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.
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.
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.
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.
- Comet C/2011 N3 (SOHO) was observed by the Solar Dynamics Observatory as it passed through the low solar corona in July 2011.
- The comet survived within the corona until it came within 0.146 solar radii (approximately 100,000 km) of the solar surface, at which point its extreme ultraviolet signal disappeared.
- Before being destroyed, material released from the comet was first seen in absorption against the solar corona, then formed an emission nebula as it interacted with the coronal plasma.
The document discusses the discovery of the dwarf planet Eris. In 2003, astronomers Mike Brown, Chad Trujillo, and David Rabinowitz discovered an object they initially called 2003 UB313 that was later named Eris. Eris is over 25% more massive than Pluto and orbits further from the sun. Its discovery reignited the debate around what defines a planet. In 2006, the International Astronomical Union officially designated Eris as a dwarf planet along with Pluto, defining a planet as clearing its orbit. Eris' moon was named Dysnomia, the goddess of lawlessness in Greek mythology.
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.
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.
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.
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.
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.
- Comet C/2011 N3 (SOHO) was observed by the Solar Dynamics Observatory as it passed through the low solar corona in July 2011.
- The comet survived within the corona until it came within 0.146 solar radii (approximately 100,000 km) of the solar surface, at which point its extreme ultraviolet signal disappeared.
- Before being destroyed, material released from the comet was first seen in absorption against the solar corona, then formed an emission nebula as it interacted with the coronal plasma.
The document discusses the discovery of the dwarf planet Eris. In 2003, astronomers Mike Brown, Chad Trujillo, and David Rabinowitz discovered an object they initially called 2003 UB313 that was later named Eris. Eris is over 25% more massive than Pluto and orbits further from the sun. Its discovery reignited the debate around what defines a planet. In 2006, the International Astronomical Union officially designated Eris as a dwarf planet along with Pluto, defining a planet as clearing its orbit. Eris' moon was named Dysnomia, the goddess of lawlessness in Greek mythology.
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.
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 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
1. Scientists used stellar occultation to measure the size of the dwarf planet Eris more accurately. They found it has a radius of 1,163 km, smaller than previous estimates, though not definitively smaller than Pluto due to uncertainties in Pluto's size.
2. Surprisingly, Eris' surface was found to be very bright, which could indicate a collapsed or localized atmosphere had recently condensed onto the surface from sublimated ices as Eris moves closer to the Sun in its orbit.
3. The discovery of Eris and other large Kuiper Belt objects has challenged definitions of planets and our understanding of the outer solar system, showing Pluto is not unique and sparking debate about what constitutes
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) The study analyzed images of the supernova remnant SNR 0509-67.5 to search for a companion star to the type Ia supernova that occurred around 400 years ago.
2) They found no evidence of a companion star with a luminosity greater than 3% of the sun's luminosity, ruling out stars ranging from supergiants to K-type main sequence stars.
3) The results provide evidence that the progenitor system for this supernova was a pair of white dwarfs, known as a double-degenerate system, rather than a single white dwarf with a non-white dwarf companion.
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.
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
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.
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
This document presents the target selection process for the first year of the Breakthrough Listen search for intelligent life using the Green Bank Telescope, Parkes Telescope, and Automated Planet Finder. The targets include: 1) The 60 nearest stars within 5.1 parsecs to search for faint signals; 2) 1649 stars spanning stellar types from the Hipparcos catalog; 3) 123 nearby galaxies representing different morphological types to search billions of stars simultaneously; and 4) several classes of exotic objects like white dwarfs and neutron stars. The telescopes will observe 1,000,000 stars and galaxies at radio and optical wavelengths between 350 MHz to 100 GHz and 374-950nm, respectively, to search for technological signals.
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.
A 100 parsec elliptical and twisted ring of cold and dense molecular clouds r...Sérgio Sacani
The document summarizes observations from the Herschel satellite that reveal a 100-parsec elliptical and twisted ring of cold, dense molecular clouds orbiting the Galactic Center. The ring has a mass of about 3 million solar masses and semi-major axes of 100 and 60 parsecs. Its major axis is inclined 40 degrees to the plane of the sky and perpendicular to the Galactic Bar. The ring appears to trace stable x2 orbits predicted for the barred Galactic potential.
Sloan digital sky survey iii mapping the universe on the largest scalesSérgio Sacani
The Sloan Digital Sky Survey III (SDSS-III) is mapping the universe on the largest scales through four main surveys: 1) the largest multicolor image of the night sky, 2) the largest 3D map of the universe, 3) the largest map of the outer Milky Way, and 4) public data releases that serve as a resource for astronomers and the public. SDSS-III builds on the previous SDSS surveys and uses spectroscopy to measure galaxy distances and map the distant universe.
- 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.
The Search for Distant Objects in the Solar System Using Spacewatch - Astrono...Eric Roe
This document describes a survey conducted by the Spacewatch Project to search for distant and slow-moving bright objects in the outer solar system beyond Neptune. The survey used data taken over 34 months with multiple night detections to achieve sensitivity to motions as slow as 0.012 arcsec/hr. This allowed the survey to be sensitive to Mars-sized objects out to 300 AU and Jupiter-sized planets out to 1200 AU. No large objects were found at low inclinations despite having sufficient sensitivity, allowing the authors to rule out more than one or two Pluto-sized objects to 100 AU and one or two Mars-sized objects to 200 AU for low inclinations.
Searching for alien_artifacts_on_the_moonSérgio Sacani
1. The authors propose searching lunar surface photos from the Lunar Reconnaissance Orbiter for signs of extraterrestrial artifacts or technology.
2. Possible artifacts could include probes left to monitor Earth, trash from alien expeditions, or signs of mining or construction activities.
3. The moon is a good target for this search because it is close, signs would be well-preserved over immense timescales, and high-resolution photos are already being taken for other scientific purposes. Systematically analyzing these photos could help widen the search for extraterrestrial intelligence.
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
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.
Measurements of energetic_particle_radiation_in_transit_to_mars_on_the_mars_s...Sérgio Sacani
The Radiation Assessment Detector on the Mars Science Laboratory measured the radiation environment inside the spacecraft during its 253-day cruise to Mars. It found a galactic cosmic ray dose rate of 332 mGy/day in silicon or 481 mGy/day in water. The quality factor for the radiation field was 3.82, indicating it was more biologically damaging than an equal dose of low-LET radiation. Integrating the measured energy and linear energy transfer spectra against quality factors yielded a total mission dose equivalent of 0.66 sievert for the round-trip cruise, posing health risks for future human Mars missions with current propulsion technologies and shielding.
This document reports the detection of five planets orbiting the star Kepler-62, including two super-Earth-size planets (Kepler-62e and Kepler-62f) in the habitable zone of the star. Kepler-62e receives 1.2 times the solar flux at Earth's orbit, while Kepler-62f receives 0.41 times the solar flux. Theoretical models suggest that both planets could be solid, with either a rocky composition or composed mostly of solid water.
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.
This document summarizes VLBI observations of supernova SN 2011dh made 14 days after its discovery, providing the earliest radio image of a supernova. The observations detected SN 2011dh at 22 GHz using a subset of the EVN array. The recovered flux density was approximately half the value measured by the EVLA at the same frequency and epoch, possibly due to extended emission or calibration issues. Precise coordinates for SN 2011dh were determined, linked to the ICRF, which may help improve future VLBI observations of the supernova.
The document discusses the training that Apollo astronauts received for making observations and taking photographs from lunar orbit. It summarizes that (1) astronauts were trained to add to scientific knowledge by describing lunar features from their unique viewpoint in orbit, and (2) photographs from orbit could provide regional context for detailed surface exploration findings. The training grew over missions from briefings to extensive classroom sessions. Outstanding results from astronaut observations and photos included realizing limitations of depicting lunar surface colors photographically and discovering previously unknown farside features.
