Issue |
A&A
Volume 437, Number 1, July I 2005
|
|
---|---|---|
Page(s) | 235 - 245 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361:20042045 | |
Published online | 10 June 2005 |
V4140 Sgr: A short period dwarf nova with a peculiar behavior
Departamento de Física, Universidade Federal de Santa Catarina, CEP 88040-900, Florianópolis, Brazil e-mail: [bernardo;bap]@astro.ufsc.br
Received:
21
September
2004
Accepted:
19
March
2005
We report on time series of CCD photometry of V4140 Sgr between 1991 and 2001. The analysis reveals that the object
was in the decline from an outburst in 1992 and again in outburst in
2001. The historical light curve collected by amateur astronomers
shows low amplitude ( mag) outbursts 5–10 days long,
recurrent every 80–90 days, confirming its dwarf nova nature. We
derive an outburst decline time scale of 1.2 days mag-1.
The orbital parameters are revised. We find a mass ratio
, an inclination
, and
and
, respectively for the primary and secondary
star masses. The predicted values for the semi-amplitude of the
radial velocity curve of the primary and secondary stars are
km s-1 and
km s-1, respectively. Eclipse
mapping techniques were applied to data both in quiescence and in
outburst to derive accretion disc surface brightness maps. A
distance of
pc is obtained from a method similar to
that used to constrain the distance to open clusters. From this
distance, disc radial brightness temperature distributions are
determined. The temperatures in the quiescent disc vary from
6000 K in the inner regions to 3000 K near the outer disc
and are flatter than the
law for
optically thick steady-state disc. The outburst occurs mainly with a
significant increase in brightness of the intermediate and outer
disc regions. The disc temperatures remain below the critical
effective temperature Tcrit at all disc radii during
outburst. The radial temperature distributions in quiescence and in
outburst are significantly different from those of other dwarf novae
of similar orbital period. These results cannot be explained within
the framework of the disc instability model. We suggest that the
small amplitude outbursts of V4140 Sgr are caused by bursts
of enhanced mass transfer rate from the secondary star.
Key words: accretion, accretion disks / eclipses / stars: binaries: close / stars: individual: V4140 Sgr / novae, cataclysmic variables
© 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.