the 130.4 nm emission (15).
We focus our analysis on the emission above the limb of Europa, which is only marginally
influenced by the surface reflectance due to instrument-scattered light from the on-disk features.
Above the south polar limb in the December 2012 composite images an OI130.4 nm
enhancement of similar appearance is found in the same region as the Lyman-α enhancement
(compare Fig. 1I and L). Detectable Lyman-α and OI130.4 nm emissions are persistently found
above the southern anti-Jovian limb during all five HST orbits of the December 2012
observations (Fig. 2A-J). Bright OI]135.6 nm emissions across the entire south polar region shift
from the sub-Jovian to the anti-Jovian hemisphere between the first and last orbit (Fig. 2K-O). A
persistent or significant above-limb OI]135.6 nm emission surplus is not detected.
3
4. Fig. 2. Individual STIS images of the 5 HST orbits from December 2012: Lyman-α before diskreflectance subtraction (A-E), and reflectance-subtracted Lyman-α and oxygen emissions (F-T).
The persistent plume emission is highlighted in dashed-red. Sub-observer longitude φobs, Jovian
System-III-longitude λIII, magnetic latitude ψmag and projected magnetic field line B are listed
below. Leading meridian (90º W) is dashed-white, equator is solid-white. Other details are as in
Fig. 1.
In a next step, we subdivided the region between 1 RE (Europa radius, 1561 km) and 1.25 RE
(corresponding to an above-limb altitude of 390 km) in 18 bins spanning angles of 20º around
the disk of Europa in all images (Fig. 3). The December 2012 Lyman-α image brightnesses of all
pixels in limb bins #12 and #13 are 420±136 R and 604±140 R, which exceed the faint average
limb emission of 46 R (outside the anomaly) by 2.8 and 4.0 times the propagated uncertainty (σ),
respectively. The OI130.4 emission of 59±18 R in bin #13 is also significantly (2.4σ) higher than
the average limb emission of 16 R, and bin #12 shows a slight enhancement (35±17 R). At both
lines the emission anomaly appears to have two individual peaks in bins #12 and #13, which can,
however, not be clearly separated within the measurement uncertainties. No significant emission
4
5. surplus is found in either of the bins at 135.6 nm (Fig. 3E). In 1999 and November 2012 all of
the Lyman-α bins are consistent with zero signal within 2σ (17).
Fig. 3. Comparison of December 2012 observations and atmosphere plume model results: (A-D)
Lyman-α and OI 130.4 nm STIS images (as in Fig. 1) and model aurora images from a global
atmosphere with two H2O plumes. The south polar above-limb emission is found in bins #12 and
#13 of the eighteen 20º bins illustrated by the dotted yellow lines. The patchiness of the 130.4
nm on-disk emissions might originate from surface reflectance, atmospheric, or plasma
inhomogeneities, but is also consistent with statistically expected variations across a uniform
disk (15). (E) Measured (solid black) and modeled (dotted) brightnesses of each 20º-wide limb
bin around Europa’s disk. The best-fit plume model atmosphere is shown in red, and plume
densities decreased by factor 2 and factor 3 are shown in blue and green, respectively. (F) Radial
profiles of measured and modeled brightness versus altitude in bins 12+13.
Detectable Lyman-α emission is not expected for the generally assumed abundance of hydrogen
bearing molecules (≤ 1017 m-2) in the global sputtered atmosphere (7-9). Lyman-α emission from
a global atomic hydrogen corona that is not gravitationally bound as observed at Ganymede (18)
would be isotropic. Lyman-α solar resonant scattering on atomic H also would require opticallythick columns (> 1017 m-2) to produce brightnesses >400 R and can be excluded. In contrast, H2O
freezes (19) and any enhancement must be localized to its source. In addition, electron impact on
H2O yields HI121.6 nm and OI130.4 nm, but has a lower cross section at 135.6 nm (20). Hence,
the emission surplus at HI121.6 nm and OI130.4 nm in an area, where no remarkable
enhancement of OI]135.6 nm is found, suggests a local atmospheric H2O enhancement.