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
1. Scientists used stellar occultation to measure the size of the dwarf planet Eris more accurately. They found it has a radius of 1,163 km, smaller than previous estimates, though not definitively smaller than Pluto due to uncertainties in Pluto's size.
2. Surprisingly, Eris' surface was found to be very bright, which could indicate a collapsed or localized atmosphere had recently condensed onto the surface from sublimated ices as Eris moves closer to the Sun in its orbit.
3. The discovery of Eris and other large Kuiper Belt objects has challenged definitions of planets and our understanding of the outer solar system, showing Pluto is not unique and sparking debate about what constitutes
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) The study analyzed images of the supernova remnant SNR 0509-67.5 to search for a companion star to the type Ia supernova that occurred around 400 years ago.
2) They found no evidence of a companion star with a luminosity greater than 3% of the sun's luminosity, ruling out stars ranging from supergiants to K-type main sequence stars.
3) The results provide evidence that the progenitor system for this supernova was a pair of white dwarfs, known as a double-degenerate system, rather than a single white dwarf with a non-white dwarf companion.
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.
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
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.
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
This document presents the target selection process for the first year of the Breakthrough Listen search for intelligent life using the Green Bank Telescope, Parkes Telescope, and Automated Planet Finder. The targets include: 1) The 60 nearest stars within 5.1 parsecs to search for faint signals; 2) 1649 stars spanning stellar types from the Hipparcos catalog; 3) 123 nearby galaxies representing different morphological types to search billions of stars simultaneously; and 4) several classes of exotic objects like white dwarfs and neutron stars. The telescopes will observe 1,000,000 stars and galaxies at radio and optical wavelengths between 350 MHz to 100 GHz and 374-950nm, respectively, to search for technological signals.
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.
A 100 parsec elliptical and twisted ring of cold and dense molecular clouds r...Sérgio Sacani
The document summarizes observations from the Herschel satellite that reveal a 100-parsec elliptical and twisted ring of cold, dense molecular clouds orbiting the Galactic Center. The ring has a mass of about 3 million solar masses and semi-major axes of 100 and 60 parsecs. Its major axis is inclined 40 degrees to the plane of the sky and perpendicular to the Galactic Bar. The ring appears to trace stable x2 orbits predicted for the barred Galactic potential.
Sloan digital sky survey iii mapping the universe on the largest scalesSérgio Sacani
The Sloan Digital Sky Survey III (SDSS-III) is mapping the universe on the largest scales through four main surveys: 1) the largest multicolor image of the night sky, 2) the largest 3D map of the universe, 3) the largest map of the outer Milky Way, and 4) public data releases that serve as a resource for astronomers and the public. SDSS-III builds on the previous SDSS surveys and uses spectroscopy to measure galaxy distances and map the distant universe.
- 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.
The Search for Distant Objects in the Solar System Using Spacewatch - Astrono...Eric Roe
This document describes a survey conducted by the Spacewatch Project to search for distant and slow-moving bright objects in the outer solar system beyond Neptune. The survey used data taken over 34 months with multiple night detections to achieve sensitivity to motions as slow as 0.012 arcsec/hr. This allowed the survey to be sensitive to Mars-sized objects out to 300 AU and Jupiter-sized planets out to 1200 AU. No large objects were found at low inclinations despite having sufficient sensitivity, allowing the authors to rule out more than one or two Pluto-sized objects to 100 AU and one or two Mars-sized objects to 200 AU for low inclinations.
Searching for alien_artifacts_on_the_moonSérgio Sacani
1. The authors propose searching lunar surface photos from the Lunar Reconnaissance Orbiter for signs of extraterrestrial artifacts or technology.
2. Possible artifacts could include probes left to monitor Earth, trash from alien expeditions, or signs of mining or construction activities.
3. The moon is a good target for this search because it is close, signs would be well-preserved over immense timescales, and high-resolution photos are already being taken for other scientific purposes. Systematically analyzing these photos could help widen the search for extraterrestrial intelligence.
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
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.
Measurements of energetic_particle_radiation_in_transit_to_mars_on_the_mars_s...Sérgio Sacani
The Radiation Assessment Detector on the Mars Science Laboratory measured the radiation environment inside the spacecraft during its 253-day cruise to Mars. It found a galactic cosmic ray dose rate of 332 mGy/day in silicon or 481 mGy/day in water. The quality factor for the radiation field was 3.82, indicating it was more biologically damaging than an equal dose of low-LET radiation. Integrating the measured energy and linear energy transfer spectra against quality factors yielded a total mission dose equivalent of 0.66 sievert for the round-trip cruise, posing health risks for future human Mars missions with current propulsion technologies and shielding.
This document reports the detection of five planets orbiting the star Kepler-62, including two super-Earth-size planets (Kepler-62e and Kepler-62f) in the habitable zone of the star. Kepler-62e receives 1.2 times the solar flux at Earth's orbit, while Kepler-62f receives 0.41 times the solar flux. Theoretical models suggest that both planets could be solid, with either a rocky composition or composed mostly of solid water.
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.
This document summarizes VLBI observations of supernova SN 2011dh made 14 days after its discovery, providing the earliest radio image of a supernova. The observations detected SN 2011dh at 22 GHz using a subset of the EVN array. The recovered flux density was approximately half the value measured by the EVLA at the same frequency and epoch, possibly due to extended emission or calibration issues. Precise coordinates for SN 2011dh were determined, linked to the ICRF, which may help improve future VLBI observations of the supernova.
The document discusses the training that Apollo astronauts received for making observations and taking photographs from lunar orbit. It summarizes that (1) astronauts were trained to add to scientific knowledge by describing lunar features from their unique viewpoint in orbit, and (2) photographs from orbit could provide regional context for detailed surface exploration findings. The training grew over missions from briefings to extensive classroom sessions. Outstanding results from astronaut observations and photos included realizing limitations of depicting lunar surface colors photographically and discovering previously unknown farside features.
The document summarizes research on the South Pole-Aitken basin, the largest impact crater on the Moon. It is over 2,500 km in diameter and more than 12 km deep. Spacecraft data show the basin has a higher concentration of iron than surrounding lunar highlands, suggesting it may expose deeper mantle rocks. However, the exact composition is debated, with some researchers arguing mantle rocks are not present based on mineral analysis. Understanding the basin's composition could provide insights into the Moon's interior structure and composition from the impact that formed the giant crater.
This article reports the detection of two gas clouds with no discernible elements heavier than hydrogen, representing the lowest heavy-element abundance observed in the early universe. One cloud at z=3.4 exhibits a deuterium abundance matching predictions from Big Bang nucleosynthesis, providing direct evidence for the standard cosmological model. The sparse metal enrichment of these clouds implies an inhomogeneous process for transporting heavy elements from galaxies into the surrounding intergalactic medium.
1) Newly-born pulsars offer favorable conditions for accelerating heavy nuclei like iron to ultrahigh energies via unipolar induction. However, these nuclei must escape the surrounding dense supernova envelope.
2) The paper analytically and numerically examines the escape of ultrahigh energy cosmic rays (UHECRs) from supernova envelopes. It finds that at early times when protons could reach energies above 10^20 eV, the envelope prevents their escape. However, heavier iron nuclei can still reach the highest observed energies at later times when the envelope has thinned.
3) The authors conclude that a small fraction (0.01%) of extragalactic rapidly rotating young pulsars embedded in supernov
The document summarizes a study of tungsten isotope ratios in lunar metals. The key findings are:
1) All lunar metal samples studied have identical tungsten isotope ratios within measurement error, indicating the lunar magma ocean did not crystallize within the first 60 million years as previously suggested.
2) Tungsten isotope ratios in lunar metals are identical to those in the Earth's mantle, suggesting the Moon and Earth mantles equilibrated after the giant impact that formed the Moon.
3) Together with previous samarium-neodymium dating of oldest lunar rocks, the results constrain the age of the Moon and Earth to 62 ± 10 million years after solar system formation.
