Search Publications
A measurement of the Hubble constant from angular diameter distances to two gravitational lenses
Fassnacht, Christopher D.; Hilbert, Stefan; Suyu, Sherry H. +3 more
The local expansion rate of the Universe is parametrized by the Hubble constant, H0, the ratio between recession velocity and distance. Different techniques lead to inconsistent estimates of H0. Observations of Type Ia supernovae (SNe) can be used to measure H0, but this requires an external calibrator to convert relative distances to absolute one…
Close Cassini flybys of Saturn's ring moons Pan, Daphnis, Atlas, Pandora, and Epimetheus
Brown, R. H.; Baines, K. H.; Buratti, B. J. +35 more
Saturn's main ring system is associated with a set of small moons that either are embedded within it or interact with the rings to alter their shape and composition. Five close flybys of the moons Pan, Daphnis, Atlas, Pandora, and Epimetheus were performed between December 2016 and April 2017 during the ring-grazing orbits of the Cassini mission. …
Close-range remote sensing of Saturn's rings during Cassini's ring-grazing orbits and Grand Finale
Nicholson, Philip D.; Hedman, Matthew M.; Sotin, Christophe +22 more
Saturn's rings are an accessible exemplar of an astrophysical disk, tracing the Saturn system's dynamical processes and history. We present close-range remote-sensing observations of the main rings from the Cassini spacecraft. We find detailed sculpting of the rings by embedded masses, and banded texture belts throughout the rings. Saturn-orbiting…
Galactic archaeology with Gaia
Wyse, Rosemary
The past and present merger activity of the Milky Way galaxy has recently been put into sharp focus through the analysis of data from the Gaia astrometric satellite. These data were released by the European Space Agency in 2016 (DR1) and 2018 (DR2). The emerging picture created is one of persistent disequilibrium, with high merger activity some 10…
Radar evidence of subglacial liquid water on Mars
Pajola, M.; Lauro, S. E.; Pettinelli, E. +19 more
The presence of liquid water at the base of the martian polar caps has long been suspected but not observed. We surveyed the Planum Australe region using the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) instrument, a low-frequency radar on the Mars Express spacecraft. Radar profiles collected between May 2012 and December 20…
Ground-based detection of an extended helium atmosphere in the Saturn-mass exoplanet WASP-69b
Henning, Thomas; Dreizler, Stefan; Sánchez-López, Alejandro +25 more
Hot gas giant exoplanets can lose part of their atmosphere due to strong stellar irradiation, and these losses can affect their physical and chemical evolution. Studies of atmospheric escape from exoplanets have mostly relied on space-based observations of the hydrogen Lyman-α line in the far ultraviolet region, which is strongly affected by inter…
Spectrally resolved helium absorption from the extended atmosphere of a warm Neptune-mass exoplanet
Ehrenreich, D.; Lecavelier des Etangs, A.; Lovis, C. +7 more
Stellar heating causes atmospheres of close-in exoplanets to expand and escape. These extended atmospheres are difficult to observe because their main spectral signature—neutral hydrogen at ultraviolet wavelengths—is strongly absorbed by interstellar medium. We report the detection of the near-infrared triplet of neutral helium in the transiting w…
A dust-enshrouded tidal disruption event with a resolved radio jet in a galaxy merger
Bondi, M.; Lundqvist, P.; Clements, D. L. +33 more
Tidal disruption events (TDEs) are transient flares produced when a star is ripped apart by the gravitational field of a supermassive black hole (SMBH). We have observed a transient source in the western nucleus of the merging galaxy pair Arp 299 that radiated >1.5 × 1052 erg at infrared and radio wavelengths but was not luminous at …
Saturn's magnetic field revealed by the Cassini Grand Finale
Cao, Hao; Dougherty, Michele K.; Hunt, Gregory J. +10 more
During 2017, the Cassini fluxgate magnetometer made in situ measurements of Saturn's magnetic field at distances ~2550 ± 1290 kilometers above the 1-bar surface during 22 highly inclined Grand Finale orbits. These observations refine the extreme axisymmetry of Saturn's internal magnetic field and show displacement of the magnetic equator northward…
Fast molecular outflow from a dusty star-forming galaxy in the early Universe
Béthermin, M.; Stark, A. A.; Vieira, J. D. +20 more
Galaxies grow inefficiently, with only a small percentage of the available gas converted into stars each free-fall time. Feedback processes, such as outflowing winds driven by radiation pressure, supernovae, or supermassive black hole accretion, can act to halt star formation if they heat or expel the gas supply. We report a molecular outflow laun…