Volume 455, Number 2, August IV 2006
|Page(s)||673 - 677|
|Section||Stellar structure and evolution|
|Published online||04 August 2006|
Pulsation of the Lambda Bootis star HD 210111
Institut für Astronomie der Universität Wien, Türkenschanzstr. 17, 1180 Wien, Austria e-mail: firstname.lastname@example.org
2 Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT, Australia e-mail: email@example.com
Accepted: 12 May 2006
Context.The λ Bootis stars are a small spectroscopic subgroup of Population I A-type stars and show significant underabundances of metals. Many are δ Scuti pulsators.
Aims.HD 210111 was selected for a detailed multisite pulsation study to determine whether its pulsation properties differ from those of normal A stars.
Methods.262 h of high-precision photometry were obtained at the SAAO and SSO observatories.
Results.13 statistically significant pulsation frequencies were detected with very small photometric amplitudes from 1 to 7 millimag in the visual. A comparison with earlier 1994 measurements indicates a small increase in amplitude. As a byproduct, one of the comparison stars, HD 210571, was discovered to be a millimag variable with a frequency of 1.235 cd-1 and is probably a new γ Doradus variable. The observed wide range of excited frequencies from 12 to 30 cd-1 in HD 210111 can be explained with both the single- and double-star hypothesis. HD 210111 is in a similar evolutionary status to FG Vir, which also shows a wide range of excited frequencies with a similar frequency spacing near 4 cd-1. This is interpreted as successive radial orders of the excited nonradial modes. In the double-star hypothesis previously evoked for HD 210111, the low and the high frequencies originate in different stars: here HD 210111 would resemble Tau.
Conclusions.The pulsation of the λ Bootis star HD 210111 does not differ from that of normal δ Scuti stars.
Key words: stars: variables: δ Sct / stars: oscillations / stars: chemically peculiar / stars: individual: HD 210111 / stars: individual: HD 210571
© ESO, 2006
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