This document summarizes a study that uses ab initio calculations to examine the solubility of magnesium oxide (MgO) in fluid hydrogen at conditions relevant to giant planet cores like Jupiter. The study finds that MgO is highly soluble in hydrogen for temperatures exceeding around 10,000 K, indicating rocky core materials would significantly redistribute within Jupiter and larger exoplanets. Free energy calculations based on density functional theory molecular dynamics and coupling constant integration techniques were used to determine the Gibbs free energy of solubilizing MgO in hydrogen at pressures from 10 to 40 megabars and temperatures from 10,000 to 20,000 K.
This document reports the detection of a low-mass dark satellite galaxy in a gravitational lens system. Using pixelated lens modeling of adaptive optics images, the researchers detected a positive density correction indicating the presence of a mass substructure. They estimate the mass of the substructure to be 1.9 x 108 solar masses located 600 parsecs from the density peak. Combining this detection with a previous one, they constrain the logarithmic slope of the mass function for dark matter substructure in elliptical galaxies to be 1.1-0.4 with an average mass fraction of 3.3-1.8%. This is consistent with predictions from cold dark matter simulations.
Characterizing interstellar filaments with herschel in ic5146Sérgio Sacani
This document summarizes early results from the Herschel Gould Belt survey of the IC5146 molecular cloud. It reveals a complex network of filaments identified in the cloud, which are shown to be the main sites of prestellar core formation. Analysis of 27 filaments finds that their radial column density profiles fall off with radii as r^-1.5 to r^-2.5. Remarkably, the filaments seem to have a narrow distribution of widths centered around 0.1 pc, in contrast to a broader distribution of central Jeans lengths. This characteristic width corresponds to the sonic scale below which turbulence becomes subsonic, supporting the argument that filaments may form from dissipating large-scale turbulence.
This document appears to be a citation to a 1996 Astrophysical Journal paper with the volume number 458 and page number 600, but it provides no other contextual information about the content or findings of the cited paper. The summary is limited due to the lack of substantive information in the given document.
This document summarizes the discovery of a luminous quasar (ULAS J112001.481064124.3) with a redshift of z=7.085, located approximately 777 million years after the Big Bang. It has a luminosity of 6.3 x 10^13 solar luminosities and hosts a black hole with a mass of 2 x 10^9 solar masses. The radius of its ionized region is 1.9 megaparsecs, smaller than typical quasars from z=6.0 to z=6.4. Analysis of its spectrum is consistent with a high neutral fraction (>0.1) of the intergalactic medium in front of it. This makes it the most
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.
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.
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.
A population of_fast_radio_bursts_ar_cosmological_distancesSérgio Sacani
1) Four fast radio bursts (FRBs) lasting only a few milliseconds were detected in a radio survey of the high Galactic latitude sky.
2) The bursts' properties indicate they are of celestial rather than terrestrial origin and likely originate from cosmological distances of 0.5 to 3 billion light years.
3) No coincident x-ray or gamma-ray signals were found associated with the bursts. Characterizing the population of FRBs could help determine the baryonic content of the universe.
A uranian trojan_and_the_frequency_of_temporary_giant_planet_co_orbitalsSérgio Sacani
1) Researchers detected a 60 km diameter object called 2011 QF99 that orbits the Sun in a 1:1 resonance with Uranus, never straying far from Uranus' Lagrangian point 60 degrees ahead of it (L4).
2) Numerical simulations show 2011 QF99 oscillating around the L4 point for over 70,000 years before transitioning to other co-orbital behavior and eventually becoming unstable within 1 million years.
3) Based on these simulations and estimates of supply from the trans-Neptunian region, the researchers calculate that temporarily around 0.4% of Centaurs should be Uranian co-orbitals and 2.8% should be Neptun
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.
Baryons at the edge of the x ray–brightest galaxy clusterSérgio Sacani
This article discusses observations of the outskirts of the Perseus galaxy cluster, which is the brightest extended X-ray source. The observations find evidence of gas beyond the virial radius that has been shock heated to high temperatures by accretion and mergers. The results provide insights into the formation and evolution of large-scale structure in the universe.
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.
Evidence for a Dynamo in the Main Group Pallasite Parent BodyCarlos Bella
Evidence is presented that the parent body of pallasite meteorites hosted a dynamo. Pallasite olivines contain tiny magnetic inclusions that can record magnetic fields. Paleointensity measurements from these inclusions indicate strong ancient magnetic fields, suggesting the parent body generated its own magnetic field through dynamo action. Thermal modeling suggests pallasites formed when liquid iron-nickel from the core of an impactor was injected as dikes into the shallow mantle of a ~200 km radius protoplanet that remained intact long enough to sustain a dynamo.
Geoffroy Lerosey has published extensively in peer-reviewed journals, with over 35 publications. His work focuses on manipulating waves and controlling propagation at subwavelength scales using techniques like time reversal and metamaterials. Some of his publications have been highlighted in prominent journals and received significant attention.
This document describes observations of the Seyfert 1 galaxy Mrk 509 using the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST). The observations detected absorption features in the ultraviolet spectrum, which are attributed to outflowing gas from the active galactic nucleus as well as gas in the galaxy's interstellar medium and halo. The COS observations provide higher signal-to-noise and resolution than previous observations, detecting additional complexity in the absorption features. Variability in some features constrains the distances of absorbing gas components to be less than 250 pc and 1.5 kpc from the active nucleus. The absorption lines only partially cover the emission from the active nucleus, possibly due to
Chiotelis Ioannis, Theodoropoulou Maria, “Searching for Black Holes. Photometry in our Classrooms”, Hellenic Conference on Innovating STEM Education, 16-18 December 2016, Athens, Greece.
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.
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.
Search for potential collaborators and students in UJ research fields: Nuclea...Rene Kotze
Prof Azwinndini Muronga (UJ Physics Department and Soweto Science Centre Director) is in search for potential collaborators and students in their research fields which are Nuclear, Particle, Astrophysics and Cosmology at the University of Johannesburg. If you know students and staff who will be interested please pass this on to anyone you know on the African continent. Students may come and study at UJ from Honours level up to PhD level. Staff interested in collaborating with us at UJ are strongly encouraged to do so.
Attached please find an electronic poster that depicts the UJ research activities
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.
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.
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.
This was a talk I gave at CU Boulder SEDs in Nov 2011 to showcase the variety and opportunities for student-run science and engineering experiments on suborbital platforms. The area of suborbital space is rapidly expanding and is set to change how we expand our use of technology for future science and exploration space missions.
Compositions of iron-meteorite parent bodies constrainthe structure of the pr...Sérgio Sacani
Magmatic iron-meteorite parent bodies are the earliest planetesimals in the Solar System,and they preserve information about conditions and planet-forming processes in thesolar nebula. In this study, we include comprehensive elemental compositions andfractional-crystallization modeling for iron meteorites from the cores of five differenti-ated asteroids from the inner Solar System. Together with previous results of metalliccores from the outer Solar System, we conclude that asteroidal cores from the outerSolar System have smaller sizes, elevated siderophile-element abundances, and simplercrystallization processes than those from the inner Solar System. These differences arerelated to the formation locations of the parent asteroids because the solar protoplane-tary disk varied in redox conditions, elemental distributions, and dynamics at differentheliocentric distances. Using highly siderophile-element data from iron meteorites, wereconstruct the distribution of calcium-aluminum-rich inclusions (CAIs) across theprotoplanetary disk within the first million years of Solar-System history. CAIs, the firstsolids to condense in the Solar System, formed close to the Sun. They were, however,concentrated within the outer disk and depleted within the inner disk. Future modelsof the structure and evolution of the protoplanetary disk should account for this dis-tribution pattern of CAIs.