5
6. We derive average H2O and O2 column densities using measured cross sections for electronimpact dissociative excitation and the standard plasma parameters for Europa (15). Neglecting
presumably small contributions from e+O or e+H2O, the observed OI]135.6 nm brightness of bin
#13 requires a line-of-sight O2 column of ~5 ×1019 m-2. The Lyman-α brightness in bin #13
implies an optically thin H2O column density of 1.5×1020 m-2. In this case, excitation of O2 and
H2O would contribute 27 R and 29 R, respectively, to the OI130.4 nm emission consistent with
the measured brightness of 59±18 R in bin #13. Thus, the Lyman-α/OI130.4 nm/OI]135.6 nm
ratios are diagnostic of e + H2O in an approach similar to the average OI]135.6 nm/OI130.4 nm
ratio being diagnostic of e + O2 (10,11).
We generated model images for two three-dimensional plume distributions taking into account
H2O continuum absorption and resonant scattering. We started by generating a standard model
for an average background atmosphere by adjusting the density of an exponentially decreasing
O2 atmosphere with low O and H2O mixing ratios (15) to the observed OI]135.6 nm limb
brightness for all observations (Fig. 3E,F, dotted grey). The fitted vertical O2 column density of
NO2 = 3.5 ×1018 m-2 agrees well with the observed OI130.4 limb brightness and is consistent with
previous results (7-11,21). Deviations from the model in several bins for both oxygen aurora
lines are likely attributed to the variable plasma environment.
We then generated model images with two local H2O plumes (15). We adjusted the plume height
of 200 km and the latitudinal expansion of 10º (or ~270 km on the surface) to the observed
spatial profile of the Lyman-α emissions. The implemented density profile resembles an
intermediate case between Io’s shock-dominated Pele-type plumes (22) and the low-gravity
outgassing of the Enceladus plumes (23). Because the surface source locations cannot be
determined from the images, the plumes were arbitrarily centered on the anti-Jovian meridian
(180ºW) and in the center of the bins #12 and #13 at 55ºS and 75ºS, respectively. The densities
of the plumes were fit to the observed Lyman-α bin brightness yielding total contents of 4.9
×1031 and 8.2 ×1031 H2O molecules for the plumes at 55ºS and 75ºS, respectively. The combined
plume content is 1-2 orders of magnitude higher than the H2O abundance in global atmosphere
models without plumes (7-9). The derived H2O plume densities independently match the
observed OI130.4 nm emission surplus if resonant scattering and electron impact on O with an
estimated mixing ratio of O/H2O ~ 0.2% is taken into account (15).
The model reasonably reproduces the Lyman-α plume morphology and brightness decrease with
altitude (Fig. 3). At low altitudes (< 100 km) the measured brightness decreases for both the
Lyman-α and OI130.4 nm emission. Because bright OI]135.6 nm emission is also detected up to
altitudes of 200 km, the OI130.4 nm profile might be best explained by a peak in oxygen
abundance at higher altitudes. Also, the derived plume height of 200 km is higher than expected
from model results (24) and would require large super-sonic eruption velocities of ~700 m/s.
However, interpretation of the derived height and radial profile requires caution because of the
systematic uncertainties of the disk location by 1-2 pixels or ~100 km. Moreover, a local density
enhancement within a smooth global atmosphere would substantially alter the plasma
environment, which in turn modifies the aurora morphology and brightness (25).
The high plume velocities and relatively low number densities we inferred are consistent with
vapor emission from narrow fractures (15), as occurs at Enceladus (23,26). The surface area of
Europa’s fractures is too small to produce a thermal anomaly detectable by the Galileo
Photopolarimeter-Radiometer instrument (27). Plume fallback could produce terrain softening in
the near-polar regions, which might be detectable in suitable high-resolution images (15).
