Search Publications
On Galactic Density Modeling in the Presence of Dust Extinction
Bovy, Jo; Rix, Hans-Walter; Finkbeiner, Douglas P. +2 more
Inferences about the spatial density or phase-space structure of stellar populations in the Milky Way require a precise determination of the effective survey volume. The volume observed by surveys such as Gaia or near-infrared spectroscopic surveys, which have good coverage of the Galactic midplane region, is highly complex because of the abundant…
The Shape of the Inner Milky Way Halo from Observations of the Pal 5 and GD--1 Stellar Streams
Bovy, Jo; Kallivayalil, Nitya; Fritz, Tobias K. +1 more
We constrain the shape of the Milky Way’s halo by dynamical modeling of the observed phase-space tracks of the Pal 5 and GD-1 tidal streams. We find that the only information about the potential gleaned from the tracks of these streams are precise measurements of the shape of the gravitational potential—the ratio of vertical to radial acceleration…
The Coupled Physical Structure of Gas and Dust in the IM Lup Protoplanetary Disk
Wilner, David J.; Cleeves, L. Ilsedore; Andrews, Sean M. +4 more
The spatial distribution of gas and solids in protoplanetary disks determines the composition and formation efficiency of planetary systems. A number of disks show starkly different distributions for the gas and small grains compared to millimeter-centimeter-sized dust. We present new Atacama Large Millimeter/Submillimeter Array observations of th…
Estimating Distances from Parallaxes. II. Performance of Bayesian Distance Estimators on a Gaia-like Catalogue
Bailer-Jones, Coryn A. L.; Astraatmadja, Tri L.
Estimating a distance by inverting a parallax is only valid in the absence of noise. As most stars in the Gaia catalog will have non-negligible fractional parallax errors, we must treat distance estimation as a constrained inference problem. Here we investigate the performance of various priors for estimating distances, using a simulated Gaia cata…
Estimating Distances from Parallaxes. III. Distances of Two Million Stars in the Gaia DR1 Catalogue
Bailer-Jones, Coryn A. L.; Astraatmadja, Tri L.
We infer distances and their asymmetric uncertainties for two million stars using the parallaxes published in the Gaia DR1 (GDR1) catalogue. We do this with two distance priors: A minimalist, isotropic prior assuming an exponentially decreasing space density with increasing distance, and an anisotropic prior derived from the observability of stars…
Evidence for a Systematic Offset of -0.25 mas in the Gaia DR1 Parallaxes
Torres, Guillermo; Stassun, Keivan G.
We test the parallaxes reported in the Gaia first data release using the sample of eclipsing binaries with accurate, empirical distances from Stassun & Torres. We find an average offset of -0.25 ± 0.05 mas in the sense of the Gaia parallaxes being too small (I.e., the distances too long). The offset does not depend strongly on obvious paramete…
First Gaia Local Group Dynamics: Magellanic Clouds Proper Motion and Rotation
van der Marel, Roeland P.; Sahlmann, Johannes
We use the Gaia data release 1 (DR1) to study the proper motion (PM) fields of the Large and Small Magellanic Clouds (LMC, SMC). This uses the Tycho-Gaia Astrometric Solution (TGAS) PMs for 29 Hipparcos stars in the LMC and 8 in the SMC. The LMC PM in the West and North directions is inferred to be ({µ }W,{µ }N) =…
A Dipole on the Sky: Predictions for Hypervelocity Stars from the Large Magellanic Cloud
Boubert, Douglas; Evans, N. Wyn
We predict the distribution of hypervelocity stars (HVSs) ejected from the Large Magellanic Cloud (LMC), under the assumption that the dwarf galaxy hosts a central massive black hole (MBH). For the majority of stars ejected from the LMC, the orbital velocity of the LMC has contributed a significant fraction of their galactic rest-frame velocity, l…
New Parallaxes and a Convergence Analysis for the TW Hya Association
Faherty, J. K.; Weinberger, A. J.; Gagné, J. +3 more
The TW Hya Association (TWA) is a nearby stellar association with an age of ∼5-10 Myr. This is an important age for studying the late stages of star and planet formation. We measure the parallaxes of 14 candidate members of TWA. That brings to 38 the total number of individual stars with fully measured kinematics, I.e., proper motion, radial veloc…
A New M Dwarf Debris Disk Candidate in a Young Moving Group Discovered with Disk Detective
Kuchner, Marc J.; Gagné, Jonathan; Wisniewski, John P. +14 more
We used the Disk Detective citizen science project and the BANYAN II Bayesian analysis tool to identify a new candidate member of a nearby young association with infrared excess. WISE J080822.18-644357.3, an M5.5-type debris disk system with significant excess at both 12 and 22 µm, is a likely member (∼ 90 % BANYAN II probability) of the ∼45…