| Issue |
A&A
Volume 470, Number 3, August II 2007
|
|
|---|---|---|
| Page(s) | 1051 - 1057 | |
| Section | Stellar structure and evolution | |
| DOI | https://doi.org/10.1051/0004-6361:20077657 | |
| Published online | 30 May 2007 | |
Multiperiodicity in the newly discovered mid-late Be star V2104 Cygni *,**
1
INAF-Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate e-mail: [katrien.uytterhoeven;ennio.poretti]@brera.inaf.it
2
Instituto de Astrofísica de Andalucía (CSIC), Apartado 3004, 18080 Granada, Spain e-mail: [eloy;victor]@iaa.es
3
Royal Observatory of Belgium, Ringlaan 3, 1180 Brussel, Belgium e-mail: peter@oma.be
4
Observatoire de la Côte d'Azur, GEMINI, CNRS, Université Nice Sophia-Antipolis, BP 4229, 06304 Nice Cedex 4, France e-mail: Philippe.Mathias@oca.eu
5
Nordic Optical Telescope, Apartado 474, 38700 Santa Cruz de La Palma, Spain e-mail: jht@not.iac.es
6
Institut d'Astrophysique et de Géophysique de l'Université de Liège, Allée du 6 Août 17, 4000 Liège, Belgium e-mail: a.miglio@ulg.ac.be
Received:
17
April
2007
Accepted:
15
May
2007
Aims.We obtained the first long, homogenous time-series of
V2104 Cyg, consisting of 679 datapoints, with the 
photometers of the Sierra Nevada and San Pedro
Mártir Observatories. Our aim was to detect and subsequently
interpret the intrinsic frequencies of this previously unstudied
variable star, which turned out to be a Be star. We evaluate its
place among the variable B stars on the upper Main Sequence. To
obtain additional information on physical parameters we collected a
few spectra with the Elodie and FIES
instruments.
Methods.We searched for frequencies in the uvby
passbands using 2 different frequency analysis methods and used the
criterion to select the significant periodicities. We
obtained an estimate of the physical parameters of the underlying B
star of spectral type between B5 and B7, by correcting for the
presence of a circumstellar disk using a formalism based on the
strength of the Hα line emission.
Results.We detected 3 independent
frequencies with amplitudes below 0.01 mag, 
d-1 ,
d-1 and 
d-1 , and discovered that
V2104 Cyg is a Be star. The fast rotation (
= 290±10
km s-1, and 27°
45°) hampered the investigation of the
associated pulsational parameters 
.
Conclusions.The most plausible explanation for the observed variability of this mid-late type Be star is a non-radial pulsation model.
Key words: stars: oscillations / stars: emission-line, Be / stars: individual: V2104 Cyg
Based on observations obtained at the Observatorio Astronómico Nacional San Pedro Mártir (Mexico), Observatorio de Sierra Nevada (Spain) and Observatoire de Haute Provence (France), and on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.
© ESO, 2007
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