6
7. The modeled Lyman-α limb brightnesses for the 1999 and November 2012 geometries are not
consistent with persistent plumes. Also, no striking surplus of OI130.4 nm emission is detected.
The model indicates that the plumes were less dense by at least a factor of 2 and 3 during the
1999 and November 2012 observations, respectively, if present (Fig. S3). Thus, the plume
activity appears to undergo considerable variability.
Recently, the plumes at Enceladus’ south pole have been shown to be more active near apocenter
than at the pericenter (28). Similar tidal stress variability for Europa is expected to open and
close its Linea features (Fig. S4, (15)). Europa was very close to its apocenter during the
December 2012 observations, and was shortly before and at the pericenter during the 1999 and
November 2012 observations (Table 1). This causal relationship might explain the observed
variability and the lack of detections in 1999 and November 2012. The plume variability, if real,
verifies a key prediction of tidal-flexing models based on the existence of a subsurface ocean.
References and Notes:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
M. H. Carr, et al., Evidence for a subsurface ocean on Europa, Nature, 391, 363 (1998);
R. T. Pappalardo, et al., Does Europa have a subsurface ocean? Evaluation of the geological
evidence, J. Geophys. Res., 104 (1999);
K. K. Khurana, et al., Induced magnetic fields as evidence for subsurface oceans in Europa
and Callisto, Nature, 395, 777-780 (1998);
B. E. Schmidt, D. D. Blankenship, G. W. Patterson, P. M. Schenk, Active formation of
‘chaos terrain’ over shallow subsurface water on Europa, Nature, 479, 502-505 (2011);
C. B. Phillips, et al., The search for current geologic activity on Europa, J. Geophys. Res.,
105 (2000);
S. A. Fagents, Considerations for effusive cryovolcanism on Europa: The post-Galileo
perspective, J. Geophys. Res., 108 (2003);
V. I. Shematovich, R. E. Johnson, J. F. Cooper, M. C. Wong, Surface-bounded atmosphere of
Europa, Icarus, 173, 480-498 (2005);
W. H. Smyth, M. L. Marconi, Europa’s atmosphere, gas tori, and magnetospheric
implications, Icarus, 181, 510-526 (2006);
C. Plainaki, A. Milillo, A. Mura, S. Orsini, S. Massetti, T. Cassidy, The role of sputtering and
radiolysis in the generation of Europa exosphere, Icarus, 218, 956-966 (2012);
D.T. Hall, D. F. Strobel, P. D. Feldman, M. A. McGrath, H. A. Weaver, Detection of an
oxygen atmosphere on Jupiter’s moon Europa, Nature, 373, 677-679 (1995);
D. T. Hall, P. D. Feldman, M. A. McGrath, D. F. Strobel, The far-ultraviolet oxygen airglow
of Europa and Ganymede, Astrophys. J., 499(5), 475-481 (1998);
M. A. McGrath, C. J. Hansen, A. R. Hendrix, in Europa, R. T. Pappalardo, W. B. McKinnon,
and K. K. Khurana (Univ. of Arizona Press, 2009), pp. 485-505;
T. A. Cassidy, R. E. Johnson, M. A. McGrath, M. C. Wong, J. F. Cooper, The spatial
morphology of Europa’s near-surface O2 atmosphere, Icarus, 191, 755-764 (2007);
J. Saur, et al., Hubble Space Telescope/Advanced Camera for Surveys Observations of
Europa’s Atmospheric Ultraviolet Emission at Eastern Elongation, Astrophys. J., 738 (2011);
See Supplementary Material for more information;
Rayleigh [R] is the column emission rate of 1010 photons per square meter per column per
second, 1 R = 1010/4π photons m-2 sr-1 s-1.
The 1999 Lyman-α image might hint a plume feature in the south polar region (Fig. 1G), but
is not statistically significant and is therefore not considered further.
