The Dawn spacecraft's VIR instrument obtained hyperspectral images of Vesta's surface. Analysis of the spectra showed considerable regional variations in mineralogy. The south polar region, including the Rheasilvia basin, displayed a higher diogenitic component with deeper pyroxene absorption bands. Equatorial regions showed a higher eucritic component with shallower bands. This lithological distribution indicates Vesta had a deeper diogenitic crust exposed by the Rheasilvia impact, overlain by an upper eucritic crust. Evidence for layering was observed on crater walls and in ejecta, broadly consistent with magma ocean differentiation models. However, spectral variability also highlighted local variations, suggesting a complex crustal
Citizen science projects have the potential to transform earthquake detection by greatly increasing the number of seismic sensor locations. Individuals can host sensors in their homes and buildings to record ground motion data during quakes. However, data quality standards must be maintained and networks need to remain operational long-term for the data to be scientifically useful. If these challenges can be addressed, dense citizen sensor networks may provide new insights into earthquake processes.
The document summarizes findings from studying asteroid 4 Vesta using data from NASA's Dawn spacecraft. It finds that Vesta has experienced a violent collisional history, with large impacts creating steep slopes and resurfacing much of the surface. While no unambiguous volcanic deposits were found, some dark material in impact craters may be from excavated subsurface volcanic features. Smooth ponds found on Vesta are also seen on asteroid Eros and are thought to form from impact ejecta collecting in depressions.
Color and albedo_heterogeneity_on_vestaSérgio Sacani
The document summarizes findings from the Dawn spacecraft about the composition and geology of Vesta. It found that Vesta's surface has significant heterogeneity in color and albedo. Spectroscopic data revealed variations in the mineralogy and composition, with the Oppia region showing differences possibly related to mass movements. Craters exposed layers with different mineral and chemical compositions, providing insights into Vesta's complex, stratified crust formed from magmatic processes during planetary differentiation.
Topography of northern_hemisphere_of_mercury_from_messenger_altimeterSérgio Sacani
The document describes a study that used laser altimetry from the MESSENGER spacecraft to create a topographic model of Mercury's northern hemisphere. The study found that Mercury has a much smaller range of elevations compared to Mars or the Moon, likely due to Mercury's higher density and gravitational acceleration smoothing out topographic features. The model revealed numerous large impact structures that influence the shape of the hemisphere but do not significantly affect the distribution of elevations.
Bright and dark_polar_deposits_on_mercury_evidence_for_surface_volatilesSérgio Sacani
1) Measurements from MESSENGER's Mercury Laser Altimeter revealed regions of unusually dark and bright surface deposits near Mercury's north pole.
2) These deposits are concentrated on pole-facing slopes and spatially correlate with areas exhibiting high radar backscatter, suggesting the presence of near-surface water ice.
3) Analysis found the bright deposits are consistent with surface water ice, while the dark regions likely overlie buried ice and provide thermal insulation, such as from complex organic materials delivered by comets or asteroids.
1) Apatite samples from the Grand Canyon basement were analyzed using 4He/3He thermochronometry to constrain the near-surface cooling history associated with canyon incision.
2) Data from eastern Grand Canyon apatites indicate substantial canyon incision by ~70 million years ago, earlier than conventional models suggesting incision began 5-6 million years ago.
3) Similar data from western Grand Canyon provide evidence that it was excavated to within a few hundred meters of its modern depth by ~70 million years ago, challenging the view that the entire canyon was carved only in the last 5-6 million years.
This study examines a reservoir of ionized gas in the galactic halo that can sustain star formation in the Milky Way. The authors detect a substantial amount of warm-hot gas in the halo of a star-forming galaxy at z=0.2 through detection of Ne VIII absorption lines. This warm-hot gas reservoir contains as much mass as the galaxy's stars and can replenish its supply of cool gas to sustain star formation over billions of years.
The study examines a post-starburst galaxy outflow using ultraviolet spectroscopy of multiple ions including hydrogen. It finds the outflow extends at least 160,000 light-years from the galaxy and contains a hidden mass of at least 6x10^9 times the mass of our Sun. This challenges previous assumptions about the extent and mass of galaxy outflows, suggesting they may play a larger role in regulating galaxy evolution than thought.
Citizen science projects have the potential to transform earthquake detection by greatly increasing the number of seismic sensor locations. Individuals can host sensors in their homes and buildings to record ground motion data during quakes. However, data quality standards must be maintained and networks need to remain operational long-term for the data to be scientifically useful. If these challenges can be addressed, dense citizen sensor networks may provide new insights into earthquake processes.
The document summarizes findings from studying asteroid 4 Vesta using data from NASA's Dawn spacecraft. It finds that Vesta has experienced a violent collisional history, with large impacts creating steep slopes and resurfacing much of the surface. While no unambiguous volcanic deposits were found, some dark material in impact craters may be from excavated subsurface volcanic features. Smooth ponds found on Vesta are also seen on asteroid Eros and are thought to form from impact ejecta collecting in depressions.
Color and albedo_heterogeneity_on_vestaSérgio Sacani
The document summarizes findings from the Dawn spacecraft about the composition and geology of Vesta. It found that Vesta's surface has significant heterogeneity in color and albedo. Spectroscopic data revealed variations in the mineralogy and composition, with the Oppia region showing differences possibly related to mass movements. Craters exposed layers with different mineral and chemical compositions, providing insights into Vesta's complex, stratified crust formed from magmatic processes during planetary differentiation.
Topography of northern_hemisphere_of_mercury_from_messenger_altimeterSérgio Sacani
The document describes a study that used laser altimetry from the MESSENGER spacecraft to create a topographic model of Mercury's northern hemisphere. The study found that Mercury has a much smaller range of elevations compared to Mars or the Moon, likely due to Mercury's higher density and gravitational acceleration smoothing out topographic features. The model revealed numerous large impact structures that influence the shape of the hemisphere but do not significantly affect the distribution of elevations.
Bright and dark_polar_deposits_on_mercury_evidence_for_surface_volatilesSérgio Sacani
1) Measurements from MESSENGER's Mercury Laser Altimeter revealed regions of unusually dark and bright surface deposits near Mercury's north pole.
2) These deposits are concentrated on pole-facing slopes and spatially correlate with areas exhibiting high radar backscatter, suggesting the presence of near-surface water ice.
3) Analysis found the bright deposits are consistent with surface water ice, while the dark regions likely overlie buried ice and provide thermal insulation, such as from complex organic materials delivered by comets or asteroids.
1) Apatite samples from the Grand Canyon basement were analyzed using 4He/3He thermochronometry to constrain the near-surface cooling history associated with canyon incision.
2) Data from eastern Grand Canyon apatites indicate substantial canyon incision by ~70 million years ago, earlier than conventional models suggesting incision began 5-6 million years ago.
3) Similar data from western Grand Canyon provide evidence that it was excavated to within a few hundred meters of its modern depth by ~70 million years ago, challenging the view that the entire canyon was carved only in the last 5-6 million years.
This study examines a reservoir of ionized gas in the galactic halo that can sustain star formation in the Milky Way. The authors detect a substantial amount of warm-hot gas in the halo of a star-forming galaxy at z=0.2 through detection of Ne VIII absorption lines. This warm-hot gas reservoir contains as much mass as the galaxy's stars and can replenish its supply of cool gas to sustain star formation over billions of years.
The study examines a post-starburst galaxy outflow using ultraviolet spectroscopy of multiple ions including hydrogen. It finds the outflow extends at least 160,000 light-years from the galaxy and contains a hidden mass of at least 6x10^9 times the mass of our Sun. This challenges previous assumptions about the extent and mass of galaxy outflows, suggesting they may play a larger role in regulating galaxy evolution than thought.
Delivery of dark_material_to_vesta_via_carbonaceous_chondritic_impactsSérgio Sacani
This document analyzes dark material (DM) observed on the surface of asteroid Vesta by NASA's Dawn spacecraft. Spectral analysis finds the DM has properties similar to carbonaceous chondrite meteorites mixed with Vestan surface materials. Laboratory experiments matching the albedo and absorption bands of DM used mixtures of carbonaceous chondrites and eucrite basalt. Impact modeling suggests the DM was delivered via impacts of carbonaceous chondrite asteroids during the formation of the large Veneneia impact basin on Vesta. This supports the idea that carbonaceous chondrites were an important early source of carbon and volatiles in the solar system.
1) NASA's Kepler mission discovered two distinct transit signals around a bright G-type star, Kepler-10.
2) Statistical tests established the planetary nature of the shorter period signal, now called Kepler-10b.
3) Forty precision Doppler measurements confirmed Kepler-10b, finding it has a radius of 1.416+0.033 R⊕ and is the smallest transiting exoplanet discovered.
1) Researchers have developed a new technique called mechanophotopatterning (MPP) that uses light irradiation and mechanical deformation to precisely control the topology of light-responsive elastomers, establishing a new patterning method.
2) Using MPP, a variety of surface topologies can be produced, making it potentially useful for applications. When optically thick samples are irradiated, they bow into 3D shapes with promising applications in advanced optics.
3) The intrinsic material properties of the polymers remain unchanged after deformation, allowing for diverse applications at the interface of cell biology and tissue engineering through dynamic control of mechanical feedback to cells.
Kepler-62 is a star with five planets detected via the Kepler spacecraft, including two super-Earth planets in the star's habitable zone (HZ). The outermost planets, Kepler-62e and Kepler-62f, are 1.61 and 1.41 Earth radii respectively and receive fluxes of 1.2 and 0.41 times that of Earth. Theoretical models suggest these planets could be solid, with rocky or water compositions. Kepler-62e and Kepler-62f are the smallest planets detected by Kepler to orbit in another star's HZ.
1) The EPOXI mission flew by comet Hartley 2 in 2010, obtaining over 105 images and spectra.
2) Hartley 2 has an unusually small but very active bi-lobed nucleus with dimensions of 2.33 km and a rotation period of about 18 hours.
3) The nucleus shows substantial differences in volatile composition between its lobes and waist region.
The document summarizes findings from a study published in Science about the detection of water ice in the protoplanetary disk surrounding the young star TW Hydrae. Using the Herschel Space Observatory, researchers detected a large reservoir of water stored as ice in the disk. This suggests icy planetesimals could form in the outer parts of the disk beyond the "snow line." The water vapor observed likely originates from ultraviolet light releasing water molecules trapped in the ice grains. The results provide insights into the distribution and transport of water in protoplanetary disks, which influenced the formation of planets like Earth.
Ancient igneous intrusions_and_early_expansion_of_the_moon_revealed_by_grailSérgio Sacani
1) Application of gravity gradiometry to data from the GRAIL mission revealed numerous linear gravity anomalies on the Moon with lengths of hundreds of kilometers.
2) Inversion of the anomalies indicates they are dense vertical intrusions or dikes formed by ancient magmatism during extension of the lunar lithosphere before the end of heavy bombardment.
3) The distribution, orientation, and size of the intrusions suggest they formed as the Moon's radius increased by 0.6-4.9 km early in its history, consistent with predictions of thermal evolution models.
This document introduces the VLT-FLAMES Tarantula Survey, which obtained multi-epoch optical spectroscopy of over 800 massive stars in the 30 Doradus region of the Large Magellanic Cloud. The survey aims to detect massive binary systems through variations in radial velocities and to characterize the properties of O- and B-type stars, addressing questions about stellar and cluster evolution. Spectral classifications are provided for newly discovered emission-line stars, including a new Wolf-Rayet star. The survey data and reduction procedures are overviewed, and upcoming analyses of the massive star properties are announced.
