Search Publications
An excess of small-scale gravitational lenses observed in galaxy clusters
Grillo, Claudio; Rosati, Piero; Meneghetti, Massimo +11 more
Cold dark matter (CDM) constitutes most of the matter in the Universe. The interplay between dark and luminous matter in dense cosmic environments, such as galaxy clusters, is studied theoretically using cosmological simulations. Observations of gravitational lensing are used to characterize the properties of substructures—the small-scale distribu…
Stormy water on Mars: The distribution and saturation of atmospheric water during the dusty season
Montmessin, Franck; Belyaev, Denis A.; Fedorova, Anna A. +19 more
The loss of water from Mars to space is thought to result from the transport of water to the upper atmosphere, where it is dissociated to hydrogen and escapes the planet. Recent observations have suggested large, rapid seasonal intrusions of water into the upper atmosphere, boosting the hydrogen abundance. We use the Atmospheric Chemistry Suite on…
Ammonium salts are a reservoir of nitrogen on a cometary nucleus and possibly on some asteroids
Longobardo, Andrea; Palomba, Ernesto; Schmitt, Bernard +29 more
The measured nitrogen-to-carbon ratio in comets is lower than for the Sun, a discrepancy which could be alleviated if there is an unknown reservoir of nitrogen in comets. The nucleus of comet 67P/Churyumov-Gerasimenko exhibits an unidentified broad spectral reflectance feature around 3.2 micrometers, which is ubiquitous across its surface. On the …
(Sub)stellar companions shape the winds of evolved stars
Waters, L. B. F. M.; Sahai, R.; De Ridder, J. +32 more
Binary interactions dominate the evolution of massive stars, but their role is less clear for low- and intermediate-mass stars. The evolution of a spherical wind from an asymptotic giant branch (AGB) star into a nonspherical planetary nebula (PN) could be due to binary interactions. We observed a sample of AGB stars with the Atacama Large Millimet…
The dark matter interpretation of the 3.5-keV line is inconsistent with blank-sky observations
Safdi, Benjamin R.; Dessert, Christopher; Rodd, Nicholas L.
Observations of nearby galaxies and galaxy clusters have reported an unexpected x-ray emission line around 3.5 kilo-electron volts (keV). Proposals to explain this line include decaying dark matter—in particular, that the decay of sterile neutrinos with a mass around 7 keV could match the available data. If this interpretation is correct, the 3.5-…
A triple-star system with a misaligned and warped circumstellar disk shaped by disk tearing
Monnier, John D.; Schaefer, Gail H.; Lanthermann, Cyprien +29 more
Young stars are surrounded by a circumstellar disk of gas and dust, within which planet formation can occur. Gravitational forces in multiple star systems can disrupt the disk. Theoretical models predict that if the disk is misaligned with the orbital plane of the stars, the disk should warp and break into precessing rings, a phenomenon known as d…
Meridional flow in the Sun’s convection zone is a single cell in each hemisphere
Gizon, Laurent; Cameron, Robert H.; Liang, Zhi-Chao +4 more
The Sun’s magnetic field is generated by subsurface motions of the convecting plasma. The latitude at which the magnetic field emerges through the solar surface (as sunspots) drifts toward the equator over the course of the 11-year solar cycle. We use helioseismology to infer the meridional flow (in the latitudinal and radial directions) over two …
The Sun is less active than other solar-like stars
Solanki, Sami K.; Reinhold, Timo; Shapiro, Alexander I. +4 more
The magnetic activity of the Sun and other stars causes their brightness to vary. We investigated how typical the Sun’s variability is compared with other solar-like stars, i.e., those with near-solar effective temperatures and rotation periods. By combining 4 years of photometric observations from the Kepler space telescope with astrometric data …
A multiplanet system of super-Earths orbiting the brightest red dwarf star GJ 887
Amado, P. J.; Reiners, A.; Ribas, I. +28 more
The closet exoplanets to the Sun provide opportunities for detailed characterization of planets outside the Solar System. We report the discovery, using radial velocity measurements, of a compact multiplanet system of super-Earth exoplanets orbiting the nearby red dwarf star GJ 887. The two planets have orbital periods of 9.3 and 21.8 days. Assumi…
Ammonium salts on comet 67P
Smith, Keith T.