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.
A highly magnetized twin-jet base pinpoints a supermassive black holeSérgio Sacani
Supermassive black holes (SMBH) are essential for the production of jets in radio-loud active galactic nuclei (AGN). Theoretical
models based on (Blandford & Znajek 1977, MNRAS, 179, 433) extract the rotational energy from a Kerr black hole, which could
be the case for NGC1052, to launch these jets. This requires magnetic fields on the order of 103 G to 104 G. We imaged the vicinity
of the SMBH of the AGN NGC1052 with the Global Millimetre VLBI Array and found a bright and compact central feature that is
smaller than 1.9 light days (100 Schwarzschild radii) in radius. Interpreting this as a blend of the unresolved jet bases, we derive the
magnetic field at 1 Schwarzschild radius to lie between 200 G and 8:3 104 G consistent with Blandford & Znajek models.
Galaxy dynamics and the mass density of the universeSérgio Sacani
Dynamical evidence accumulated over the
past 20 years has convinced astronomers that luminous matter
in a spiral galaxy constitutes no more than 10% of the mass of
a galaxy. An additional 90% is inferred by its gravitational
effect on luminous material. Here I review recent observations
concerning the distribution of luminous and nonluminous
matter in the Milky Way, in galaxies, and in galaxy clusters.
Observations of neutral hydrogen disks, some extending in
radius several times the optical disk, confirm that a massive
dark halo is a major component of virtually every spiral. A
recent surprise has been the discovery that stellar and gas
motions in ellipticals are enormously complex. To date, only for
a few spheroidal galaxies do the velocities extend far enough to
probe the outer mass distribution. But the diverse kinematics
of inner cores, peripheral to deducing the overall mass distribution,
offer additional evidence that ellipticals have acquired
gas-rich systems after initial formation. Dynamical results are
consistent with a low-density universe, in which the required
dark matter could be baryonic. On smallest scales of galaxies
[10 kiloparsec (kpc); H. = 50 kmsec'lmegaparsec'11 the
luminous matter constitutes only 1% of the closure density. On
scales greater than binary galaxies (i.e., .100 kpc) all systems
indicate a density -10% of the closure density, a density
consistent with the low baryon density in the universe. If
large-scale motions in the universe require a higher mass
density, these motions would constitute the first dynamical
evidence for nonbaryonic matter in a universe of higher
density.
PROBING FOR EVIDENCE OF PLUMES ON EUROPA WITH HST/STISSérgio Sacani
Roth et al. (2014a) reported evidence for plumes of water venting from a southern high latitude
region on Europa – spectroscopic detection of off-limb line emission from the dissociation
products of water. Here, we present Hubble Space Telescope (HST) direct images of Europa in
the far ultraviolet (FUV) as it transited the smooth face of Jupiter, in order to measure absorption
from gas or aerosols beyond the Europa limb. Out of ten observations we found three in which
plume activity could be implicated. Two show statistically significant features at latitudes similar
to Roth et al., and the third, at a more equatorial location. We consider potential systematic
effects that might influence the statistical analysis and create artifacts, and are unable to find any
that can definitively explain the features, although there are reasons to be cautious. If the
apparent absorption features are real, the magnitude of implied outgassing is similar to that of the
Roth et al. feature, however the apparent activity appears more frequently in our data.
The ASTRODEEP Frontier Fields catalogues II. Photometric redshifts and rest f...Sérgio Sacani
Aims. We present the first public release of photometric redshifts, galaxy rest frame properties and associated magnification values
in the cluster and parallel pointings of the first two Frontier Fields, Abell-2744 and MACS-J0416. The released catalogues aim to
provide a reference for future investigations of extragalactic populations in these legacy fields: from lensed high-redshift galaxies to
cluster members themselves.
Methods.We exploit a multiwavelength catalogue, ranging from Hubble Space Telescope (HST) to ground-based K and Spitzer IRAC,
which is specifically designed to enable detection and measurement of accurate fluxes in crowded cluster regions. The multiband
information is used to derive photometric redshifts and physical properties of sources detected either in the H-band image alone, or
from a stack of four WFC3 bands. To minimize systematics, median photometric redshifts are assembled from six dierent approaches
to photo-z estimates. Their reliability is assessed through a comparison with available spectroscopic samples. State-of-the-art lensing
models are used to derive magnification values on an object-by-object basis by taking into account sources positions and redshifts.
Results. We show that photometric redshifts reach a remarkable 3–5% accuracy. After accounting for magnification, the H-band
number counts are found to be in agreement at bright magnitudes with number counts from the CANDELS fields, while extending
the presently available samples to galaxies that, intrinsically, are as faint as H 32 33, thanks to strong gravitational lensing. The
Frontier Fields allow the galaxy stellar mass distribution to be probed, depending on magnification, at 0.5–1.5 dex lower masses with
respect to extragalactic wide fields, including sources at Mstar 107–108 M at z > 5. Similarly, they allow the detection of objects
with intrinsic star formation rates (SFRs) >1 dex lower than in the CANDELS fields reaching 0.1–1 M=yr at z 6–10.
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.
A highly magnetized twin-jet base pinpoints a supermassive black holeSérgio Sacani
Supermassive black holes (SMBH) are essential for the production of jets in radio-loud active galactic nuclei (AGN). Theoretical
models based on (Blandford & Znajek 1977, MNRAS, 179, 433) extract the rotational energy from a Kerr black hole, which could
be the case for NGC1052, to launch these jets. This requires magnetic fields on the order of 103 G to 104 G. We imaged the vicinity
of the SMBH of the AGN NGC1052 with the Global Millimetre VLBI Array and found a bright and compact central feature that is
smaller than 1.9 light days (100 Schwarzschild radii) in radius. Interpreting this as a blend of the unresolved jet bases, we derive the
magnetic field at 1 Schwarzschild radius to lie between 200 G and 8:3 104 G consistent with Blandford & Znajek models.
Galaxy dynamics and the mass density of the universeSérgio Sacani
Dynamical evidence accumulated over the
past 20 years has convinced astronomers that luminous matter
in a spiral galaxy constitutes no more than 10% of the mass of
a galaxy. An additional 90% is inferred by its gravitational
effect on luminous material. Here I review recent observations
concerning the distribution of luminous and nonluminous
matter in the Milky Way, in galaxies, and in galaxy clusters.
Observations of neutral hydrogen disks, some extending in
radius several times the optical disk, confirm that a massive
dark halo is a major component of virtually every spiral. A
recent surprise has been the discovery that stellar and gas
motions in ellipticals are enormously complex. To date, only for
a few spheroidal galaxies do the velocities extend far enough to
probe the outer mass distribution. But the diverse kinematics
of inner cores, peripheral to deducing the overall mass distribution,
offer additional evidence that ellipticals have acquired
gas-rich systems after initial formation. Dynamical results are
consistent with a low-density universe, in which the required
dark matter could be baryonic. On smallest scales of galaxies
[10 kiloparsec (kpc); H. = 50 kmsec'lmegaparsec'11 the
luminous matter constitutes only 1% of the closure density. On
scales greater than binary galaxies (i.e., .100 kpc) all systems
indicate a density -10% of the closure density, a density
consistent with the low baryon density in the universe. If
large-scale motions in the universe require a higher mass
density, these motions would constitute the first dynamical
evidence for nonbaryonic matter in a universe of higher
density.
PROBING FOR EVIDENCE OF PLUMES ON EUROPA WITH HST/STISSérgio Sacani
Roth et al. (2014a) reported evidence for plumes of water venting from a southern high latitude
region on Europa – spectroscopic detection of off-limb line emission from the dissociation
products of water. Here, we present Hubble Space Telescope (HST) direct images of Europa in
the far ultraviolet (FUV) as it transited the smooth face of Jupiter, in order to measure absorption
from gas or aerosols beyond the Europa limb. Out of ten observations we found three in which
plume activity could be implicated. Two show statistically significant features at latitudes similar
to Roth et al., and the third, at a more equatorial location. We consider potential systematic
effects that might influence the statistical analysis and create artifacts, and are unable to find any
that can definitively explain the features, although there are reasons to be cautious. If the
apparent absorption features are real, the magnitude of implied outgassing is similar to that of the
Roth et al. feature, however the apparent activity appears more frequently in our data.
