Extreme Horizontal Branch stars in {omega} Cen Virtual Observatory Resource

Authors
  1. Randall S.K.
  2. Calamida A.
  3. Fontaine G.
  4. Monelli M.
  5. Bono G.
  6. Alonso M.L.,Van Grootel V.
  7. Brassard P.
  8. Chayer P.
  9. Catelan M.
  10. Littlefair S.,Dhillon V.S.
  11. Marsh T.R.
  12. Published by
    CDS
Abstract

We present the results of an extensive survey for rapid pulsators among Extreme Horizontal Branch (EHB) stars in {omega} Cen. The observations performed consist of nearly 100 hours of time-series photometry for several off-centre fields of the cluster, as well as low-resolution spectroscopy for a partially overlapping sample. We obtained photometry for some 300 EHB stars, for aro und half of which we are able to recover light curves of sufficient quality to either detect or place meaningful non-detection limits for rapid pulsations. Based on the spectroscopy, we derive reliable values of logg, Teff and logN(He)/N(H) for 38 targets, as well as good estimates of the effective temperature for another nine targets, whose spectra are slightly polluted by a close neighbour in the image. The survey uncovered a total of five rapid variables with multi-periodic oscillations between 85 and 125s. Spectroscopically, they form a homogeneous group of hydrogen-rich subdwarf O stars clustered between 48000 and 54000K. For each of the variables we are able to measure between two and three significant pulsations believed to constitute independent harmonic oscillations. However, the interpretation of the Fourier spectra is not straightforward due to significant fine structure attributed to strong amplitude variations. In addition to the rapid variables, we found an EHB star with an apparently periodic luminosity variation of ~2700s, which we tentatively suggest may be caused by ellipsoidal variations in a close binary.

Keywords
  1. globular-star-clusters
  2. horizontal-branch-stars
  3. photometry
  4. spectroscopy
Bibliographic source Bibcode
2016A&A...589A...1R
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/589/A1
IVOA Identifier IVOID
ivo://CDS.VizieR/J/A+A/589/A1
Document Object Identifer DOI
doi:10.26093/cds/vizier.35890001

Access

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http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/589/A1/table5?

History

2016-04-04T06:49:30Z
Resource record created
2016-04-04T06:49:30Z
Created
2018-05-11T15:19:50Z
Updated

Contact

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