Thursday, August 10, 2017

August 2017 "Star of the Month"

In all fairness, with the impending eclipse, August's Star ought to be our own sun. But sticking to the night sky, I'm going to go this month with T Coronae Borealis.

So why spend any time looking for and observing this 10.8 magnitude speck in the (let's face it) rather boring constellation of Corona Borealis? Because it is one of only 10 stars in the entire sky known to be a recurrent nova. And of all 10, it is by far the most dramatic. The first recorded instance of its flaring up was in 1866, when it peaked at 2nd magnitude. The second was in 1946, when it flared to magnitude 3. (Presumably there were earlier, unrecorded, instances.)

Hmm... that's 80 years between flare ups, and it's now 70 years since the last one... Could we be due for another? I have searched the internet in vain to find out how long it takes for a nova to flare. I doubt that it's instantaneous, but wouldn't it be cool to watch T CrB brighten from magnitude 10.8 to 3 (or even 2) before your very eyes?

Coordinates: Right Ascension 15h 59m 30.16 Declination 25° 55′ 12.6″ 

Attached is a finder chart I stole from Sky and Telescope. T CrB is near the lower left corner. It's a fairly dim star, so I wouldn't attempt to find it when the Moon is in the sky (unless you have a really big scope).