The ASTRODEEP Frontier Fields catalogues II. Photometric redshifts and rest f...Sérgio Sacani
Aims. We present the first public release of photometric redshifts, galaxy rest frame properties and associated magnification values
in the cluster and parallel pointings of the first two Frontier Fields, Abell-2744 and MACS-J0416. The released catalogues aim to
provide a reference for future investigations of extragalactic populations in these legacy fields: from lensed high-redshift galaxies to
cluster members themselves.
Methods.We exploit a multiwavelength catalogue, ranging from Hubble Space Telescope (HST) to ground-based K and Spitzer IRAC,
which is specifically designed to enable detection and measurement of accurate fluxes in crowded cluster regions. The multiband
information is used to derive photometric redshifts and physical properties of sources detected either in the H-band image alone, or
from a stack of four WFC3 bands. To minimize systematics, median photometric redshifts are assembled from six dierent approaches
to photo-z estimates. Their reliability is assessed through a comparison with available spectroscopic samples. State-of-the-art lensing
models are used to derive magnification values on an object-by-object basis by taking into account sources positions and redshifts.
Results. We show that photometric redshifts reach a remarkable 3–5% accuracy. After accounting for magnification, the H-band
number counts are found to be in agreement at bright magnitudes with number counts from the CANDELS fields, while extending
the presently available samples to galaxies that, intrinsically, are as faint as H 32 33, thanks to strong gravitational lensing. The
Frontier Fields allow the galaxy stellar mass distribution to be probed, depending on magnification, at 0.5–1.5 dex lower masses with
respect to extragalactic wide fields, including sources at Mstar 107–108 M at z > 5. Similarly, they allow the detection of objects
with intrinsic star formation rates (SFRs) >1 dex lower than in the CANDELS fields reaching 0.1–1 M=yr at z 6–10.
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.
Mapping spiral structure on the far side of the Milky WaySérgio Sacani
Little is known about the portion of the Milky Way lying beyond the Galactic center at distances
of more than 9 kiloparsec from the Sun. These regions are opaque at optical wavelengths
because of absorption by interstellar dust, and distances are very large and hard to measure.
We report a direct trigonometric parallax distance of 20:4þ2:8
2:2 kiloparsec obtained with the Very
Long Baseline Array to a water maser source in a region of active star formation. These
measurements allow us to shed light on Galactic spiral structure by locating the ScutumCentaurus
spiral arm as it passes through the far side of the Milky Way and to validate a
kinematic method for determining distances in this region on the basis of transverse motions.
A kiloparsec scale_internal_shock_collision_in_the_jet_of_a_nearby_radio_galaxySérgio Sacani
Pesquisa feita com dados do Hubble mostram ondas de choque em colisão dentro dos chamados jatos extragalácticos emitidos pelos buracos negros supermassivos.
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.
Magnetic interaction of_a_super_cme_with_the_earths_magnetosphere_scenario_fo...Sérgio Sacani
Solar eruptions, known as Coronal Mass Ejections (CMEs), are
frequently observed on our Sun. Recent Kepler observations of super
ares
on G-type stars have implied that so called super-CMEs, possessing kinetic
energies 10 times of the most powerful CME event ever observed on the Sun,
could be produced with a frequency of 1 event per 800-2000 yr on solar-
like slowly rotating stars. We have performed a 3D time-dependent global
magnetohydrodynamic simulation of the magnetic interaction of such a CME
cloud with the Earth's magnetosphere. We calculated the global structure
of the perturbed magnetosphere and derive the latitude of the open-closed
magnetic eld boundary. We also estimated energy
uxes penetrating the
Earth's ionosphere and discuss the consequences of energetic particle
uxes
on biological systems on early Earth.
Mapping spiral structure on the far side of the Milky WaySérgio Sacani
Little is known about the portion of the Milky Way lying beyond the Galactic center at distances
of more than 9 kiloparsec from the Sun. These regions are opaque at optical wavelengths
because of absorption by interstellar dust, and distances are very large and hard to measure.
We report a direct trigonometric parallax distance of 20:4þ2:8
2:2 kiloparsec obtained with the Very
Long Baseline Array to a water maser source in a region of active star formation. These
measurements allow us to shed light on Galactic spiral structure by locating the ScutumCentaurus
spiral arm as it passes through the far side of the Milky Way and to validate a
kinematic method for determining distances in this region on the basis of transverse motions.
A kiloparsec scale_internal_shock_collision_in_the_jet_of_a_nearby_radio_galaxySérgio Sacani
Pesquisa feita com dados do Hubble mostram ondas de choque em colisão dentro dos chamados jatos extragalácticos emitidos pelos buracos negros supermassivos.
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.
Magnetic interaction of_a_super_cme_with_the_earths_magnetosphere_scenario_fo...Sérgio Sacani
Solar eruptions, known as Coronal Mass Ejections (CMEs), are
frequently observed on our Sun. Recent Kepler observations of super
ares
on G-type stars have implied that so called super-CMEs, possessing kinetic
energies 10 times of the most powerful CME event ever observed on the Sun,
could be produced with a frequency of 1 event per 800-2000 yr on solar-
like slowly rotating stars. We have performed a 3D time-dependent global
magnetohydrodynamic simulation of the magnetic interaction of such a CME
cloud with the Earth's magnetosphere. We calculated the global structure
of the perturbed magnetosphere and derive the latitude of the open-closed
magnetic eld boundary. We also estimated energy
uxes penetrating the
Earth's ionosphere and discuss the consequences of energetic particle
uxes
on biological systems on early Earth.
Chandra deep observation_of_xdcpj004402033_a_massive_galaxy_cluster_at_z_1_5Sérgio Sacani
Artigo apresenta os resultados obtidos pelo Chandra ao medir com precisão a massa do mais massivo aglomerado de galáxias do universo distante, o Aglomerado Gioiello.
Triple Spiral Arms of a Triple Protostar System Imaged in Molecular LinesSérgio Sacani
Most stars form in multiple-star systems. For a better understanding of their formation processes, it is important to
resolve the individual protostellar components and the surrounding envelope and disk material at the earliest
possible formation epoch, because the formation history can be lost in a few orbital timescales. Here we present
Atacama Large Millimeter/submillimeter Array observational results of a young multiple protostellar system,
IRAS 04239+2436, where three well-developed large spiral arms were detected in the shocked SO emission.
Along the most conspicuous arm, the accretion streamer was also detected in the SO2 emission. The observational
results are complemented by numerical magnetohydrodynamic simulations, where those large arms only appear in
magnetically weakened clouds. Numerical simulations also suggest that the large triple spiral arms are the result of
gravitational interactions between compact triple protostars and the turbulent infalling envelope.
Fleeting Small-scale Surface Magnetic Fields Build the Quiet-Sun CoronaSérgio Sacani
Arch-like loop structures filled with million Kelvin hot plasma form the building blocks of the quiet-Sun corona.
Both high-resolution observations and magnetoconvection simulations show the ubiquitous presence of magnetic
fields on the solar surface on small spatial scales of ∼100 km. However, the question of how exactly these quietSun coronal loops originate from the photosphere and how the magnetic energy from the surface is channeled to
heat the overlying atmosphere is a long-standing puzzle. Here we report high-resolution photospheric magnetic
field and coronal data acquired during the second science perihelion of Solar Orbiter that reveal a highly dynamic
magnetic landscape underlying the observed quiet-Sun corona. We found that coronal loops often connect to
surface regions that harbor fleeting weaker, mixed-polarity magnetic field patches structured on small spatial
scales, and that coronal disturbances could emerge from these areas. We suggest that weaker magnetic fields with
fluxes as low as 1015 Mx and/or those that evolve on timescales less than 5 minutes are crucial to understanding
the coronal structuring and dynamics.
