Astronomy and Astrophysics – Astrophysics
Scientific paper
2007-12-20
Astronomy and Astrophysics
Astrophysics
4 pages, 3 figures; accepted for publication in Astronomy & Astrophysics
Scientific paper
10.1051/0004-6361:20079183
We present the discovery of pulsational variations in the cool magnetic Ap star HD 115226 -- the first high-amplitude rapidly oscillating Ap star discovered with time-series spectroscopy. Using high-resolution spectra obtained with the HARPS instrument at the ESO 3.6-m telescope, we detect radial velocity variations with a period of 10.86 min in Pr III, Nd III, Dy III lines and in the narrow cores of hydrogen lines. Pulsational amplitudes exceed 1 km/s in individual lines of Nd III. The presence of running waves in the stellar atmosphere is inferred from a phase shift between the radial velocity maxima of rare-earth and hydrogen lines. Our abundance analysis demonstrates that HD 115226 exhibits typical roAp spectroscopic signature, notably ionization anomaly of Pr, Nd and Dy. We discuss the discovery of pulsations in HD 115226 in the context of recent spectroscopic studies of roAp stars and point to the existence of correlation between spectroscopic pulsational amplitude and the stellar rotation rate.
Bagnulo Stefano
Kochukhov Oleg
Lo Curto Gaspare
Ryabchikova Tanya
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