Neowise observations of near earth objects- preliminary resultsSérgio Sacani
The NEOWISE survey observed near-Earth objects at infrared wavelengths, detecting over 130 new NEOs. Analysis of the 428 NEOs detected allows estimates of the total NEO population between 100m and 1km in size. The survey found an estimated 981±19 NEOs larger than 1km have been detected, meeting the Spaceguard goal of detecting 90% of objects this size. It also estimates 20,500±3000 NEOs larger than 100m. The cumulative size distribution is best represented by a broken power law.
The small blue_straggler_star_population_in_the_dense_galactic_globular_clust...Sérgio Sacani
This document summarizes a study of blue straggler star (BSS) populations in the globular cluster NGC 6752. The study used high-resolution Hubble Space Telescope images of the cluster core and wide-field ground-based images covering the outer regions. A total of 28 BSS candidates were identified in the HST images, and an additional 15 BSS candidates were found in the outer regions from the ground-based images. The radial distribution of BSS will be analyzed to understand the dynamical evolution of the cluster.
Herschel observations of_the_w3_gmc_clues_to_the_formation_of_clusters_of_hig...Sérgio Sacani
1) Herschel observations of the W3 GMC reveal the most massive and luminous clumps - W3 East, W3 West, and W3 (OH) - which have the highest column densities and ongoing high-mass star formation.
2) The observations suggest a "convergent constructive feedback" scenario where feedback from high-mass stars ensures material availability during cluster formation, leading to a decreasing age and increasing system mass towards the inner regions and possibly the formation of Trapezium-like systems.
3) Feedback plays an active role in accumulating, compressing, and confining material, distinguishing high-from low-mass star formation, though different environmental conditions and triggers could lead to a
The first hyper_luminous_infrared_galaxy_discovered_by_wiseSérgio Sacani
This document summarizes the discovery of WISE J181417.29+341224.9 (WISE 1814+3412), the first hyper-luminous infrared galaxy (LIR > 1013 L⊙) discovered by the Wide-field Infrared Survey Explorer (WISE). Follow-up images of WISE 1814+3412 revealed four nearby sources - a QSO, two Lyman Break Galaxies at z=2.45, and an M dwarf star. The brighter LBG dominates the bolometric emission of WISE 1814+3412 and has a star formation rate of ~300M⊙ yr−1, accounting for <10% of the total luminosity. An obscured
This study analyzed high-resolution spectra of 125 compact stellar systems (CSSs) in the giant elliptical galaxy NGC 5128 to measure their radial velocities and velocity dispersions. Combining these measurements with structural parameters from imaging, dynamical masses were derived for 112 CSSs, including 89 for the first time. Two distinct sequences were found in the dynamical mass-to-light ratio vs dynamical mass plane, which can be approximated by power laws. The shallower sequence corresponds to bright globular clusters, while the steeper relation appears to be populated by objects requiring significant dark matter such as central black holes or concentrated dark matter. This suggests different formation histories for these CSSs compared to classical globular clusters in NGC 5128 and
This document summarizes follow-up observations of galaxies selected from WISE as being hyperluminous. The authors observed 14 galaxies at 350-850 μm with SHARC-II and 18 galaxies at 1.1 mm with Bolocam, detecting 9 and 5 galaxies respectively. They also observed 25 targets at 3.6 and 4.5 μm with Spitzer and obtained optical spectra for 12 targets. By combining these data with WISE observations, they constructed mid-IR to millimeter spectral energy distributions that showed hotter dust temperatures than galaxy templates, estimated to be 60-120 K. These galaxies have infrared luminosities over 10^13 solar luminosities and represent an extreme population of luminous, hot dust-ob
Olivine in an_unexpected_location_on_vesta_surfaceSérgio Sacani
The document reports on the discovery of olivine on the surface of the asteroid Vesta in unexpected locations, based on data from the Dawn spacecraft's VIR instrument. Specifically:
- Olivine was found in the northern hemisphere of Vesta, rather than the southern basins where mantle rocks were expected based on previous models.
- The olivine occurs in large patches hundreds of meters across mixed with howardite regolith, unlike in meteorites where it is a minor component of diogenites.
- The amount and distribution of olivine-rich material suggests a complex evolutionary history for Vesta and is not consistent with previous ideas of olivine occurrence being associated with diogenites
Properties of rubble-pile asteroid (101955) Bennu from OSIRIS-REx imaging and...Sérgio Sacani
This document summarizes findings from imaging and thermal analysis of asteroid Bennu by NASA's OSIRIS-REx spacecraft. It finds that Bennu's surface is globally rough, dense with boulders over 1 meter in size, and has a low albedo of 4.4%. Thermal data indicates a moderate global thermal inertia of 350 J m-2 K-1 s-1/2, suggesting surface particle sizes of 0.5-5 cm by simple models, however images show the surface is dominated by boulders over 1 meter. Over 80% of the surface was analyzed, finding a power law distribution of boulder sizes with an index of -2.9 for boulders 8 meters
Thermal models of Mercury's north polar region, based on MESSENGER spacecraft measurements, show that regions of high radar backscatter match areas where water ice is predicted to be thermally stable on the surface. MESSENGER also found bright surfaces in the coldest areas and dark surfaces in warmer areas, consistent with water ice being stable only below ground in those regions. The distribution of radar-bright and dark areas provides strong evidence that Mercury's anomalous radar features are dominated by thermally stable water ice.
Discovery of a_probable_4_5_jupiter_mass_exoplanet_to_hd95086_by_direct_imagingSérgio Sacani
The document reports the discovery of a probable 4-5 Jupiter-mass exoplanet orbiting the young star HD 95086. Deep imaging observations using VLT/NaCo detected a faint source at a separation of 56 AU from the star. Follow-up observations over more than a year found the source to be co-moving with the star, suggesting it is bound. Its luminosity corresponds to a predicted mass of 4-5 Jupiter masses, making it the lowest mass exoplanet directly imaged around a star. If confirmed, this discovery could provide insights into giant planet formation and evolution.
This article presents evidence for past groundwater activity on Mars that could have supported a deep subsurface biosphere. The researchers developed a conceptual model of the martian subsurface divided into four zones based on depth and predicted fluid chemistry. Evidence is presented that crustal fluids emerged at the surface of McLaughlin Crater, forming an alkaline lacustrine system. This contrasts with more acidic environments implied by other sulfate deposits and suggests groundwater activity on Mars may have occurred sporadically on a local scale rather than regionally or globally.
Small dust particles escaping from Pluto's moons Nix and Hydra could temporarily form a ring around Pluto due to impacts, but the solar radiation pressure would remove about half of 1 micrometer particles within a year by causing collisions with Pluto and its moons. Numerical simulations found that a tenuous ring with an optical depth of 6×10^-11 could be maintained by dust released from Nix and Hydra.
Delivery of dark_material_to_vesta_via_carbonaceous_chondritic_impactsSérgio Sacani
This document analyzes dark material (DM) observed on the surface of asteroid Vesta by NASA's Dawn spacecraft. Spectral analysis finds the DM has properties similar to carbonaceous chondrite meteorites mixed with Vestan surface materials. Laboratory experiments matching the albedo and absorption bands of DM used mixtures of carbonaceous chondrites and eucrite basalt. Impact modeling suggests the DM was delivered via impacts of carbonaceous chondrite asteroids during the formation of the large Veneneia impact basin on Vesta. This supports the idea that carbonaceous chondrites were an important early source of carbon and volatiles in the solar system.
1) NASA's Kepler mission discovered two distinct transit signals around a bright G-type star, Kepler-10.
2) Statistical tests established the planetary nature of the shorter period signal, now called Kepler-10b.
3) Forty precision Doppler measurements confirmed Kepler-10b, finding it has a radius of 1.416+0.033 R⊕ and is the smallest transiting exoplanet discovered.
1) Researchers have developed a new technique called mechanophotopatterning (MPP) that uses light irradiation and mechanical deformation to precisely control the topology of light-responsive elastomers, establishing a new patterning method.
2) Using MPP, a variety of surface topologies can be produced, making it potentially useful for applications. When optically thick samples are irradiated, they bow into 3D shapes with promising applications in advanced optics.
3) The intrinsic material properties of the polymers remain unchanged after deformation, allowing for diverse applications at the interface of cell biology and tissue engineering through dynamic control of mechanical feedback to cells.
Kepler-62 is a star with five planets detected via the Kepler spacecraft, including two super-Earth planets in the star's habitable zone (HZ). The outermost planets, Kepler-62e and Kepler-62f, are 1.61 and 1.41 Earth radii respectively and receive fluxes of 1.2 and 0.41 times that of Earth. Theoretical models suggest these planets could be solid, with rocky or water compositions. Kepler-62e and Kepler-62f are the smallest planets detected by Kepler to orbit in another star's HZ.
1) The EPOXI mission flew by comet Hartley 2 in 2010, obtaining over 105 images and spectra.
2) Hartley 2 has an unusually small but very active bi-lobed nucleus with dimensions of 2.33 km and a rotation period of about 18 hours.
3) The nucleus shows substantial differences in volatile composition between its lobes and waist region.
The document summarizes findings from a study published in Science about the detection of water ice in the protoplanetary disk surrounding the young star TW Hydrae. Using the Herschel Space Observatory, researchers detected a large reservoir of water stored as ice in the disk. This suggests icy planetesimals could form in the outer parts of the disk beyond the "snow line." The water vapor observed likely originates from ultraviolet light releasing water molecules trapped in the ice grains. The results provide insights into the distribution and transport of water in protoplanetary disks, which influenced the formation of planets like Earth.
Ancient igneous intrusions_and_early_expansion_of_the_moon_revealed_by_grailSérgio Sacani
1) Application of gravity gradiometry to data from the GRAIL mission revealed numerous linear gravity anomalies on the Moon with lengths of hundreds of kilometers.
2) Inversion of the anomalies indicates they are dense vertical intrusions or dikes formed by ancient magmatism during extension of the lunar lithosphere before the end of heavy bombardment.
3) The distribution, orientation, and size of the intrusions suggest they formed as the Moon's radius increased by 0.6-4.9 km early in its history, consistent with predictions of thermal evolution models.
This document introduces the VLT-FLAMES Tarantula Survey, which obtained multi-epoch optical spectroscopy of over 800 massive stars in the 30 Doradus region of the Large Magellanic Cloud. The survey aims to detect massive binary systems through variations in radial velocities and to characterize the properties of O- and B-type stars, addressing questions about stellar and cluster evolution. Spectral classifications are provided for newly discovered emission-line stars, including a new Wolf-Rayet star. The survey data and reduction procedures are overviewed, and upcoming analyses of the massive star properties are announced.
Neowise observations of near earth objects- preliminary resultsSérgio Sacani
The NEOWISE survey observed near-Earth objects at infrared wavelengths, detecting over 130 new NEOs. Analysis of the 428 NEOs detected allows estimates of the total NEO population between 100m and 1km in size. The survey found an estimated 981±19 NEOs larger than 1km have been detected, meeting the Spaceguard goal of detecting 90% of objects this size. It also estimates 20,500±3000 NEOs larger than 100m. The cumulative size distribution is best represented by a broken power law.
