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Rapid strengthening of iron forbidden lines in the spectrum of V838 Mon

ATel #803; E. Barsukova (SAO, Russia), V. Goranskij (SAI, Moscow Univ.), P. Abolmasov and S. Fabrika (SAO, Russia)
on 5 May 2006; 17:02 UT
Distributed as an Instant Email Notice Novae
Credential Certification: Barsukova E.A. (bars@sao.ru)

Subjects: Optical, Binary, Nova, Star, Variables

Referred to by ATel #: 966, 1821

V838 Mon is a peculiar nova which showed a red K-M type spectrum in its outburst in 2002. Along with two similar objects, V4332 Sgr and M31 V1006/7, it forms a new class of eruptive variable stars. We report spectral observations obtained with the Russian 6-m BTA telescope (Special Astrophysical Observatory). In our spectrum taken on 2005 December 11 (3960-5741A, resolution 4.6A) two known companions of this binary system are seen, B3V star and cool oxygen-rich L type supergiant, the remnant of the outburst. Our observation confirms the description of spectral evolution given by Henden et al., IAUC 8655 , 2006 based also on December 2005 spectra. But additionally, we observe strong narrow emissions in the blue region over continuum of B3V companion. The strength of these emissions increased by factor of 2-3 since our previous observation on 2004 November 18. We identify these emissions with [FeII] lines (the equivalent widths in Angstroms are given in parentheses for 2004 and 2005 spectra respectively) 4244.0 (-1.1,-2.5); 4287.4 (-1.2,-2.9); 4359.3 (-1.1,-3.5); 4413.8 (-1.7,-3.7); 4452.1/4458.0 blend (-1.2,-3.4); 4814.6A (-0.5,-1.4). The radial velocity of [FeII] emission is about zero and agrees with the velocity of B3V companion. Formation of [FeII] lines needs a hot source of ionization and excitation, and B3V companion may be such a source. Strengthening of [FeII] spectrum may be concerned with the rarefied gas of ejecta which arrive at the vicinity of B3V companion.

Blue spectra of V838 Mon