Abstract
Aims. Emission lines in polars show complex profiles with multiple components that are typically ascribed to the accretion stream, threading region, accretion spot, and the irradiated secondary-star. In low-state polars the fractional contribution by the accretion stream, and the accretion spot is greatly reduced offering an opportunity to study the effect of the secondary-star irradiation or stellar activity. We observed VV Pup during an exceptional low-state to study and constrain the properties of the line-forming regions and to search for evidence of chromospheric activity and/or irradiation.Methods. We obtained phase-resolved optical spectra at the ESO VLT+FORS1 with the aim of analyzing the emission line profile and radial velocity as a function of the orbital period. We also tailored irradiated secondary-star models to compare the predicted and the observed emission lines and to establish the nature of the line-forming regions.Results. Our observations and data analysis, when combined with models of the irradiated secondary-star, show that, while the weak low ionization metal lines (FeI and MgI) may be consistent with irradiation processes, the dominant Balmer H emission lines, as well as NaI and HeI, cannot be reproduced by the irradiated secondary-star models. We favor the secondary-star chromospheric activity as the main forming region and cause of the observed H, NaI, and He emission lines, though a threading region very close to the L1 point cannot be excluded. .
Original language | English (US) |
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Pages (from-to) | 279-286 |
Number of pages | 8 |
Journal | Astronomy and astrophysics |
Volume | 490 |
Issue number | 1 |
DOIs | |
State | Published - Oct 2008 |
Externally published | Yes |
Keywords
- Line: profiles
- Novae, cataclysmic variables
- Stars: chromospheres
- Stars: individiual: VV Puppis
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science