Probable nonradial g-mode pulsation in early A-type stars

Free access article

Issue		A&A Volume 445, Number 1, January I 2006


Page(s)		L15 - L18
Section		Letters
DOI		http://dx.doi.org/10.1051/0004-6361:200500216

A&A 445, L15-L18 (2006)
DOI: 10.1051/0004-6361:200500216

Letter

Probable nonradial g-mode pulsation in early A-type stars

E. Antonello¹, L. Mantegazza¹, M. Rainer¹ and A. Miglio²

¹ INAF-Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate, Italy
e-mail: [elio;luciano;rainer]@merate.mi.astro.it
² Institut d'Astrophysique et de Géophysique de l'Université de Liège, 17 allée du 6 Août, 4000 Liège, Belgium
e-mail: miglio@astro.ulg.ac.be

( Received 12 October 2005 / Accepted 13 November 2005 )

Abstract
Aims.Asteroseismology of early A-type stars could be a new tool to test stellar convection theories.
Methods.A survey for line profile variability in early A-type stars has been performed in order to detect nonradial pulsation signatures.
Results.The star HR 6139, with spectral type A2V and estimated $T_{\rm {eff}}=8800$ K, shows evident line profile variations that can be explained by oscillations in prograde g-modes. This feature and the known photometric variability are similar to those observed in the Slowly Pulsating B-type stars. However HR 6139 is much cooler than the cool border of the instability strip of such variables, and it is hotter than the blue edge of the $\delta$ Scuti instability strip. There are indications of a tiny variability also in other four objects, whose nature is not yet clear.

Key words: stars: oscillations -- stars: variables: general

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