ALMA Observations of the Extraordinary Carina Pillars: A Complementary SampleSérgio Sacani
We present a study of six dusty and gaseous pillars (containing the HH 1004 and HH 1010 objects)
and globules (that contain the HH 666, HH 900, HH 1006, and HH 1066 objects) localized in the Carina
nebula using sensitive and high angular resolution (∼0.3′′) Atacama Large Millimeter/Sub-millimeter
Array (ALMA) observations. This is a more extensive study that the one presented in Cortes-Rangel
et al. (2020). As in this former study, we also analyzed the 1.3 mm continuum emission and C18O(2−1),
N2D+(3−2) and 12CO(2−1) spectral lines. These new observations revealed the molecular outflows
emanating from the pillars, the dusty envelopes+disks that are exciting them, and the extended HH
objects far from their respective pillars. We reveal that the masses of the disks+envelopes are in a
range of 0.02 to 0.38 M⊙, and those for the molecular outflows are of the order of 10−3 M⊙, which
suggests that their exciting sources might be low- or intermediate-mass protostars as already revealed
in recent studies at infrared and submillimeter bands. In the regions associated with the objects HH
900 and HH 1004, we report multiple millimeter continuum sources, from where several molecular
outflows emanate.
X-Ray Properties of NGC 253ʼs Starburst-driven OutflowSérgio Sacani
We analyze image and spectral data from ≈365 ks of observations from the Chandra X-ray Observatory of the
nearby, edge-on starburst galaxy NGC 253 to constrain properties of the hot phase of the outflow. We focus our
analysis on the −1.1 to +0.63 kpc region of the outflow and define several regions for spectral extraction where we
determine best-fit temperatures and metal abundances. We find that the temperatures and electron densities peak in
the central ∼250 pc region of the outflow and decrease with distance. These temperature and density profiles are in
disagreement with an adiabatic spherically expanding starburst wind model and suggest the presence of additional
physics such as mass loading and nonspherical outflow geometry. Our derived temperatures and densities yield
cooling times in the nuclear region of a few million years, which may imply that the hot gas can undergo bulk
radiative cooling as it escapes along the minor axis. Our metal abundances of O, Ne, Mg, Si, S, and Fe all peak in
the central region and decrease with distance along the outflow, with the exception of Ne, which maintains a flat
distribution. The metal abundances indicate significant dilution outside of the starburst region. We also find
estimates of the mass outflow rates, which are 2.8 Me yr−1 in the northern outflow and 3.2 Me yr−1 in the southern
outflow. Additionally, we detect emission from charge exchange and find it makes a significant contribution (20%–
42%) to the total broadband (0.5–7 keV) X-ray emission in the central and southern regions of the outflow.
Todo mundo sabe que os raios produzidos pela Estrela da Morte em Guerra nas Estrelas não pode existir na vida real, porém no universo existem fenômenos que as vezes conseguem superar até a mais surpreendente ficção.
A galáxia Pictor A, é um desses objetos que possuem fenômenos tão espetaculares quanto aqueles exibidos no cinema. Essa galáxia localiza-se a cerca de 500 milhões de anos-luz da Terra e possui um buraco negro supermassivo no seu centro. Uma grande quantidade de energia gravitacional é lançada, à medida que o material cai em direção ao horizonte de eventos, o ponto sem volta ao redor do buraco negro. Essa energia produz um enorme jato de partículas que viajam a uma velocidade próxima da velocidade da luz no espaço intergaláctico, chamado de jato relativístico.
Para obter imagens desse jato, os cientistas usaram o Observatório de Raios-X Chandra, da NASA várias vezes durante 15 anos. Os dados do Chandra, apresentados em azul nas imagens, foram combinados com os dados obtidos em ondas de rádio a partir do Australia Telescope Compact Array, e são aparesentados em vermelho nas imagens.
We present long-baseline Atacama Large Millimeter/submillimeter Array (ALMA) observations of
the 870 m continuum emission from the nearest gas-rich protoplanetary disk, around TW Hya, that
trace millimeter-sized particles down to spatial scales as small as 1 AU (20 mas). These data reveal
a series of concentric ring-shaped substructures in the form of bright zones and narrow dark annuli
(1{6AU) with modest contrasts (5{30%). We associate these features with concentrations of solids
that have had their inward radial drift slowed or stopped, presumably at local gas pressure maxima.
No signicant non-axisymmetric structures are detected. Some of the observed features occur near
temperatures that may be associated with the condensation fronts of major volatile species, but the
relatively small brightness contrasts may also be a consequence of magnetized disk evolution (the
so-called zonal
ows). Other features, particularly a narrow dark annulus located only 1 AU from the
star, could indicate interactions between the disk and young planets. These data signal that ordered
substructures on AU scales can be common, fundamental factors in disk evolution, and that high
resolution microwave imaging can help characterize them during the epoch of planet formation.
Keywords: protoplanetary disks | planet-disk interactions | stars: individual (TW Hydrae)
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.
A giant galaxy in the young Universe with a massive ringSérgio Sacani
In the local (redshift z ≈ 0) Universe, collisional ring galaxies make up only ~0.01% of galaxies1 and are formed by head-on galactic collisions that trigger radially propagating density waves2–4. These striking systems provide key snapshots for dissecting galactic disks and are studied extensively in the local Universe5–9. However, not much is known about distant (z > 0.1) collisional rings10–14. Here we present a detailed study of a ring galaxy at a look-back time of 10.8 Gyr (z = 2.19). Compared with our Milky Way, this galaxy has a similar stellar mass, but has a stellar half-light radius that is 1.5–2.2 times larger and is forming stars 50 times faster. The extended, dif- fuse stellar light outside the star-forming ring, combined with a radial velocity on the ring and an intruder galaxy nearby, provides evidence for this galaxy hosting a collisional ring. If the ring is secularly evolved15,16, the implied large bar in a giant disk would be inconsistent with the current understand- ing of the earliest formation of barred spirals17–21. Contrary to previous predictions10–12, this work suggests that massive col- lisional rings were as rare 11 Gyr ago as they are today. Our discovery offers a unique pathway for studying density waves in young galaxies, as well as constraining the cosmic evolution of spiral disks and galaxy groups.
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.
A dust-enshrouded tidal disruption event with a resolved radio jet in a galax...Sérgio Sacani
Tidal disruption events (TDEs) are transient flares produced when a star is ripped apart by the
gravitational field of a supermassive black hole (SMBH). We have observed a transient source in the
western nucleus of the merging galaxy pair Arp 299 that radiated >1.5 × 1052 erg in the infrared and radio
but was not luminous at optical or x-ray wavelengths. We interpret this as a TDE with much of its emission
reradiated at infrared wavelengths by dust. Efficient reprocessing by dense gas and dust may explain the
difference between theoretical predictions and observed luminosities of TDEs. The radio observations
resolve an expanding and decelerating jet, probing the jet formation and evolution around a SMBH.
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.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Sérgio Sacani
Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the
atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets
receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric
composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet
transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (Porb) of 12.76 days.
The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous Porb from TESS data. We
confirmed the transit signal and Porb using ground-based photometry with MuSCAT2 and MuSCAT3, and
validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as
well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope
and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host
star is inactive, with an X-ray-to-bolometric luminosity ratio of log 5.7 L L X bol » - . Joint analysis of the light
curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R⊕,a3σ mass upper limit of
3.9 M⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric
(TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small
list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.
Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TES...Sérgio Sacani
We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a
bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the
lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors
42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations
with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory,
as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of
12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent
future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar
compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool
stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
The importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox
(1) by adding two additional terms to the Drake Equation: foc
(the fraction of habitable exoplanets
with significant continents and oceans) and fpt
(the fraction of habitable exoplanets with significant
continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by
demonstrating that the product of foc
and fpt
is very small (< 0.00003–0.002). We propose that the lack
of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on
exoplanets with primitive life.
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. Itremains enigmatic how subduction could be initiated so soon after the presumably Moon‐forming giant impact(MGI). Earlier studies found an increase in Earth's core‐mantle boundary (CMB) temperature due to theaccumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, withsome of the impactor's mantle potentially surviving as the large low‐shear velocity provinces (LLSVPs). Here,we show that a hot post‐impact CMB drives the initiation of strong mantle plumes that can induce subductioninitiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMBtemperature is the primary factor triggering early subduction, with enrichment of heat‐producing elements inLLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications forunderstanding the diverse tectonic regimes of rocky planets.
Climate extremes likely to drive land mammal extinction during next supercont...Sérgio Sacani
Mammals have dominated Earth for approximately 55 Myr thanks to their
adaptations and resilience to warming and cooling during the Cenozoic. All
life will eventually perish in a runaway greenhouse once absorbed solar
radiation exceeds the emission of thermal radiation in several billions of
years. However, conditions rendering the Earth naturally inhospitable to
mammals may develop sooner because of long-term processes linked to
plate tectonics (short-term perturbations are not considered here). In
~250 Myr, all continents will converge to form Earth’s next supercontinent,
Pangea Ultima. A natural consequence of the creation and decay of Pangea
Ultima will be extremes in pCO2 due to changes in volcanic rifting and
outgassing. Here we show that increased pCO2, solar energy (F⨀;
approximately +2.5% W m−2 greater than today) and continentality (larger
range in temperatures away from the ocean) lead to increasing warming
hostile to mammalian life. We assess their impact on mammalian
physiological limits (dry bulb, wet bulb and Humidex heat stress indicators)
as well as a planetary habitability index. Given mammals’ continued survival,
predicted background pCO2 levels of 410–816 ppm combined with increased
F⨀ will probably lead to a climate tipping point and their mass extinction.
The results also highlight how global landmass configuration, pCO2 and F⨀
play a critical role in planetary habitability.
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Sérgio Sacani
The recently reported observation of VFTS 243 is the first example of a massive black-hole binary
system with negligible binary interaction following black-hole formation. The black-hole mass (≈10M⊙)
and near-circular orbit (e ≈ 0.02) of VFTS 243 suggest that the progenitor star experienced complete
collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to
constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence
level, the natal kick velocity (mass decrement) is ≲10 km=s (≲1.0M⊙), with a full probability distribution
that peaks when ≈0.3M⊙ were ejected, presumably in neutrinos, and the black hole experienced a natal
kick of 4 km=s. The neutrino-emission asymmetry is ≲4%, with best fit values of ∼0–0.2%. Such a small
neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions.
Detectability of Solar Panels as a TechnosignatureSérgio Sacani
In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like
exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the
UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept
like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide
the 2022 human energy needs with a land cover of ∼ 2.4%, and projecting the future energy demand
assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope.
Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the
ultraviolet-to-visible (0.34 − 0.52 µm), we find that several 100s of hours of observation time is needed
to reach a SNR of 5 for an Earth-like planet around a Sun-like star at 10pc, even with a solar panel
coverage of ∼ 23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev
Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even
with much larger populations than today, the total energy use of human civilization would be orders of
magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev
Type I civilization. Any extraterrrestrial civilization that likewise achieves sustainable population
levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization
as imagined in the Fermi paradox may not exist.
Jet reorientation in central galaxies of clusters and groups: insights from V...Sérgio Sacani
Recent observations of galaxy clusters and groups with misalignments between their central AGN jets
and X-ray cavities, or with multiple misaligned cavities, have raised concerns about the jet – bubble
connection in cooling cores, and the processes responsible for jet realignment. To investigate the
frequency and causes of such misalignments, we construct a sample of 16 cool core galaxy clusters and
groups. Using VLBA radio data we measure the parsec-scale position angle of the jets, and compare
it with the position angle of the X-ray cavities detected in Chandra data. Using the overall sample
and selected subsets, we consistently find that there is a 30% – 38% chance to find a misalignment
larger than ∆Ψ = 45◦ when observing a cluster/group with a detected jet and at least one cavity. We
determine that projection may account for an apparently large ∆Ψ only in a fraction of objects (∼35%),
and given that gas dynamical disturbances (as sloshing) are found in both aligned and misaligned
systems, we exclude environmental perturbation as the main driver of cavity – jet misalignment.
Moreover, we find that large misalignments (up to ∼ 90◦
) are favored over smaller ones (45◦ ≤ ∆Ψ ≤
70◦
), and that the change in jet direction can occur on timescales between one and a few tens of Myr.
We conclude that misalignments are more likely related to actual reorientation of the jet axis, and we
discuss several engine-based mechanisms that may cause these dramatic changes.
The solar dynamo begins near the surfaceSérgio Sacani
The magnetic dynamo cycle of the Sun features a distinct pattern: a propagating
region of sunspot emergence appears around 30° latitude and vanishes near the
equator every 11 years (ref. 1). Moreover, longitudinal flows called torsional oscillations
closely shadow sunspot migration, undoubtedly sharing a common cause2. Contrary
to theories suggesting deep origins of these phenomena, helioseismology pinpoints
low-latitude torsional oscillations to the outer 5–10% of the Sun, the near-surface
shear layer3,4. Within this zone, inwardly increasing differential rotation coupled with
a poloidal magnetic field strongly implicates the magneto-rotational instability5,6,
prominent in accretion-disk theory and observed in laboratory experiments7.
Together, these two facts prompt the general question: whether the solar dynamo is
possibly a near-surface instability. Here we report strong affirmative evidence in stark
contrast to traditional models8 focusing on the deeper tachocline. Simple analytic
estimates show that the near-surface magneto-rotational instability better explains
the spatiotemporal scales of the torsional oscillations and inferred subsurface
magnetic field amplitudes9. State-of-the-art numerical simulations corroborate these
estimates and reproduce hemispherical magnetic current helicity laws10. The dynamo
resulting from a well-understood near-surface phenomenon improves prospects
for accurate predictions of full magnetic cycles and space weather, affecting the
electromagnetic infrastructure of Earth.
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...Sérgio Sacani
In the Nice model of solar system formation, Uranus and Neptune undergo an orbital upheaval,
sweeping through a planetesimal disk. The region of the disk from which material is accreted by
the ice giants during this phase of their evolution has not previously been identified. We perform
direct N-body orbital simulations of the four giant planets to determine the amount and origin of solid
accretion during this orbital upheaval. We find that the ice giants undergo an extreme bombardment
event, with collision rates as much as ∼3 per hour assuming km-sized planetesimals, increasing the
total planet mass by up to ∼0.35%. In all cases, the initially outermost ice giant experiences the
largest total enhancement. We determine that for some plausible planetesimal properties, the resulting
atmospheric enrichment could potentially produce sufficient latent heat to alter the planetary cooling
timescale according to existing models. Our findings suggest that substantial accretion during this
phase of planetary evolution may have been sufficient to impact the atmospheric composition and
thermal evolution of the ice giants, motivating future work on the fate of deposited solid material.
