Observation: February 2, 2005

Exposure time:Seven images. First two images are 1 evening apart, last five images are each ~1 hour apart.

Description of Object:

On the night of February 2, 2005, David Levy caught the variable star TV Corvi just as it was starting one of its rare explosions. These images begin with the star barely visible as a faint speck at its normal minimimum brightness of about 1magnitude 18.5; that first image was taken the night before. At the end of the sequence, the star is brighter than the 14.8 and 14.6 magnitude stars that are on either side of it. Thus, TV Corvi increased in brightness by about 40 times.

According to research done at PSI (by Steve Howell), TV Corvi appears to be a most unusual binary star system. It is a high galactic latitude cataclysmic variable star, itself unusual since most such stars are at low galactic latitudes; i.e. near the plane of the Milky Way. According to Howell, the TV Corvi system is two small stars orbiting each other in a space smaller than our own Sun, in a period of under two hours. In this system, hydrogen leaves a brown dwarf star and travels to a spot on an accretion disk orbiting a white dwarf star. When the spot overflows with hydrogen, then a thermonuclear explosion occurs and the system brightens enormously, then fades slowly over a few days.

During his search for trans-Saturnian planets, Clyde Tombaugh discovered this star in its outburst of March 23, 1931. It was subsequently ignored until David Levy (of PSI and Jarnac Observatory) uncovered Tombaugh's observation while doing research for his book Clyde Tombaugh: Discoverer of Planet Pluto (University of Arizona Press, 1991). Levy then observed the star visually in outburst on March 23, 1990 (coincidentally 59 years to day after Tombaugh; cf. IAUC. 4983) TV Corvi was then observed by the International Ultraviolet Explorer satellite during its next outburst in June 1991. Levy has caught TV Corvi at its observed outbursts since then, including one again on a March 23, in 2000. In 2005, TV Corvi's outburst happens a day before what would have been Tombaugh's 99th birthday.

The spiral galaxy to the left is ESO573-12. It is similar to our own Milky Way but 350 million light years from us.