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Astron. Astrophys. 348, 364-370 (1999)

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On the linewidth/K vs. mass ratio relation for SU Ursae Majoris stars and the removal of the inner disk

R.E. Mennickent *

Universidad de Concepción, Departamento de Física, Casilla 4009, Concepción, Chile (rmennick@stars.cfm.udec.cl)

Received 7 April 1999 / Accepted 23 June 1999


We have calibrated the linewidth/K vs. mass ratio relation for SU UMa stars using the "superhump" mass ratio derived from the tidal resonance model. We find that the relation by Jurcevic et al. (1994) is valid for dwarf novae above the period gap but not for SU UMa stars. Under the hypothesis of Keplerian disks, our results are compatible with the removal of the inner disk in SU UMa stars with extreme cycle lengths. The large long-term FWHM variability observed in WZ Sge suggests that the fraction of mass removed from the disk is variable and possibly a function of the supercycle phase.

We show a new empirical formula between mass ratio and [FORMULA]. It fits the mass ratio of dwarf novae above and below the period gap with a mean relative dispersion of 16% and 26%, respectively, except for the post-period minimum candidates EG Cnc and WZ Sge.

Key words: accretion, accretion disks – methods: statistical – stars: binaries: general – stars: evolution – stars: novae, cataclysmic variables

* On leave in Harvard-Smithsonian Center for Astrophysics, 60 Garden St, MA 02138, Cambridge, USA

Send offprint requests to: R.E. Mennickent

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© European Southern Observatory (ESO) 1999

Online publication: July 26, 1999