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...Sérgio Sacani
The highest priority recommendation of the Astro2020 Decadal Survey for space-based astronomy
was the construction of an observatory capable of characterizing habitable worlds. In this paper series
we explore the detectability of and interference from exomoons and exorings serendipitously observed
with the proposed Habitable Worlds Observatory (HWO) as it seeks to characterize exoplanets, starting
in this manuscript with Earth-Moon analog mutual events. Unlike transits, which only occur in systems
viewed near edge-on, shadow (i.e., solar eclipse) and lunar eclipse mutual events occur in almost every
star-planet-moon system. The cadence of these events can vary widely from ∼yearly to multiple events
per day, as was the case in our younger Earth-Moon system. Leveraging previous space-based (EPOXI)
lightcurves of a Moon transit and performance predictions from the LUVOIR-B concept, we derive
the detectability of Moon analogs with HWO. We determine that Earth-Moon analogs are detectable
with observation of ∼2-20 mutual events for systems within 10 pc, and larger moons should remain
detectable out to 20 pc. We explore the extent to which exomoon mutual events can mimic planet
features and weather. We find that HWO wavelength coverage in the near-IR, specifically in the 1.4 µm
water band where large moons can outshine their host planet, will aid in differentiating exomoon signals
from exoplanet variability. Finally, we predict that exomoons formed through collision processes akin
to our Moon are more likely to be detected in younger systems, where shorter orbital periods and
favorable geometry enhance the probability and frequency of mutual events.
Emergent ribozyme behaviors in oxychlorine brines indicate a unique niche for...Sérgio Sacani
Mars is a particularly attractive candidate among known astronomical objects
to potentially host life. Results from space exploration missions have provided
insights into Martian geochemistry that indicate oxychlorine species, particularly perchlorate, are ubiquitous features of the Martian geochemical landscape. Perchlorate presents potential obstacles for known forms of life due to
its toxicity. However, it can also provide potential benefits, such as producing
brines by deliquescence, like those thought to exist on present-day Mars. Here
we show perchlorate brines support folding and catalysis of functional RNAs,
while inactivating representative protein enzymes. Additionally, we show
perchlorate and other oxychlorine species enable ribozyme functions,
including homeostasis-like regulatory behavior and ribozyme-catalyzed
chlorination of organic molecules. We suggest nucleic acids are uniquely wellsuited to hypersaline Martian environments. Furthermore, Martian near- or
subsurface oxychlorine brines, and brines found in potential lifeforms, could
provide a unique niche for biomolecular evolution.
Continuum emission from within the plunging region of black hole discsSérgio Sacani
The thermal continuum emission observed from accreting black holes across X-ray bands has the potential to be leveraged as a
powerful probe of the mass and spin of the central black hole. The vast majority of existing ‘continuum fitting’ models neglect
emission sourced at and within the innermost stable circular orbit (ISCO) of the black hole. Numerical simulations, however,
find non-zero emission sourced from these regions. In this work, we extend existing techniques by including the emission
sourced from within the plunging region, utilizing new analytical models that reproduce the properties of numerical accretion
simulations. We show that in general the neglected intra-ISCO emission produces a hot-and-small quasi-blackbody component,
but can also produce a weak power-law tail for more extreme parameter regions. A similar hot-and-small blackbody component
has been added in by hand in an ad hoc manner to previous analyses of X-ray binary spectra. We show that the X-ray spectrum
of MAXI J1820+070 in a soft-state outburst is extremely well described by a full Kerr black hole disc, while conventional
models that neglect intra-ISCO emission are unable to reproduce the data. We believe this represents the first robust detection of
intra-ISCO emission in the literature, and allows additional constraints to be placed on the MAXI J1820 + 070 black hole spin
which must be low a• < 0.5 to allow a detectable intra-ISCO region. Emission from within the ISCO is the dominant emission
component in the MAXI J1820 + 070 spectrum between 6 and 10 keV, highlighting the necessity of including this region. Our
continuum fitting model is made publicly available.
WASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 RpSérgio Sacani
Studying the escaping atmospheres of highly irradiated exoplanets is critical for understanding the physical
mechanisms that shape the demographics of close-in planets. A number of planetary outflows have been observed
as excess H/He absorption during/after transit. Such an outflow has been observed for WASP-69b by multiple
groups that disagree on the geometry and velocity structure of the outflow. Here, we report the detection of this
planet’s outflow using Keck/NIRSPEC for the first time. We observed the outflow 1.28 hr after egress until the
target set, demonstrating the outflow extends at least 5.8 × 105 km or 7.5 Rp This detection is significantly longer
than previous observations, which report an outflow extending ∼2.2 planet radii just 1 yr prior. The outflow is
blueshifted by −23 km s−1 in the planetary rest frame. We estimate a current mass-loss rate of 1 M⊕ Gyr−1
. Our
observations are most consistent with an outflow that is strongly sculpted by ram pressure from the stellar wind.
However, potential variability in the outflow could be due to time-varying interactions with the stellar wind or
differences in instrumental precision.
X-rays from a Central “Exhaust Vent” of the Galactic Center ChimneySérgio Sacani
Using deep archival observations from the Chandra X-ray Observatory, we present an analysis of
linear X-ray-emitting features located within the southern portion of the Galactic center chimney,
and oriented orthogonal to the Galactic plane, centered at coordinates l = 0.08◦
, b = −1.42◦
. The
surface brightness and hardness ratio patterns are suggestive of a cylindrical morphology which may
have been produced by a plasma outflow channel extending from the Galactic center. Our fits of the
feature’s spectra favor a complex two-component model consisting of thermal and recombining plasma
components, possibly a sign of shock compression or heating of the interstellar medium by outflowing
material. Assuming a recombining plasma scenario, we further estimate the cooling timescale of this
plasma to be on the order of a few hundred to thousands of years, leading us to speculate that a
sequence of accretion events onto the Galactic Black Hole may be a plausible quasi-continuous energy
source to sustain the observed morphology
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
ESR spectroscopy in liquid food and beverages.pptxPRIYANKA PATEL
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
The use of Nauplii and metanauplii artemia in aquaculture (brine shrimp).pptxMAGOTI ERNEST
Although Artemia has been known to man for centuries, its use as a food for the culture of larval organisms apparently began only in the 1930s, when several investigators found that it made an excellent food for newly hatched fish larvae (Litvinenko et al., 2023). As aquaculture developed in the 1960s and ‘70s, the use of Artemia also became more widespread, due both to its convenience and to its nutritional value for larval organisms (Arenas-Pardo et al., 2024). The fact that Artemia dormant cysts can be stored for long periods in cans, and then used as an off-the-shelf food requiring only 24 h of incubation makes them the most convenient, least labor-intensive, live food available for aquaculture (Sorgeloos & Roubach, 2021). The nutritional value of Artemia, especially for marine organisms, is not constant, but varies both geographically and temporally. During the last decade, however, both the causes of Artemia nutritional variability and methods to improve poorquality Artemia have been identified (Loufi et al., 2024).
Brine shrimp (Artemia spp.) are used in marine aquaculture worldwide. Annually, more than 2,000 metric tons of dry cysts are used for cultivation of fish, crustacean, and shellfish larva. Brine shrimp are important to aquaculture because newly hatched brine shrimp nauplii (larvae) provide a food source for many fish fry (Mozanzadeh et al., 2021). Culture and harvesting of brine shrimp eggs represents another aspect of the aquaculture industry. Nauplii and metanauplii of Artemia, commonly known as brine shrimp, play a crucial role in aquaculture due to their nutritional value and suitability as live feed for many aquatic species, particularly in larval stages (Sorgeloos & Roubach, 2021).
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
Salas, V. (2024) "John of St. Thomas (Poinsot) on the Science of Sacred Theol...Studia Poinsotiana
I Introduction
II Subalternation and Theology
III Theology and Dogmatic Declarations
IV The Mixed Principles of Theology
V Virtual Revelation: The Unity of Theology
VI Theology as a Natural Science
VII Theology’s Certitude
VIII Conclusion
Notes
Bibliography
All the contents are fully attributable to the author, Doctor Victor Salas. Should you wish to get this text republished, get in touch with the author or the editorial committee of the Studia Poinsotiana. Insofar as possible, we will be happy to broker your contact.