The small blue_straggler_star_population_in_the_dense_galactic_globular_clust...Sérgio Sacani
This document summarizes a study of blue straggler star (BSS) populations in the globular cluster NGC 6752. The study used high-resolution Hubble Space Telescope images of the cluster core and wide-field ground-based images covering the outer regions. A total of 28 BSS candidates were identified in the HST images, and an additional 15 BSS candidates were found in the outer regions from the ground-based images. The radial distribution of BSS will be analyzed to understand the dynamical evolution of the cluster.
Herschel observations of_the_w3_gmc_clues_to_the_formation_of_clusters_of_hig...Sérgio Sacani
1) Herschel observations of the W3 GMC reveal the most massive and luminous clumps - W3 East, W3 West, and W3 (OH) - which have the highest column densities and ongoing high-mass star formation.
2) The observations suggest a "convergent constructive feedback" scenario where feedback from high-mass stars ensures material availability during cluster formation, leading to a decreasing age and increasing system mass towards the inner regions and possibly the formation of Trapezium-like systems.
3) Feedback plays an active role in accumulating, compressing, and confining material, distinguishing high-from low-mass star formation, though different environmental conditions and triggers could lead to a
The first hyper_luminous_infrared_galaxy_discovered_by_wiseSérgio Sacani
This document summarizes the discovery of WISE J181417.29+341224.9 (WISE 1814+3412), the first hyper-luminous infrared galaxy (LIR > 1013 L⊙) discovered by the Wide-field Infrared Survey Explorer (WISE). Follow-up images of WISE 1814+3412 revealed four nearby sources - a QSO, two Lyman Break Galaxies at z=2.45, and an M dwarf star. The brighter LBG dominates the bolometric emission of WISE 1814+3412 and has a star formation rate of ~300M⊙ yr−1, accounting for <10% of the total luminosity. An obscured
This study analyzed high-resolution spectra of 125 compact stellar systems (CSSs) in the giant elliptical galaxy NGC 5128 to measure their radial velocities and velocity dispersions. Combining these measurements with structural parameters from imaging, dynamical masses were derived for 112 CSSs, including 89 for the first time. Two distinct sequences were found in the dynamical mass-to-light ratio vs dynamical mass plane, which can be approximated by power laws. The shallower sequence corresponds to bright globular clusters, while the steeper relation appears to be populated by objects requiring significant dark matter such as central black holes or concentrated dark matter. This suggests different formation histories for these CSSs compared to classical globular clusters in NGC 5128 and
This document summarizes follow-up observations of galaxies selected from WISE as being hyperluminous. The authors observed 14 galaxies at 350-850 μm with SHARC-II and 18 galaxies at 1.1 mm with Bolocam, detecting 9 and 5 galaxies respectively. They also observed 25 targets at 3.6 and 4.5 μm with Spitzer and obtained optical spectra for 12 targets. By combining these data with WISE observations, they constructed mid-IR to millimeter spectral energy distributions that showed hotter dust temperatures than galaxy templates, estimated to be 60-120 K. These galaxies have infrared luminosities over 10^13 solar luminosities and represent an extreme population of luminous, hot dust-ob
Olivine in an_unexpected_location_on_vesta_surfaceSérgio Sacani
The document reports on the discovery of olivine on the surface of the asteroid Vesta in unexpected locations, based on data from the Dawn spacecraft's VIR instrument. Specifically:
- Olivine was found in the northern hemisphere of Vesta, rather than the southern basins where mantle rocks were expected based on previous models.
- The olivine occurs in large patches hundreds of meters across mixed with howardite regolith, unlike in meteorites where it is a minor component of diogenites.
- The amount and distribution of olivine-rich material suggests a complex evolutionary history for Vesta and is not consistent with previous ideas of olivine occurrence being associated with diogenites
Properties of rubble-pile asteroid (101955) Bennu from OSIRIS-REx imaging and...Sérgio Sacani
This document summarizes findings from imaging and thermal analysis of asteroid Bennu by NASA's OSIRIS-REx spacecraft. It finds that Bennu's surface is globally rough, dense with boulders over 1 meter in size, and has a low albedo of 4.4%. Thermal data indicates a moderate global thermal inertia of 350 J m-2 K-1 s-1/2, suggesting surface particle sizes of 0.5-5 cm by simple models, however images show the surface is dominated by boulders over 1 meter. Over 80% of the surface was analyzed, finding a power law distribution of boulder sizes with an index of -2.9 for boulders 8 meters
Thermal models of Mercury's north polar region, based on MESSENGER spacecraft measurements, show that regions of high radar backscatter match areas where water ice is predicted to be thermally stable on the surface. MESSENGER also found bright surfaces in the coldest areas and dark surfaces in warmer areas, consistent with water ice being stable only below ground in those regions. The distribution of radar-bright and dark areas provides strong evidence that Mercury's anomalous radar features are dominated by thermally stable water ice.
Discovery of a_probable_4_5_jupiter_mass_exoplanet_to_hd95086_by_direct_imagingSérgio Sacani
The document reports the discovery of a probable 4-5 Jupiter-mass exoplanet orbiting the young star HD 95086. Deep imaging observations using VLT/NaCo detected a faint source at a separation of 56 AU from the star. Follow-up observations over more than a year found the source to be co-moving with the star, suggesting it is bound. Its luminosity corresponds to a predicted mass of 4-5 Jupiter masses, making it the lowest mass exoplanet directly imaged around a star. If confirmed, this discovery could provide insights into giant planet formation and evolution.
This article presents evidence for past groundwater activity on Mars that could have supported a deep subsurface biosphere. The researchers developed a conceptual model of the martian subsurface divided into four zones based on depth and predicted fluid chemistry. Evidence is presented that crustal fluids emerged at the surface of McLaughlin Crater, forming an alkaline lacustrine system. This contrasts with more acidic environments implied by other sulfate deposits and suggests groundwater activity on Mars may have occurred sporadically on a local scale rather than regionally or globally.
Small dust particles escaping from Pluto's moons Nix and Hydra could temporarily form a ring around Pluto due to impacts, but the solar radiation pressure would remove about half of 1 micrometer particles within a year by causing collisions with Pluto and its moons. Numerical simulations found that a tenuous ring with an optical depth of 6×10^-11 could be maintained by dust released from Nix and Hydra.
1. The document describes observations of the Seyfert-1 galaxy Mrk 509 using XMM-Newton and Swift.
2. It analyzes the optical-UV and X-ray variability over a 100 day monitoring campaign with a few day resolution.
3. The results suggest that on these timescales, the soft X-ray excess in Mrk 509 is produced by warm Comptonization of thermal optical-UV photons from the accretion disk by a warm, optically thick corona surrounding the inner disk regions.
Relativistic collapse and explosion of rotating supermassive stars with therm...Sérgio Sacani
1) The document describes general relativistic simulations of collapsing supermassive stars with and without rotation using a numerical code called Nada.
2) The simulations include effects of gas pressure, radiation, electron-positron pairs, and thermonuclear energy from hydrogen and helium burning.
3) Objects with a mass of around 5×105 solar masses explode if non-rotating with a metallicity over 0.007, while rotation lowers the threshold to 0.001. More massive objects have a higher critical metallicity for explosion.
This document summarizes observations from the Cassini spacecraft of a giant thunderstorm on Saturn in late 2010 and early 2011. The storm produced lightning at a rate over an order of magnitude higher than previous storms, with peak rates over 10 flashes per second. It originated at a latitude of 32° north and grew to a size comparable to Great White Spots, with a latitudinal extension of over 10,000 km. Unlike storms on Earth, the total power of this storm was comparable to Saturn's total emitted power. The storm drifted westward with the winds and eventually wrapped around the entire planet by February 2011.
An exceptional xray_view_of_the_young_open_cluster_ngc6231Sérgio Sacani
The XMM-Newton satellite observed the young open star cluster NGC 6231 for a total of 180 kiloseconds, providing an unprecedented X-ray view. Around 600 point-like X-ray sources were detected, including many early-type O stars. The data helped refine the relationship between X-ray and bolometric luminosities for O stars, finding less scatter than previously thought, with the main exception being X-ray emission from wind interactions in binary systems. The data also provided insight into the low-mass pre-main sequence star population and star formation history of the cluster.
This article discusses findings from the MESSENGER spacecraft revealing details about Mercury's dynamic atmosphere. The spacecraft found that Mercury's polar regions contain large amounts of water ice, fulfilling predictions. However, measurements also surprisingly showed that the laser altimeter detected very low reflectance of Mercury's surface in polar regions, indicating it is coated in a dark, absorbing material in addition to water ice. Further studies are needed to understand the nature and origin of this dark material.
This document reports on the detection of water vapor in the protoplanetary disk around the young star TW Hydrae using the Heterodyne Instrument for the Far-Infrared on the Herschel Space Observatory. Models suggest the water originates from ice on dust grains near the disk surface, indicating a water ice reservoir equivalent to thousands of Earth oceans. The water's ortho-to-para ratio is lower than comets, suggesting comets collected ice mixtures across the early solar nebula.
This document presents color-magnitude diagrams derived from Hubble Space Telescope photometry of 6 outer Galactic globular clusters: Pyxis, Ruprecht 106, IC 4499, NGC 6426, NGC 7006, and Palomar 15. The deep photometry allows the ages of the clusters to be estimated from the main sequence turnoff. Preliminary age analysis reveals that IC 4499, Ruprecht 106, and Pyxis appear 1-2 billion years younger than inner halo clusters of similar metallicity, while NGC 7006 and Palomar 5 are marginally younger. NGC 6426 and Palomar 15, the two most metal-poor clusters, appear coeval with other metal-poor clusters within
This document describes a study that determines the relative abundances of elements in the warm absorber of the active galaxy Mrk 509 using X-ray spectra from XMM-Newton and Chandra observations. The study finds relative abundances that are consistent with proto-solar values, with the exception of sulfur which is slightly underabundant. Specifically, the study measures relative abundances of carbon, nitrogen, neon, magnesium, silicon, sulfur, calcium, and iron with respect to oxygen. These abundances provide information about the enrichment processes in the host galaxy and can be compared to abundances measured in other galaxies to study abundance evolution.
Non mare silicic volcanism on the lunar farside at compton–belkovichSérgio Sacani
1. Images from the Lunar Reconnaissance Orbiter reveal a central feature within the Compton–Belkovich thorium anomaly on the lunar farside characterized by elevated topography and relatively high reflectance.
2. The central feature contains several volcanic domes ranging from less than 1 km to over 6 km across, as well as arcuate and irregular depressions interpreted as collapse features associated with volcanism.
3. Spectral data indicates the volcanic feature is enriched in silica and alkali-feldspar, suggesting a composition of rhyolitic volcanic materials. This provides evidence for rare non-basaltic volcanism on the lunar farside far from the Procellarum
This document summarizes long-slit spectroscopic observations of four planetary nebulae - Hb 4, IC 4634, NGC 6369, and NGC 7354 - conducted with the Palomar 5 m telescope. The observations were aimed at investigating the spectroscopic properties of microstructures like jets and FLIERs (fast, low-ionization emission regions) seen in these planetary nebulae. Physical conditions and chemical abundances were derived from emission line ratios along the structural axes of the microstructures. In most cases, no evidence of shock activity or nitrogen-to-oxygen abundance anomalies was found, unlike some previous studies of similar structures. Microstructures appear to be a heterogeneous class of structures aside from their generally supersonic
This document summarizes a scientific paper published in Science in 2011 about the discovery that the large, oxygen-rich halos surrounding star-forming galaxies are a major reservoir of heavy elements ejected from galaxies. The paper presents evidence that these halos contain a significant portion of metals produced by massive stars. It also describes how these findings help scientists better understand the cycling of matter on large scales throughout the universe.
