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Astron. Astrophys. 342, L45-L48 (1999)

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5. Distance

With galactic coordinates [FORMULA], the reddening to V592 Her is probably not very large. Using the stellar reddening data for this direction from Guarinos (1992), the estimated visual extinction is [FORMULA], which gives [FORMULA]. [FORMULA] then corresponds to a late-A spectral type.

We can obtain crude estimates of the distance via statistical comparisons with other dwarf novae. With the orbital period [FORMULA] hr estimated by Duerbeck & Mennickent (1998) from the superhump period, the correlation between [FORMULA], [FORMULA], and the outburst recurrence time (Warner 1987) suggests [FORMULA], which yields [FORMULA] pc. The correlation between [FORMULA] and [FORMULA] suggests (for a superoutburst) [FORMULA] (Warner 1995), which, when combined with the recent maximum brightness of 12.0, yields a distance of [FORMULA] pc. A similar distance estimate can be obtained by using Eq. (11) of Warner (1987), which gives the visual magnitude of an optically thick disk with a mean surface brightness depending on [FORMULA] and a size depending on [FORMULA] and the white dwarf mass. With an assumed very blue disk with [FORMULA], we find [FORMULA], in agreement with the estimate above. It is possible that TOADs do not fit very well in the above correlations, in particular because the mass in the thermally critical pre-outburst disk may be significantly larger than in a typical dwarf nova, in which case the outburst disk could be brighter by 1-2 mag. In any case, however, the distance of V592 Her is certainly less than 1 kpc.

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© European Southern Observatory (ESO) 1999

Online publication: February 23, 1999