Remote Sensing and Computational, Evolutionary, Supercomputing, and Intellige...University of Maribor
Slides from talk:
Aleš Zamuda: Remote Sensing and Computational, Evolutionary, Supercomputing, and Intelligent Systems.
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Inter-Society Networking Panel GRSS/MTT-S/CIS Panel Session: Promoting Connection and Cooperation
https://www.etran.rs/2024/en/home-english/
Toxic effects of heavy metals : Lead and Arsenicsanjana502982
Heavy metals are naturally occuring metallic chemical elements that have relatively high density, and are toxic at even low concentrations. All toxic metals are termed as heavy metals irrespective of their atomic mass and density, eg. arsenic, lead, mercury, cadmium, thallium, chromium, etc.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
ANAMOLOUS SECONDARY GROWTH IN DICOT ROOTS.pptxRASHMI M G
Abnormal or anomalous secondary growth in plants. It defines secondary growth as an increase in plant girth due to vascular cambium or cork cambium. Anomalous secondary growth does not follow the normal pattern of a single vascular cambium producing xylem internally and phloem externally.
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
and analysis methods, numerous infrastructure platforms have been developed for phenotyping.
1. A&A 570, L14 (2014)
DOI: 10.1051/0004-6361/201425029
c ESO 2014
Astronomy
Astrophysics
Letter to the Editor
The wonderful complexity of the Mira AB system
S. Ramstedt1, S. Mohamed2,W. H. T. Vlemmings3, M. Maercker3, R. Montez4, A. Baudry5, E. De Beck3,
M. Lindqvist3, H. Olofsson3, E. M. L. Humphreys6, A. Jorissen7, F. Kerschbaum8, A. Mayer8, M. Wittkowski6,
N. L. J. Cox9, E. Lagadec10, M. L. Leal-Ferreira11, C. Paladini7, A. Pérez-Sánchez12, and S. Sacuto1
1 Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
e-mail: sofia.ramstedt@physics.uu.se
2 South African Astronomical Observatory, PO box 9, 7935 Observatory, South Africa
3 Dept. of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden
4 Department of Physics Astronomy, Vanderbilt University, Nashville, TN, USA
5 Univ. Bordeaux, LAB, UMR 5804, 33270 Floirac, France
6 ESO, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
7 Institut d’Astronomie et d’Astrophysique, Université Libre de Bruxelles, CP 226, Boulevard du Triomphe, 1050 Brussels, Belgium
8 Dept. of Astrophysics, Univ. of Vienna, Türkenschanzstr. 17, 1180 Vienna, Austria
9 Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan, 200D, 3001 Leuven, Belgium
10 Laboratoire Lagrange, UMR7293, Univ. Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d’Azur, 06300 Nice, France
11 Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
12 Centro de Radioastronomía y Astrofísica, Univ. Nacional Autónoma de Mexico, PO Box 3-72, 58090 Morelia, Mexico
Received 18 September 2014 / Accepted 3 October 2014
ABSTRACT
We have mapped the 12CO(3–2) line emission around the Mira AB system at 0.5 resolution using the Atacama Large
Millimeter/submillimeter Array (ALMA). The CO map shows amazing complexity. The circumstellar gas has been shaped by dif-ferent
dynamical actors during the evolution of the system, and several morphological components can be identified. The companion
is marginally resolved in continuum emission and is currently at 0.487 ± 0.006 separation. In the main line component, centered
on the stellar velocity, spiral arcs around Mira A are found. The spiral appears to be relatively flat and oriented in the orbital plane.
An accretion wake behind the companion is clearly visible, and the projected arc separation is about 5 . In the blue wing of the
line emission, offset from the main line, several large (∼5–10) opposing arcs are found. We tentatively suggest that this structure is
created by the wind of Mira B blowing a bubble in the expanding envelope of Mira A.
Key words. stars: AGB and post-AGB – binaries: symbiotic – circumstellar matter – submillimeter: stars
1. Introduction
The Mira AB system is well-studied and nearby (the parallax
distance is 92 pc, van Leeuwen 2007). It is a regularly pulsat-ing
M-type AGB star with a companion detected at 0. 6 sepa-ration
(Karovska et al. 1997). The latest calculation of the or-bit
(Prieur et al. 2002) gives an inclination of 112◦, an orbital
period of ∼500 yr, and the current separation is expected to
be ∼0. 5 with a position angle of ∼100◦. The mass-loss rate from
Mira A is estimated to a few times 10−7 M yr−1 (e.g., Knapp
et al. 1998; Ryde Schöier 2001, without taking the asymme-tries
of the wind into account) and CO gas emission is detected
with local-standard-of-rest (lsr) velocities from 37 to 54 kms−1,
which indicates a relatively low wind velocity (∼5 kms−1).
Several imaging studies have already shown the morpholog-ical
intricacy of the circumstellar material on different scales.
GALEX images revealed how interaction with the interstellar
medium (ISM) has created a 2◦ tail and a bowshock ∼3 south of
the system (Martin et al. 2007). They also show a series of knots
on a 10-scale, later studied in Hα (Meaburn et al. 2009), and
referred to as the north and south stream. The streams are tilted
relative to the plane of the sky by 69◦ with the north part receding
Appendix A is available in electronic form at
http://www.aanda.org
and the south approaching. On a somewhat smaller scale (∼5),
Herschel/PACS imaged the cold dust (Mayer et al. 2011). The
PACS images show the complex circumstellar dust distribution
with several large arcs surrounding the system. Previous images
of the CO emission show a wide bipolar structure with the north
part approaching and the south receding (Planesas et al. 1990;
Josselin et al. 2000; Fong et al. 2006), that is perpendicular to the
north and south stream. The higher resolution (2. 5) map shows
a 20 butterfly shape where the molecular emission is believed
to have been shaped by a low-velocity atomic outflow (Josselin
et al. 2000). HST images first resolved the two stars and showed
material flowing from Mira A to B (Karovska et al. 1997). This
overflow was later confirmed by the Chandra X-ray image that
shows a weak bridge between the two components (Karovska
et al. 2005). It has been suggested that the accretion generates a
wind fromMira B, which is confirmed by the P-Cygni profile of
its strong Mg II k line (e.g.,Wood Karovska 2006). The wind
is variable with mass-loss rates ranging from 5 × 10−13 M yr−1
to 1×10−11 M yr−1, and with terminal wind velocities observed
between 250 km s−1 and 450 km s−1.
We have mapped the CO(3–2) line emission around the sys-tem
with considerably higher spatial resolution than previous ob-servations
(∼0. 5). In Sect. 2, we present the observations. In
Sect. 3, the results are shown and interpreted. In Sect. 4, the
Article published by EDP Sciences L14, page 1 of 6
2. AA 570, L14 (2014)
morphology is set into the context created by previous obser-vations,
and possible shaping scenarios are discussed.
2. Observations
Mira was observed on 25 February 2014 with 27, and
on 3 May 2014 with 30 of the main array 12m antennas. It
was also observed with seven Atacama Compact Array (ACA)
7m antennas on 8 October 2013. The main array observations
consist of a ten-point mosaic covering an area of ∼25 × 25.
The same area is covered with three mosaic pointings with
the ACA. The observations have four spectral windows with
a width of 1.875 GHz (main array) and 2 GHz (ACA) cen-tered
on 331, 333, 343, and 345 GHz. The resulting spectral
resolution is 0.488 MHz (∼0.42km s−1) for the main array and
ACA. The total time on source is 6.25 min with the main array
and 6 min with the ACA. The baseline length of the main ar-ray
ranges from 13 to 450 m, from which we find a maximum
recoverable scale (MRS) of ∼6. The ACA covers 9 to 45m
baselines, and the MRS is ∼9. Calibration on the separate data
sets was carried out using CASA, following standard proce-dures,
using the quasar J0217+0144 as complex gain calibra-tor,
quasars J0423-0120 and J006-0623 as bandpass calibrators,
and Ganymede, Uranus and the quasar J0334-401 as flux cal-ibrators.