This document summarizes the results of a deep near-infrared survey of the Carina Nebula complex using the HAWK-I instrument on the VLT. The survey imaged an area of 0.36 square degrees down to magnitudes of J=23, H=22, and Ks=21, detecting over 600,000 infrared sources. Color-magnitude diagrams of the sources were analyzed to determine properties of the low-mass stellar population such as ages and masses. The survey found that about 3200 sources have masses above 1 solar mass, consistent with expectations from the initial mass function. It also found that about half of the young stars in Carina are in a widely distributed, non-clustered configuration. Six
1) The document reports the discovery of the first known Trojan asteroid of Earth, 2010 TK7.
2) 2010 TK7 was discovered in infrared data from the WISE spacecraft. Follow-up optical observations confirmed it is trapped in a stable orbit around the L4 Lagrangian point ahead of Earth.
3) The asteroid's orbit is stable over at least 10,000 years, though its position becomes chaotic beyond 250 years in the past or future due to gravitational interactions.
This document is a 3-page excerpt from a book about polarized light in nature. It provides an overview of the book's contents and structure. The book is divided into three parts: Part I discusses what polarized light is and how to observe it. Part II acts as a guide to observing polarized light phenomena in nature, including the sky, natural scenery, and nocturnal light sources. Part III examines the physical mechanisms that create polarized light in nature, such as reflection, scattering, refraction, and double refraction. The excerpt concludes by noting that the book aims to guide readers in observing the color and light phenomena around us with a focus on polarization effects, which comprise a largely overlooked aspect of nature.
This document presents observations from the VLT X-shooter instrument of two quasars, SDSS J1106+1939 and SDSS J1512+1119. For SDSS J1106+1939, a broad absorption line (BAL) outflow is detected with a kinetic luminosity of at least 10^46 erg/s, which is 5% of the quasar's bolometric luminosity. This outflow has a velocity of ~8000 km/s and is located ~300 pc from the quasar. For SDSS J1512+1119, two separate outflows are detected using the same technique, with distances ranging from 100-2000 pc from the central source. The distances of the outflows
X rays and-protostars_in_the_trifid_nebulaSérgio Sacani
This document summarizes an astronomical study of the Trifid Nebula using X-ray and infrared observations. The ROSAT X-ray image revealed over a dozen X-ray sources in the nebula, including the bright O7 star that provides most of the ionization. Infrared observations identified 85 young star candidates. Ten X-ray sources had infrared counterparts. Spectroscopy of the brightest X-ray source with ASCA showed unusually hot plasma up to 10 keV, suggesting interaction between winds or flares from embedded young stars.
The two largest impact basins recently discovered at Vesta's south pole are Rheasilvia and Veneneia. Rheasilvia is ~500 km wide and 19 km deep, making it one of the largest impact features on Vesta. It has a central massif and spiral ridge patterns on its floor. Veneneia is an older, partially buried ~400 km basin located beneath Rheasilvia. Crater counts date both basins to 1-2 billion years old, indicating major geological resetting of Vesta occurred relatively recently.
Science laser altimetry of small scale features on 433 eros from near-shoemakerFelipe Correa
This article summarizes findings from laser altimetry observations of asteroid 433 Eros made by the NEAR spacecraft during its close flyby. The laser observations revealed surface features on scales of meters to hundreds of meters, showing that the surface has a fractal structure dominated by blocks, structural features, and small crater walls. This fractal structure suggests a single process, likely impacts, dominates the surface morphology on these scales. Laser altimetry also measured local surface elevations and slopes, correlating elevations with morphological evidence of downslope movement of loose surface materials.
- Hollows on Mercury range from tens of meters to kilometers across and are irregular depressions found within impact craters.
- Many hollows have high-reflectance interiors and halos and are associated with crater central peaks, peak rings, floors, and walls.
- The most likely formation mechanisms involve recent loss of volatiles through processes like sublimation, outgassing, or pyroclastic volcanism.
- The discovery of hollows provides evidence that Mercury has higher abundances of volatile materials than predicted.
Observations of ejecta_clouds_produced_by_impacts_onto_saturn_ringsSérgio Sacani
Three key points from the document:
1. Cassini observations detected dusty ejecta clouds above Saturn's rings that were produced by impacts onto the rings 1 to 50 hours prior.
2. The largest cloud was observed twice, and its brightness and position evolved consistently with this impact hypothesis.
3. The responsible interplanetary meteoroids were initially between 1 cm and several meters in size, and their influx rate is consistent with prior knowledge of smaller meteoroids in the outer solar system.
This document summarizes a study that identified 195 compact elliptical galaxies across different environments using data from optical and ultraviolet sky surveys. The researchers constructed the sample by selecting galaxies that were outliers from the universal color-magnitude relation and had small sizes and high stellar velocity dispersions based on spectral modeling. They found that 7 of the galaxies were isolated, not belonging to any known galaxy groups. For these isolated galaxies, the researchers identified possible host galaxies located up to 3.3 Mpc away. The stellar populations of the isolated compact elliptical galaxies were found to be similar to those in galaxy groups and clusters, suggesting a common formation mechanism.
The absolute chronology and thermal processing of solids in the solar protopl...Carlos Bella
CAIs define a brief formation interval corresponding to an age of 4567.30 ± 0.16 million years, whereas chondrules range from 4567.32 ± 0.42 to 4564.71 ± 0.30 million years. U-Pb dating refutes the long-held view of an age gap between CAIs and chondrules, instead indicating chondrule formation started contemporaneously with CAIs and lasted ~3 million years. This timeline is similar to protoplanetary disk lifetimes from astronomy, suggesting CAI and chondrule formation occurred during the evolution of the solar protoplanetary disk.
The SPHERE view of three interacting twin disc systems in polarised lightSérgio Sacani
Dense stellar environments as hosts of ongoing star formation increase the probability of gravitational encounters among stellar
systems during the early stages of evolution. Stellar interaction may occur through non-recurring, hyperbolic or parabolic passages
(a so-called ‘fly-by’), through secular binary evolution, or through binary capture. In all three scenarios, the strong gravitational
perturbation is expected to manifest itself in the disc structures around the individual stars. Here, we present near-infrared
polarised light observations that were taken with the SPHERE/IRDIS instrument of three known interacting twin-disc systems:
AS 205, EM* SR 24, and FU Orionis. The scattered light exposes spirals likely caused by the gravitational interaction. On
a larger scale, we observe connecting filaments between the stars. We analyse their very complex polarised intensity and put
particular attention to the presence of multiple light sources in these systems. The local angle of linear polarisation indicates
the source whose light dominates the scattering process from the bridging region between the two stars. Further, we show
that the polarised intensity from scattering with multiple relevant light sources results from an incoherent summation of the
individuals’ contribution. This can produce nulls of polarised intensity in an image, as potentially observed in AS 205.We discuss
the geometry and content of the systems by comparing the polarised light observations with other data at similar resolution,
namely with ALMA continuum and gas emission. Collective observational data can constrain the systems’ geometry and stellar
trajectories, with the important potential to differentiate between dynamical scenarios of stellar interaction.
This document describes the process of communicating scientific research to non-specialists through a magazine article about planetary system formation. It involves taking data and concepts from scientific papers and reworking them so a general audience can understand. Notes are taken on a paper discussing spiral density waves in protoplanetary disks caused by planets or other stars. A draft description of this is written for the magazine article. Graphics show the evolution of a hypothetical planetary system from the initial disk to fully formed planets. Spectra correspond to different evolutionary stages. The goal is to make scientific breakthroughs accessible to the public.
XUE: Molecular Inventory in the Inner Region of an Extremely Irradiated Proto...Sérgio Sacani
This document presents the first results from the JWST XUE program, which observed 15 protoplanetary disks in the NGC 6357 star-forming region using MIRI. For the disk XUE 1, located near massive stars, the following was found:
1) Abundant water, CO, CO2, HCN, and C2H2 were detected in the inner few AU, indicating an oxygen-dominated gas-phase chemistry similar to isolated disks.
2) Small crystalline silicate dust is present at the disk surface.
3) The column densities and chemistry are surprisingly similar to isolated disks despite the extreme radiation environment, implying inner disks can retain conditions conducive to rocky planet
Disks of Stars in the Galactic Center Triggered by Tidal Disruption EventsSérgio Sacani
This document proposes that tidal disruption events (TDEs) from wandering stars could trigger episodes of positive star formation feedback in the Galactic Center, providing an explanation for the observed disks of young stars near Sgr A*. When a star is tidally disrupted by the supermassive black hole, the resulting jet compresses gas clouds to densities high enough to resist tidal forces and form stars within the disk plane perpendicular to the jet. The estimated rate of jetted TDEs is consistent with the age of the disk stars. This mechanism predicts a random orientation for each disk and the potential for multiple misaligned disks from separate TDE events.
The gravity field_and_interior_structure_of_enceladusSérgio Sacani
The gravity field and interior structure of Enceladus were determined using Doppler data from three Cassini flybys. There is a negative mass anomaly in the south polar region, largely compensated by a positive subsurface anomaly consistent with a regional subsurface sea at depths of 30-40 km extending to 50° south latitude. Enceladus deviates mildly from hydrostatic equilibrium, with estimated quadrupole coefficients indicating a differentiated body with a low-density core.
The gravity fieldandinteriorstructureofenceladusGOASA
The Cassini spacecraft measured Enceladus' gravity field during three flybys. The results indicate a negative mass anomaly over the south pole, likely compensated by a subsurface sea of water 30-40 km deep extending to 50° south latitude. Analysis of the gravity data suggests Enceladus has differentiated into a low-density core with a moment of inertia around 0.335 times its mass times the square of its radius, consistent with the presence of liquid water beneath the surface. The endogenic heat output and gravity data are best explained by models involving tidal heating of Enceladus' interior through past or current orbital resonances.
Measurements of a_massive_galaxy_clusterSérgio Sacani
This document reports on observations of IDCS J1426.5+3508, a galaxy cluster located at a redshift of 1.75. A Sunyaev-Zeldovich decrement was detected towards this cluster, indicating a total mass of 4.3×1014 solar masses. This makes it the most distant cluster detected via the Sunyaev-Zeldovich effect to date and the most massive cluster found at a redshift greater than 1.4. Despite its rarity, the cluster is not unexpected given cosmological models and the large area surveyed. However, it remains one of the rarest and most extreme clusters discovered and provides insight into the early formation of the most massive clusters.
