Search Publications
The CHARA Array Interferometric Program on the Multiplicity of Classical Be Stars: New Detections and Orbits of Stripped Subdwarf Companions
Gies, Douglas R.; Klement, Robert; Rivinius, Thomas +8 more
Rapid rotation and nonradial pulsations enable Be stars to build decretion disks, where the characteristic line emission forms. A major but unconstrained fraction of Be stars owe their rapid rotation to mass and angular momentum transfer in a binary. The faint, stripped companions can be helium-burning subdwarf OB-type stars (sdOBs), white dwarfs …
Expanded Sample of Small Magellanic Cloud Ultraviolet Dust Extinction Curves: Correlations between the 2175 Å Bump, q PAH, Ultraviolet Extinction Shape, and N(H I)/A(V)
Murray, Claire E.; Gordon, Karl D.; Fitzpatrick, E. L. +7 more
The Small Magellanic Cloud (SMC) shows a large variation in ultraviolet (UV) dust extinction curves, ranging from Milky Way (MW) like to significantly steeper curves with no detectable 2175 Å bump. This result is based on a sample of only nine sight lines. From Hubble Space Telescope Space Telescope Imaging Spectrograph and IUE spectra of OB stars…
High mass function ellipsoidal variables in the Gaia Focused Product Release: searching for black hole candidates in the binary zoo
Kochanek, Christopher S.; Thompson, Todd A.; Jayasinghe, Tharindu +2 more
The recent Gaia Focused Product Release contains radial velocity time-series for more than 9,000 Gaia long-period photometric variables. Here we search for binary systems with large radial velocity amplitudes to identify candidates with massive, unseen companions. Eight targets have binary mass function f(M)>1M⊙, three of which are eclipsing bi…
An Angular Diameter Measurement of β UMa via Stellar Intensity Interferometry with the VERITAS Observatory
Benbow, W.; Feng, Q.; Furniss, A. +45 more
We use the Very Energetic Radiation Imaging telescope Array System (VERITAS) imaging air Cherenkov telescope array to obtain the first measured angular diameter of β UMa at visual wavelengths using stellar intensity interferometry (SII) and independently constrain the limb-darkened angular diameter. The age of the Ursa Major moving group has been …
Cassini spacecraft reveals global energy imbalance of Saturn
West, Robert A.; Nixon, Conor A.; Guillot, Tristan +16 more
The global energy budget is pivotal to understanding planetary evolution and climate behaviors. Assessing the energy budget of giant planets, particularly those with large seasonal cycles, however, remains a challenge without long-term observations. Evolution models of Saturn cannot explain its estimated Bond albedo and internal heat flux, mainly …
Mapping the core of the Tarantula Nebula with VLT-MUSE - III. A template for metal-poor starburst regions in the visual and far-ultraviolet
Castro, N.; Crowther, Paul A.
We present the integrated VLT-MUSE spectrum of the central 2 × 2 arcmin2 (30 × 30 pc2) of NGC 2070, the dominant giant H II region of the Tarantula Nebula in the Large Magellanic Cloud, together with an empirical far-ultraviolet spectrum constructed via LMC template stars from the ULLYSES survey and Hubble Tarantula Treasury …
The Orbit and Mass of the Cepheid AW Per
Mérand, Antoine; Lanthermann, Cyprien; Anugu, Narsireddy +17 more
The Cepheid AW Per is a component in a multiple system with a long-period orbit. The radial velocities of Griffin cover the 38 yr orbit well. An extensive program of interferometry with the Center for High Angular Resolution Astronomy array is reported here, from which the long-period orbit is determined. In addition, a Hubble Space Telescope high…
Oxygen abundance of γ Vel from [O III] 88 µm Herschel/PACS spectroscopy
Hillier, D. J.; Morris, P. W.; Barlow, M. J. +4 more
We present Herschel PACS spectroscopy of the [O III] 88.4 µm fine-structure line in the nearby WC8+O binary system γ Vel to determine its oxygen abundance. The critical density of this line corresponds to several 105R* such that it is spatially extended in PACS observations at the 336 pc distance to γ Vel. Two approache…
ϵ Sagittarii: An Extreme Rapid Rotator with a Decretion Disk
Lewis, Fiona; Bailey, Jeremy; Cotton, Daniel V. +3 more
We report high-precision, multiwavelength linear-polarization observations of the bright B9 (or A0) star ϵ Sagittarii. The polarization shows the distinctive wavelength dependence expected for a rapidly rotating star. Analysis of the polarization data reveals an angular rotation rate ω (=Ω/Ωcrit) of 0.995 or greater, the highest yet mea…
Accretion rates of 42 nova-like stars with IUE and Gaia data
Selvelli, Pierluigi; Gilmozzi, Roberto
We analyzed more than 700 ultraviolet spectra of 45 nova-like stars (NLs) observed with the International Ultraviolet Explorer (IUE) satellite, obtaining reliable data for 42 of them. Combining these with the distances from the Gaia Early Data Release 3 (EDR3) and with results from the literature, for each object we determined the reddening E…