Issue |
A&A
Volume 462, Number 3, February II 2007
|
|
---|---|---|
Page(s) | 1069 - 1080 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361:20052906 | |
Published online | 13 November 2006 |
Determination of the basic parameters of the dwarf nova EY Cygni
1
Instituto de Astronomía, Universidad Nacional Autónoma de México, Apartado Postal 70-264, 04510 México, DF, México e-mail: jer,costero@astroscu.unam.mx
2
Instituto de Astronomía, Universidad Nacional Autónoma de México, Apartado Postal 877, 22830, Ensenada, Baja California, México e-mail: rmm,zhar@astrosen.unam.mx
Received:
29
March
2006
Accepted:
27
October
2006
Context.High-dispersion spectroscopy of EY Cyg obtained from data spanning
twelve years show, for the first time, the radial velocity curves from
both emission and absorption line systems, yielding semi-amplitudes
±
and
±
. The orbital period of this system
is found to be 0.4593249(1) d. The masses of the stars, their mass ratio and
their separation are found to be
±
,
±
,
and
±
.
We also found that the spectral type of the secondary star is around K0,
consistent with an early determination by Kraft (1962).
Aims.From the spectral type of the secondary star and simple comparisons with single main sequence stars, we conclude that the radius of the secondary star is about 30 per cent larger than a main sequence star of the same mass.
Methods.We also present VRI CCD photometric observations, some of them simultaneous with the spectroscopic runs. The photometric data shows several light modulations, including a sinusoidal behaviour with twice the frequency of the orbital period, characteristic of the modulation coming from an elongated, irradiated secondary star. Low and high states during quiescence are also detected and discussed.
Results.From several constrains, we obtain tight limits for the inclination angle of the binary system between 13 and 15 degrees, with a best value of 14 degrees obtained from the sinusoidal light curve analysis.
Conclusions.From the above results we derive masses ±
,
±
, and a binary separation
±
.
Key words: stars: dwarf novae / techniques: spectroscopic / techniques: photometric / stars: individual: EY Cygni
© ESO, 2007
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.