Search Publications
Hubble Space Telescope Imaging of Antlia B: Star Formation History and a New Tip of the Red Giant Branch Distance
Carlin, J. L.; Dolphin, A. E.; Crnojević, D. +8 more
A census of the satellite population around dwarf galaxy primary hosts in environments outside the Local Group is essential to understanding Λ cold dark matter galaxy formation and evolution on the smallest scales. We present deep optical Hubble Space Telescope imaging of the gas-rich, faint dwarf galaxy Antlia B (M V = -9.4)—a likely…
Coronal Mini-jets in an Activated Solar Tornado-like Prominence
Zhang, Jun; De Pontieu, Bart; Kliem, Bernhard +3 more
High-resolution observations from the Interface Region Imaging Spectrometer reveal the existence of a particular type of small solar jet, which arose singly or in clusters from a tornado-like prominence suspended in the corona. In this study, we perform a detailed statistical analysis of 43 selected mini-jets in the tornado event. Our results show…
Dynamical Masses of Young Stars. II. Young Taurus Binaries Hubble 4, FF Tau, and HP Tau/G3
Rizzuto, Aaron C.; Dupuy, Trent J.; Ireland, Michael J. +1 more
One of the most effective ways to test stellar evolutionary models is to measure dynamical masses for binary systems at a range of temperatures. In this paper, we present orbits of three young K+M binary systems in Taurus (Hubble 4, FF Tau, and HP Tau/G3) with very long baseline interferometry parallaxes. We obtained precision astrometry with Keck…
Turbulence and Energetic Particles in Radiative Shock Waves in the Cygnus Loop. II. Development of Postshock Turbulence
Blair, William P.; Slavin, Jonathan D.; Raymond, John C. +3 more
Radiative shock waves in the Cygnus Loop and other supernova remnants show different morphologies in [O III] and Hα emission. We use HST spectra and narrowband images to study the development of turbulence in the cooling region behind a shock on the west limb of the Cygnus Loop. We refine our earlier estimates of shock parameters that were based u…
Numerical Modeling of Suprathermal Electron Transport in the Solar Wind: Effects of Whistler Turbulence
Zank, Gary P.; Tang, Bofeng; Kolobov, Vladimir I.
The solar wind electron velocity distribution function deviates significantly from an equilibrium Maxwellian distribution and is composed of a Maxwellian core, a suprathermal halo, a field-aligned component strahl, and a higher-energy superhalo. Wave-particle interactions associated with whistler wave turbulence are introduced into the kinetic tra…
Significant Suppression of Star Formation in Radio-quiet AGN Host Galaxies with Kiloparsec-scale Radio Structures
Koss, Michael; Ricci, Claudio; Mushotzky, Richard +4 more
We conducted 22 GHz 1″ Jansky Very Large Array imaging of 100 radio-quiet X-ray-selected active galactic nuclei (AGN) from the Swift-Burst Array Telescope (Swift-BAT) survey. We find AGN-driven kiloparsec-scale radio structures inconsistent with pure star formation in 11 AGN. The host galaxies of these AGN lie significantly below the star-forming …
Modeling the Precession of the Warped Inner Accretion Disk in the Pulsars LMC X-4 and SMC X-1 with NuSTAR and XMM-Newton
Pottschmidt, Katja; Wilms, Jörn; Hickox, Ryan C. +3 more
We present a broadband X-ray study of the effect of superorbital periods on X-ray spectra and pulse profiles in the neutron star X-ray binaries LMC X-4 and SMC X-1. These two sources display periodic or quasiperiodic variations in luminosity of the order of tens of days, which are known to be superorbital, and are attributed to warped, precessing …
The Strikingly Metal-rich Halo of the Sombrero Galaxy
Cohen, Roger E.; Chandar, Rupali; Goudfrooij, Paul +5 more
The nature of the Sombrero galaxy (M104 = NGC 4594) has remained elusive despite many observational studies at a variety of wavelengths. Here we present Hubble Space Telescope imaging of two fields at ∼16 and 33 kpc along the minor axis to examine stellar metallicity gradients in the extended spheroid. We use this imaging, extending more than 2 ma…
A DESGW Search for the Electromagnetic Counterpart to the LIGO/Virgo Gravitational-wave Binary Neutron Star Merger Candidate S190510g
Smith, M.; Lidman, C.; Rest, A. +90 more
We present the results from a search for the electromagnetic counterpart of the LIGO/Virgo event S190510g using the Dark Energy Camera (DECam). S190510g is a binary neutron star (BNS) merger candidate of moderate significance detected at a distance of 227 ± 92 Mpc and localized within an area of 31 (1166) square degrees at 50% (90%) confidence. Wh…
Near-infrared Spectroscopy of CK Vulpeculae: Revealing a Remarkably Powerful Blast from the Past
Gehrz, R. D.; Shahbandeh, M.; Eyres, S. P. S. +6 more
CK Vulpeculae (CK Vul), which erupted in AD 1670-71, was long considered to be a nova outburst; however, recent observations have required that alternative scenarios be considered. Long-slit infrared spectroscopy of a forbidden line of iron reported here has revealed high line-of-sight velocities (∼±900 km s-1) of the ansae at the tips …