Search Publications
NuSTAR and XMM-Newton Observations of the Neutron Star X-Ray Binary 1RXS J180408.9-34205
Harrison, F. A.; Fabian, A. C.; Miller, J. M. +8 more
We report on observations of the neutron star (NS) residing in the low-mass X-ray binary 1RXS J180408.9-34205 taken 2015 March by NuSTAR and XMM-Newton while the source was in the hard spectral state. We find multiple reflection features (Fe {{{K}}}α detected with NuSTAR; N vii, O vii, and O viii detected in the RGS) from different ion…
Acetylene on Titan’s Surface
Le Mouélic, S.; Cornet, T.; Rodriguez, S. +6 more
Titan’s atmosphere is opaque in the near-infrared due to gaseous absorptions, mainly by methane, and scattering by aerosols, except in a few “transparency windows.” Thus, the composition of Titan’s surface remains difficult to access from space and is still poorly constrained. Photochemical models suggest that most of the organic compounds formed …
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…
Distributions of Quasar Hosts on the Galaxy Main Sequence Plane
Rieke, George H.; Shi, Yong; Zhang, Zhoujian +4 more
The relation between star formation rates (SFRs) and stellar masses, I.e., the galaxy main sequence, is a useful diagnostic of galaxy evolution. We present the distributions relative to the main sequence of 55 optically selected PG and 12 near-IR-selected Two Micron All Sky Survey (2MASS) quasars at z ≤ 0.5. We estimate the quasar host stellar mas…
ALMA Observations of the Debris Disk of Solar Analog τ Ceti
MacGregor, Meredith A.; Matthews, Brenda C.; Wilner, David J. +4 more
We present 1.3 mm observations of the Sun-like star τ Ceti with the Atacama Large Millimeter/submillimeter Array that probe angular scales of ∼ 1\prime\prime (4 au). This first interferometric image of the τ Ceti system, which hosts both a debris disk and a possible multiplanet system, shows emission from a nearly face-on belt of cold d…
Maps of Evolving Cloud Structures in Luhman 16AB from HST Time-resolved Spectroscopy
Apai, Dániel; Marley, Mark S.; Karalidi, Theodora +1 more
WISE J104915.57-531906.1 is the nearest brown dwarf binary to our solar system, consisting of two brown dwarfs in the L/T transition: Luhman 16A and B. In this paper, we present the first map of Luhman 16A, and maps of Luhman 16B for two epochs. Our maps were created by applying Aeolus, a Markov-Chain Monte Carlo code that maps the top-of-the-atmo…
Microarcsecond VLBI Pulsar Astrometry with PSRπ. I. Two Binary Millisecond Pulsars with White Dwarf Companions
Lazio, T. J. W.; Chatterjee, S.; Cordes, J. M. +9 more
Model-independent distance constraints to binary millisecond pulsars (MSPs) are of great value to both the timing observations of the radio pulsars and multiwavelength observations of their companion stars. Astrometry using very long baseline interferometry (VLBI) can be employed to provide these model-independent distances with very high precisio…
Second Epoch Hubble Space Telescope Observations of Kepler's Supernova Remnant: The Proper Motions of Balmer Filaments
Blair, William P.; Reynolds, Stephen P.; Raymond, John C. +5 more
We report on the proper motions of Balmer-dominated filaments in Kepler’s supernova remnant using high resolution images obtained with the Hubble Space Telescope at two epochs separated by about 10 years. We use the improved proper motion measurements and revised values of shock velocities to derive a distance to Kepler of {5.1}-0.7
The Influence of the Extreme Ultraviolet Spectral Energy Distribution on the Structure and Composition of the Upper Atmosphere of Exoplanets
Guo, J. H.; Ben-Jaffel, Lotfi
By varying the profiles of stellar extreme ultraviolet (EUV) spectral energy distributions (SEDs), we tested the influences of stellar EUV SEDs on the physical and chemical properties of an escaping atmosphere. We apply our model to study four exoplanets: HD 189733b, HD 209458b, GJ 436b, and Kepler-11b. We find that the total mass loss rates of an…
Toward Precision Black Hole Masses with ALMA: NGC 1332 as a Case Study in Molecular Disk Dynamics
Ho, Luis C.; Barth, Aaron J.; Buote, David A. +4 more
We present first results from a program of Atacama Large Millimeter/submillimeter Array (ALMA) CO(2-1) observations of circumnuclear gas disks in early-type galaxies. The program was designed with the goal of detecting gas within the gravitational sphere of influence of the central black holes (BHs). In NGC 1332, the 0.″3-resolution ALMA data reve…