7
8. 18 C. A. Barth, et al., Galileo ultraviolet spectrometer observations of atomic hydrogen in the
atmosphere at Ganymede, Geophys. Res. Lett., 24 (1997);
19 J. R. Spencer, L. K. Tamppari, T. Z. Martin, L. D. Travis, Temperatures on Europa from
Galileo Photopolarimeter-Radiometer: Nighttime Thermal Anomalies, Science, 284 (1999);
20 O. P. Makarov, et al., Kinetic energy distributions and line profile measurements of
dissociation products of water upon electron impact, J. Geophys. Res., 109(A18) (2004);
21 J. Saur, D. F. Strobel, F. M. Neubauer, Interaction of the Jovian magnetosphere with Europa:
Constraints on the neutral atmosphere, J. Geophys. Res., 103(E9) (1998);
22 J. Zhang, et al., Simulation of gas dynamics and radiation in volcanic plumes on Io, Icarus,
163, 182-197 (2003);
23 F. Tian, A. I. F. Stewart, O. B. Toon, K. W. Larsen, L. W. Esposito, Monte Carlo simulations
of the water vapor plumes on Enceladus, Icarus, 188, 154-161 (2007);
24 S. A. Fagents, et al., Cryomagmatic Mechanisms for the Formation of Rhadamanthys Linea,
Triple Band Margins, and Other Low-Albedo Features on Europa, Icarus, 144, 54-88 (2000);
25 L. Roth, J. Saur, K. D. Retherford, D. F. Strobel, J. R. Spencer, Simulation of Io’s auroral
emission: Constraints on the atmosphere in eclipse, Icarus, 214, 495-509 (2011);
26 C. J. Hansen, et al., The composition and structure of the Enceladus plume. Geophys. Res.
Lett., 38(11) (2011);
27 J. A. Rathbun, N. J. Rodriguez, J. R. Spencer, Galileo PPR observations of Europa: Hotspot
detection limits and surface thermal properties, Icarus, 210(2), 763-769 (2010);
28 M. M. Hedman, et al., An observed correlation between plume activity and tidal stresses on
Enceladus, Nature, 500, 182-184 (2013);
References continued (only called out in the SM)
29 Z. A. Selvans, "Time, tides and tectonics on icy satellites.", PhD thesis, University of
Colorado at Boulder (2009);
30 F. Nimmo, J. R. Spencer, R. T. Pappalardo, M. E. Mullen, Shear heating as the origin of the
plumes and heat flux on Enceladus. Nature, 447(7142), 289-291 (2007);
31 G. V. Hoppa, B. R. Tufts, R. Greenberg, P. E. Geissler, Strike-Slip Faults on Europa: Global
Shear Patterns Driven by Tidal Stress, Icarus, 141, 287-298 (1999);
32 G. V. Hoppa, R. Greenberg, B. R. Tufts, P. E. Geissler, Plume Detection on Europa:
Locations of Favorable Tidal Stress, in Lunar and Planetary Institute Science Conference
Abstracts, 30, p. 1603 (1999);
33 F. L. Roesler, et al., Far-ultraviolet imaging spectroscopy of Io’s atmosphere with HST/STIS,
Science, 283(5400), 353–357 (1999);
34 P. D. Feldman, et al., HST/STIS Ultraviolet Imaging of Polar Aurora on Ganymede,
Astrophys. J., 535, 1085–1090 (2000);
