Search Publications
The Second APOKASC Catalog: The Empirical Approach
Chaplin, William J.; Cunha, Katia; Smith, Verne V. +33 more
We present a catalog of stellar properties for a large sample of 6676 evolved stars with Apache Point Observatory Galactic Evolution Experiment spectroscopic parameters and Kepler asteroseismic data analyzed using five independent techniques. Our data include evolutionary state, surface gravity, mean density, mass, radius, age, and the spectroscop…
Gaia DR2 proper motions of dwarf galaxies within 420 kpc. Orbits, Milky Way mass, tidal influences, planar alignments, and group infall
Fritz, T. K.; Battaglia, G.; Brook, C. +5 more
A proper understanding of the Milky Way (MW) dwarf galaxies in a cosmological context requires knowledge of their 3D velocities and orbits. However, proper motion (PM) measurements have generally been of limited accuracy and are available only for more massive dwarfs. We therefore present a new study of the kinematics of the MW dwarf galaxies. We …
Discovery of pulsations from NGC 300 ULX1 and its fast period evolution
Haberl, F.; Vasilopoulos, G.; Maitra, C. +1 more
The supernova impostor SN 2010da located in the nearby galaxy NGC 300, later identified as a likely supergiant B[e] high-mass X-ray binary, was simultaneously observed by NuSTAR and XMM-Newton between 2016 December 16 and 20, over a total time span of ∼310 ks. We report the discovery of a strong periodic modulation in the X-ray flux with a pulse p…
The optical afterglow of the short gamma-ray burst associated with GW170817
Im, M.; Pian, E.; Palazzi, E. +33 more
The binary neutron star merger GW170817 was the first multi-messenger event observed in both gravitational and electromagnetic waves1,2. The electromagnetic signal began approximately two seconds post-merger with a weak, short burst of gamma rays3, which was followed over the next hours and days by the ultraviolet, optical an…
Dark Energy Survey Year 1 Results: The Photometric Data Set for Cosmology
Benoit-Lévy, A.; Bechtol, K.; Smith, M. +87 more
We describe the creation, content, and validation of the Dark Energy Survey (DES) internal year-one cosmology data set, Y1A1 GOLD, in support of upcoming cosmological analyses. The Y1A1 GOLD data set is assembled from multiple epochs of DES imaging and consists of calibrated photometric zero-points, object catalogs, and ancillary data products—e.g…
Solar wind stream interaction regions throughout the heliosphere
Richardson, Ian G.
This paper focuses on the interactions between the fast solar wind from coronal holes and the intervening slower solar wind, leading to the creation of stream interaction regions that corotate with the Sun and may persist for many solar rotations. Stream interaction regions have been observed near 1 AU, in the inner heliosphere (at
Elucidating ΛCDM: Impact of Baryon Acoustic Oscillation Measurements on the Hubble Constant Discrepancy
Halpern, M.; Weiland, J. L.; Hinshaw, G. +3 more
We examine the impact of baryon acoustic oscillation (BAO) scale measurements on the discrepancy between the value of the Hubble constant (H 0) inferred from the local distance ladder and that from Planck cosmic microwave background (CMB) data. While the BAO data alone cannot constrain H 0, we show that combining the latest B…
Planetary Spectrum Generator: An accurate online radiative transfer suite for atmospheres, comets, small bodies and exoplanets
Villanueva, G. L.; Smith, M. D.; Faggi, S. +2 more
We have developed an online radiative-transfer suite (https://psg.gsfc.nasa.gov) applicable to a broad range of planetary objects (e.g., planets, moons, comets, asteroids, TNOs, KBOs, exoplanets). The Planetary Spectrum Generator (PSG) can synthesize planetary spectra (atmospheres and surfaces) for a broad range of wavelengths (UV/Vis/near-IR/IR/f…
H- Opacity and Water Dissociation in the Dayside Atmosphere of the Very Hot Gas Giant WASP-18b
Fortney, Jonathan J.; Stevenson, Kevin B.; Désert, Jean-Michel +7 more
We present one of the most precise emission spectra of an exoplanet observed so far. We combine five secondary eclipses of the hot Jupiter WASP-18b (T day ∼ 2900 K) that we secured between 1.1 and 1.7 µm with the Wide Field Camera 3 instrument on board the Hubble Space Telescope. Our extracted spectrum (S/N = 50, R ∼ 40) does not …
Macromolecular organic compound s from the depths of Enceladus
Postberg, Frank; Trieloff, Mario; Schmidt, Jürgen +18 more
Saturn's moon Enceladus harbours a global water ocean, which lies under an ice crust and above a rocky core. Through warm cracks in the crust a cryo-volcanic plume ejects ice grains and vapour into space that contain materials originating from the ocean. Hydrothermal activity is suspected to occur deep inside the porous core, powered by tidal diss…