Probing the Accretion Flow in the Cataclysmic Variable V795 Her

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Session 65 -- Interacting Binaries: Compact Stars
Oral presentation, Thursday, January 13, 2:15-3:45, Salon V Room (Crystal Gateway)

[65.04] Probing the Accretion Flow in the Cataclysmic Variable V795 Her

C.A.Haswell (STScI), G. Thomas (Columbia U.), K. Horne (U. of Utrecht)

Observations of ${\rm H\alpha}$ and He~I ${\rm \lambda \lambda ~5876,6678}$ in the cataclysmic variable V795 Her are presented; these emission lines are modulated with period 2.6 hours, in agreement with the ephemeris of Shafter et al. 1990. The H${\rm \alpha}$ profile is double-peaked with peak-to-peak separation of ${\rm \sim 900~km~s^{-1}}$. A strong S-wave threads between the peaks in the profile. A second S-wave with semi-amplitude of ${\rm \sim 1500~km~s^{-1}}$ is apparent. Tomography of ${\rm H\alpha}$ shows a prominent bright spot associated with the inner S-wave. The He~I tomogram shows a crescent-shaped emission structure displaced from the ${\rm H\alpha}$ bright spot in phase. Models motivated by the observations are discussed. The S-wave emission may arise in magnetically channeled accretion onto the white dwarf, in which case the system is a DQ Her star. If the photometric period indicates the orbital period of the binary, then the white dwarf is rotating close to synchronism, and V795 Her may share some characteristics with the AM Her stars.

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