Signatures of wave erosion in Titan’s coastsSérgio Sacani
The shorelines of Titan’s hydrocarbon seas trace flooded erosional landforms such as river valleys; however, it isunclear whether coastal erosion has subsequently altered these shorelines. Spacecraft observations and theo-retical models suggest that wind may cause waves to form on Titan’s seas, potentially driving coastal erosion,but the observational evidence of waves is indirect, and the processes affecting shoreline evolution on Titanremain unknown. No widely accepted framework exists for using shoreline morphology to quantitatively dis-cern coastal erosion mechanisms, even on Earth, where the dominant mechanisms are known. We combinelandscape evolution models with measurements of shoreline shape on Earth to characterize how differentcoastal erosion mechanisms affect shoreline morphology. Applying this framework to Titan, we find that theshorelines of Titan’s seas are most consistent with flooded landscapes that subsequently have been eroded bywaves, rather than a uniform erosional process or no coastal erosion, particularly if wave growth saturates atfetch lengths of tens of kilometers.
SDSS1335+0728: The awakening of a ∼ 106M⊙ black hole⋆Sérgio Sacani
Context. The early-type galaxy SDSS J133519.91+072807.4 (hereafter SDSS1335+0728), which had exhibited no prior optical variations during the preceding two decades, began showing significant nuclear variability in the Zwicky Transient Facility (ZTF) alert stream from December 2019 (as ZTF19acnskyy). This variability behaviour, coupled with the host-galaxy properties, suggests that SDSS1335+0728 hosts a ∼ 106M⊙ black hole (BH) that is currently in the process of ‘turning on’. Aims. We present a multi-wavelength photometric analysis and spectroscopic follow-up performed with the aim of better understanding the origin of the nuclear variations detected in SDSS1335+0728. Methods. We used archival photometry (from WISE, 2MASS, SDSS, GALEX, eROSITA) and spectroscopic data (from SDSS and LAMOST) to study the state of SDSS1335+0728 prior to December 2019, and new observations from Swift, SOAR/Goodman, VLT/X-shooter, and Keck/LRIS taken after its turn-on to characterise its current state. We analysed the variability of SDSS1335+0728 in the X-ray/UV/optical/mid-infrared range, modelled its spectral energy distribution prior to and after December 2019, and studied the evolution of its UV/optical spectra. Results. From our multi-wavelength photometric analysis, we find that: (a) since 2021, the UV flux (from Swift/UVOT observations) is four times brighter than the flux reported by GALEX in 2004; (b) since June 2022, the mid-infrared flux has risen more than two times, and the W1−W2 WISE colour has become redder; and (c) since February 2024, the source has begun showing X-ray emission. From our spectroscopic follow-up, we see that (i) the narrow emission line ratios are now consistent with a more energetic ionising continuum; (ii) broad emission lines are not detected; and (iii) the [OIII] line increased its flux ∼ 3.6 years after the first ZTF alert, which implies a relatively compact narrow-line-emitting region. Conclusions. We conclude that the variations observed in SDSS1335+0728 could be either explained by a ∼ 106M⊙ AGN that is just turning on or by an exotic tidal disruption event (TDE). If the former is true, SDSS1335+0728 is one of the strongest cases of an AGNobserved in the process of activating. If the latter were found to be the case, it would correspond to the longest and faintest TDE ever observed (or another class of still unknown nuclear transient). Future observations of SDSS1335+0728 are crucial to further understand its behaviour. Key words. galaxies: active– accretion, accretion discs– galaxies: individual: SDSS J133519.91+072807.4
Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...Sérgio Sacani
We present the JWST discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS
+
53.13485
−
27.82088
with a host spectroscopic redshift of
2.903
±
0.007
. The transient was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic followup with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (
�
(
�
−
�
)
∼
0.9
) despite a host galaxy with low-extinction and has a high Ca II velocity (
19
,
000
±
2
,
000
km/s) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-
�
Ca-rich population. Although such an object is too red for any low-
�
cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement (
≲
1
�
) with
Λ
CDM. Therefore unlike low-
�
Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high-
�
truly diverge from their low-
�
counterparts, and to confirm that standardized luminosities nevertheless remain constant with redshift.
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...Sérgio Sacani
Wereport the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in the blazar OJ287. In the binary black hole model, it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our multifrequency observing campaign was set up to search for such a signature of the impact based on a prediction made 8 yr earlier. The first I-band results of the flare have already been reported by Kishore et al. (2024). Here we combine these data with our monitoring in the R-band. There is a big change in the R–I spectral index by 1.0 ±0.1 between the normal background and the flare, suggesting a new component of radiation. The polarization variation during the rise of the flare suggests the same. The limits on the source size place it most reasonably in the jet of the secondary BH. We then ask why we have not seen this phenomenon before. We show that OJ287 was never before observed with sufficient sensitivity on the night when the flare should have happened according to the binary model. We also study the probability that this flare is just an oversized example of intraday variability using the Krakow data set of intense monitoring between 2015 and 2023. We find that the occurrence of a flare of this size and rapidity is unlikely. In machine-readable Tables 1 and 2, we give the full orbit-linked historical light curve of OJ287 as well as the dense monitoring sample of Krakow.
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...Sérgio Sacani
Context. The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact Doppler-shifted Brγ emission. The ionized hydrogen in combination with the observation of mid-infrared L-band continuum emission suggests that most of these sources are embedded in a dusty envelope. These embedded sources are part of the S-cluster, and their relationship to the S-stars is still under debate. To date, the question of the origin of these two populations has been vague, although all explanations favor migration processes for the individual cluster members. Aims. This work revisits the S-cluster and its dusty members orbiting the supermassive black hole SgrA* on bound Keplerian orbits from a kinematic perspective. The aim is to explore the Keplerian parameters for patterns that might imply a nonrandom distribution of the sample. Additionally, various analytical aspects are considered to address the nature of the dusty sources. Methods. Based on the photometric analysis, we estimated the individual H−K and K−L colors for the source sample and compared the results to known cluster members. The classification revealed a noticeable contrast between the S-stars and the dusty sources. To fit the flux-density distribution, we utilized the radiative transfer code HYPERION and implemented a young stellar object Class I model. We obtained the position angle from the Keplerian fit results; additionally, we analyzed the distribution of the inclinations and the longitudes of the ascending node. Results. The colors of the dusty sources suggest a stellar nature consistent with the spectral energy distribution in the near and midinfrared domains. Furthermore, the evaporation timescales of dusty and gaseous clumps in the vicinity of SgrA* are much shorter ( 2yr) than the epochs covered by the observations (≈15yr). In addition to the strong evidence for the stellar classification of the D-sources, we also find a clear disk-like pattern following the arrangements of S-stars proposed in the literature. Furthermore, we find a global intrinsic inclination for all dusty sources of 60 ± 20◦, implying a common formation process. Conclusions. The pattern of the dusty sources manifested in the distribution of the position angles, inclinations, and longitudes of the ascending node strongly suggests two different scenarios: the main-sequence stars and the dusty stellar S-cluster sources share a common formation history or migrated with a similar formation channel in the vicinity of SgrA*. Alternatively, the gravitational influence of SgrA* in combination with a massive perturber, such as a putative intermediate mass black hole in the IRS 13 cluster, forces the dusty objects and S-stars to follow a particular orbital arrangement. Key words. stars: black holes– stars: formation– Galaxy: center– galaxies: star formation
JAMES WEBB STUDY THE MASSIVE BLACK HOLE SEEDSSérgio Sacani
The pathway(s) to seeding the massive black holes (MBHs) that exist at the heart of galaxies in the present and distant Universe remains an unsolved problem. Here we categorise, describe and quantitatively discuss the formation pathways of both light and heavy seeds. We emphasise that the most recent computational models suggest that rather than a bimodal-like mass spectrum between light and heavy seeds with light at one end and heavy at the other that instead a continuum exists. Light seeds being more ubiquitous and the heavier seeds becoming less and less abundant due the rarer environmental conditions required for their formation. We therefore examine the different mechanisms that give rise to different seed mass spectrums. We show how and why the mechanisms that produce the heaviest seeds are also among the rarest events in the Universe and are hence extremely unlikely to be the seeds for the vast majority of the MBH population. We quantify, within the limits of the current large uncertainties in the seeding processes, the expected number densities of the seed mass spectrum. We argue that light seeds must be at least 103 to 105 times more numerous than heavy seeds to explain the MBH population as a whole. Based on our current understanding of the seed population this makes heavy seeds (Mseed > 103 M⊙) a significantly more likely pathway given that heavy seeds have an abundance pattern than is close to and likely in excess of 10−4 compared to light seeds. Finally, we examine the current state-of-the-art in numerical calculations and recent observations and plot a path forward for near-future advances in both domains.
