Issue |
A&A
Volume 474, Number 1, October IV 2007
|
|
---|---|---|
Page(s) | 213 - 220 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361:20077803 | |
Published online | 28 August 2007 |
A multicolor near-infrared study of the dwarf nova IP Pegasi
1
Departamento de Física, Universidade Federal de Santa Catarina, Campus Trindade, 88040-900 Florianópolis, SC, Brazil e-mail: tiago@astro.ufsc.br
2
Soar Telescope, Colina El Pino s/n, Casilla 603, La Serena, Chile
3
Institute of Space Applications and Remote Sensing, National Observatory of Athens, PO Box 20048, Athens 118 10, Greece
4
Dept. of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK
5
Isaac Newton Group of Telescopes, Apartado de Correos 321, 38700 Santa Cruz de La Palma, Spain
Received:
7
May
2007
Accepted:
15
August
2007
We report the analysis of light curves of the eclipsing dwarf nova IP Peg in quiescence. The light curves are dominated by the
ellipsoidal variation of the mass-donor star, with additional
contributions from the accretion disc and anisotropic emission from the bright
spot. A secondary eclipse is visible in the J and H light curves, with
2% and 3% of the flux disappearing at minimum light, respectively.
We modeled the observed ellipsoidal variation of the secondary star (including
possible illumination effects on its inner face) to find a mass ratio of
q = 0.42 and an inclination of i = 84.5°, consistent in the three bands
within the uncertainties. Illumination effects are negligible. The secondary is
responsible for 83%, 84% and 88% of the flux in J, H and Ks,
respectively. We fitted a black body spectrum to the
fluxes of the
secondary star to find a temperature of Tbb = 3100 ± 500 K and a distance of
d = 115 ± 30 pc to the system. We subtracted the contribution of the secondary star
and applied 3D eclipse mapping techniques to the resulting light curves to
map the surface brightness of a
disc with half-opening angle α and a circular rim at the radius of the
bright spot. The eclipse maps show enhanced emission along the stream
trajectory ahead of the bright spot position, providing evidence of gas stream
overflow. The inferred radial brightness-temperature distribution in the disc
is flat for R < 0.3 RL1 with temperatures
3500 K and colors
consistent with those of cool opaque radiators.
Key words: stars: novae, cataclysmic variables / stars: individual: IP Peg / stars: binaries: eclipsing / infrared: stars
© ESO, 2007
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