April 26, 2012: Focus on Algol (Beta Persei) and Lynx

It was rather chilly out, and the sky was a bit hazy, but it also looks like today will be the best viewing day for the next several days, so I popped out for a few minutes. A few days ago, I focused on α Persei, so today I decided to focus on β Persei. Not only is it the beta star, but it’s also the lowest from my position so I’m catching it shortly before setting.

I wrote about Algol (β Persei) a few days ago. It’s actually a triple star system (β Persei A, B, and C). As I noted before, we’re in the plane of the orbits of β Per A and B around each other. β Per B is dimmer, and when it passes in front of β Per A, the combined star magnitude drops from 2.1 to 3.4. A and B are only 0.06 astronomical units (the distance from Earth to Sun) apart! That’s closer than Mercury is to the Sun, and only some thirty times the distance from the Earth to the Moon. C is 2.7 AU away, about as far as our asteroid belt is from the Sun.

Computer simulation on how Algol may rotate

Computer simulation on how Algol may rotate

This type of eclipsing binary star, where we happen to be in the orbital plane and so one star periodically eclipses the other, is now called an Algol variable.

I also really tried to see Camelopardalis, the constellation I read about yesterday. No luck — it’s just too faint. Monoceros has a new friend. I also tried to see Lynx, and I was able to just make out α Lincis — the other stars are all too faint. That’s fine — I don’t mind having a single star represent the constellation.