Search Publications
An Improved Distance to NGC 4258 and Its Implications for the Hubble Constant
Riess, A. G.; Reid, M. J.; Pesce, D. W.
NGC 4258 is a critical galaxy for establishing the extragalactic distance scale and estimating the Hubble constant ({H}0). Water masers in the nucleus of the galaxy orbit about its supermassive black hole, and very long baseline interferometric observations of their positions, velocities, and accelerations can be modeled to give a geome…
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…
A Large Catalog of Accurate Distances to Local Molecular Clouds: The Gaia DR2 Edition
Alves, João; Speagle, Joshua S.; Zucker, Catherine +4 more
We present a uniform catalog of accurate distances to local molecular clouds informed by the Gaia DR2 data release. Our methodology builds on that of Schlafly et al. First, we infer the distance and extinction to stars along sightlines toward the clouds using optical and near-infrared photometry. When available, we incorporate knowledge of the ste…
An Embedded X-Ray Source Shines through the Aspherical AT 2018cow: Revealing the Inner Workings of the Most Luminous Fast-evolving Optical Transients
Berger, E.; Hurley, K.; Götz, D. +42 more
We present the first extensive radio to γ-ray observations of a fast-rising blue optical transient, AT 2018cow, over its first ∼100 days. AT 2018cow rose over a few days to a peak luminosity L pk ∼ 4 × 1044 erg s-1, exceeding that of superluminous supernovae (SNe), before declining as L ∝ t -2. Initial s…
An Older, More Quiescent Universe from Panchromatic SED Fitting of the 3D-HST Survey
Franx, Marijn; van Dokkum, Pieter; Conroy, Charlie +8 more
Galaxy observations are influenced by many physical parameters: stellar masses, star formation rates (SFRs), star formation histories (SFHs), metallicities, dust, black hole activity, and more. As a result, inferring accurate physical parameters requires high-dimensional models that capture or marginalize over this complexity. Here we reassess inf…
Confirmation of the Gaia DR2 Parallax Zero-point Offset Using Asteroseismology and Spectroscopy in the Kepler Field
Huber, Daniel; Stello, Dennis; Pinsonneault, Marc H. +1 more
We present an independent confirmation of the zero-point offset of Gaia Data Release 2 parallaxes using asteroseismic data of evolved stars in the Kepler field. Using well-characterized red giant branch stars from the APOKASC-2 catalog, we identify a Gaia astrometric pseudocolor ({ν }eff})- and Gaia G-band magnitude-dependent zero-point…
A Decade of Gamma-Ray Bursts Observed by Fermi-LAT: The Second GRB Catalog
Troja, E.; Caraveo, P. A.; Mirabal, N. +120 more
The Large Area Telescope (LAT) aboard the Fermi spacecraft routinely observes high-energy emission from gamma-ray bursts (GRBs). Here we present the second catalog of LAT-detected GRBs, covering the first 10 yr of operations, from 2008 to 2018 August 4. A total of 186 GRBs are found; of these, 91 show emission in the range 30-100 MeV (17 of which …
The Spur and the Gap in GD-1: Dynamical Evidence for a Dark Substructure in the Milky Way Halo
Conroy, Charlie; Hogg, David W.; Price-Whelan, Adrian M. +1 more
We present a model for the interaction of the GD-1 stellar stream with a massive perturber that naturally explains many of the observed stream features, including a gap and an off-stream spur of stars. The model involves an impulse by a fast encounter, after which the stream grows a loop of stars at different orbital energies. At specific viewing …
MOSFIRE Spectroscopy of Quiescent Galaxies at 1.5 < z < 2.5. II. Star Formation Histories and Galaxy Quenching
Ellis, Richard S.; Belli, Sirio; Newman, Andrew B.
We investigate the stellar populations for a sample of 24 quiescent galaxies at 1.5 < z < 2.5 using deep rest-frame optical spectra obtained with Keck MOSFIRE. By fitting templates simultaneously to the spectroscopic and photometric data and exploring a variety of star formation histories, we obtain robust measurements of median stellar ages…
An Analysis of the Shapes of Interstellar Extinction Curves. VII. Milky Way Spectrophotometric Optical-through-ultraviolet Extinction and Its R-dependence
Gordon, Karl D.; Fitzpatrick, E. L.; Clayton, Geoffrey C. +2 more
We produce a set of 72 NIR-through-UV extinction curves by combining new Hubble Space Telescope/STIS optical spectrophotometry with existing International Ultraviolet Explorer spectrophotometry (yielding gapless coverage from 1150 to 10000 Å) and NIR photometry. These curves are used to determine a new, internally consistent NIR-through-UV Milky W…