UV and Hα HST observations of 6 GASP jellyfish galaxiesSérgio Sacani
Star-forming, Hα-emitting clumps are found embedded in the gaseous tails of galaxies undergoing
intense ram pressure stripping in galaxy clusters, so-called jellyfish galaxies. These clumps offer a
unique opportunity to study star formation under extreme conditions, in the absence of an underlying
disk and embedded within the hot intracluster medium. Yet, a comprehensive, high spatial resolution
study of these systems is missing. We obtained UVIS/HST data to observe the first statistical sample
of clumps in the tails and disks of six jellyfish galaxies from the GASP survey; we used a combination
of broad-band (UV to I) filters and a narrow-band Hα filter. HST observations are needed to study
the sizes, stellar masses and ages of the clumps and their clustering hierarchy. These observations will
be used to study the clump scaling relations, the universality of the star formation process and verify
whether a disk is irrelevant, as hinted by jellyfish galaxy results. This paper presents the observations,
data reduction strategy, and some general results based on the preliminary data analysis. The UVIS
high spatial resolution gives an unprecedented sharp view of the complex structure of the inner regions
of the galaxies and of the substructures in the galaxy disks. We found clear signatures of stripping
in regions very close in projection to the galactic disk. The star-forming regions in the stripped tails
are extremely bright and compact while we did not detect a significant number of star-forming clumps
outside those detected by MUSE. The paper finally presents the development plan for the project.
UV and Hα HST observations of 6 GASP jellyfish galaxiesSérgio Sacani
Star-forming, Hα-emitting clumps are found embedded in the gaseous tails of galaxies undergoing
intense ram pressure stripping in galaxy clusters, so-called jellyfish galaxies. These clumps offer a
unique opportunity to study star formation under extreme conditions, in the absence of an underlying
disk and embedded within the hot intracluster medium. Yet, a comprehensive, high spatial resolution
study of these systems is missing. We obtained UVIS/HST data to observe the first statistical sample
of clumps in the tails and disks of six jellyfish galaxies from the GASP survey; we used a combination
of broad-band (UV to I) filters and a narrow-band Hα filter. HST observations are needed to study
the sizes, stellar masses and ages of the clumps and their clustering hierarchy. These observations will
be used to study the clump scaling relations, the universality of the star formation process and verify
whether a disk is irrelevant, as hinted by jellyfish galaxy results. This paper presents the observations,
data reduction strategy, and some general results based on the preliminary data analysis. The UVIS
high spatial resolution gives an unprecedented sharp view of the complex structure of the inner regions
of the galaxies and of the substructures in the galaxy disks. We found clear signatures of stripping
in regions very close in projection to the galactic disk. The star-forming regions in the stripped tails
are extremely bright and compact while we did not detect a significant number of star-forming clumps
outside those detected by MUSE. The paper finally presents the development plan for the project.
UV and Hα HST observations of 6 GASP jellyfish galaxiesSérgio Sacani
Star-forming, Hα-emitting clumps are found embedded in the gaseous tails of galaxies undergoing
intense ram pressure stripping in galaxy clusters, so-called jellyfish galaxies. These clumps offer a
unique opportunity to study star formation under extreme conditions, in the absence of an underlying
disk and embedded within the hot intracluster medium. Yet, a comprehensive, high spatial resolution
study of these systems is missing. We obtained UVIS/HST data to observe the first statistical sample
of clumps in the tails and disks of six jellyfish galaxies from the GASP survey; we used a combination
of broad-band (UV to I) filters and a narrow-band Hα filter. HST observations are needed to study
the sizes, stellar masses and ages of the clumps and their clustering hierarchy. These observations will
be used to study the clump scaling relations, the universality of the star formation process and verify
whether a disk is irrelevant, as hinted by jellyfish galaxy results. This paper presents the observations,
data reduction strategy, and some general results based on the preliminary data analysis. The UVIS
high spatial resolution gives an unprecedented sharp view of the complex structure of the inner regions
of the galaxies and of the substructures in the galaxy disks. We found clear signatures of stripping
in regions very close in projection to the galactic disk. The star-forming regions in the stripped tails
are extremely bright and compact while we did not detect a significant number of star-forming clumps
outside those detected by MUSE. The paper finally presents the development plan for the project.
This summarizes a scientific study on long-distance quantum teleportation between two laboratories separated by 55 meters but connected by 2 kilometers of fiber optic cable. The key points are:
1) Researchers teleported quantum states (qubits) carried by photons at 1.3 micrometer wavelengths onto photons at 1.55 micrometer wavelengths between the two laboratories.
2) The qubits were encoded in time-bin superpositions and entanglement rather than polarization to make them more robust against decoherence in optical fibers.
3) A partial Bell state measurement was performed using linear optics at the receiving end to probabilistically teleport the quantum states over the long distance.
The Expansion of the X-Ray Nebula Around η CarSérgio Sacani
1. The author analyzes over 20 years of Chandra X-ray images to measure for the first time the expansion of the X-ray nebula around η Carinae.
2. A combined Chandra image reveals a faint, nearly uniform elliptical shell surrounding the X-ray bright ring, with a similar orientation and shape as the Homunculus nebula but about 3 times larger.
3. The author measures proper motions of brighter regions associated with the X-ray emitting ring, such as the S-ridge and W-arc. Motions are consistent with optical studies of ejecta from the 1840s Great Eruption.
Star formation at the smallest scales; A JWST study of the clump populations ...Sérgio Sacani
We present the clump populations detected in 18 lensed galaxies at redshifts 1 to 8.5 within the lensing cluster field SMACS0723.
The recent JWST Early Release Observations of this poorly known region of the sky have revealed numerous point-like sources
within and surrounding their host galaxies, undetected in the shallower HST images. We use JWST multiband photometry and
the lensing model of this galaxy cluster to estimate the intrinsic sizes and magnitudes of the stellar clumps. We derive optical
restframe effective radii from <10 to hundreds pc and masses ranging from ∼ 105
to 109 M, overlapping with massive star
clusters in the local universe. Clump ages range from 1 Myr to 1 Gyr. We compare the crossing time to the age of the clumps
and determine that between 45 and 60 % of the detected clumps are consistent with being gravitationally bound. On average,
the dearth of Gyr old clumps suggests that the dissolution time scales are shorter than 1 Gyr. We see a significant increase in the
luminosity (mass) surface density of the clumps with redshift. Clumps in reionisation era galaxies have stellar densities higher
than star clusters in the local universe. We zoom in into single galaxies at redshift < 6 and find for two galaxies, the Sparkler and
the Firework, that their star clusters/clumps show distinctive colour distributions and location surrounding their host galaxy that
are compatible with being accredited or formed during merger events. The ages of some of the compact clusters are between
1 and 4 Gyr, e.g., globular cluster precursors formed around 9-12 Gyr ago. Our study, conducted on a small sample of galaxies,
shows the potential of JWST observations for understanding the conditions under which star clusters form in rapidly evolving
galaxies.
The hazardous km-sized NEOs of the next thousands of yearsSérgio Sacani
This document discusses methods for assessing the long-term impact risk of km-sized near-Earth objects (NEOs) over thousands of years. It analyzes the evolution of the Minimum Orbit Intersection Distance (MOID) between NEOs and Earth to identify objects that remain in close proximity for extended periods. It then estimates the probability of a deep Earth encounter during these low-MOID periods based on the growth of orbital uncertainties over time. This allows the authors to rank km-sized NEOs by their long-term impact hazard and identify targets that warrant further observation and analysis.
Similar to Spectroscopic characterization vesta_mineralogy (20)
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Sérgio Sacani
Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the
atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets
receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric
composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet
transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (Porb) of 12.76 days.
The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous Porb from TESS data. We
confirmed the transit signal and Porb using ground-based photometry with MuSCAT2 and MuSCAT3, and
validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as
well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope
and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host
star is inactive, with an X-ray-to-bolometric luminosity ratio of log 5.7 L L X bol » - . Joint analysis of the light
curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R⊕,a3σ mass upper limit of
3.9 M⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric
(TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small
list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.
Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TES...Sérgio Sacani
We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a
bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the
lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors
42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations
with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory,
as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of
12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent
future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar
compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool
stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
The importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox
(1) by adding two additional terms to the Drake Equation: foc
(the fraction of habitable exoplanets
with significant continents and oceans) and fpt
(the fraction of habitable exoplanets with significant
continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by
demonstrating that the product of foc
and fpt
is very small (< 0.00003–0.002). We propose that the lack
of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on
exoplanets with primitive life.
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. Itremains enigmatic how subduction could be initiated so soon after the presumably Moon‐forming giant impact(MGI). Earlier studies found an increase in Earth's core‐mantle boundary (CMB) temperature due to theaccumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, withsome of the impactor's mantle potentially surviving as the large low‐shear velocity provinces (LLSVPs). Here,we show that a hot post‐impact CMB drives the initiation of strong mantle plumes that can induce subductioninitiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMBtemperature is the primary factor triggering early subduction, with enrichment of heat‐producing elements inLLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications forunderstanding the diverse tectonic regimes of rocky planets.
Climate extremes likely to drive land mammal extinction during next supercont...Sérgio Sacani
Mammals have dominated Earth for approximately 55 Myr thanks to their
adaptations and resilience to warming and cooling during the Cenozoic. All
life will eventually perish in a runaway greenhouse once absorbed solar
radiation exceeds the emission of thermal radiation in several billions of
years. However, conditions rendering the Earth naturally inhospitable to
mammals may develop sooner because of long-term processes linked to
plate tectonics (short-term perturbations are not considered here). In
~250 Myr, all continents will converge to form Earth’s next supercontinent,
Pangea Ultima. A natural consequence of the creation and decay of Pangea
Ultima will be extremes in pCO2 due to changes in volcanic rifting and
outgassing. Here we show that increased pCO2, solar energy (F⨀;
approximately +2.5% W m−2 greater than today) and continentality (larger
range in temperatures away from the ocean) lead to increasing warming
hostile to mammalian life. We assess their impact on mammalian
physiological limits (dry bulb, wet bulb and Humidex heat stress indicators)
as well as a planetary habitability index. Given mammals’ continued survival,
predicted background pCO2 levels of 410–816 ppm combined with increased
F⨀ will probably lead to a climate tipping point and their mass extinction.
The results also highlight how global landmass configuration, pCO2 and F⨀
play a critical role in planetary habitability.
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Sérgio Sacani
The recently reported observation of VFTS 243 is the first example of a massive black-hole binary
system with negligible binary interaction following black-hole formation. The black-hole mass (≈10M⊙)
and near-circular orbit (e ≈ 0.02) of VFTS 243 suggest that the progenitor star experienced complete
collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to
constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence
level, the natal kick velocity (mass decrement) is ≲10 km=s (≲1.0M⊙), with a full probability distribution
that peaks when ≈0.3M⊙ were ejected, presumably in neutrinos, and the black hole experienced a natal
kick of 4 km=s. The neutrino-emission asymmetry is ≲4%, with best fit values of ∼0–0.2%. Such a small
neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions.
Detectability of Solar Panels as a TechnosignatureSérgio Sacani
In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like
exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the
UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept
like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide
the 2022 human energy needs with a land cover of ∼ 2.4%, and projecting the future energy demand
assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope.
Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the
ultraviolet-to-visible (0.34 − 0.52 µm), we find that several 100s of hours of observation time is needed
to reach a SNR of 5 for an Earth-like planet around a Sun-like star at 10pc, even with a solar panel
coverage of ∼ 23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev
Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even
with much larger populations than today, the total energy use of human civilization would be orders of
magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev
Type I civilization. Any extraterrrestrial civilization that likewise achieves sustainable population
levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization
as imagined in the Fermi paradox may not exist.
