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Unexpected change in the spectrum of V4332 Sgr

ATEL # 876; V. Goranskij (SAI, Moscow University); E. Barsukova, S. Kaisin, and O. Sholukhova (Special Astrophysical Observatory, Russia)
on 19 Aug 2006; 15:54 UT
Password Certification: Vitaly Goranskij (goray@sai.msu.ru)

Subjects: Optical, Binaries, Nova, Variables

V4332 Sgr (N Sgr 1994 No.1) is a peculiar nova which displayed the spectrum of a cool M supergiant in the outburst. Along with two similar objects, V838 Mon and V1006/7 in M31 it forms a new class of eruptive variable stars. The remnant of this nova has an unusual spectrum containing a cool M7 type star continuum and emission lines of neutral metals and metal oxyde molecules attributed to cool rarefied gas cloud. Our BVRcIc photometry taken with SAO 1-m telescope shows unexpected rapid decay of the remnant in the short-wave bands for the last few months. BVRcIc magnitudes measured on 2005 July were correspondingly the following (19.43, 17.60, 16.30, 14.77), but those ones measured on 2006 July 27 were (20.28, 18.36, 16.88, 14.72). On 2006 August 4, we obtained spectra with Russian 6-m telescope in the range of 5630-7350A with resolution of 5A. In these spectra, strong emissions of NaI D_1,D_2, CaI 6571A, and molecular emissions of ScO, TiO and VO are seen as described by Kimeswenger 2006, AN V.327, 44. But the equivalent widths of these features jumped up. So, NaI D blend equivalent width increased from 225A (Kimeswenger, 2006) to 293A what may be due mostly to decay in the red continuum. Banergee et al., 2003, ApJ V.598, L31 reported the development of a new dust shell around V4332 Sgr in 2003 June seen in the infrared range, but this event did not accompanied by such strong changes in visible spectrum as those are going now.

Java developed BVRI light curves of V4332 Sgr


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