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Blue Straggler Stars Beyond the Milky Way. III. Detection of Evolved Blue Straggler Candidates in Large Magellanic Cloud Clusters
Hong, Jongsuk; Deng, Licai; de Grijs, Richard +3 more
We analyze Hubble Space Telescope observations of nine Large Magellanic Cloud star clusters with ages of 1-2 Gyr to search for evolved counterparts of blue straggler stars. Near the red clump regions in the clusters’ color-magnitude diagrams, we find branches of evolved stars that are much brighter than normal evolved stars. We examine the effects…
Visual Orbit and Individual Masses of the Single-lined Spectroscopic Binary 94 AQR A (HD 219834A; MCA 74)
Docobo, José A.; Tamazian, Vakhtang S.; Campo, Pedro P. +1 more
By combining our improved visual orbit with the last spectroscopic solution of the single-lined spectroscopic binary, MCA 74 (ADS 16672Aa, Ab; HD 219834A), we derived its orbital solution to have a period of 6.321 years. Using the Gaia parallax, a systemic mass of 1.87 ± 0.09 {{ \mathcal M }}⊙ and a mass ratio of q = 0.725 were obtaine…
Phase-dependent Photometric and Spectroscopic Characterization of the MASTER-Net Optical Transient J212444.87+321738.3: An Oxygen-rich Mira
Banerjee, D. P. K.; Hambsch, Franz-Josef; Dutta, Somnath +4 more
We describe the time-dependent properties of a new spectroscopically confirmed Mira variable, which was discovered in 2013 as MASTER-Net Optical Transient J212444.87+321738.3 toward the Cygnus constellation. We have performed long-term optical/near-infrared (NIR) photometric and spectroscopic observations to characterize the object. From the optic…
K2 Targets Observed with SPHERE/VLT: An M4-7 Dwarf Companion Resolved around EPIC 206011496
Gratton, Raffaele; Vigan, Arthur; Bonavita, Mariangela +6 more
The quest to discover exoplanets is one of the most important missions in astrophysics, and is widely performed using the transit method, which allows for the detection of exoplanets down to the size of Mercury. However, to confirm these detections, additional vetting is mandatory. We selected six K2 targets from campaigns #1 to #8 that show trans…
Young and Eccentric: The Quadruple System HD 86588
Law, Nicholas M.; Walter, Frederick M.; Tokovinin, Andrei +5 more
High-resolution spectroscopy and speckle interferometry reveal the young star HD 86588 as a quadruple system with a three-tier hierarchy. The 0.″3 resolved binary A,B with an estimated period around 300 years contains the 8-yr pair Aa,Abc (also potentially resolvable), where Ab,Ac is a double-lined binary with equal components, for which we comput…
Spectroscopic Orbits for Late-type Stars. II
Abt, Helmut A.; Fekel, Francis C.; Willmarth, Daryl W. +1 more
We have determined spectroscopic orbital elements for 13 systems—10 single-lined binaries and three double-lined binaries. For the three binaries with previously published spectroscopic orbits, we have computed improved or comparable elements. While two systems have relatively short periods between 10 and 19 days, the remaining systems have much l…
The Three-dimensional Orbit, Orbital Parallax, and Individual Masses of the Double-lined Spectroscopic Binaries HD 183255, HD 114882, and HD 30712
Docobo, J. A.; Horch, Elliott P.; Campo, P. P. +1 more
Recent speckle observations performed at the Discovery Channel Telescope, the Gemini North Telescope, and the Special Astrophysical Observatory 6 m Telescope have permitted us to calculate the visual orbit of SB2 HD 114882 for the first time and to improve the visual orbits of two other SB2 systems, HD 30712 and HD 183255, using algorithms publish…
Speckle Interferometry at the U.S. Naval Observatory. XXIII.
Mason, Brian D.; Hartkopf, William I.; Josties, Jordan D. +1 more
The results of 3989 intensified CCD observations of double stars, made with the 26-inch refractor of the U.S. Naval Observatory, are presented. Each observation of a system represents a combination of over 2000 short-exposure images. These observations are averaged into 1911 mean relative positions and range in separation from 0.″289 to 128.″638, …
Radial Velocity Comparison of Gaia DR2 and RAVE DR5 Survey: A Systematic Offset in Radial Velocities among a Group of Highly Accurate Radial Velocity Stars
Deepak; Reddy, Bacham E.
Here, we report a comparative study of radial velocity (RV) data of two major surveys: Gaia Data Release 2 and RAVE Data Release 5. We restricted the sample to stars with relatively accurate RVs ({σ }RV}{Gaia}}≤slant 2 km s-1 or ≤2%, and {σ }RV}RAVE}}≤slant 2 km s-1 or ≤2%). The dif…
Kinematics of Type II Cepheids of the Galactic Halo
Wallerstein, George; Farrell, Elizabeth M.
In a step toward understanding the origin of the Galactic Halo, we have reexamined Type II Cepheids (T2C) in the field with new input from the second data release (DR2) of Gaia. For 45 T2C with periods from 1 to 20 days, parallaxes, proper motions, and [Fe/H] values are available for 25 stars. Only five show [Fe/H] < -1.5, while the remaining s…