EDP Sciences
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Volume 429, Number 3, January III 2005
Page(s) L55 - L58
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:200400112

A&A 429, L55-L58 (2005)
DOI: 10.1051/0004-6361:200400112


Rotational periods of four roAp stars

T. Ryabchikova1, 2, G. A. Wade3, M. Aurière4, S. Bagnulo5, J.-F. Donati6, S. V. Jeffers7, N. Johnson3, J. D. Landstreet8, F. Lignières4, T. Lueftinger1, S. Marsden9, D. Mouillet4, F. Paletou6, P. Petit10, P. Reegen1, J. Silvester3, 11, S. Strasser12 and N. Toque4

1  Institute for Astronomy, University of Vienna, Türkenschanzstrasse 17, 1180 Wien, Austria
    e-mail: ryabchik@jan.astro.univie.ac.at
2  Institute of Astronomy, Russian Academy of Sciences, Pyatnitskaya 48, 109017 Moscow, Russia
3  Physics Department, Royal Military College of Canada, Kingston, Ontario, K7K 7B4, Canada
4  Observatoire Midi Pyrénées, 57 avenue d'Azereix, BP 826, 65008 Tarbes Cedex, France
5  European Southern Observatory, Casilla 19001, Santiago 19, Chile
6  Observatoire Midi-Pyrénées, 14 avenue Édouard Belin, Toulouse, France
7  School of Physics and Astronomy, University of St Andrews, St Andrews, Fife, KY16 9SS, UK
8  Department of Physics & Astronomy, The University of Western Ontario, London, Ontario, N6A 3K7, Canada
9  Institute of Astronomy, ETH-Zentrum, 8092 Zurich, Switzerland
10  Max-Planck Institut fuer Sonnensystemforschung Max-Planck-Str. 2, 37191 Katlenburg-Lindau, Germany
11  Department of Physics, Queen's University, Kingston, Ontario, Canada
12  Deptartment of Astronomy, University of Minnesota, 116 Church St. S.E., Minneapolis, MN 55455, USA

(Received 8 November 2004 / Accepted 26 November 2004)

Forty-five new measurements of the mean longitudinal magnetic fields and mean equivalent widths of 4 roAp stars have obtained using the MuSiCoS spectropolarimeter at Pic du Midi observatory. These new high-precision data have been combined with archival measurements in order to constrain the rotational periods of HD 12098, HD 24712 = HR 1217, HD 122970 and HD 176232 = 10 Aql. We report a revised rotational period for HD 24712 ( $P_{\rm rot} = 12.45877$  $\pm$ 0.00016 d, crucial for interpretation of upcoming MOST observations of this star), new rotational periods for HD 12098 and HD 122970 ( $P_{\rm rot}=5.460$  $\pm$ 0.001 d and $P_{\rm
rot}=3.877$   $\pm$ 0.001 d, respectively) and evidence for an extremely long period for HD 176232.

Key words: stars: individual: HD 12098, HD 24712, HD 122970, HD 176232 -- stars: peculiar -- magnetic fields

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