Rapidly Pulsating Hot Subdwarfs in ω Centauri: A New Instability Strip on the Extreme Horizontal Branch?

Details Rapidly Pulsating Hot Subdwarfs in ω Centauri: A New Instability Strip on the Extreme Horizontal Branch? Rapidly Pulsating Hot Subdwarfs in ω Centauri: A New Instability Strip on the Extreme Horizontal Branch?

Aug 2011

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011apj...737l..27r&link_type=abstract

The Astrophysical Journal Letters, Volume 737, Issue 2, article id. L27 (2011).

Astronomy and Astrophysics

Astronomy

4

Globular Clusters: Individual: Ω Centauri, Stars: Oscillations, Subdwarfs

Scientific paper

Pulsating extreme horizontal branch (EHB) stars offer the unique opportunity to use asteroseismology to probe their fundamental parameters and thus constrain one of the more poorly understood phases of stellar evolution. However, they have been observed only among the field population, which necessarily prevents asteroseismological tools from being applied to globular cluster EHB stars. We launched a search for rapid EHB pulsators in ω Cen on the basis of fast time-series photometry obtained with EFOSC2 at the New Technology Telescope. Fourier analysis uncovered four multi-mode oscillators with rather similar periods between 84 and 124 s and amplitudes up to 2.7% of the mean stellar brightness. Initially, it was assumed that these stars constitute the globular cluster counterparts to the EC 14026 stars, rapid subdwarf B pulsators with T eff ~ 31,000 K that have been extensively studied among the field population, yet a subsequent atmospheric analysis of FORS MXU spectra reveals effective temperatures closely clustered around 50,000 K, implying that the four ω Cen variables are in fact helium-poor subdwarf O (sdO) stars rather than EC 14026 pulsators. It remains to be seen whether they are related to the one significantly hotter sdO oscillator known among the field star population, or belong to a hitherto unknown class of stellar pulsator that can now be subjected to asteroseismological scrutiny.
Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (proposal ID 083.D-0833 and 386.D-0669).

Affiliated with

Also associated with

No associations

Rating

Rapidly Pulsating Hot Subdwarfs in ω Centauri: A New Instability Strip on the Extreme Horizontal Branch? does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Rapidly Pulsating Hot Subdwarfs in ω Centauri: A New Instability Strip on the Extreme Horizontal Branch?, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rapidly Pulsating Hot Subdwarfs in ω Centauri: A New Instability Strip on the Extreme Horizontal Branch? will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1741897