Search Publications
A noninteracting low-mass black hole-giant star binary system
Bieryla, Allyson; Latham, David W.; Berlind, Perry +14 more
Black hole binary systems with companion stars are typically found via their x-ray emission, generated by interaction and accretion. Noninteracting binaries are expected to be plentiful in the Galaxy but must be observed using other methods. We combine radial velocity and photometric variability data to show that the bright, rapidly rotating giant…
Water Vapor and Clouds on the Habitable-zone Sub-Neptune Exoplanet K2-18b
Fortney, Jonathan J.; Knutson, Heather A.; Howard, Andrew W. +13 more
Results from the Kepler mission indicate that the occurrence rate of small planets (<3 R ⊕) in the habitable zone of nearby low-mass stars may be as high as 80%. Despite this abundance, probing the conditions and atmospheric properties on any habitable-zone planet is extremely difficult and has remained elusive to date. Here, we repo…
Primordial Black Holes as a Dark Matter Candidate Are Severely Constrained by the Galactic Center 511 keV γ -Ray Line
Laha, Ranjan
We derive the strongest constraint on the fraction of dark matter that can be composed of low mass primordial black holes by using the observation of the Galactic Center 511 keV γ -ray line. Primordial black holes of masses ≲1015 kg will evaporate to produce e± pairs. The positrons will lose energy in the Galactic Center, bec…
The origin of accreted stellar halo populations in the Milky Way using APOGEE, Gaia, and the EAGLE simulations
Bovy, Jo; Majewski, Steven R.; Holtzman, Jon +12 more
Recent work indicates that the nearby Galactic halo is dominated by the debris from a major accretion event. We confirm that result from an analysis of APOGEE-DR14 element abundances and Gaia-DR2 kinematics of halo stars. We show that ∼2/3 of nearby halo stars have high orbital eccentricities (e ≳ 0.8), and abundance patterns typical of massive Mi…
juliet: a versatile modelling tool for transiting and non-transiting exoplanetary systems
Espinoza, Néstor; Kossakowski, Diana; Brahm, Rafael
Here we present juliet, a versatile tool for the analysis of transits, radial velocities, or both. juliet is built over many available tools for the modelling of transits, radial velocities, and stochastic processes (here modelled as Gaussian Processes; GPs) in order to deliver a tool/wrapper which can be used for the analysis of transit photometr…
Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18
Khan, S.; Jordi, C.; Anders, F. +19 more
Combining the precise parallaxes and optical photometry delivered by Gaia's second data release with the photometric catalogues of Pan-STARRS1, 2MASS, and AllWISE, we derived Bayesian stellar parameters, distances, and extinctions for 265 million of the 285 million objects brighter than G = 18. Because of the wide wavelength range used, our result…
Proper motions and dynamics of the Milky Way globular cluster system from Gaia DR2
Vasiliev, Eugene
We use Gaia Data Release 2 to determine the mean proper motions for 150 Milky Way globular clusters (almost the entire known population), with a typical uncertainty of 0.05 mas yr-1 limited mainly by systematic errors. Combining them with distance and line-of-sight velocity measurements from the literature, we analyse the distribution o…
The ASAS-SN catalogue of variable stars - II. Uniform classification of 412 000 known variables
Kochanek, C. S.; Stanek, K. Z.; Dong, Subo +12 more
The variable stars in the VSX catalogue are derived from a multitude of inhomogeneous data sources and classification tools. This inhomogeneity complicates our understanding of variable star types, statistics, and properties, and it directly affects attempts to build training sets for current (and next) generation all-sky, time-domain surveys. We …
Footprints of the Sagittarius dwarf galaxy in the Gaia data set
Laporte, Chervin F. P.; Gómez, Facundo A.; Minchev, Ivan +1 more
We analyse an N-body simulation of the interaction of the Milky Way (MW) with a Sagittarius-like dSph (Sgr), looking for signatures which may be attributed to its orbital history in the phase space volume around the Sun in light of Gaia DR2 discoveries. The repeated impacts of Sgr excite coupled vertical and radial oscillations in the disc which q…
What is a globular cluster? An observational perspective
D'Orazi, Valentina; Gratton, Raffaele; Bragaglia, Angela +3 more
Globular clusters are large and dense agglomerate of stars. At variance with smaller clusters of stars, they exhibit signs of some chemical evolution. At least for this reason, they are intermediate between open clusters and massive objects such as nuclear clusters or compact galaxies. While some facts are well established, the increasing amount o…