Open AccessThe mass of the white dwarf in the old nova BT Mon
Author(s) -
Smith D. A.,
Dhillon V. S.,
Marsh T. R.
Publication year - 1998
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1998.00743.x
Subject(s) - physics , white dwarf , astrophysics , radial velocity , nova (rocket) , amplitude , intermediate polar , stars , star (game theory) , astronomy , spectral line , dwarf nova , aeronautics , quantum mechanics , engineering
We present spectrophotometry of the eclipsing old nova BT Mon (Nova Mon 1939). By detecting weak absorption features from the secondary star, we find its radial velocity semi‐amplitude to be K R = 205 ± 5 km s −1 and its rotational velocity to be v sin i = 138 ± 5 km s −1 . We also measure the radial velocity semi‐amplitude of the primary star to be K R = 170 ± 10 km s −1 . From these parameters we obtain a mass of 1.04 ± 0.06 M⊙ for the white dwarf primary star and a mass of 0.87 ⊙ 0.06 M⊙ for the G8 V secondary star. The inclination of the system is found to be 82 ° . 2 ± 32 ° . 2 and we estimate that the system lies at a distance of 1700 ± 300 pc. The high mass of the white dwarf and our finding that BT Mon was probably a fast nova together constitute a new piece of evidence in favour of the thermonuclear runaway model of classical nova outbursts. The emission lines are single‐peaked throughout the orbital cycle, showing absorption around phase 0.5, high‐velocity S‐wave components and large phase offsets in their radial velocity curves. In each of these respects, BT Mon is similar to the SW Sex stars. We also find quasi‐periodic flaring in the trailed spectra, which makes BT Mon a candidate intermediate polar.