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Session 109 - Novae & Cataclysmic Variables.
Display session, Saturday, January 10
Exhibit Hall,

[109.04] Orbital Periods for the Interesting Old Novae V446 Her and V533 Her

J. R. Thorstensen, C. J. Taylor (Dartmouth Coll.)

V446 Her (= Nova Her 1960) is nearly unique among classical novae in that it shows dwarf nova outbursts which apparently began only a few decades after its nova outburst (Honeycutt et al, 1997, ApJ, in press). We report here spectroscopy which establishes the orbital period as 0.2070 d (or 4.97 hr) from H\alpha radial velocity variations. This is a quite ordinary period for an old nova, so the unusual dwarf-nova behavior is evidently unrelated to the orbital period.

Patterson (1979, ApJL 233, L13) established that V533 Her (= Nova Her 1963) shows a strictly coherent 63.6 s oscillation in its light curve, establishing its credentials as a DQ Her star, one of the few among the old novae (DQ Her itself being another). Hutchings (1987, PASP, 99, 57) obtained spectra which were difficult to interpret and did not yield an unambiguous orbital period, but a period near 5 hours seemed likely. Here I report intensive spectroscopy from 1996 July aimed at establishing the orbital period, which proves to be 0.1468(3) d = 3.52 h. Subsequent work at later epochs indicates a more precise period of 0.146883(2), while a less-likely choice of cycle count between observations yields 0.147370(2) d. In single-trailed spectrograms constructed from the radial-velocity spectra, the HeI lines show phase-dependent absorption features reminiscent of the SW Sex phenomenon. The Balmer line strengths vary between observing runs, as noted earlier by Hutchings.

Program listing for Saturday