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Optical Studies of Seven Bright Southern Cataclysmic Variable Stars
Thorstensen, John R.; Alvarado-Anderson, Chase K.; Burrows, Abigail D. +2 more
We report spectroscopic observations of seven bright southern cataclysmic variable stars, collected on a single two-week observing run using the 1.9 m Radcliffe telescope at the South African Astronomical Observatory. We used a radial-velocity time series, in some cases in combination with other data, to determine or clarify orbital periods for fi…
Physical Properties of the Young Asteroid Pair 2010 UM26 and 2010 RN221
Mutchler, Max; Jewitt, David; Li, Jing +1 more
The main belt asteroids 458271 (2010 UM26) and 2010 RN221 share almost identical orbital elements, and currently appear as comoving objects ~30″ apart in the plane of the sky. They are products of the breakup of a parent object, or the splitting of a binary, with a separation age measured in decades rather than thousands or millions of years as fo…
Empirical 2MASS-WFC3/IR Filter Transformations Across the H-R Diagram from Synthetic Photometry
Dalcanton, J. J.; Durbin, M. J.; Beaton, R. L. +2 more
Near-infrared bandpasses on spaceborne observatories diverge from their ground-based counterparts as they are free of atmospheric telluric absorption. Available transformations between respective filter systems in the literature rely on theoretical stellar atmospheres, which are known to have difficulties reproducing the observed spectral energy d…
IRAS 00450+7401 and the Mid-infrared Fade/Burst Cycle of R Coronae Borealis-type Stars
Melis, Carl; Wright, E. L.; Della Costa, John +3 more
We present optical and infrared imaging and spectroscopy of the R Coronae Borealis-type (R Cor Bor) star IRAS 00450+7401. Optical spectra further confirm its classification as a cool R Cor Bor system, having a hydrogen-deficient carbon star spectral subclass of HdC5 or later. Mid-infrared spectroscopy reveals the typical ~8 µm "hump" seen in…
V1507 CYGNI (HD187399): A Highly Evolved, Enigmatic Interacting Binary System with an Eccentric Orbit
Davidge, T. J.
The properties of the interacting, eccentric orbit binary V1507 Cyg (HD187399) are examined with spectra that cover wavelengths from 0.63-0.68 µm. The spectrum of the brightest star is similar to that of the B8 I star β Ori, although with absorption lines that show substructure possibly related to a varying tidal field. The bulk of the Hα em…
Most Rotational Variables Dominated by a Single Bright Feature Are α 2 CVn Stars
Heinze, A. N.; Huber, Mark E.; Flewelling, Heather
We previously reported a rare class of variable star light curves isolated from a sample of 4.7 million candidate variables from the ATLAS survey. Dubbed "UCBH" light curves, they have broad minima and narrow, symmetrical maxima, with typical periods of 1-10 days and amplitudes of 0.05-0.20 mag. They maintain constant amplitude, shape, and phase c…
Observational Constraints on Close Binary Star Evolution. I. Putative Contact Binaries with Long Periods and High Mass Ratios
Kobulnicky, Henry A.; Cook, Evan M.
Evolutionary and structural models for contact binary stars make quantitative predictions about the distribution of systems in the mass ratio (q)-orbital period (P) plane. Specifically, contact binaries containing primaries with convective envelopes are predicted to be absent at mass ratios larger than a critical threshold that is a function of or…
The True Nature of the Brightest Local Triple Stellar Candidates within 100 pc in the Galaxy
Al-Wardat, Mashhoor A.; Annuar, A.; Yousef, Z. T. +1 more
We present a study of a sample of bright (V ≤ 10 mag) and close (d ≤ 100 pc) triple-stellar system candidates in the galaxy, consisting of eight systems in total. Our aim is to determine their actual multiplicity and the physical properties of each stellar component in the systems. The sample was analyzed using a complex spectrophotometric techniq…
Multifilter Time-series Observations of Eleven Blue Short-period ATLAS Variable Stars
Kniazev, A.; Schaffenroth, V.; Koen, C.
Eleven periodic variable stars were observed photometrically through two to four filters from the set UBVR C I C . Phase-folded data for each star cover full cycles of variation. Spectral energy distributions, based on absolute photometry extracted from the literature, are used to inform models of the stars. The stars incl…
Estimation of the Flux at 1450 MHz of OB Stars for FAST and SKA
Jiang, Biwei; Deng, Dingshan; Zijlstra, Albert +2 more
Radio observation is crucial to understanding the wind mechanism of OB stars but very scarce. This work estimates the flux at 1450 MHz (S 1.4GHz) of about 5000 OB stars identified by the LAMOST spectroscopic survey and confirmed by the Gaia astrometric as well as astrophysical measurements. The calculation is performed under the free-fr…