Metal-rich SX Phe stars in the Kepler field

Nemec, James M. and Balona, Luis A. and Murphy, Simon J. and Kinemuchi, Karen and Jeon, Young-Beom (2016) Metal-rich SX Phe stars in the Kepler field. Monthly Notices of the Royal Astronomical Society, 466 (2). pp. 1290-1329. ISSN 0035-8711

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A spectroscopic and photometric analysis has been carried out for 32 candidate SX Phe variable blue straggler stars in the Kepler field. Radial velocities (RVs), space motions (U, V, W), projected rotation velocities (vsin i), spectral types and atmospheric characteristics (Teff, log g, [Fe/H], ξt, ζRT, etc.) are presented for 30 of the 32 stars. Although several stars are metal-weak with extreme halo orbits, the mean [Fe/H] of the sample is near-solar, thus the stars are more metal-rich than expected for a typical sample of Pop. II stars and more like halo metal-rich A-type stars. Two-thirds of the stars are fast rotators with vsin i > 50 km s−1, including four stars with vsin i > 200 km s−1. Three of the stars have (negative) RVs > 250 km s−1, five have retrograde space motions and 21 have total speeds (relative to the Local Standard of Rest) >400 km s−1. All but one of the 30 stars have positions in a Toomre diagram consistent with the kinematics of bona fide halo stars (the exception being a thick-disc star). Observed Rømer time delays, pulsation frequency modulations and light curves suggest that at least one-third of the stars are in binary (or triple) systems with orbital periods ranging from 2.3 d to more than four years.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: File reproduced in accordance with the copyright policy of the publisher/author.
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 28 Apr 2022 23:56
Last Modified: 16 May 2022 01:52
Uncontrolled Keywords: Blue stragglers; Stars: abundances; Stars: kinematics and dynamics; Stars: oscillations; Stars: Population II; Stars: variables: δ Scuti; Astrophysics - Solar and Stellar Astrophysics
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
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