The data were subsequently combined, weighing the
ACA data down by a factor of 0.3 to account for the lower sen-sitivity
of the 7m antennas. Tests indicate that the exact weight
does not affect our results. A continuum image was made using
the emission free channels from all spectral windows. Because
the continuum emission is sufficiently strong, this image was
used for self-calibration. After applying the self-calibration, fi-nal
imaging was done after subtracting the continuum and av-eraging
over two channels to ∼0.85km s−1 spectral resolution.
The images have a beam full width half maximum (FWHM)
of 0. 576 × 0. 403 and reach an rms noise of 23 mJy/beam in
the emission-free channels.
3. Results
3.1. Continuum emission and current positions
The binary pair is marginally resolved when imaged in the con-tinuum
channels of the data (Fig. 2). The current positions de-termined
by uv fitting (Martí-Vidal et al. 2014) are given in
Table 1 together with the measured flux density at 338 GHz of
the two sources. The separation is 0. 482 ± 0. 005 in right ascen-sion
(RA) and 0. 069 ± 0. 003 in declination (Dec). This gives
a total separation of 0. 487 ± 0. 006. The flux density of Mira B
fits the VLA radio continuum spectral index determination of
Matthews Karovska (2006) quite well, but that of Mira A is
stronger by a factor of a few. For the S ν ∝ν1.5 relation deter-mined
by Matthews Karovska (2006) for Mira A to hold to
submmwavelengths,Mira A radio continuum must have become
stronger by a factor 4 since 2005.
3.2. Circumstellar morphology
The line profile is shown in Fig. 1 (left) and channel maps are
presented in Appendix A. Comparison of our spectrum with pre-vious
single-dish observations (Young 1995) indicates that even
with the ACA, only 50% of the extended flux is recovered. As a
result, the channels with strong emission only reach a dynamic
range (peak flux/S/N) of ∼50. The highly complex circumstellar
morphology seen in the channelmaps (Fig. A.1) has clearly been
shaped by many different, probably interacting dynamical pro-cesses
during the evolution of the system. Here we focus on the
two most striking features: the large bubble-like structure found
in the blue bump of the line (at ∼41.5 kms−1, Figs. 1 and 3,
left), and the spiral arcs (Fig. 3, right) found in the main line
component centered on the stellar velocity at 47.0 kms−1.
In the channel maps corresponding to the blue bump in the
line profile, there is a large (5–10) arc centered on Mira A and
facing the companion. It grows with velocity and bends inward
at the edges until, at vlsr = 43.0 kms−1, the gas forms a distinct
bubble (Fig. 3, left) on the south-east side of Mira A. At higher
velocities, the southern part becomes more noticeable until, be-yond
vlsr = 44.5 kms−1, other structures become more apparent.
The edges of the bubble are sharp on the eastern (companion)
side of Mira A, and no emission above the noise level of the ob-servations
is picked up inside the bubble, but, smooth, extended
emission is resolved out (also when the ACA is used). Figure 1
(right) shows a position-velocity diagram created along the ma-jor
axis (position angle 38◦) of the southeastern bubble. It shows
the slight velocity shift between the northern and southern part
and that the northern part of the arc shifts from 2 to 6 offset
from39 to 44 kms−1, indicating that part of the frontside of the
bubble is visible at the velocities moving toward us. Although
low surface brightness prevents detection at the extreme veloc-ities
at the very front- and back-side of the bubble, this gives a
lower limit of the radial expansion velocity of ∼5 kms−1.
Spiral arcs are seen from vlsr = 45 to 54 km s−1 (Fig. A.1).
These channels make up the main part of the CO line profile and
dominate the emission. At vlsr = 47.5 kms−1, the accretion wake
behind the companion is apparent and is present through all red-der
velocity channels (Figs. 3 and A.2). The spiral can be traced
out to two to three windings (Fig. A.2) and different parts are vis-ible
in different velocity channels, indicating that it is flatter and
more confined to the orbital plane than the spiral around R Scl
(Maercker et al. 2012), for instance. Since the orbital plane is
inclined and seen close to edge-on (22◦ south of edge-on), the
real winding separation cannot be determined directly from the
map. The projected separation is about 3–5, which would cor-respond
to 8–13, if the spiral is confined to the orbital plane.
4. Discussion
4.1. Comparison with previous observations
From the continuum emission (Sect. 3.1), the current position of
Mira B is ≈0. 5 east of Mira A at a position angle of 98◦. This
agrees with predictions from the orbit by Prieur et al. (2002).
The same north-south asymmetry as seen in previous CO ob-servations
is found in the ALMACO line data; but because of the
greatly improved spatial resolution and sensitivity, the ALMA
data show much more detail. For instance, it is likely that the
northeastern feature at 42.5 kms−1 in the OVRO map (Planesas
et al. 1990) is the large blueshifted arc detected with ALMA,
but at low resolution. The butterfly shape found in the PdB map
(Josselin et al. 2000) is not detected in the ALMA data, but it is
possible that it is a low-resolution version of the structures seen
in Fig. 3 (left). In the ALMAmaps (Fig. A.1) there is no clear in-dication
of the molecular gas being disrupted by a high-velocity
outflow, as the one detected in KI emission (Josselin et al. 2000),
or by the north and south stream.
It is not straightforward to connect the large dust arcs found
in the PACS image (Mayer et al. 2011) and the inner spiral shape
found in the ALMA data, since the dust distribution is affected
by other processes. In addition, the PACS image only shows the
L14, page 2 of 6
3. S. Ramstedt et al.: The wonderful complexity of the Mira AB system
250
200
150
100
50
0
35 40 45 50 55
Flux [Jy]
vlsr [km s−1]
12CO(3-2)
vl s r [km s−1]
Offset [arcsec]
38 40 42 44 46 48 50 52 54
6
4
2
0
−2
−4
−6
−8
Fig. 1. Left: ALMA CO(3–2) line profile generated using an 25 beam centered on Mira A. Right: position-velocity diagram showing the positional
offset relative to the center of the bubble along a position angle of 38◦, as a function of lsr velocity.
East Offset [arcsec]
Offset [arcsec]
1 0 −1
1
0
−1
Fig. 2. Continuum emission at 338 GHz with the current positions of
Mira A (west) and B (east, marked by crosses). The contours are
drawn at 5, 10, 20, 40, 80, 160, and 320 times the rms noise level
at 0.6 mJy/beam. The beam is shown in the lower left corner.
velocity-integrated information, and detailed structures may not
be apparent (cf. PolCor and ALMA images of the spiral and shell
around R Scl, Maercker et al. 2014). The separation between the
dust arcs is about 15–30, which is significantly larger than in
the inner spiral detected with ALMA.
Finally, the interaction between the circumstellar material
and the ISM is seen in the GALEX images (Martin et al. 2007),
and an extended bow shock is detected ≈5 south of Mira AB.
While the large-scale dust distribution is clearly shaped by this
interaction (Mayer et al. 2011), this is not the case of the smaller-scale
gas distribution mapped by ALMA. The presence of the
bow shock much farther out means that the inner structures can-not
be explained by (hydrodynamic) interaction with the ISM.
4.2. Possible shaping scenarios
The bubble found on the southeastern side of Mira A is ∼800 AU
across, and there is a similar, filled structure on the opposite,
Table 1. Current positions (ep = J2000.0) and continuum flux density
at 338 GHz, S ν, of Mira A and B determined from the ALMA data.