35 P. D. Feldman, et al., Lyman-alpha Imaging of the SO2 Distribution on Io, Geophys. Res.
Lett., 27, 1787-1790 (2000);
36 K. D. Retherford, H. W. Moos, D. F. Strobel, B. C. Wolven, F. L. Roesler, Io’s equatorial
spots: Morphology of neutral UV emissions, J. Geophys. Res., 105, (2000);
37 K. D. Retherford, H. W. Moos, D. F. Strobel, Io’s auroral limb glow: Hubble Space
Telescope FUV observations, J. Geophys. Res., 108, 1333-1341 (2003);
38 B. C. Wolven, et al., Emission profiles of neutral oxygen and sulfur in Io's exospheric
corona, J. Geophys. Res., 106(A11), 26155-26 (2001);
8
9. 39 D. F. Strobel, J. Saur, J., P. D. Feldman, M. A. McGrath, Hubble Space Telescope space
telescope imaging spectrograph search for an atmosphere on Callisto: A Jovian unipolar
inductor. Astrophy. J. Lett., 581(1), L51 (2002);
40 L. M. Feaga, M. A. McGrath, P. D. Feldman, The Abundance of Atomic Sulfur in the
Atmosphere of Io, Astrophys. J., 570, 439-446 (2002);
41 L. M. Feaga, M. McGrath, P. D. Feldman, Io’s dayside SO2 atmosphere, Icarus, 201, 570584, (2009);
42 M. A. McGrath, et al., Aurora on Ganymede, J. Geophys. Res., 118, 2043-2054 (2013);
43 L. Roth, J. Saur, K. D. Retherford, D. F. Strobel, P. D. Feldman, A phenomenological model
for Io’s UV aurora based on HST/STIS observations, Icarus, 228, 386-406 (2014);
44 C. R. Proffitt, “Changes in the STIS FUVMAMA Dark Current”, (Space Telescope STIS
Instrument Science Report, Space Telescope Science Institute, 2007);
45 W. Curdt, et al., The SUMER spectral atlas of solar-disk features, Astronomy and
Astrophysics, 375, 591-613 (2001);
46 T. N. Woods, et al., Validation of the UARS solar ultraviolet irradiances: Comparison with
the ATLAS 1 and 2 measurements, J. Geophys. Res., 101(D6), 9541-9569 (1996);
47 T. N. Woods, et al., Solar EUV Experiment (SEE): Mission overview and first results, J.
Geophys. Res., 110(A1), A01312 (2005);
48 J. E. Krist, R. N. Hook, F. Stoehr, 20 years of Hubble Space Telescope optical modeling
using Tiny Tim, Society of Photo-Optical Instrumentation Engineers (SPIE) Conference
Series, 8127 (2011);
49 R. Greeley, et al., , Bagenal, F., T. E. Dowling and W.B. McKinnon (Cambridge Univ. Press,
2004), pp. 457-483;
50 R. L. Lucke, R. C. Henry, W. G. Fastie, Far-ultraviolet albedo of the moon, Astronom. J., 81,
1162-1169 (1976);
51 R. C. Henry, W. G Fastie, R. L. Lucke, B. Q. Hapke, B. W. A far-ultraviolet photometer for
planetary surface analysis. The moon, 15(1-2), 51-65 (1976);
52 J. P. Doering, E. E. Gulcicek, Absolute differential and integral electron excitation cross
sections for atomic oxygen. VII - The 3P-1D and 3P-1S transitions from 4.0 to 30 eV, J.
Geophys. Res., 94, 1541–1546 (1989);
53 J. P. Doering, E. E. Gulcicek, Absolute differential and integral electron excitation cross
sections for atomic oxygen. VIII - The 3P-5S0 transition (1356 Å) from 13.9 to 30 eV, J.
Geophys. Res., 94, 2733–2736 (1989);
54 J. P. Doering, Absolute differential and integral electron excitation cross sections for atomic
oxygen. IX - Improved cross section for the 3P-1D transition from 4.0 to 30 eV. J. Geophys.
