RS Ophiuchi

From Slackerpedia Galactica

RS Oph is a special type of cataclysmic variable called a recurrent nova. Like the classical novae, the giant outbursts of RS Oph and the other recurrent novae are caused by the thermonuclear ignition of the hydrogen layer accreted from the secondary star to the white dwarf in these close binary systems. However, most of the things that we normally called "novae" seemed to be one-off things -- outburst once and they're done, at least on human timescales. But a few of these critters seem to accrete enough hydrogen regularly enough that they go into outburst every few to several decades, hence recurrent.

RS Oph was in the news in 2006 after 21 years of relative quiet. A Japanese amateur astronomer first noticed RS Oph in outburst in mid-February, and subsequently notified the rest of the astronomical community. Everyone and their cousin Ted with a telescope, radio dish, or X-ray satellite started watching over the next several months to try to learn more about these things. It even got a mention on BBC News, twice.

It is apparently a Type-I Supernova in waiting, since the white dwarf is close to the Chandrasekhar limit, and it doesn't seem to suffer a net loss of mass during nova eruptions (as happens with most other novae). When it does become a supernova, of course, it will definitely not recur, but it'll be a pretty show.