Anti-Universe And Emergent Gravity and the Dark UniverseSérgio Sacani
Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. Using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. Due to the competition between area and volume law entanglement the microscopic de Sitter states do not thermalise at sub-Hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. The emergent laws of gravity contain an additional ‘dark’ gravitational force describing the ‘elastic’ response due to the entropy displacement. We derive an estimate of the strength of this extra force in terms of the baryonic mass, Newton’s constant and the Hubble acceleration scale a0 = cH0, and provide evidence for the fact that this additional ‘dark gravity force’ explains the observed phenomena in galaxies and clusters currently attributed to dark matter.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Sérgio Sacani
Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the
atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets
receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric
composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet
transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (Porb) of 12.76 days.
The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous Porb from TESS data. We
confirmed the transit signal and Porb using ground-based photometry with MuSCAT2 and MuSCAT3, and
validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as
well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope
and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host
star is inactive, with an X-ray-to-bolometric luminosity ratio of log 5.7 L L X bol » - . Joint analysis of the light
curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R⊕,a3σ mass upper limit of
3.9 M⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric
(TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small
list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.
Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TES...Sérgio Sacani
We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a
bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the
lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors
42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations
with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory,
as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of
12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent
future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar
compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool
stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
The importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox
(1) by adding two additional terms to the Drake Equation: foc
(the fraction of habitable exoplanets
with significant continents and oceans) and fpt
(the fraction of habitable exoplanets with significant
continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by
demonstrating that the product of foc
and fpt
is very small (< 0.00003–0.002). We propose that the lack
of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on
exoplanets with primitive life.
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. Itremains enigmatic how subduction could be initiated so soon after the presumably Moon‐forming giant impact(MGI). Earlier studies found an increase in Earth's core‐mantle boundary (CMB) temperature due to theaccumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, withsome of the impactor's mantle potentially surviving as the large low‐shear velocity provinces (LLSVPs). Here,we show that a hot post‐impact CMB drives the initiation of strong mantle plumes that can induce subductioninitiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMBtemperature is the primary factor triggering early subduction, with enrichment of heat‐producing elements inLLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications forunderstanding the diverse tectonic regimes of rocky planets.
Climate extremes likely to drive land mammal extinction during next supercont...Sérgio Sacani
Mammals have dominated Earth for approximately 55 Myr thanks to their
adaptations and resilience to warming and cooling during the Cenozoic. All
life will eventually perish in a runaway greenhouse once absorbed solar
radiation exceeds the emission of thermal radiation in several billions of
years. However, conditions rendering the Earth naturally inhospitable to
mammals may develop sooner because of long-term processes linked to
plate tectonics (short-term perturbations are not considered here). In
~250 Myr, all continents will converge to form Earth’s next supercontinent,
Pangea Ultima. A natural consequence of the creation and decay of Pangea
Ultima will be extremes in pCO2 due to changes in volcanic rifting and
outgassing. Here we show that increased pCO2, solar energy (F⨀;
approximately +2.5% W m−2 greater than today) and continentality (larger
range in temperatures away from the ocean) lead to increasing warming
hostile to mammalian life. We assess their impact on mammalian
physiological limits (dry bulb, wet bulb and Humidex heat stress indicators)
as well as a planetary habitability index. Given mammals’ continued survival,
predicted background pCO2 levels of 410–816 ppm combined with increased
F⨀ will probably lead to a climate tipping point and their mass extinction.
The results also highlight how global landmass configuration, pCO2 and F⨀
play a critical role in planetary habitability.
[OReilly Superstream] Occupy the Space: A grassroots guide to engineering (an...Jason Yip
The typical problem in product engineering is not bad strategy, so much as “no strategy”. This leads to confusion, lack of motivation, and incoherent action. The next time you look for a strategy and find an empty space, instead of waiting for it to be filled, I will show you how to fill it in yourself. If you’re wrong, it forces a correction. If you’re right, it helps create focus. I’ll share how I’ve approached this in the past, both what works and lessons for what didn’t work so well.
Dandelion Hashtable: beyond billion requests per second on a commodity serverAntonios Katsarakis
This slide deck presents DLHT, a concurrent in-memory hashtable. Despite efforts to optimize hashtables, that go as far as sacrificing core functionality, state-of-the-art designs still incur multiple memory accesses per request and block request processing in three cases. First, most hashtables block while waiting for data to be retrieved from memory. Second, open-addressing designs, which represent the current state-of-the-art, either cannot free index slots on deletes or must block all requests to do so. Third, index resizes block every request until all objects are copied to the new index. Defying folklore wisdom, DLHT forgoes open-addressing and adopts a fully-featured and memory-aware closed-addressing design based on bounded cache-line-chaining. This design offers lock-free index operations and deletes that free slots instantly, (2) completes most requests with a single memory access, (3) utilizes software prefetching to hide memory latencies, and (4) employs a novel non-blocking and parallel resizing. In a commodity server and a memory-resident workload, DLHT surpasses 1.6B requests per second and provides 3.5x (12x) the throughput of the state-of-the-art closed-addressing (open-addressing) resizable hashtable on Gets (Deletes).
Skybuffer SAM4U tool for SAP license adoptionTatiana Kojar
Manage and optimize your license adoption and consumption with SAM4U, an SAP free customer software asset management tool.
SAM4U, an SAP complimentary software asset management tool for customers, delivers a detailed and well-structured overview of license inventory and usage with a user-friendly interface. We offer a hosted, cost-effective, and performance-optimized SAM4U setup in the Skybuffer Cloud environment. You retain ownership of the system and data, while we manage the ABAP 7.58 infrastructure, ensuring fixed Total Cost of Ownership (TCO) and exceptional services through the SAP Fiori interface.
5th LF Energy Power Grid Model Meet-up SlidesDanBrown980551
5th Power Grid Model Meet-up
It is with great pleasure that we extend to you an invitation to the 5th Power Grid Model Meet-up, scheduled for 6th June 2024. This event will adopt a hybrid format, allowing participants to join us either through an online Mircosoft Teams session or in person at TU/e located at Den Dolech 2, Eindhoven, Netherlands. The meet-up will be hosted by Eindhoven University of Technology (TU/e), a research university specializing in engineering science & technology.
Power Grid Model
The global energy transition is placing new and unprecedented demands on Distribution System Operators (DSOs). Alongside upgrades to grid capacity, processes such as digitization, capacity optimization, and congestion management are becoming vital for delivering reliable services.
Power Grid Model is an open source project from Linux Foundation Energy and provides a calculation engine that is increasingly essential for DSOs. It offers a standards-based foundation enabling real-time power systems analysis, simulations of electrical power grids, and sophisticated what-if analysis. In addition, it enables in-depth studies and analysis of the electrical power grid’s behavior and performance. This comprehensive model incorporates essential factors such as power generation capacity, electrical losses, voltage levels, power flows, and system stability.
Power Grid Model is currently being applied in a wide variety of use cases, including grid planning, expansion, reliability, and congestion studies. It can also help in analyzing the impact of renewable energy integration, assessing the effects of disturbances or faults, and developing strategies for grid control and optimization.
What to expect
For the upcoming meetup we are organizing, we have an exciting lineup of activities planned:
-Insightful presentations covering two practical applications of the Power Grid Model.
-An update on the latest advancements in Power Grid -Model technology during the first and second quarters of 2024.
