By Jett Peters
Watch for a New Star!
It isn’t often that you can look up in the night sky with the naked eye and see something that was not there before. As Gary Shaw brought to our attention recently, one night you are going to look up at the “Northern Crown,” a small constellation of seven stars known as Corona Borealis, and there will be a new star in their midst.
T Coronae Borealis, which is called the Blaze Star or T CrB is part of a binary system sitting just outside the Northern Crown. This type of system is known as a cataclysmic variable star. It is a red giant and a white dwarf, which are circling around a common center of gravity. The white dwarf, which is a small, very dense star has a much larger gravitational pull and thus is constantly pulling hydrogen, the outer atmosphere, from the red giant, which has a much lower gravitational pull. The hydrogen builds up on the surface of the white dwarf and eventually reaches a limit at which the pressure and heat cause a thermonuclear reaction. The explosion, called a Nova event, blasts off the collected material. The explosion will result in the Blaze Star’s magnitude jumping from a magnitude 10 to a magnitude of only 2. The white dwarf survives the explosion (the star does not die as it would in a supernova), and the process begins again. On average the cycle repeats every 80 years.
We are currently in a two year period during which the nova event is expected. In fact, it is considered by some to be a bit overdue, so it would be worth keeping an eye on the Northern Crown this winter!
Credit: Stellarium