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The Discovery of Pulsating Hot Subdwarfs in NGC 2808
- Publication Year :
- 2013
- Publisher :
- arXiv, 2013.
-
Abstract
- We present the results of a Hubble Space Telescope program to search for pulsating hot subdwarfs in the core of NGC 2808. These observations were motivated by the recent discovery of such stars in the outskirts of omega Cen. Both NGC 2808 and omega Cen are massive globular clusters exhibiting complex stellar populations and large numbers of extreme horizontal branch stars. Our far-UV photometric monitoring of over 100 hot evolved stars has revealed six pulsating subdwarfs with periods ranging from 85 to 149 s and UV amplitudes of 2.0 to 6.8%. In the UV color-magnitude diagram of NGC 2808, all six of these stars lie immediately below the canonical horizontal branch, a region populated by the subluminous "blue-hook" stars. For three of these six pulsators, we also have low-resolution far-UV spectroscopy that is sufficient to broadly constrain their atmospheric abundances and effective temperatures. Curiously, and in contrast to the omega Cen pulsators, the NGC 2808 pulsators do not exhibit the spectroscopic or photometric uniformity one might expect from a well-defined instability strip, although they all fall within a narrow band (0.2 mag) of far-UV luminosity.<br />Comment: 5 pages, 1 table, 2 color and 2 grayscale figures. Accepted for publication in The Astrophysical Journal Letters
- Subjects :
- Physics
Astrophysics::High Energy Astrophysical Phenomena
FOS: Physical sciences
Astronomy and Astrophysics
Astrophysics
Astrophysics::Cosmology and Extragalactic Astrophysics
Horizontal branch
Omega
Luminosity
Stars
Amplitude
Astrophysics - Solar and Stellar Astrophysics
Space and Planetary Science
Globular cluster
Astrophysics::Solar and Stellar Astrophysics
Astrophysics::Earth and Planetary Astrophysics
Instability strip
Spectroscopy
Astrophysics::Galaxy Astrophysics
Solar and Stellar Astrophysics (astro-ph.SR)
Subjects
Details
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....df68bb84370c48812e615c444e1de332
- Full Text :
- https://doi.org/10.48550/arxiv.1310.0835