-An interactive brainstorming session to discuss and propose new feature requests.
-An opportunity to connect with fellow Power Grid Model enthusiasts and users.
Programming Foundation Models with DSPy - Meetup SlidesZilliz
Prompting language models is hard, while programming language models is easy. In this talk, I will discuss the state-of-the-art framework DSPy for programming foundation models with its powerful optimizers and runtime constraint system.
How information systems are built or acquired puts information, which is what they should be about, in a secondary place. Our language adapted accordingly, and we no longer talk about information systems but applications. Applications evolved in a way to break data into diverse fragments, tightly coupled with applications and expensive to integrate. The result is technical debt, which is re-paid by taking even bigger "loans", resulting in an ever-increasing technical debt. Software engineering and procurement practices work in sync with market forces to maintain this trend. This talk demonstrates how natural this situation is. The question is: can something be done to reverse the trend?
Digital Banking in the Cloud: How Citizens Bank Unlocked Their MainframePrecisely
Inconsistent user experience and siloed data, high costs, and changing customer expectations – Citizens Bank was experiencing these challenges while it was attempting to deliver a superior digital banking experience for its clients. Its core banking applications run on the mainframe and Citizens was using legacy utilities to get the critical mainframe data to feed customer-facing channels, like call centers, web, and mobile. Ultimately, this led to higher operating costs (MIPS), delayed response times, and longer time to market.
Ever-changing customer expectations demand more modern digital experiences, and the bank needed to find a solution that could provide real-time data to its customer channels with low latency and operating costs. Join this session to learn how Citizens is leveraging Precisely to replicate mainframe data to its customer channels and deliver on their “modern digital bank” experiences.
Northern Engraving | Nameplate Manufacturing Process - 2024Northern Engraving
Manufacturing custom quality metal nameplates and badges involves several standard operations. Processes include sheet prep, lithography, screening, coating, punch press and inspection. All decoration is completed in the flat sheet with adhesive and tooling operations following. The possibilities for creating unique durable nameplates are endless. How will you create your brand identity? We can help!
Introduction of Cybersecurity with OSS at Code Europe 2024Hiroshi SHIBATA
I develop the Ruby programming language, RubyGems, and Bundler, which are package managers for Ruby. Today, I will introduce how to enhance the security of your application using open-source software (OSS) examples from Ruby and RubyGems.
The first topic is CVE (Common Vulnerabilities and Exposures). I have published CVEs many times. But what exactly is a CVE? I'll provide a basic understanding of CVEs and explain how to detect and handle vulnerabilities in OSS.
Next, let's discuss package managers. Package managers play a critical role in the OSS ecosystem. I'll explain how to manage library dependencies in your application.
I'll share insights into how the Ruby and RubyGems core team works to keep our ecosystem safe. By the end of this talk, you'll have a better understanding of how to safeguard your code.
1. The Hidden Mass and Large Spatial Extent of a Post-Starburst Galaxy
Outflow
Todd M. Tripp, et al.
Science 334, 952 (2011);
DOI: 10.1126/science.1209850
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2. REPORTS
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33 (2003). this gas is most likely associated with the ISM and not NASA/ESA Hubble Space Telescope, obtained at the
13. T. M. Tripp, B. D. Savage, E. B. Jenkins, Astrophys. J. the CGM. Space Telescope Science Institute, operated by AURA
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SOM Text
(2011). 36. M. Fumagalli et al., http://arxiv.org/abs/1103.2130 Figs. S1 to S5
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galaxies resembles the high end of the column-density 38. T. M. Tripp et al., Astrophys. J. Suppl. Ser. 177, 15 June 2011; accepted 27 September 2011
distribution seen in blind surveys of intergalactic clouds 39 (2008). 10.1126/science.1209840
the total column density and mass of the outflows
The Hidden Mass and Large Spatial are poorly constrained. Previous outflow obser-
vations were often limited to low-resolution spec-
Extent of a Post-Starburst Galaxy Outflow tra of only one or two ions (e.g., Na I or Mg II) or
relied on composite spectra that cannot yield precise
Todd M. Tripp,1* Joseph D. Meiring,1 J. Xavier Prochaska,2 Christopher N. A. Willmer,3 column densities. Without any constraints on hydro-
J. Christopher Howk,4 Jessica K. Werk,2 Edward B. Jenkins,5 David V. Bowen,5 Nicolas Lehner,4 gen (the vast bulk of the mass) or other elements
Kenneth R. Sembach,6 Christopher Thom,6 Jason Tumlinson6 and ions, these studies were forced to make highly
uncertain assumptions to correct for ionization,
Outflowing winds of multiphase plasma have been proposed to regulate the buildup of galaxies, elemental abundances, and depletion of species
but key aspects of these outflows have not been probed with observations. By using ultraviolet by dust. Lastly, galactic winds contain multiple
absorption spectroscopy, we show that “warm-hot” plasma at 105.5 kelvin contains 10 to 150 times phases with a broad range of physical conditions
more mass than the cold gas in a post-starburst galaxy wind. This wind extends to distances > 68 (6), and wind gas in the key temperature range
kiloparsecs, and at least some portion of it will escape. Moreover, the kinematical correlation of between 105 to 106 K (where radiative cooling is
the cold and warm-hot phases indicates that the warm-hot plasma is related to the interaction of maximized) is too cool to be observed in x-rays;
the cold matter with a hotter (unseen) phase at >>106 kelvin. Such multiphase winds can detection of this so-called “warm-hot” phase
remove substantial masses and alter the evolution of post-starburst galaxies. requires observations in the ultraviolet (UV).
To study the more extended gas around gal-
alaxies do not evolve in isolation. They in- galaxies (2) and eventually into elliptical-type axies, including regions affected by outflows, we
G teract with other galaxies and, more subtly,
with the gas in their immediate environ-
ments. Mergers of comparable-mass, gas-rich
galaxies with little or no star formation (3).
Mergers are not required to propel galaxy evo-
lution, however. Even relatively secluded galaxies
used the Cosmic Origins Spectrograph (COS)
on the Hubble Space Telescope (HST) to obtain
high-resolution spectra of the quasi-stellar object
galaxies trigger star-formation bursts by driving accrete matter from the intergalactic medium (QSO) PG1206+459 (at redshift zQSO = 1.1625).
matter into galaxy centers, but theory predicts that (IGM), form stars, and drive matter outflows into By exploiting absorption lines imprinted on the
such starbursts are short-lived: The central gas is their halos or out of the galaxies entirely (4, 5). QSO spectrum by foreground gaseous material,
rapidly driven away by escaping galactic winds In either case, the competing processes of gas we can detect the low-density outer gaseous en-
powered by massive stars and supernova explo- inflows and outflows are expected to regulate velopes of galaxies, regions inaccessible to other
sions or by a central supermassive black hole galaxy evolution. techniques. We focus on far-ultraviolet (FUV) ab-
(1). Such feedback mechanisms could trans- Outflows are evident in some nearby objects sorption lines at rest wavelengths lrest < 912 Å.
form gas-rich spiral galaxies into post-starburst (6–9) and are ubiquitous in some types of gal- This FUV wavelength range is rich in diagnostic
axies (10–15); their speeds can exceed the escape transitions (23), including the Ne VIII 770.409,
1 velocity. Nevertheless, their broader impact on 780.324 Å doublet, a robust probe of warm-hot
Department of Astronomy, University of Massachusetts, Am-
herst, MA 01003, USA. 2University of California Observatories/ galaxy evolution is poorly understood. First, their gas, as well as banks of adjacent ionization stages.
