Search Publications
A New Class of Large-amplitude Radial-mode Hot Subdwarf Pulsators
Duev, Dmitry A.; Riddle, Reed; Szkody, Paula +22 more
Using high-cadence observations from the Zwicky Transient Facility at low Galactic latitudes, we have discovered a new class of pulsating, hot compact stars. We have found four candidates, exhibiting blue colors (g - r ≤ -0.1 mag), pulsation amplitudes of >5%, and pulsation periods of 200-475 s. Fourier transforms of the light curves show only …
The Star Formation History in the Solar Neighborhood as Told by Massive White Dwarfs
Isern, Jordi
White dwarfs (WDs) are the remnants of low- and intermediate-mass stars. Because of electron degeneracy, their evolution is just a simple gravothermal process of cooling. Recently, thanks to Gaia data, it has been possible to construct the luminosity function of massive (0.9≤slant M/{M}⊙ ≤slant 1.1) WDs in the solar neighborhood (d< …
The Fraction of Active Galactic Nuclei in the USS 1558-003 Protocluster at z = 2.53
Miller, Eric D.; Koyama, Yusei; Kodama, Tadayuki +8 more
The incidence of active galactic nuclei (AGNs) within the local environment is a potentially valuable probe of the mechanisms that trigger and provide fuel for accretion onto supermassive black holes. While the correlation between AGN fraction and environment has been well-studied in the local universe, AGN fractions have been measured for relativ…
METAL: The Metal Evolution, Transport, and Abundance in the Large Magellanic Cloud Hubble Program. I. Overview and Initial Results
Jenkins, Edward B.; Yanchulova Merica-Jones, Petia; Meixner, Margaret +8 more
Metal Evolution, Transport, and Abundance in the LMC (METAL) is a large Cycle 24 program on the Hubble Space Telescope aimed at measuring dust extinction properties and interstellar depletions in the Large Magellanic Cloud (LMC) at half-solar metallicity. The 101-orbit program is composed of Cosmic Origins Spectrograph and Space Telescope Imaging …
Photochemical Hazes in Sub-Neptunian Atmospheres with a Focus on GJ 1214b
Showman, Adam P.; García Muñoz, Antonio; Steinrueck, Maria E. +2 more
We study the properties of photochemical hazes in super-Earth/mini-Neptune atmospheres with particular focus on GJ 1214b. We evaluate photochemical haze properties at different metallicities between solar and 10,000× solar. Within the four-order-of-magnitude change in metallicity, we find that the haze precursor mass fluxes change only by a factor…
The Sporadic Activity of (6478) Gault: A YORP-driven Event?
Wainscoat, Richard J.; Tonry, John; Ebeling, Harald +15 more
On 2019 January 5 a streamer associated with the 4-10 km main belt asteroid (6478) Gault was detected by the ATLAS sky survey, a rare discovery of activity around a main belt asteroid. Archival data from ATLAS and Pan-STARRS1 show the trail in early 2018 December, but not between 2010 and 2018 January. The feature has significantly changed over on…
Delayed Circumstellar Interaction for Type Ia SN 2015cp Revealed by an HST Ultraviolet Imaging Survey
Fox, O. D.; Smith, M.; Sullivan, M. +11 more
The nature and role of the binary companion of carbon-oxygen white dwarf stars that explode as Type Ia supernovae (SNe Ia) are not yet fully understood. Past detections of circumstellar material (CSM) that contain hydrogen for a small number of SN Ia progenitor systems suggest that at least some have a nondegenerate companion. In order to constrai…
Multiepoch Ultraviolet HST Observations of Accreting Low-mass Stars
Espaillat, Catherine C.; Robinson, Connor E.
Variability is a defining characteristic of young low-mass stars that are still accreting material from their primordial protoplanetary disk. Here we present the largest Hubble Space Telescope (HST) variability study of classical T Tauri stars (CTTS) to date. For five of these objects, we obtained a total of 25 spectra with the Space Telescope Ima…
Interstellar Medium and Star Formation of Starburst Galaxies on the Merger Sequence
Ho, Luis C.; Li, Zhihui; Zhuang, Ming-Yang +3 more
The interstellar medium is a key ingredient that governs star formation in galaxies. We present a detailed study of the infrared (∼1-500 µm) spectral energy distributions of a large sample of 193 nearby (z≲ 0.088) luminous infrared galaxies (LIRGs) covering a wide range of evolutionary stages along the merger sequence. The entire sample has …
The Far-infrared Polarization Spectrum of ρ Ophiuchi A from HAWC+/SOFIA Observations
Morris, Mark R.; Staguhn, Johannes; Ward-Thompson, Derek +23 more
We report on polarimetric maps made with HAWC+/SOFIA toward ρ Oph A, the densest portion of the ρ Ophiuchi molecular complex. We employed HAWC+ bands C (89 µm) and D (154 µm). The slope of the polarization spectrum was investigated by defining the quantity {{ \mathcal R }}{DC}={p}D/{p}C, where p C…