Nova FH Serpentis as a Test of Outburst Model

Abstract

FH Serpentis is one of only two novae observed in the UV, IR, and visible for which new constraints on nova models can be obtained. The UV measurements of Gallagher and Code (Ap. J. 189, 303 1974), combined with the IR observations of Geisel et al (Ap. J. 161, L 101, 1970), indicate that if the interstellar absorption correction of Gallagher and Code is correct, the energy distribution was nearly Planckian for more than a month after the visual maximum. Photospheric temperatures and radii can be determined, as well as luminosities taking into account radiation of all wavelengths. In the first month the temperature determined rises from 5200 to 9200°, the radius decreases from 320 to 60 R₀, and the luminosity (near the Eddington limit) decreases from 6.9 to 2.4 x 10⁴ L_O. Thus the last quantity may not have been constant as claimed by Gallagher and Code. These results are unfortunately sensitive to the corrections for interstellar absorption; if the true correction is 1 1/2 times larger, the energy distribution is less Planckian, the temperatures higher, and the luminosity almost constant.