Lick Observatory, University of California, Santa Cruz, CA 95064, full spatial extent is unknown. Previous studies The sight line to PG1206+459 pierces an absorp-
USA. 3Steward Observatory, University of Arizona, Tucson, AZ (6, 9, 16–22) have revealed flows with spatial tion system, at redshift zabs = 0.927, that provides
85721, USA. 4Department of Physics, University of Notre Dame, extents ranging from a few parsecs up to ~20 kilo- insights about galactic outflows. This absorber
Notre Dame, IN 46556, USA. 5Princeton University Obser-
vatory, Princeton, NJ 08544, USA. 6Space Telescope Science parsecs (kpc). However, because of their low has been studied before (24), but previous obser-
Institute, Baltimore, MD 21218, USA. densities, outer regions of outflows may not have vations did not cover Ne VIII and could not pro-
*To whom correspondence should be addressed. E-mail: been detected with previously used techniques, vide accurate constraints on H I in the individual
tripp@astro.umass.edu and thus the flows could be much larger. Second, absorption components.
952 18 NOVEMBER 2011 VOL 334 SCIENCE www.sciencemag.org
3. REPORTS
This absorber is illustrated in Figs. 1 to 3, in- er Lyman series lines are not saturated), which H I lines were detected in at least nine compo-
cluding the COS data (25). The absorber is a enables accurate H I column density [N(H I)] mea- nents (25) spanning a large velocity range from
“partial” Lyman limit (LL) system (i.e., the high- surement (Fig. 1). A wide variety of metals and −317 to +1131 km s−1 (Figs. 1 and 2). The Ne VIII
doublet was unambiguously detected (Fig. 2)
with a total N(Ne VIII) = 1014.9 cm−2 (25), which
is ~10 times higher than any previous N(Ne VIII)
measurements in intervening absorbers (26, 27).
The component at +1131 km s−1 exceeds vescape
of any individual galaxy, and the other compo-
nents have very similar properties to the +1131
km s−1 component (25), suggesting a common
origin. Whether the other components have v >
vescape depends on the (unknown) potential well,
but allowing for projection effects and noting
that the gas is already far from the affiliated gal-
axy (see below), several of the other components
could also be escaping. Combined with detec-
tion of Ne VIII, the detections of banks of adjacent
Downloaded from www.sciencemag.org on November 27, 2011
ions (N II, N III, N IV, N V; O III, O IV; S III, S IV,
S V) place tight constraints on physical condi-
tions of the gas. Notably, the velocity centroids
and profile shapes of lower and higher ioniza-
tion stages are quite similar (Fig. 3).
This strong Ne VIII/LL absorber is affiliated
with a galaxy near the QSO sight line (24, 25).
Fig. 1. (Top) Small portion of the Keck HIRES spectrum of PG1206+459 (24). Tick marks at top indicate This galaxy, which we refer to as 177_9, is the
components detected at various velocities in the Mg II 2803.53 Å transition. A velocity scale in the rest type of galaxy expected to drive a galactic su-
frame of the affiliated galaxy 177_9 is inset at bottom. Gray indicates a feature not due to Mg II 2803.53 Å. perwind (Fig. 4). Like post-starburst (11) and
(Bottom) Small portion of the ultraviolet spectrum of PG1206+459 recorded with the COS on HST that ultraluminous infrared galaxies (28), galaxy 177_9
shows H I Lyman series absorption lines (marked with ticks and labels) at the redshift of the Mg II complex in is very luminous and blue (29); based on the
the top graph, including H I Lyz through Lys (highest lines are marked but not labeled). characteristic magnitude (M*) of the z ~ 1 lumi-
nosity function from the Deep Evolutionary
Exploratory Probe 2 (DEEP2) (30), the galaxy
luminosity L = 1.8 L*. The Multiple Mirror Tel-
escope (MMT) spectrum in Fig. 4 is also similar
to those of the post-starburst galaxies in (11),
with higher Balmer series absorption lines, [O II]
emission and [Ne V] emission indicative of an
active galactic nucleus (AGN) (25). Most impor-
tantly, the galaxy has a large impact parameter
from the QSO sight line, r = 68 kpc (31), which
implies that the gaseous envelope of 177_9 has
a large spatial extent.
The component-to-component similarity of
the absorption lines (Fig. 3) suggests a related
origin. To further investigate the nature of this
absorber, we used photoionization models (32) to
derive ionization corrections and elemental abun-
dances (25). These models indicate that the indi-
vidual components have high abundances ranging
from ~0.5 to 3 times those in the Sun (table S2).
Such high abundances (or metallicities) favor an
origin in outflowing ejecta enriched by nucleo-
synthesis products from stars; at the large impact
parameter of 177_9, corotating outer-disk or halo
gas or tidal debris from a low-mass satellite gal-
axy would be expected to have much lower me-
tallicity. Tidal debris from a massive galaxy could
Fig. 2. Continuum-normalized absorption profiles (black lines) of various species detected in the LL /Mg II have high metallicity, but we are currently aware
absorber shown in Fig. 1, plotted in velocity with respect to the galaxy 177_9 redshift (i.e., v = 0 km s−1 at of only one luminous galaxy near the sight line at
z = 0.927). Labels below each absorption profile indicate the species and rest wavelength. We fitted nine the absorber redshift (33); another luminous gal-
components to the COS and Space Telescope Imaging Spectrograph data (24). Component centroids are axy interacting with 177_9 is not evident. The
indicated by gray lines, and the Voigt-profile fits are overplotted with red lines (25). Yellow lines indicate absorber could also be intragroup gas, but some-
contaminating features from other redshifts or transitions. The two graphs at lower left compare apparent how it must have been metal-enriched, so some
column density profiles (39) of the N V and Ne VIII doublets. type of galactic outflow is implicated in any case.
www.sciencemag.org SCIENCE VOL 334 18 NOVEMBER 2011 953
4. REPORTS
The photoionization models also constrain
the total hydrogen column (i.e., H I and H II),
and, combined with spatial extent ≥ 68 kpc, this
allows mass estimates. By using fiducial thin-
shell models (25), we find that the mass of cool,
photoionized gas in individual components
ranges from 0.6 × 108 to 14 × 108 solar masses
(M◉). However, photoionization fails (sometimes
by orders of magnitude) to produce enough S V,
N V, and Ne VIII; these species must arise in hot
gas at temperature T > 105 K. By using equi-
librium and nonequilibrium collision ionization
models (25), we find that the warm-hot gas con-
tains much more mass than the cold gas, with
individual components harboring 10 × 108 to
400 × 108 M◉ in hot material. These are rough
estimates with many uncertainties. For example,
if the absorption arises in thin filaments analo-
Downloaded from www.sciencemag.org on November 27, 2011
gous to those seen in starburst galaxies (6) or
AGN bubbles (34), the cold-gas mass could
reduce to ~106 M◉ per component. However, as
in the thin-shell models, the warm-hot gas could
harbor 10 to 150 times more mass in such
filaments (25). In either case (shells or filaments),
given the similarity of the cold and warm-hot
absorption lines (Fig. 3), the Ne VIII–bearing
plasma must be a transitional phase that links the
colder and hotter material and thus provides
insights on the outflow physics. The Ne VIII/N V
phase is not photoionized, so it must be generated
through interaction of the cold gas with a hotter
ambient medium analogous to x-ray–emitting
regions seen in nearby galaxies. How this occurs
is an open question; the absorbers could be
Fig. 3. Comparison of apparent column density profiles (39) of the LL absorber affiliated with material cooling from the hot phase down to the
galaxy 177_9. In each graph, the C II 687.05 Å profile (black histogram) is compared to another cool gas, or the cool clouds could have a hotter
species (colored circles) as labeled at upper left; the comparison species profile is also scaled by the and more-ionized surface that is evaporating.
factor in parentheses after the species label. Gray lines indicate regions contaminated by unrelated Low-density plasma in the T = 105 to 106 K
absorption. As in Fig. 2, v = 0 km s−1 at z = 0.927. range has been effectively hidden from most
Fig. 4. Montage of observations of the galaxy at
zgal = 0.927 that drives a large-scale outflow of
metal-enriched plasma. (Top left) The galaxy, and
the background QSO that reveals the outflow via
absorption spectroscopy, is shown in a multicolor
image obtained with the Large Binocular Telescope.
