Spectroscopy of the double-lined dwarf nova AT Ara*
Laboratório Nacional de Astrofísica, CP 21, 37500–000 Itajubá – MG, Brazil
Corresponding author: albert@lna.br
Received:
6
November
2001
Accepted:
3
July
2003
The first time-resolved spectroscopic observations of the dwarf
nova AT Ara are presented. The system is a double lined spectroscopic
binary. Thus, radial velocity curves of both,
emission lines from the accretion disk (in this particular case of Hα)
and of the secondary star can be measured.
An orbital period of 0.37551 days is derived,
placing AT Ara among the cataclysmic variables with the longest revolution
periods. The RV-amplitudes yield a mass ratio of 
. The spectral type of the secondary
star is K2. AT Ara has an intermediate
orbital inclination of 
.
The secondary star has a mass and a radius of
and 
, respectively.
It is thus significantly larger than a main sequence star of the same
mass. Evolutionary calculations of cataclysmic variables suggest that
the secondary is nuclearly evolved to a certain degree.
The distance to AT Ara is estimated to be of the order of 600 pc.
Key words: stars: binaries: close / stars: novae, cataclysmic variables / stars: individual: AT Ara
© ESO, 2003