Res., 97, 19531–19534 (1992);
55 I. Kanik, et al., Electron impact dissociative excitation of O2: 2. Absolute emission cross
sections of the OI(130.4 nm) and OI(135.6 nm) lines, J. Geophys. Res., 108, 5126 (2003);
56 P. V. Johnson, I. Kanik, D. E. Shemansky, X. Liu, Electron-impact cross sections of atomic
oxygen. J. of Physics B: Atomic, Molecular and Optical Physics, 36(15), 3203 (2003);
57 S. P. Sander, et al., “Chemical Kinetics and Photochemical Data for Use in Atmospheric
Studies, Evaluation No. 17” (JPL Publication 10-6, Jet Propulsion Laboratory, Pasadena,
2011);
58 K. Yoshino, W.H. Parkinson, K. Ito, T. Matsui, Absolute absorption cross-section
measurements of Schumann Runge continuum of O2 at 90 and 295 K, J. of Molecular
Spectroscopy, 229, 238-243 (2005);
9
10. 59 H.-C. Lu, K.-K. Chen, H.-F. Chen, B.-M. Cheng, J.F. Ogilvie, Absorption cross section of
molecular oxygen in the transition E 3Σu- v = 0 – X 3Σg- v = 0 at 38 K, Astronom. Astrophys.,
520 (2010);
60 T. Harb, W. Kedzierski, J. W. McConkey, Production of ground state OH following electron
impact on H2O, J. Chem. Phys., 115, 5507-5512 (2001);
61 J. S. Lee, R. R. Meier, Angle-dependent frequency redistribution in a plane-parallel medium
- External source case, Astroph. J., 240, 185-195 (1980);
62 D. C. Morton, Atomic data for resonance absorption lines. I - Wavelengths longward of the
Lyman limit, Astrophys. J. Suppl., 77, 119-202 (1991);
63 J. Marti, K. Mauersberger, A survey and new measurements of ice vapor pressure at
temperatures between 170 and 250K. Geophys. Res. Lett., 20(5), 363-366 (1993);
64 J. D. Goguen, et al., The temperature and width of an active fissure on Enceladus measured
with Cassini VIMS during the 14 April 2012 South Pole flyover, Icarus, 226(1), 1128-1137
(2013);
65 P. Schenk, J. Schmidt, O. White. The Snows of Enceladus. In EPSC-DPS Joint Meeting
2011, Vol. 1, 1358 (2011);
66 A. P. Ingersoll, A. A. Pankine, Subsurface heat transfer on Enceladus: Conditions under
which melting occurs. Icarus, 206(2), 594-607 (2010);
67 F. Nimmo, Stresses generated in cooling viscoelastic ice shells: Application to Europa, J.
Geophys. Res., 109(E12) (2004);
68 H. Hussmann, T. Spohn, Thermal-orbital evolution of Io and Europa. Icarus, 171(2), 391410 (2004);
69 A. P. Ingersoll, S. P. Ewald, Total particulate mass in Enceladus plumes and mass of Saturn’s
E ring inferred from Cassini ISS images. Icarus, 216(2), 492-506 (2011);
70 F. Nimmo, P. D. Thomas, R. T. Pappalardo, W. B. Moore, The global shape of Europa:
Constraints on lateral shell thickness variations. Icarus, 191(1), 183-192 (2007);
Acknowledgments: This work is based upon Hubble Space Telescope observations available at
the NASA MAST data archive. Support for program number GO-13040 was provided by NASA
through a grant from the Space Telescope Science Institute, which is operated by the Association
of Universities for Research in Astronomy, Inc., under contract NAS5-26555; and by
Verbundforschung Astronomie und Astrophysik.
Table 1. HST/STIS G140L observations of Europa’s UV emissions (a: PI McGrath, b: PI Saur)
Observation
start
date
and
time
HST
orbits/
ex-‐
posures
Total
exp.
time
[min]
Spatial
resolution
[km/pixel]
Sub-‐
observer
W
long.
[º]
System
III
longitude
[º]
Mag.
lat.
range
[º]
True
anomaly
f
[º]
Water
vapor
detected
5-‐Oct-‐1999
8:39
a
5
/
9
156
71.5
245
–
274
300
–
158
-‐9.5
–
6.8
343
–
13
No
8-‐Nov-‐2012
20:41
b
5
/
10
183
73.9
209
–
238
25
-‐
243
-‐9.3
–
9.5
289
-‐
318
No
30-‐Dec-‐2012
18:49
b
5
/
9
164
74.9
79
–
108
0
–
218
-‐9.5
–
9.5
185
-‐
218
Yes
10