Alpha Centauri. Not only is it an alien in Dr.who, a strategy game released in 1999, and an album released by the German electronic band tangerine dream, but it’s the brightest star in our closest stellar system. Named for being the brightest star in the constellation Centaurus in the southern sky, its a little over 4 light years away from Earth, and is very similar to our sun in terms of size, age, mass, composition, and temperature. Here is a great infographic from Space.com.
Scientists have recently discovered that Alpha Centauri shares yet another resemblance to our home star: It has a strange, cooler layer in its atmosphere.
Layers of the Stellar Atmosphere Credit: ESA
The surface of the sun, called the photosphere, has a temperature of about 5700 Kelvin. That’s about as hot as flames in the ol’ fireplace. The center of the sun, where all the fusion happens, is upwards of 15 million Kelvin. But further out past the photosphere we reach the corona, a powerful radiative zone where the temperature can reach about 2 million Kelvin. We see the solar corona during a total eclipse of the sun. Although the temperatures vary slightly in Alpha Centauri, it shares a similar pattern.
So why the drop in temperature? Or rather why the boost in temperature farther out? Astronomers aren’t completely sure, though they think its due to the same phenomenon that gives rise to solar flares: Twisting of magnetic field lines.
The important point is that this is the first time we’ve observed this phenomenon in a star other than the sun. Is it present in all stars? Or only sun-like stars? Further study of Alpha Centauri and its similarities and differences when compared to the sun will give us an idea of the answers to these questions, and surely will result in a lot more questions, as is the way of science.
This morning was the launch of the second SpaceX dragon capsule mission, officially designated mission CRS-2. It launched at 10:10am today, Friday, March 1st from Cape Canaveral space launch complex 40.
A bit of background on Dragon:
The two-stage rocket uses 9 engines to power the first stage out of the atmosphere, before the single rocket stage 2 takes the capsule the rest of the way. The 14.4 foot tall dragon capsule is capable of carrying more than 7000 lbs of cargo split between pressurized and unpressurized sections.
On March 2nd, Astronauts will use the CanadaArm 2 to grab onto the capsule and unload the contents. The crew will also load more than 2600 lbs of experiment samples and equipment for return to Earth during a scheduled parachute-assisted splashdown off the coast of California on March 25th.
This is the second of at least 12 planned missions by SpaceX for commercial resupply purposes for NASA.
Mission Update: The rendezvous with the International Space Station (ISS) will be delayed slightly, due to an issue with a propellant valve after achieving orbit. The solar arrays have been deployed, though for a time only one of the three thruster pods was responsive. At this point, according to the twitter feed of Elon Musk, CEO of SpaceX, a second thruster pod is up and running, and the craft has moved from free orbit to active control, and can now begin a burn to rendezvous with the ISS.
4:04pm – Thurster pods 1 through 4 all up and running, preparing to raise orbit to catch the ISS!
The purpose of this blog is mainly Astronomy, but also to connect the world to my personal adventures and to my company Astronomy in Action (www.astronomyinaction.com). I want to become more connected to the digital world and especially to the Astronomy community as a whole.