Volume 439, Number 3, September I 2005
|Page(s)||1093 - 1098|
|Section||Stellar structure and evolution|
|Published online||12 August 2005|
Inhomogeneous distribution of mercury on the surfaces of rapidly rotating HgMn stars
Department of Astronomy and Space Physics, Uppsala University, 751 20 Uppsala, Sweden e-mail: firstname.lastname@example.org
2 Institute of Astronomy, Russian Academy of Sciences, Pyatnitskaya 48, 119017 Moscow, Russia
3 Special Astrophysical Observatory, Russian Academy of Sciences, Nizhnij Arkhyz, 357147 Karachai-Cherkessian Republic, Russia
Accepted: 26 April 2005
Starspots are usually associated with the action of magnetic fields at stellar surfaces. However, an inhomogeneous chemical distribution of mercury was found recently for the mercury-manganese (HgMn) star α And – a well-established member of a non-magnetic subclass of the chemically peculiar stars of the upper main sequence. In this study we present first results of the high-resolution survey of the 3984 Å resonance line in the spectra of rapidly rotating HgMn stars with atmospheric parameters similar to those of α And. We use spectrum synthesis modelling and take advantage of the Doppler resolution of stellar surfaces to probe the horizontal structure of mercury distribution. Clear signatures of spots are found in the 3984 Å line profiles of HR 1185 and HR 8723. Two observations of the latter star separated by two days give evidence for line profile variability. We conclude that inhomogeneous distribution of Hg is a common phenomenon for the rapidly rotating HgMn stars in the 13 000–13 800 K effective temperature range independent of the stellar evolutionary stage. These results establish the existence of a new class of spectrum variable spotted B-type stars. It is suggested that the observed Hg inhomogeneities arise from dynamical instabilities in the chemical diffusion processes and are unrelated to magnetic phenomena.
Key words: line: profiles / stars: atmospheres / stars: chemically peculiar / stars: individual: HR 1185 / stars: individual: HR 8723
© ESO, 2005
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.