Search Publications
The Warm Gas in the MW: A Kinematical Model
Bregman, Joel N.; Qu, Zhijie; Lindley, Ryan +2 more
We develop a kinematical model for the Milky Way Si IV-bearing gas to determine its density distribution and kinematics. This model is constrained by a column density line-shape sample extracted from the Hubble Space Telescope/Cosmic Origins Spectrograph archival data, which contains 186 active galactic nucleus sight lines. We find that the Si IV …
The Large-scale Behavior in the Disk of δ Scorpii from 2000 to 2018
Carciofi, A. C.; Mota, B. C.; Tycner, C. +4 more
We model the circumstellar disk of δ Sco using the three-dimensional Monte Carlo radiative transfer code HDUST in order to quantify the large-scale changes in the disk through the years 2000-2018, and to see if these changes can be attributed to the secondary star affecting the disk throughout its orbit. We determine our best-fitting models throug…
The Hα Emission Line Variations of HR 6819
Gies, Douglas R.; Wang, Luqian
The star system HR 6819 was recently proposed by Rivinius et al. as the site of the nearest example of a stellar-mass black hole. Their spectra show evidence of two components: a B3 III star in a 40 day orbit and a stationary B-emission line star. Based upon the orbital mass function and the lack of evidence of a spectral component with reflex orb…
HST/COS Spectra of the Wind Lines of VFTS 102 and 285
Gies, Douglas R.; Lester, Kathryn V.; Wang, Luqian +5 more
Rapid rotation in massive stars imposes a latitudinal variation in the mass loss from radiatively driven winds that can lead to enhanced mass loss at the poles (with little angular momentum loss) and/or equator (with maximal angular momentum loss). Here we present an examination of the stellar wind lines of the two O-type stars with the fastest kn…
Spatially Resolved C III] λ1909 Emission in Haro 11
Hayes, Matthew; Inoue, Akio K.; Östlin, Göran +7 more
The C III] 1909 (hereafter C III]) line is the strongest ultraviolet emission line after Lyα and is therefore of interest to high-redshift studies of star-forming (SF) galaxies near the epoch of reionization. It is thought that C III] emission is strongest in galaxies with subsolar metallicity and low mass; however, spectral observations of numero…
ASASSN-16oh: A Nova Outburst with No Mass Ejection—A New Type of Supersoft X-Ray Source in Old Populations
Kato, Mariko; Hachisu, Izumi; Saio, Hideyuki
ASASSN-16oh is a peculiar transient supersoft X-ray source without a mass-ejection signature in the field of the Small Magellanic Cloud. Maccarone et al. concluded that ASASSN-16oh is the first dwarf nova with supersoft X-ray that originated from an equatorial accretion belt on a white dwarf (WD). Hillman et al. proposed a thermonuclear runaway mo…
Accretion and Intercycle Variations in the PMS Interacting Binary AK Sco
France, Kevin; Gómez de Castro, Ana I.; Vallejo, Juan Carlos +2 more
There are only a handful of known short-period pre-main-sequence spectroscopic binaries with significant accretion rates (Class II sources). AK Sco stands out in this list because the system is composed of two equal mass F5 stars in a highly eccentric orbit thus both stars get as close as 11 stellar radii at periastron passage. This configuration …
Inferring Contributions from Unresolved Point Sources to Diffuse Emissions Measured in UV Sky Surveys: General Method and SOHO/SWAN Case Study
Bzowski, M.; Kubiak, M. A.; Kowalska-Leszczynska, I. +1 more
In observations of diffuse emissions like, e.g., the Lyα heliospheric glow, contributions to the observed signal from point sources (e.g., stars) are considered to be a contamination. There are relatively few bright point sources that are usually properly resolved and can be subtracted or masked. We present results of an analysis of the distributi…