Nova Monocerotis 2002 (V838 Mon) at early outburst stages |
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Authors: | V P Goranskii A V Kusakin N V Metlova S Yu Shugarov E A Barsukova N V Borisov |
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Institution: | (1) Sternberg Astronomical Institute, Universitetskii pr. 13, Moscow, 119992, Russia;(2) Special Astrophysical Observatory, Russian Academy of Sciences, Nizhnii Arkhys, Karachai-Cherkessian Republic, 369167, Russia |
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Abstract: | We obtained U BV R photometric and spectroscopic observations during the outburst of V838 Mon. Before its outburst, the B brightness of the star had been stable ( $\tilde15.^m 85$ ) for 45 years. This was a blue star with the color index $(B - V)_0 = - 0\mathop .\limits^m 03 \pm 0\mathop .\limits^m 1$ and may have been a cataclysmic variable. In the middle of March 2002, the outburst amplitude reached $8\mathop .\limits^m 1$ in B. The star has the counterpart V 1006/7 in M 31 in luminosity at maximum and in spectrum. The unusual spectrum at the premaximum stage originated in the expanding photosphere of a cool K-type giant. The expansion velocity of the photosphere was 150 km s?1; the maximum velocity in the expanding stellar envelope reached 500 km s?1. The absorption components of neutral metal lines were enhanced by a factor of 3 or 4 compared to a normal K-type star. No overabundance of s-process elements was found. One day before the brightness peak, an intense Hα emission line with broad wings, FWZI=3100 km s?1, and numerous lines of ionized metals appeared in V838 Mon, which is characteristic of normal classical novae. We show light, color, and spectral variations of the object. |
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Keywords: | stars— variable and peculiar stars— properties and classification stars— structure and evolution |
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