Search Publications
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…
Chemical interactions between Saturn's atmosphere and its rings
Kurth, W. S.; Mitchell, D. G.; Wahlund, J. -E. +25 more
The Pioneer and Voyager spacecraft made close-up measurements of Saturn's ionosphere and upper atmosphere in the 1970s and 1980s that suggested a chemical interaction between the rings and atmosphere. Exploring this interaction provides information on ring composition and the influence on Saturn's atmosphere from infalling material. The Cassini Io…
In situ collection of dust grains falling from Saturn's rings into its atmosphere
Postberg, Frank; Schmidt, Jürgen; Spahn, Frank +16 more
Saturn's main rings are composed of >95% water ice, and the nature of the remaining few percent has remained unclear. The Cassini spacecraft's traversals between Saturn and its innermost D ring allowed its cosmic dust analyzer (CDA) to collect material released from the main rings and to characterize the ring material infall into Saturn. We rep…
In situ measurements of Saturn’s ionosphere show that it is dynamic and interacts with the rings
Gurnett, D. A.; Persoon, A. M.; Kurth, W. S. +10 more
The ionized upper layer of Saturn’s atmosphere, its ionosphere, provides a closure of currents mediated by the magnetic field to other electrically charged regions (for example, rings) and hosts ion-molecule chemistry. In 2017, the Cassini spacecraft passed inside the planet’s rings, allowing in situ measurements of the ionosphere. The Radio and P…
Magnetic seismology of interstellar gas clouds: Unveiling a hidden dimension
Tassis, Konstantinos; Tritsis, Aris
Stars and planets are formed inside dense interstellar molecular clouds by processes imprinted on the three-dimensional (3D) morphology of the clouds. Determining the 3D structure of interstellar clouds remains challenging because of projection effects and difficulties measuring the extent of the clouds along the line of sight. We report the detec…