Metal-Rich SX Phe stars in the Kepler Field

Abstract

A spectroscopic and photometric analysis has been carried out for thirty-two candidate SX_Phe variable blue straggler stars in the Kepler-field (Balona & Nemec 2012). Radial velocities (RVs), space motions (U,V,W), projected rotation velocities (v sin i), spectral types, and atmospheric characteristics (T_eff, log g, [Fe/H], xi_t, zeta_RT, 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 (Perry 1969). Two thirds of the stars are fast rotators with v sin i > 50 km/s, including four stars with v sin i > 200 km/s. Three of the stars have (negative) RVs > 250 km/s, five have retrograde space motions, and 21 have total speeds (relative to the LSR) > 400 km/s. 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-disk star). Observed Roemer 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 days to more than four years.

43 pages, 23 figures, accepted MNRAS Nov.23,2016

References in corpus (30)

• Modules for Experiments in Stellar Astrophysics (MESA)
• Two Stellar Components in the Halo of the Milky Way
• New Grids of ATLAS9 Model Atmospheres
• A new code for automatic determination of equivalent widths: Automatic Routine for line Equivalent widths in stellar Spectra (ARES)
• Determining stellar macroturbulence using asteroseismic rotational velocities from Kepler
• ARES v2 - new features and improved performance
• A unifying explanation of complex frequency spectra of gamma Dor, SPB and Be stars: combination frequencies and highly non-sinusoidal light curves
• Disentangling the Hercules stream
• Discovery of Carbon/Oxygen depleted Blue Straggler Stars in 47 Tucanae: the chemical signature of a mass-transfer formation process
• Discovery of $\sim$ 9,000 new RR Lyrae in the Southern Catalina Surveys
• Finding binaries among Kepler pulsating stars from phase modulation of their pulsations
• Accurate Gravities of F, G, and K stars from High Resolution Spectra Without External Constraints
• Variable stars in Local Group Galaxies - II. Sculptor dSph
• On the use of the Fourier Transform to determine the projected rotational velocity of line-profile variable B stars
• Variable stars in the Fornax dSph Galaxy. II. Pulsating stars below the horizontal branch
• A delta Scuti distance to the Large Magellanic Cloud
• Deriving the orbital properties of pulsators in binary systems through their light arrival time delays
• Ecology of Blue Straggler Stars
• Super-Nyquist asteroseismology of solar-like oscillators with Kepler and K2 - expanding the asteroseismic cohort at the base of the red-giant branch
• The age structure of the Milky Way's halo
• Spots on Am stars
• A search for non-pulsating, chemically normal stars in the $\delta$ Scuti instability strip using Kepler data
• Finding binaries from phase modulation of pulsating stars with Kepler. IV. Detection limits and radial velocity verification
• Light-Element Abundances of Giant Stars in the Globular Cluster M71 (NGC 6838)
• Binarity and multiperiodicity in high-amplitude delta Scuti stars
• The Clusters AgeS Experiment (CASE). I. V209 omega Cen - An Eclipsing Post-Common Envelope Binary in the Globular Cluster omega Cen
• Blue Straggler Stars in Globular Clusters: a powerful tool to probe the internal dynamical evolution of stellar systems
• The Blue Straggler Population in Dwarf Galaxies
• Field Blue Stragglers and Related Mass Transfer Issues
• A search for dormant binaries with degenerate components in omega Centauri and NGC 6397

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• Pulsations of the SX Phe Star BL Camelopardalis
• Period-Colour and Amplitude-Colour relations for OGLE-$\delta$ Scuti stars in the Galactic Bulge and LMC
• An MCMC Approach to the Three-dimensional Structure of the Milky Way Bulge using OGLE-IV $\delta$ Scuti Stars
• KIC 10855535: An elegant Delta Scuti pulsator with Amplitude and Phase Modulation