Jet reorientation in central galaxies of clusters and groups: insights from V...Sérgio Sacani
Recent observations of galaxy clusters and groups with misalignments between their central AGN jets
and X-ray cavities, or with multiple misaligned cavities, have raised concerns about the jet – bubble
connection in cooling cores, and the processes responsible for jet realignment. To investigate the
frequency and causes of such misalignments, we construct a sample of 16 cool core galaxy clusters and
groups. Using VLBA radio data we measure the parsec-scale position angle of the jets, and compare
it with the position angle of the X-ray cavities detected in Chandra data. Using the overall sample
and selected subsets, we consistently find that there is a 30% – 38% chance to find a misalignment
larger than ∆Ψ = 45◦ when observing a cluster/group with a detected jet and at least one cavity. We
determine that projection may account for an apparently large ∆Ψ only in a fraction of objects (∼35%),
and given that gas dynamical disturbances (as sloshing) are found in both aligned and misaligned
systems, we exclude environmental perturbation as the main driver of cavity – jet misalignment.
Moreover, we find that large misalignments (up to ∼ 90◦
) are favored over smaller ones (45◦ ≤ ∆Ψ ≤
70◦
), and that the change in jet direction can occur on timescales between one and a few tens of Myr.
We conclude that misalignments are more likely related to actual reorientation of the jet axis, and we
discuss several engine-based mechanisms that may cause these dramatic changes.
The solar dynamo begins near the surfaceSérgio Sacani
The magnetic dynamo cycle of the Sun features a distinct pattern: a propagating
region of sunspot emergence appears around 30° latitude and vanishes near the
equator every 11 years (ref. 1). Moreover, longitudinal flows called torsional oscillations
closely shadow sunspot migration, undoubtedly sharing a common cause2. Contrary
to theories suggesting deep origins of these phenomena, helioseismology pinpoints
low-latitude torsional oscillations to the outer 5–10% of the Sun, the near-surface
shear layer3,4. Within this zone, inwardly increasing differential rotation coupled with
a poloidal magnetic field strongly implicates the magneto-rotational instability5,6,
prominent in accretion-disk theory and observed in laboratory experiments7.
Together, these two facts prompt the general question: whether the solar dynamo is
possibly a near-surface instability. Here we report strong affirmative evidence in stark
contrast to traditional models8 focusing on the deeper tachocline. Simple analytic
estimates show that the near-surface magneto-rotational instability better explains
the spatiotemporal scales of the torsional oscillations and inferred subsurface
magnetic field amplitudes9. State-of-the-art numerical simulations corroborate these
estimates and reproduce hemispherical magnetic current helicity laws10. The dynamo
resulting from a well-understood near-surface phenomenon improves prospects
for accurate predictions of full magnetic cycles and space weather, affecting the
electromagnetic infrastructure of Earth.
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...Sérgio Sacani
In the Nice model of solar system formation, Uranus and Neptune undergo an orbital upheaval,
sweeping through a planetesimal disk. The region of the disk from which material is accreted by
the ice giants during this phase of their evolution has not previously been identified. We perform
direct N-body orbital simulations of the four giant planets to determine the amount and origin of solid
accretion during this orbital upheaval. We find that the ice giants undergo an extreme bombardment
event, with collision rates as much as ∼3 per hour assuming km-sized planetesimals, increasing the
total planet mass by up to ∼0.35%. In all cases, the initially outermost ice giant experiences the
largest total enhancement. We determine that for some plausible planetesimal properties, the resulting
atmospheric enrichment could potentially produce sufficient latent heat to alter the planetary cooling
timescale according to existing models. Our findings suggest that substantial accretion during this
phase of planetary evolution may have been sufficient to impact the atmospheric composition and
thermal evolution of the ice giants, motivating future work on the fate of deposited solid material.
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...Sérgio Sacani
The highest priority recommendation of the Astro2020 Decadal Survey for space-based astronomy
was the construction of an observatory capable of characterizing habitable worlds. In this paper series
we explore the detectability of and interference from exomoons and exorings serendipitously observed
with the proposed Habitable Worlds Observatory (HWO) as it seeks to characterize exoplanets, starting
in this manuscript with Earth-Moon analog mutual events. Unlike transits, which only occur in systems
viewed near edge-on, shadow (i.e., solar eclipse) and lunar eclipse mutual events occur in almost every
star-planet-moon system. The cadence of these events can vary widely from ∼yearly to multiple events
per day, as was the case in our younger Earth-Moon system. Leveraging previous space-based (EPOXI)
lightcurves of a Moon transit and performance predictions from the LUVOIR-B concept, we derive
the detectability of Moon analogs with HWO. We determine that Earth-Moon analogs are detectable
with observation of ∼2-20 mutual events for systems within 10 pc, and larger moons should remain
detectable out to 20 pc. We explore the extent to which exomoon mutual events can mimic planet
features and weather. We find that HWO wavelength coverage in the near-IR, specifically in the 1.4 µm
water band where large moons can outshine their host planet, will aid in differentiating exomoon signals
from exoplanet variability. Finally, we predict that exomoons formed through collision processes akin
to our Moon are more likely to be detected in younger systems, where shorter orbital periods and
favorable geometry enhance the probability and frequency of mutual events.
Emergent ribozyme behaviors in oxychlorine brines indicate a unique niche for...Sérgio Sacani
Mars is a particularly attractive candidate among known astronomical objects
to potentially host life. Results from space exploration missions have provided
insights into Martian geochemistry that indicate oxychlorine species, particularly perchlorate, are ubiquitous features of the Martian geochemical landscape. Perchlorate presents potential obstacles for known forms of life due to
its toxicity. However, it can also provide potential benefits, such as producing
brines by deliquescence, like those thought to exist on present-day Mars. Here
we show perchlorate brines support folding and catalysis of functional RNAs,
while inactivating representative protein enzymes. Additionally, we show
perchlorate and other oxychlorine species enable ribozyme functions,
including homeostasis-like regulatory behavior and ribozyme-catalyzed
chlorination of organic molecules. We suggest nucleic acids are uniquely wellsuited to hypersaline Martian environments. Furthermore, Martian near- or
subsurface oxychlorine brines, and brines found in potential lifeforms, could
provide a unique niche for biomolecular evolution.
Continuum emission from within the plunging region of black hole discsSérgio Sacani
The thermal continuum emission observed from accreting black holes across X-ray bands has the potential to be leveraged as a
powerful probe of the mass and spin of the central black hole. The vast majority of existing ‘continuum fitting’ models neglect
emission sourced at and within the innermost stable circular orbit (ISCO) of the black hole. Numerical simulations, however,
find non-zero emission sourced from these regions. In this work, we extend existing techniques by including the emission
sourced from within the plunging region, utilizing new analytical models that reproduce the properties of numerical accretion
simulations. We show that in general the neglected intra-ISCO emission produces a hot-and-small quasi-blackbody component,
but can also produce a weak power-law tail for more extreme parameter regions. A similar hot-and-small blackbody component
has been added in by hand in an ad hoc manner to previous analyses of X-ray binary spectra. We show that the X-ray spectrum
of MAXI J1820+070 in a soft-state outburst is extremely well described by a full Kerr black hole disc, while conventional
models that neglect intra-ISCO emission are unable to reproduce the data. We believe this represents the first robust detection of
intra-ISCO emission in the literature, and allows additional constraints to be placed on the MAXI J1820 + 070 black hole spin
which must be low a• < 0.5 to allow a detectable intra-ISCO region. Emission from within the ISCO is the dominant emission
component in the MAXI J1820 + 070 spectrum between 6 and 10 keV, highlighting the necessity of including this region. Our
continuum fitting model is made publicly available.
Cosa hanno in comune un mattoncino Lego e la backdoor XZ?Speck&Tech
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Spectroscopic characterization vesta_mineralogy
1. Spectroscopic Characterization of Mineralogy and Its Diversity
Across Vesta
M. C. De Sanctis et al.
Science 336, 697 (2012);
DOI: 10.1126/science.1219270
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2. REPORTS
structurally by the inward facing scarp, arcuate ridge, 19. W. Bottke, H. J. Melosh, Icarus 124, 72 (1996). and the NASA Dawn at Vesta Participating Scientist
or break in slope. 20. If the formation time scale of Veneneia is a few hours, program for support. We thank the Dawn team for the
8. H. J. Melosh, Impact Cratering (Oxford Univ. Press, then to avoid interference with Rheasilvia a binary impactor development, cruise, orbital insertion, and operations
Oxford, 1989). would need a separation of at least ~3600 s × 5 km/s ~ of the Dawn spacecraft at Vesta. A portion of this
9. K. Keil, D. Stoffler, S. Love, E. Scott, Meteorit. Planet. Sci. 18,000 km or ~70 Vesta radii. The probability of both work was performed at the Jet Propulsion Laboratory,
32, 349 (1997). binary bodies hit Vesta would then be very small. California Institute of Technology, under contract
10. R. Jaumann et al., Science 336, 687 (2012). 21. D. Nesvorny et al., Icarus 193, 85 (2008). with NASA. Dawn data are archived with the NASA Planetary
11. S. Marchi et al., Science 336, 690 (2012). 22. F. Marzari, P. Farinella, D. R. Davis, Icarus 142, 63 (1999). Data System.
12. M. Jutzi, E. Asphaug, Geophys. Res. Lett. 38, L01102 (2011). 23. F. Marzari et al., Astron. Astrophys. 316, 248 (1996).
13. M. C. De Sanctis et al., Science 336, 697 (2012). 24. D. Bogard, Meteoritics 30, 244 (1995).
14. V. Reddy et al., Science 336, 700 (2012). 25. D. Bogard, D. Garrison, Meteorit. Planet. Sci. 38, 669 (2003). Supplementary Materials
www.sciencemag.org/cgi/content/full/336/6082/694/DC1
15. Materials and methods are available as supplementary 26. D. Bogard, Chem. Erde Geochem. 71, 207 (2011).
materials on Science Online. 27. Ar-Ar age resetting requires an extended time to diffuse Materials and Methods
16. B. Kriens, E. Shoemaker, K. Herkenhoff, J. Geophys. Res. Ar from the rocks; there is insufficient time to accomplish Supplementary Text
References (28, 29)
104, 18867 (1999). this in just the initial shock.
17. T. Kenkmann, Geology 30, 231 (2002).
18. P. Allemand, P. Thomas, J. Geophys. Res. 104, 16501 Acknowledgments: The authors thank D. Bogard, E. Asphaug, 12 April 2012; accepted 20 April 2012
(1999). and H. J. Melosh for helpful discussions and comments 10.1126/science.1223272
merous basaltic asteroids provide further support
Spectroscopic Characterization of for this hypothesis: Their orbits are distributed
Downloaded from www.sciencemag.org on May 10, 2012
from near Vesta to the 3:1 Kirkwood gap and
Mineralogy and Its Diversity the secular n-6 resonance that results in gravita-
tional perturbations. These, combined with colli-
Across Vesta sions, provide a convenient mechanism for their
delivery to Earth-crossing orbits (5–8).