This galaxy, which we refer to as 177_9, is the red
object 8.63 arc sec south of the bright QSO PG1206
+459 (zQSO = 1.1625) at a position angle of 177° (N
through E) from the QSO. At the galaxy redshift, the
angular separation from the QSO sight line corre-
sponds to an impact parameter of 68 kpc. (Top right)
The large red circle indicates the rest-frame U-B
color and absolute B magnitude of 177_9 compared
to all galaxies from the DEEP2 survey (gray scale)
(30) and DEEP2 galaxies within T0.05 of z(177_9)
(cyan points). The small purple circles show post-
starburst galaxies from (11). (Bottom) An MMT
optical spectrum of 177_9 (upper trace) with its
1s uncertainty (lower trace). The strong feature
at ≈ 7600 Å is partially due to telluric absorption.
954 18 NOVEMBER 2011 VOL 334 SCIENCE www.sciencemag.org
5. REPORTS
outflow studies. In principle, the O VI 1032,1038 Å 8. D. S. Rupke, S. Veilleux, D. B. Sanders, Astrophys. J. 36. C. Tremonti, A. M. Diamond-Stanic, J. Moustakas, in
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whether the O VI arises in photoionized 104 K 10. M. Pettini et al., Astrophys. J. 554, 981 (2001). (Astronomical Society of the Pacific Conference Series,
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Ne VIII doublet avoids this ambiguity, and we Astrophys. J. 663, L77 (2007). 37. A. L. Coil et al., http://arXiv.org/abs/1104.0681
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13. K. H. R. Rubin et al., Astrophys. J. 719, 1503 (2010). 38. J. Tumlinson et al., Science 334, 948 (2011).
stantial component in the mass inventory of a 14. F. Hamann, G. Ferland, Annu. Rev. Astron. Astrophys. 37, 39. B. D. Savage, K. R. Sembach, Astrophys. J. 379, 245
galactic wind. Moreover, this wind has a large 487 (1999). (1991).
spatial extent, and the mass carried away by the 15. J. P. Grimes et al., Astrophys. J. Suppl. Ser. 181, 272 (2009). Acknowledgments: This study has its basis in observations
outflow will affect the evolution of the galaxy. 16. K. H. R. Rubin, J. X. Prochaska, D. C. Koo, A. C. Phillips, made with the NASA/European Space Agency Hubble
B. J. Weiner, Astrophys. J. 712, 574 (2010). Space Telescope (HST); the MMT, a joint facility
Whereas earlier studies of poststarburst outflows 17. M. Moe, N. Arav, M. A. Bautista, K. T. Korista, operated by the Smithsonian Astrophysical Observatory
focused on Mg II and could not precisely con- Astrophys. J. 706, 525 (2009). and the University of Arizona; and the Large Binocular
strain the metallicity, hydrogen column, and 18. J. P. Dunn et al., Astrophys. J. 709, 611 (2010). Telescope, an international collaboration among
mass, these studies do indicate that post-starburst 19. D. Edmonds et al., Astrophys. J. 739, 7 (2011). institutions in the United States, Italy, and Germany.
20. F. Hamann et al., Mon. Not. R. Astron. Soc. 410, 1957 Support for HST program number 11741 was provided
outflows are common: 22/35 of the post-starbursts
(2011). by NASA through a grant from the Space Telescope
in (36) showed outflowing Mg II absorption with 21. G. A. Kriss et al., Astron. Astrophys. 534, 41 (2011). Science Institute, which is operated by the Association
maximum (radial) velocities of 500 to 2400 km s−1, 22. D. M. Capellupo, F. Hamann, J. C. Shields, P. Rodríguez of Universities for Research in Astronomy, Incorporated,
similar to the absorption near 177_9 (Fig. 1), and Hidalgo, T. Barlow, Mon. Not. R. Astron. Soc. 413, 908 under NASA contract NAS5-26555. Additional support
Downloaded from www.sciencemag.org on November 27, 2011
77 and 100% of the post-starburst and AGN (2011). was provided by NASA grant NNX08AJ44G. The DEEP2
23. D. A. Verner, D. Tytler, P. D. Barthel, Astrophys. J. 430, survey was supported by NSF grants AST 95-29098,
galaxies, respectively, in (37) drive outflows but 186 (1994). 00-711098, 05-07483, 08-08133, 00-71048,
with lower maximum velocities, which may be 24. J. Ding, J. C. Charlton, C. W. Churchill, C. Palma, 05-07428, and 08-07630. Funding for the Sloan Digital
due to selection of wind-driving galaxies in a Astrophys. J. 590, 746 (2003). Sky Survey has been provided by the Alfred P. Sloan
later evolutionary stage. With existing COS data, 25. See further information in supporting material on Science Foundation, the Participating Institutions, NASA, NSF, the
Online. U.S. Department of Energy Office of Science, the
the effects of large-scale outflows on galaxy evo- 26. B. D. Savage, N. Lehner, B. P. Wakker, K. R. Sembach, Japanese Monbukagakusho, and the Max Planck Society.
lution can be studied with the techniques pre- T. M. Tripp, Astrophys. J. 626, 776 (2005). We thank C. Churchill for providing the archival Keck
sented here but with larger samples (38), with 27. A. Narayanan et al., Astrophys. J. 730, 15 (2011). data and the referees for review comments that
which it will be possible to statistically track how 28. Y. Chen, J. D. Lowenthal, M. S. Yun, Astrophys. J. 712, significantly improved this paper. We are also grateful to
1385 (2010). the Hawaiian people for graciously allowing us to conduct
outflows affect galaxies. 29. The galaxy appears to be red in Fig. 4 because of its observations from Mauna Kea, a revered place in
redshift; in the rest frame of the galaxy, it has a very the culture of Hawaii. The HST data in this paper
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metal-poor gas (metallicity that is less than 10%
A Reservoir of Ionized Gas in the of that of the Sun, or Z ≲ 0.1 Z◉) to flow onto
galaxies along dense intergalactic filaments (1).
Galactic Halo to Sustain Star However, galaxies may also exchange mass with
the local intergalactic medium (IGM) through
outflows driven by galactic “feedback,” galactic
Formation in the Milky Way winds powered by massive stars and their death
and from massive black holes. Some of this ma-
Nicolas Lehner* and J. Christopher Howk terial may return to the central galaxy as recycled
infalling matter—the galactic fountain mechanism
Without a source of new gas, our Galaxy would exhaust its supply of gas through the formation (2, 3). The circumgalactic medium about a gal-
of stars. Ionized gas clouds observed at high velocity may be a reservoir of such gas, but their axy is thus a complicated blend of outflowing
distances are key for placing them in the galactic halo and unraveling their role. We have used metal-rich and infalling metal-poor gas. The rela-
the Hubble Space Telescope to blindly search for ionized high-velocity clouds (iHVCs) in the tive importance of these processes is poorly con-
foreground of galactic stars. We show that iHVCs with 90 ≤ |vLSR| ≲ 170 kilometers per second strained observationally. Here, we demonstrate
(where vLSR is the velocity in the local standard of rest frame) are within one galactic radius of the that ionized gas in the local galactic halo provides
Sun and have enough mass to maintain star formation, whereas iHVCs with |vLSR| ≳ 170 kilometers a major supply of matter for fueling ongoing star
per second are at larger distances. These may be the next wave of infalling material. formation.
he time scale for gas consumption via star eous fuel in the disks of galaxies for continued
T formation in spiral galaxies is far shorter
than a Hubble time (13.8 billion years),
requiring an ongoing replenishment of the gas-
star formation. Analytical models and hydrody-
namical simulations have emphasized the impor-
tance of cold-stream accretion as a means for
Department of Physics, University of Notre Dame, 225
Nieuwland Science Hall, Notre Dame, IN 46556, USA.
*To whom correspondence should be addressed. E-mail:
nlehner@nd.edu
www.sciencemag.org SCIENCE VOL 334 18 NOVEMBER 2011 955