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January 30, 2011
The Bulgarian Novae Search Group discovered another nova in the M31 galaxy (Andromeda). The discovery is made by using BVR-images of the central region of the galaxy, obtained with the 50/70 cm Schmidt telescope at NAO Rozhen in the evening of January 27th. The coordinates and brightness of the nova are derived immediately after the observations and published on the web-pages for novae in nearby galaxies.
The immediate report of the nova is important so different observers can continue the observations in order to get continuous light curve and spectrum. Mira variables are often masquerading as novae. The object can be classified only after the following observations.
Part of the R-images, obtained on January 27th (left) and on January 15th (right). The nova is marked.
Novae are phenomena that appear to the observer as a new star in the sky, which gives their name. They arise in close binary systems consisting of cool star of late spectral class and hot white dwarf. Outburst is due to ignition of nuclear reactions at the base of the accretion disk, formed by the accretion of gas around the white dwarf from the companion star. The brightness of the system increase to one million times and fell to its previous state for months. The study of the change in magnitude over time (light curve) of the novae is important both for understanding the physical conditions and processes leading to such explosions and for calibration of these objects as indicators of distances in the Universe.
The study of the novae is one of the main observational goals of observational astronomy in the last few years. The M31 galaxy is an excellent target for detailed studies of different novae populations, because of its nearness and orientation. Now a few different groups working in this field and one of them is a Bulgarian Novae Search Group which includes scientists from the Department of Astronomy at the University of Sofia and the Institute of Astronomy and National Astronomical Observatory Rozhen. The number of the discovered novae in the last few years in M31 galaxy is about 25 per year. The nova discovered on January 27th is the 15th nova in M31 discovered by the Bulgarian team since the end of 2004. The discovery and the estimation of the first results for the position and brightness of the nova are only the beginning of the study of these phenomena.
The research of the nova was made entirely by the Bulgarian group in the framework of the projects DO 02-340 and DO 02-362 (SMARTNET) of the Department of Astronomy at University of Sofia, Institute of Astronomy and Shumen University financed by the Scientific Foundation of the Bulgarian Ministry of education and Science.
More information for the Bulgarian team study of the novae can be found in Publications of the team and in the web-pages for novae (M31 (Apparent) Novae Page, Extragalactic Novae Page and Astronomer's Telegram).
Dr Evgeni Ovcharov, Departament of Astronomy at the University of Sofia