Geochemical, petrologic, and geochronologic
M. C. De Sanctis,1* E. Ammannito,1 M. T. Capria,1 F. Tosi,1 F. Capaccioni,1 F. Zambon,1 studies of HEDs have led to the development
of models for the magmatic evolution of their
F. Carraro,1 S. Fonte,1 A. Frigeri,1 R. Jaumann,2 G. Magni,1 S. Marchi,3 T. B. McCord,4
parent body. The consensus is that the body was
L. A. McFadden,5 H. Y. McSween,6 D. W. Mittlefehldt,7 A. Nathues,8 E. Palomba,1
substantially melted early in its history through
C. M. Pieters,9 C. A. Raymond,10 C. T. Russell,11 M. J. Toplis,12 D. Turrini1
heating by decay of 26Al and 60Fe, forming a
molten core topped by a shell of molten silicates.
The mineralogy of Vesta, based on data obtained by the Dawn spacecraft’s visible and infrared Cooling and crystallization of a global magma
spectrometer, is consistent with howardite-eucrite-diogenite meteorites. There are considerable ocean could have produced an olivine-dominated
regional and local variations across the asteroid: Spectrally distinct regions include the south-polar mantle, a lower crust rich in low-Ca pyroxene
Rheasilvia basin, which displays a higher diogenitic component, and equatorial regions, which (diogenites), and an upper crust of basaltic flows
show a higher eucritic component. The lithologic distribution indicates a deeper diogenitic crust, and gabbroic intrusions (eucrites) (9, 10). How-
exposed after excavation by the impact that formed Rheasilvia, and an upper eucritic crust. ever, some HEDs are inconsistent with this sce-
Evidence for mineralogical stratigraphic layering is observed on crater walls and in ejecta. This is nario, leading to models involving less melting
broadly consistent with magma-ocean models, but spectral variability highlights local variations, and serial magmatism (11–14). The spatial dis-
which suggests that the crust can be a complex assemblage of eucritic basalts and pyroxene tribution of lithologies within the crust of the
cumulates. Overall, Vesta mineralogy indicates a complex magmatic evolution that led to a HED parent body would thus provide essential
differentiated crust and mantle.
elescopic visible and near-infrared spec- Fig. 1. (Top left) Spectra (nor-
T troscopy shows that the asteroid Vesta has
a basaltic surface dominated by the spec-
tral signature of pyroxene. Vesta spectra show
malized at 0.7 mm) of regions A
and B indicated in the VIR im-
age. (Top right) VIR color com-
many similarities to those of howardite-eucrite- posite (red = 0.92 mm, green =
diogenite (HED) meteorites (1), leading to the 0.62 mm, blue = 0.44 mm). Spa-
consensus that Vesta is differentiated and is the tial resolution is ~25 km. Arrow
parent body of the HED achondrites (2–4). Nu- indicates the south pole. (Bottom)
Average Vesta spectrum with
1
Istituto di Astrofisica e Planetologia Spaziali, Istituto Nazionale T1 SD of the average. The data
di Astrofisica, Rome, Italy. 2Institute of Planetary Research, between 2.5 and 2.8 mm have
German Aerospace Center (DLR), Berlin, Germany. 3NASA Lunar been removed because they are
Science Institute, Boulder, CO, USA. 4Bear Fight Institute,
Winthrop, WA, USA. 5NASA, Goddard Space Flight Center,
not yet fully calibrated in this
Greenbelt, MD, USA. 6Department of Earth and Planetary region.
Sciences, University of Tennessee, Knoxville, TN, USA. 7NASA
Johnson Space Center, Houston, TX 77058, USA. 8Max-Planck-
Institut für Sonnensystemforschung, Katlenburg-Lindau, Ger-
many. 9Brown University, Providence, RI, USA. 10Jet Propulsion
Laboratory, California Institute of Technology, Pasadena, CA,
USA. 11Institute of Geophysics and Planetary Physics, University
of California, Los Angeles, CA, USA. 12Observatoire Midi-
Pyrenees, Toulouse, France.
*To whom correspondence should be addressed. E-mail:
mariacristina.desanctis@iaps.inaf.it
www.sciencemag.org SCIENCE VOL 336 11 MAY 2012 697
3. REPORTS
geological context relevant to the question of its have allowed >65% of the surface to be imaged, tral variations also reflect diurnal changes with
formation history. ranging from the south pole up to about 45°N the corresponding surface temperature changes
The visible and infrared spectrometer (VIR) (the northern polar region was in shadow). VIR (Fig. 1).
on Dawn is a high-resolution imaging spectrom- has acquired about four million spectra of Vesta’s The color composite image of Vesta (Fig. 1)
eter with a spectral range of 0.25 to 5.01 mm and a surface under different illumination conditions, demonstrates that there are large-scale variations
spatial sampling of 250 mrad (15). It combines with phase angles from 67.8° to 7.9°. in the spectral properties of the surface material
two data channels in one compact instrument: the The first data, at a resolution twice that of the and that these variations are greater in magnitude
visible-infrared (0.25 to 1.07 mm) and the infrared Hubble Space Telescope, were obtained from a than those described on other asteroids (17, 18). In
(0.95 to 5.1 mm) channels, with a spectral sam- distance of ~99,200 km (Fig. 1). The spectra show this image, the reddish color of the northern hem-
pling of DlVIS = 1.8 nm per band and DlIR = clear evidence of pyroxene absorption bands at 0.9 isphere indicates greater reflectivity at 0.92 mm,
9.8 nm per band, respectively. and 1.9 mm (hereafter BI and BII). Different re- and hence shallower pyroxene bands compared
VIR obtained spatially resolved hyperspectral gions of Vesta are characterized by distinctly dif- with the southern hemisphere. The representa-
images of Vesta (fig. S1) with a nominal spatial ferent band depths, widths, shapes, and centers. tive spectrum from region A shows stronger ab-
sampling up to ~0.7 km. The orientation of Vesta’s Beyond ~3.5 mm, thermal emission of the surface sorption at 0.92 mm relative to the continuum at
spin axis and Dawn’s orbital characteristics (16) becomes increasingly important, and the spec- 0.7 mm than does region B.
Fig. 2. Cylindrical and stereo-
graphic projections of spectral
Downloaded from www.sciencemag.org on May 10, 2012
parameters obtained by VIR.
(A) BI depths. (B) BII depths.
(C) BI centers. (D) BII centers.
Band depths and centers were
computed after continuum
removal (fig. S2).
698 11 MAY 2012 VOL 336 SCIENCE www.sciencemag.org
4. REPORTS
Although the surface of Vesta exhibits spec- whereas in the southern region they are ~0.25 to The global asymmetry evident in the distribu-
tral variations at both large and small scales, the 0.3. The depth of an absorption band is mainly tions of pyroxene band depths is also demonstrated
materials on the surface are always dominated by determined by the abundance of the absorbing by variations in band center wavelengths (Fig. 2, C
rocks formed by mafic magmatism, as indicated minerals, the grain size distribution, and the abun- and D). Laboratory studies indicate that band cen-
by the ubiquitous BI and BII pyroxene signatures. dance of opaque phases. The process known as ters for BI and BII pyroxene absorptions are sys-
These bands are caused by absorption of pho- space weathering also modifies reflectance spectra tematically different for diogenites and eucrites (26).
tons, primarily by Fe2+, and their exact position and can make lithological interpretation difficult. To directly compare Vesta band centers with HEDs,
and shape are driven by the relative proportion Regolithic howardites show some characteristics we computed the band centers of HEDs by apply-
of Fe to Mg in the M1 and M2 sites of pyroxene of exposure to the space environment, such has ing the same method to both data sets (Fig. 3). BI
crystal structures (19, 20). high noble gas and siderophile element contents, and BII centers are at slightly shorter wavelengths
VIR spatial resolution allows for the defini- and impact-produced glass, but these character- for diogenites than for eucrites (Fig. 3), a conse-
tion of localized mineralogical units: The results istics are not as well developed as in mature lunar quence of more Mg-rich pyroxenes with lower Ca
indicate a complex geological and collisional his- regolith breccias (24, 25). Vesta retains a reflec- concentrations in the former (26). Howardites, be-
tory (21–23) and reveal a crust that was differen- tance spectrum dominated by pyroxene absorp- cause of their intermediate nature, lie between, but
tiated before impact bombardment. The spectral tion bands (fig. S5), indicating that the effects of partially overlap the fields of diogenites and eucrites.
variations indicate that Vesta’s crust is composi- space weathering are much less pronounced on The BI and BII centers in the VIR spectra
tionally variable at vertical scales from a few hun- Vesta compared with the Moon or Mercury. form a trend from diogenites to eucrites, and
dred meters to 20 km, the depth of excavation of Thus, the VIR data suggest that the region of most plot in the howardites region. Band center
the southern impact basins (16). the Rheasilvia basin is richer in pyroxene than the values are not uniformly distributed on Vesta,
Downloaded from www.sciencemag.org on May 10, 2012
A global-scale spectral difference is observed equatorial regions or that the regolith in this region but they differ systematically between the equa-
between the equatorial and southern Rheasilvia has a larger average grain size distribution and/or torial and southern regions, and band center val-
regions, as shown on maps of BI and BII depths contains fewer opaque minerals. A larger grain size ues often correlate inversely with band depths
and centers (Fig. 2). In the south pole region, py- would be consistent with less impact comminution (Fig. 2). Equatorial regions are prevalently char-
roxene bands are, on average, deeper and wider in the southern region because of the younger age acterized by band centers at longer wavelengths
than in the equatorial region (fig. S3). In general, of the Rheasilvia basin (23). The lower crust is also (average BI = 0.930 mm and BII = 1.96 mm) and
BI depths in the equatorial region are ~ 0.35 to expected to have had a coarser initial grain size be- typically have intermediate to shallow band depths.
0.4, whereas those in the Rheasilvia basin are cause pyroxene grain sizes vary from diogenites, In contrast, band centers in the Rheasilvia basin
commonly 0.45 to 0.55. Similarly, BII depths in which are much larger than cumulate eucrites, are at shorter wavelengths (average BI = 0.926 mm
the equatorial region are typically ~ 0.15 to 0.2, which are larger than basaltic eucrites (12). and BII = 1.94 mm), and these often correspond
to the deepest pyroxene absorption bands (Fig. 2).
Overall, the correlations between band depths
Fig. 3. BI center versus BII center. Green,
and band centers can be interpreted in terms of
yellow, and violet ovals are the distribution
diogenite/eucrite content of the different terrains.
of howardites, eucrites, and diogenites,
respectively. The scatter plot represents Diogenites contain ~90 to 95 volume % (vol %)
the distribution of the VIR BI and BII centers pyroxene (27), whereas basaltic eucrites contain
acquired during the Survey phase. ~50 vol % pyroxene (28), implying that, for a
given grain size, the diogenites spectra have
stronger bands with respect to eucrites, as con-
firmed by HED spectra (table S1). The corre-
spondence of stronger pyroxene absorptions with
shorter BII and BI centers in the Rheasilvia basin
is consistent with a greater proportion of dioge-
nite on the surface in this deeply excavated region.
Spectra from the equatorial regions have band
centers shifted to longer wavelengths, indicat-
ing more Fe-rich pyroxenes, and intermediate or
shallow band depths, indicating lower pyroxene
abundance, both consistent with a greater eucrite
component. However, the equatorial region is
not spectrally uniform. An extensive area at about
40°E has measurably deeper absorption bands and
shorter wavelengths, suggesting a lower proportion
of eucritic material in this region, possibly related
to the influence of Rheasilvia ejecta (23–25). Over-
all, the mineralogical north-south diversity indi-
cates that the lower crust exposed in Rheasilvia is
dominated by pyroxene-rich, diogenitic material.
