Atomic lines in spectra of RR Lyrae & RHB stars Virtual Observatory Resource

Authors
  1. Preston G.W.
  2. Sneden C.
  3. Chadid M.
  4. Thompson I.B.
  5. Shectman S.A.
  6. Published by
    CDS
Abstract

We have derived relations between FWHMs and equivalent widths of metallic absorption lines in the spectra of RR Lyrae stars to estimate new upper limits on the axial equatorial rotational velocities of RR Lyrae and metal-poor red horizontal branch (RHB) stars. We have also derived the variations of RR Lyrae macroturbulent velocities during the pulsation cycles. In RRab cycles, the line widths are dominated by phase-dependent convolutions of axial rotation and macroturbulence, which we designate as V_macrot_. The behavior of V_macrot_ is remarkably uniform among the RRab stars, but the behavior of V_macrot_ among RRc stars varies strongly from star to star. The RRab stars exhibit an upper limit on V_macrot_ of 5+/-1 km/s with weak evidence of an anticorrelation with T_eff_. The RRc minima range from 2 to 12 km/s. The abrupt decline in large rotations with decreasing T_eff_ at the blue boundary of the instability strip and the apparently smooth continuous variation among the RRab and RHB stars suggests that HB stars gain/lose surface angular momentum on timescales that are short compared to HB lifetimes. The V_macrot_ values for our metal-poor RHB stars agree well with those derived by Fourier analysis of an independent but less metal-poor sample of Carney et al. (2008AJ....135..892C); they conform qualitatively to the expectations of Tanner et al. (2013ApJ...778..117T). A general conclusion of our investigation is that surface angular momentum as measured by V_rot_sin(i) is not a reliable indicator of total stellar angular momentum anywhere along the HB.

Keywords
  1. variable-stars
  2. horizontal-branch-stars
  3. metallicity
  4. effective-temperature
  5. visible-astronomy
  6. spectroscopy
  7. line-intensities
Bibliographic source Bibcode
2019AJ....157..153P
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/157/153
IVOA Identifier IVOID
ivo://CDS.VizieR/J/AJ/157/153
Document Object Identifer DOI
doi:10.26093/cds/vizier.51570153

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History

2019-08-06T07:03:49Z
Resource record created
2019-08-06T07:03:49Z
Created
2019-11-12T13:35:07Z
Updated

Contact

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CDS support team
Postal Address
CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France
E-Mail
cds-question@unistra.fr