V391 Peg: identification of the two main pulsation modes from ULTRACAM u'g'r' amplitudes

Abstract

V391 Peg (HS2201+2610) is an extreme horizontal branch subdwarf B (sdB) star, it is an hybrid pulsator showing p- and g-mode oscillations, and hosts a 3.2/sini M_Jup planet at an orbital distance of about 1.7 AU. In order to improve the characterization of the star, we measured the pulsation amplitudes in the u'g'r' SLOAN photometric bands using ULTRACAM at the William Herschel 4.2 m telescope and we compared them with theoretical values. The preliminary results presented in this article conclusively show that the two main pulsation periods at 349.5 and 354.1 s are a radial and a dipole mode respectively. This is the first time that the degree index of multiple modes has been uniquely identified for an sdB star as faint as V391 Peg (B=14.4), proving that multicolor photometry is definitely an efficient technique to constrain mode identification, provided that the data have a high enough quality.

Proceedings of the 4th HELAS Conference (Lanzarote, 1-5 Feb. 2010), Astron. Nachrichten, in press

References in corpus (7)

• ULTRACAM: an ultra-fast, triple-beam CCD camera for high-speed astrophysics
• The sdB+M Eclipsing System HW Virginis and its Circumbinary Planets
• Detection of a tertiary brown dwarf companion in the sdB-type eclipsing binary HS 0705+6700
• Connecting planets around horizontal branch stars with known exoplanets
• Mode identification for Balloon 090100001 using combined multicolour photometry and spectroscopy
• Optical variability of the ultracool dwarf TVLM 513-46546: evidence for inhomogeneous dust clouds
• The planet-hosting subdwarf B star V391 Pegasi is a hybrid pulsator

Cited by in corpus (2)

• Three new pulsating sdB stars discovered with SuperWASP
• The sdB pulsating star V391 Peg and its putative giant planet revisited after 13 years of time-series photometric data