Source RA Dec S ν
Mira A 02:19:20.784 –02:58:42.818 252.3 ± 0.3 mJy
Mira B 02:19:20.816 –02:58:42.887 15.3 ± 0.3 mJy
˙M
northwestern side of the star (Sect. 3.2 and Fig. 3, left). One
possible explanation for these shapes is that the wind from
Mira B is blowing a hole in the circumstellar envelope (CSE)
of Mira A. The time scale for a continuous wind (assuming the
higher Mira B mass-loss rate, 10−11 M− yr1, and wind velocity,
450km s−1, Wood Karovska 2006) to create a bubble of that
size is ∼380 years (assuming ∼ 10−7 Myr−1 from Mira A).
The terminal velocity of the shell surrounding the bubble would
be ≈5 kms−1 (e.g., the wind-wind interaction model for plane-tary
nebulae, Kwok 1983). The bubble is not centered onMira B
because, in the direction of Mira A, the CSE is too dense to be
significantly affected by the wind of Mira B. The wind will pre-dominantly
blow in the north-south direction since it is hindered
by the (almost edge-on) dense accretion disk around Mira B,
which might explain the bi-polar shape of the bubble. This sce-nario
is consistent with the shell radial velocity of 5 kms−1
(Fig. 1, right), and the mirrored shape on the opposite side of
Mira A, which may have been created half a period ago. The
northwestern bubble seems to be almost filled with material from
the wind ofMira A, which agrees with the time scales and an ex-pansion
velocity of 5 kms−1, but the time scale for the creation
of the bubble from these order-of-magnitude estimates (assum-ing
spherically symmetric winds) is slightly longer than the time
Mira B would stay on either side of Mira A if the orbital period
were 500 yr.
The two companions seem to be surrounded by a common
dense molecular envelope, and at red-shifted velocities, there
appears to be an accretion wake behind Mira B. Several arcs
centered on Mira A are found in the line emission from 45.5
to 54.5 kms−1 (Figs. 3, A.1 and A.2). Even though these arcs are
physically connected in a continuous spiral, they will appear as
separate arcs in velocity space, since different sections of the spi-ral
arms will have different velocities along the line of sight. The
relatively low wind velocity of Mira A (∼5 kms−1) will cause
L14, page 3 of 6
4. AA 570, L14 (2014)
43.0 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
5
0
−5
Jy/beam
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
50.0 km/s
East Offset [arcsec]
Offset [arcsec]
5 0 −5
10
5
0
−5
−10
Jy/beam
1.1
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
Fig. 3. CO(3–2) map averaged over 2 and 3 km s−1 around vlsr = 43.0 and 50.0 kms−1, respectively, showing the bubble structure (left) and the
spiral arcs (right) discussed in Sect. 3.2. The crosses mark the position of Mira A (west) and B (east). Contours are drawn at multiples of the rms
noise level. The beam is shown in the lower left corner.
the circumstellar material to slowly fill its Roche lobe and even-tually
fall ontoMira B through the inner Lagrangian point (wind
Roche-lobe overflow (WRLOF), Mohamed Podsiadlowski
2007). This will focus the outflow toward the orbital plane, and
the orbital motion will result in a rather flat spiral (Mohamed
Podsiadlowski 2012), unlike the case of R Scl for exam-ple
(Maercker et al. 2012), where the AGB wind has a much
higher expansion velocity (14.5 kms−1) resulting in a spiral
with greater vertical extension. Detailed modeling is beyond the
scope of this paper and will be presented in a future publication.
Preliminary results show that the spiral spacing will be on the or-der
of 500–1000 AU or roughly 5–10 for a distance of 100 pc
(assuming a gas outflow velocity of 5 kms−1 and an orbital pe-riod
between 500 and 1000 yr). The upper end of these theoreti-cal
estimates fit well within the observed spiral separation when
we allow for orbital inclination effects.
5. Conclusions
The CO(3–2) emission from the Mira AB system has been
mapped with ALMA in cycle 1. The maps show the circumstel-lar
molecular gas distribution in amazing detail with the high-est
spatial resolution achieved so far. The complex morphology
confirms that circumstellar material has been shaped by several
interacting dynamical processes (e.g., mass loss, binary shap-ing,
wind-wind interaction, accretion) during the evolution of
the star, and the data presented here can be analyzed to better
understand these processes.
The binary pair is marginally resolved in the continuum and
has a separation of ≈0. 5 at a position angle of 98◦. We suggest
that the features seen in the CO gas emission confirm the sce-nario
where the slow wind of the AGB star fills its Roche lobe
and flows onto the companion in the orbital plane (Mohamed
Podsiadlowski 2007). A relatively flat spiral is formed and seen
as separate arcs at different velocities. The spacing between the
spiral arms agrees with what is expected from the orbit and wind
properties of Mira A. The accretion of material onto the com-panion
gives rise to a varying wind already detected in UV line
emission (Wood Karovska 2004). A tentative explanation is
that this wind blows a large bubble in the circumstellar material
as seen at slightly blueshifted velocities in the ALMA data. The
wind from Mira B is pinched by the accretion disk and is there-fore
oriented preferentially in the north-south direction. Its flow
is also confined by the dense wind of Mira A to the east. Our
estimate of the radial velocity of the material in the shell around
the bubble fits this scenario, while the time scale for the creation
of the bubble is somewhat longer than the orbital period.
Acknowledgements. The authors would like to thank the staff of the Nordic
ALMA ARC node for their indispensable help and support. This paper makes
use of the following ALMA data: ADS/JAO.ALMA#2012.1.00524. S. ALMA
is a partnership of ESO (representing its member states), NSF (USA) and NINS
(Japan), together with NRC (Canada) and NSC and ASIAA (Taiwan), in coop-eration
with the Republic of Chile. The Joint ALMA Observatory is operated
by ESO, AUI/NRAO and NAOJ. W.V. acknowledges support from Marie Curie
Career Integration Grant 321691 and ERC consolidator grant 614264.
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L14, page 4 of 6
5. S. Ramstedt et al.: The wonderful complexity of the Mira AB system
Appendix A:
Maps of the CO(3–2) emission from 36.7 to 53.7 kms−1 at approximately 0.85 km s−1 spectral resolution. As the maps with strong
line emission are limited to a dynamic range of ∼50 because a significant amount of large scale (9) flux is not recovered, the rms
varies between 30 and 160 mJy in the different velocity channels.
36.7 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
37.6 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
38.4 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
39.3 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
40.1 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
41.0 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
41.8 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
42.7 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
43.5 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
44.3 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
45.2 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
46.9 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
47.7 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
48.6 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
49.4 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
50.3 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
51.1 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
52.0 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
52.8 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
53.7 km/s
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
10
5
0
−5
−10
Fig. A.1. CO(3–2) map at 0.9 km s−1 resolution. The crosses mark the positions of Mira A (west) and B (east). Contours are drawn at 3, 5, 10, 20,
40, and 80 times the rms noise level of the respective channel ranging from 30 to 160 mJy. The beam is shown in the lower left corner.
L14, page 5 of 6
6. AA 570, L14 (2014)
wake
East Offset [arcsec]
Offset [arcsec]
10 5 0 −5 −10
15
10
5
0
−5
−10
−15
Jy/beam
0.5
0.4
0.3
0.2
0.1
0
Fig. A.2. CO(3–2) map averaged from 49 to 54 kms−1. The crosses
mark the positions of Mira A (west) and B (east). Contours are drawn
at 3, 5, 10, 20, 40, and 80 times the rms noise level of the respective
channel ranging from 30 to 160 mJy. The beam is shown in the lower
left corner. A spiral is overplotted to clearly mark the spiral windings,
and the accretion wake behind the companion is indicated.
Figure A.2 shows an average from 49 to 54 kms−1 where the
spiral windings and the accretion wake discussed in Sects. 3.2
and 4.2 are clearly marked.
L14, page 6 of 6