Tuesday, October 16, 2012

Alpha Centauri Has a Planet!

Alpha Centauri Has a Planet!.

"Alpha Centauri is triple-star system, composed of a binary star, two stars much like the Sun – one slightly larger and hotter, called Alpha Centauri A, and the other slightly smaller and cooler, called Alpha Centauri B – orbited themselves by a red dwarf (called Proxima Centauri) much farther out.

The planet orbits close in to Alpha Cen B, and is technically called Alpha Centauri Bb – planets have lower case letters assigned to them, starting at b. Its mass is only 1.13 times the Earth’s mass, making this one of the lower mass planets yet found! But don’t get your hopes up of visiting it – its period is only 3.24 days, meaning it must be only about 6 million kilometers (less than 4 million miles) from its star. Even though Alpha Cen B is a bit cooler than the Sun, this still means the planet is baking hot, far too hot to sustain any kind of life as we know it, or even liquid water."


Richard said...

Too hot! Although what I am reading says that there is a higher chance that there must be other planets as well. I think they would be much harder to detect. How long do you have to observe the star and how accurate the measurement due to the much smaller perturbation if there is an earth sized planet orbiting every ~300 days?

Howard said...

You need two (and better yet three) orbits of the planet around it's star to confirm a pattern. It's also hard to detect smaller planets because they have a smaller effect on their star (either blocking light when they pass in front of it or gravitationally by making it wiggle when at the sides). That's why the first planets we detected were "hot Jupiters", those are the ones we'd see first (big with short orbits).