Although the difference between the south
polar and equatorial regions is the dominant
first-order feature (Fig. 2), VIR data also demon-
Fig. 4. The vestan surface near Oppia crater. E, Oppia ejecta; F, Oppia crater floor; H, Oppia crater walls; strate that Vesta’s surface and subsurface show
S, small crater near Oppia. (A) False-color image in the visible continuum. (B) Lithologic diversity around variations at local scales, that is, bright and dark
the central crater with copious “red” ejecta (shallower absorption bands) and deeper pyroxene bands on localized areas (fig. S4). Study of geological
the crater walls. (C) Image made by combining colors defining the 930-nm band depth, where the small structures at scales of tens of kilometers, in par-
crater near the Oppia rim (S) is clearly seen. ticular impact craters with copious ejecta and
www.sciencemag.org SCIENCE VOL 336 11 MAY 2012 699
5. REPORTS
mass movements, often show associated spec- evolutionary history, more similar to that of the 15. M. C. De Sanctis et al., Space Sci. Rev. (2010).
tral differences. For example, the Oppia region’s terrestrial planets than to other asteroids visited 16. C. T. Russell et al., Science 336, 684 (2012).
17. A. Coradini et al., Science 334, 492 (2011).
surface exhibits variations in albedo and spec- by spacecraft (17, 18). The occurrence of a greater 18. J. Veverka et al., Science 289, 2088 (2000).
tral slope that indicate differences in surface ma- proportion of diogenite at depth is a critical finding, 19. R. G. Burns, Mineralogical Applications of Crystal Field
terials (Fig. 4A). Moreover, the area around the not demonstrated by data from the Hubble Space Theory (Cambridge Univ. Press, Cambridge, 1993).
(Fig. 3) fresh Oppia crater (E) and the crater Telescope or telescopic observations (30, 31), 20. L. A. McFadden, T. B. McCord, C. Pieters, Icarus 31, 439
(1977).
floor (F) have shallower BI depths (Fig. 4B), and broadly consistent with magma ocean mod- 21. P. Schenk et al., Science 336, 694 (2012).
revealing material poorer in pyroxene. The els for Vesta’s differentiation. On the other hand, 22. R. Jaumann et al., Science 336, 687 (2012).
cratering process here results in inverted stratig- the fact that mixtures of diogenite and eucrite 23. S. Marchi et al., Science 336, 690 (2012).
raphy of roughly the upper third of the target appear ubiquitous in all regions, coupled with the 24. P. H. Warren, G. W. Kallemeyn, H. Huber, F. Ulff-Møller,
W. Choe, Geochim. Cosmochim. Acta 73, 5918
lithology in the ejecta blanket nearest the rim occurrence of smaller-scale variations in mineralogy, (2009).
[e.g., (29)]. The crater floor and material part- make it premature to distinguish between a simple 25. L. Wilkening, D. Lal, A. M. Reid, Earth Planet. Sci. Lett.
way up the walls have a reddish hue similar to layered crust of eucrite and underlying dioge- 10, 334 (1971).
the ejecta just outside the rim, consistent with nite (32) or a complex eucrite crust with 26. M. J. Gaffey, J. Geophys. Res. 81, 905 (1976).
27. L. E. Bowman, M. N. Spilde, J. J. Papike, Meteorit. Planet.
the lower layers in this crater being composed intruded diogenitic plutons (14). The Dawn mis-
Sci. 32, 869 (1997).
of rock poorer in pyroxene. The cyan color in- sion provides the first spatially detailed view of 28. J. S. Delaney, M. Prinz, H. Takeda, J. Geophys. Res. 89,
dicates that the soils just below the rim (H) have the distribution of the rock types, allowing insight (suppl.), C251 (1984).
stronger BI absorption and thus have higher into the magmatic processes that formed the solar 29. H. J. Melosh, Impact Cratering: A Geologic Process
pyroxene content or different grain size (Fig. 4C). system’s “smallest planet.” (Oxford Univ. Press, Oxford, 1989).
Downloaded from www.sciencemag.org on May 10, 2012
30. Telescopic data suggested a prominent diogenite region.
The small crater (S) is surrounded by a halo of References and Notes In the adopted coordinate system, this diogenite spot was
bright and green materials, similar to the layer ex- 1. T. B. McCord, J. B. Adams, T. V. Johnson, Science 168, moved to the northern hemisphere, where VIR does not
posed in Oppia (H), suggesting a similar compo- 1445 (1970). find this evidence.
sition. VIR thus reveals that the Oppia impact 2. M. A. Feierberg, M. J. Drake, Science 209, 805 (1980). 31. J. Y. Li et al., Icarus 208, 238 (2010).
3. G. J. Consolmagno, M. J. Drake, Geochim. Cosmochim. 32. H. Takeda, Icarus 40, 455 (1979).
exposed different kinds of materials, suggesting
Acta 41, 1271 (1977).
complex, small-scale crustal stratigraphy on Vesta. 4. M. J. Drake, In Asteroids, T. Gehrels, Ed. (Univ. Arizona Acknowledgments: VIR is funded by the Italian Space Agency
At all scales, pyroxene absorptions are the Press, Tucson, AZ, 1979), pp. 765–782 and was developed under the leadership of INAF-Istituto
most prominent spectral features on Vesta and, 5. R. P. Binzel et al., Icarus 128, 95 (1997). di Astrofisica e Planetologia Spaziali, Rome, Italy. The
6. M. C. De Sanctis et al., Astron. Astrophys. 533, A77 (2011). instrument was built by Selex-Galileo, Florence, Italy. The
on average, the spectral parameters of Vesta re- authors acknowledge the support of the Dawn Science,
7. N. A. Moscovitz et al., Icarus 208, 773 (2010).
semble those of howardites (fig. S5). The VIR 8. M. C. De Sanctis et al., Mon. Not. R. Astron. Soc. 412, Instrument, and Operations Teams. This work was supported
spectra are thus consistent with a surface covered 2318 (2011). by the Italian Space Agency, and NASA’s Dawn at Vesta
by a howardite-like regolith containing varying 9. K. Righter, M. J. Drake, Meteorit. Planet. Sci. 32, 929 (1997). Participating Scientists Program. A portion of this work was
10. P. H. Warren, Meteorit. Planet. Sci. 32, 945 (1997). performed at the Jet Propulsion Laboratory under contract
proportions of eucrite and diogenite at different
11. R. C. Greenwood, I. A. Franchi, A. Jambon, P. C. Buchanan, with NASA.
locations. This firmly supports the link between Nature 435, 916 (2005).
Vesta and the HEDs, providing geologic context 12. D. W. Mittlefehldt et al., in Planetary Materials: Reviews Supplementary Materials
www.sciencemag.org/cgi/content/full/336/6082/697/DC1
for these samples, which furthers our understand- in Mineralogy 36, J. J. Papike, Ed. (Mineralogical
Supplementary Text
ing of the formation and evolution of Vesta. Society of America, Chantilly, VA, 1998), pp. 4-1–4-195.
13. A. Beck, H. Y. McSween Jr., Meteorit. Planet. Sci. 45, Figs. S1 to S5
Furthermore, Vesta exhibits large color and 850 (2010).
Table S1
spectral variations that often reflect geological 14. J.-A. Barrat, A. Yamaguchi, B. Zanda, C. Bollinger, 17 January 2012; accepted 16 April 2012
structures, indicating a complex geological and M. Bohn, Geochim. Cosmochim. Acta 74, 6218 (2010). 10.1126/science.1219270
Color and Albedo Heterogeneity 1
Max Planck Institute for Solar System Research, Max-Planck-
Strasse 2, 37191 Katlenburg-Lindau, Germany. 2Department
of Space Studies, University of North Dakota, Grand Forks, ND
of Vesta from Dawn 58202, USA. 3Department of Astronomy, University of Mary-
land, College Park, MD 20742, USA. 4Planetary Science
Vishnu Reddy,1,2* Andreas Nathues,1 Lucille Le Corre,1 Holger Sierks,1 Jian-Yang Li,3 Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719,
USA. 5Department of Mineral Sciences, Smithsonian National
Robert Gaskell,4 Timothy McCoy,5 Andrew W. Beck,5 Stefan E. Schröder,1 Carle M. Pieters,6 Museum of Natural History, 10th and Constitution NW,
Kris J. Becker,7 Bonnie J. Buratti,8 Brett Denevi,9 David T. Blewett,9 Ulrich Christensen,1 Washington, DC 20560–0119, USA. 6Department of Geologi-
Michael J. Gaffey,2 Pablo Gutierrez-Marques,1 Michael Hicks,8 Horst Uwe Keller,10 cal Sciences, Brown University, Providence, RI 02912, USA.
7
Thorsten Maue,1 Stefano Mottola,11 Lucy A. McFadden,12 Harry Y. McSween,13 Astrogeology Science Center, U.S. Geological Survey, Flagstaff,
AZ 86001, USA. 8Jet Propulsion Laboratory, California In-
David Mittlefehldt,14 David P. O’Brien,4 Carol Raymond,8 Christopher Russell15 stitute of Technology, 4800 Oak Grove Drive, Pasadena, CA
91109, USA. 9Johns Hopkins University Applied Physics
Multispectral images (0.44 to 0.98 mm) of asteroid (4) Vesta obtained by the Dawn Framing Cameras Laboratory, Laurel, MD 20723, USA. 10Institut für Geophysik
reveal global color variations that uncover and help understand the north-south hemispherical und extraterrestrische Physik, TU Braunschweig Mendelssohn-
dichotomy. The signature of deep lithologies excavated during the formation of the Rheasilvia basin on strasse 3, DE 38106 Braunschweig, Germany. 11Deutsches
the south pole has been preserved on the surface. Color variations (band depth, spectral slope, and Zentrum für Luft und Raumfahrt (DLR)–German Aerospace Center,
Institute of Planetary Research, Rutherfordstrasse 2, D-12489
eucrite-diogenite abundance) clearly correlate with distinct compositional units. Vesta displays the Berlin, Germany. 12NASA/Goddard Space Flight Center, Mail
greatest variation of geometric albedo (0.10 to 0.67) of any asteroid yet observed. Four distinct color Code 160, Greenbelt, MD 20771, USA. 13Department of Earth
units are recognized that chronicle processes—including impact excavation, mass wasting, and and Planetary Sciences, University of Tennessee, 1412 Circle
space weathering—that shaped the asteroid’s surface. Vesta’s color and photometric diversity are Drive, Knoxville, TN 37996–1410, USA. 14Astromaterials
Research Office, NASA Johnson Space Center, Mail Code KR,
indicative of its status as a preserved, differentiated protoplanet. Houston, TX 77058, USA. 15Institute of Geophysics and Plan-
etary Physics, University of California Los Angeles, Los Angeles,
he Dawn spacecraft rendezvoused with in seven colors (0.44 to 0.98 mm) and one broad-
T
CA 90024–1567, USA.
the asteroid Vesta on 16 July 2011, and the band clear filter, mapping the entire sun-lit surface *To whom correspondence should be sent. E-mail: reddy@
Framing Cameras (FCs) (1) acquired images at a detail of ~9 to ~0.016 km/pixel. We used mps.mpg.de
700 11 MAY 2012 VOL 336 SCIENCE www.sciencemag.org