Multiwavelength Photometry and Hubble Space Telescope Spectroscopy of the Old Nova V842 Centaurus
Abstract
We present ground-based optical and near infrared photometric observations and Hubble Space Telescope (HST) COS spectroscopic observations of the old nova V842 Cen (Nova Cen 1986). Analysis of the optical light curves reveals a peak at 56.5 ± 0.3 s with an amplitude of 8.9 ± 4.2 mma, which is consistent with the rotation of a magnetic white dwarf primary in V842 Cen that was detected earlier by Woudt et al., and led to its classification as an intermediate polar. However, our UV lightcurve created from the COS time-tag spectra does not show this periodicity. Our synthetic spectral analysis of an HST COS spectrum rules out a hot white dwarf photosphere as the source of the FUV flux. The best-fitting model to the COS spectrum is a full optically thick accretion disk with no magnetic truncation, a low disk inclination angle, low accretion rate and a distance less than half the published distance that was determined on the basis of interstellar sodium D line strengths. Truncated accretion disks with truncation radii of 3 R wd and 5 R wd yielded unsatisfactory agreement with the COS data. The accretion rate is unexpectedly low for a classical nova only 24 yr after the explosion when the accretion rate is expected to be high and the white dwarf should still be very hot, especially if irradiation of the donor star took place. Our low accretion rate is consistent with those derived from X-ray and ground-based optical data.
Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., (AURA) under NASA contract NAS 5-26555, with the Apache Point Observatory 3.5 m telescope which is owned and operated by the Astrophysical Research Consortium.- Publication:
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The Astrophysical Journal
- Pub Date:
- August 2013
- DOI:
- 10.1088/0004-637X/772/2/116
- arXiv:
- arXiv:1305.4564
- Bibcode:
- 2013ApJ...772..116S
- Keywords:
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- accretion;
- accretion disks;
- novae;
- cataclysmic variables;
- stars: individual: V842 Cen;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- The Astrophysical Journal, 2013, in press