Maybe that name rings a bell at the back of your head, it is one of a pair and its brother is called Pollux. That’s right, it’s one of the two main stars in the constellation Gemini, the heavenly twins and birth sign for yours truly in June. It’s also a very interesting star, or as I should say stars. A binary star is not a rare thing in the heavens, it is a star that appears to the naked eye as one, but is actually a pair of stars in close orbit around each other.
A long time ago in 1718 it was discovered that Castor wasn’t just one star but appeared to be two. This is all very interesting but a long way from special, what makes this system special is that what you thought was one star is actually a sextuple system, it’s made up of six stars consisting of three binary doubles. These are designated as Castor A, Castor B and Castor C. We call A and B spectroscopic binaries and C as eclipsing red dwarf stars, quite cool and small for stars.
The arrangement of all these stars has fascinated astronomers for centuries and given mankind a sort of natural laboratory to study Newton’s first laws of motion in action. Another interesting thing is the orbital periods of all these stars. Castor A and B orbit each other every 467 years whereas Castor C orbits the systems centre of mass every 14,000 years. Castor is only 50 ish light years away, practically on our doorstep in our huge universe, imagine the view from one of the planets in the system, wow, what a view.
That’s quite enough hard facts for this month, there is very much more to learn though, if you want to learn more look at the James Webb site on this subject.
I received an odd question the other day, someone had stumbled on the story of Betelgeuse going supernova, it was a sensationalist story that gave the impression that it was imminent and that the radiation will cook us all in our beds. Total claptrap, Betelgeuse will pop sometime in the next 10,000 years, not all that soon, and the radiation will have mostly dispersed by the time it gets here. You’d get more radiation from walking on Dartmoor.
I find this kind of scaremongering nonsense quite depressing as it preys on people’s fears and gets repeated as fact. No one should do it.
Charles Oates, Vega Baja Astronomy Group.
● To find out more about observing and astronomy why not join our group, email us at vegabaja.astronomygroup@gmail.com to find out more.
