To be published in:
Astronomy and Astrophysics
The spectral variability of HD 192639 and its implications for the star's wind structure+
E. Gosset1,** and
1 Institut d'Astrophysique et de Géophysique - Université de Liège, Avenue de Cointe 5, 4000 Liège, Belgium
2 Ritter Astrophysical Research Center, Toledo OH 43606, USA
* Postdoctoral Researcher FNRS, Belgium
** Research Associate FNRS, Belgium
+ Based on observations collected at the Observatoire de Haute Provence, France and the Ritter Observatory, Toledo, USA
We report the analysis of an extensive set of spectroscopic data of
the O(f) supergiant HD 192639. A Fourier analysis of our time-series
reveals a recurrent variability with a 'period' of roughly 4.8 days
which is most prominent in the absorption components of the He
II 4686 and
H P-Cygni profiles.
The same periodicity is also detected in the blue wing of several
absorption lines (e.g. H).
The variations of the absorption components correspond most probably
to a cyclical modulation of the amount of stellar wind material along
the line of sight towards the star. The 4.8-day period affects also
the morphology of the double-peaked He II
H emission components, although
these emission components display also variations on other
(mainly longer) time scales.
The most likely explanation for the 4.8-day modulation is that this
cycle reflects the stellar rotational period (or half this period).
We find that the most important observational properties can be
explained - at least qualitatively - by a corotating interaction
region or a tilted confined corotating wind.
line: profiles - stars: early-type - stars: mass loss -
stars: individual: HD192639 - stars: variables: other