Astro round-up

By Phil Plait | March 25, 2005 12:13 pm

‘I have learned that whenever I am away from my internet connection for more than, say, an hour, that’s when lots of cool astro-news hits the street. This week was no exception. I was at a meeting for high-energy astronomy (basically, super-duper violent stuff like exploding stars and black holes), and since my life is nothing without irony, some of the news dealt with the same stuff I was listening to and talking about at the meeting. Some of this news was way cool, so here’s a quick-and-dirty list, with links.

  • Astronomers have found a black hole in another galaxy that’s a mesomorph. For a long time we knew of two kinds of black holes: ones that mass a few times what the Sun does, which are formed when big stars blow up, and huge ones in the centers of galaxies which can mass millions or billions of times the Sun. Recently, intermediate mass black holes have been detected, with a few hundred or few thousand times the Sun’s mass. These are not well-understood, and not many are known, so every time a new one is found it helps astronomers a lot. This new one was detected by the Chandra X-Ray observatory.
  • In 1995, planets were first detected indirectly around other stars like the Sun. As they orbit their star, the planets tug on the stars, and this can be detected. Then, a few years back, one was found that actually passed directly in front of its star, eclipsing it a little bit, and that drop in light was detected. Now, using the Spitzer Space Telescope, astronomers have for the first time seen the light from the planet itself. Basically, the planet is hot because it’s close to the star, and that means it glows in infrared. Happily, stars are weaker in IR, so it’s easier to see the planet that way (stars way overpower planets in optical light). We don’t have actual images yet, because the planets are too close to their parent stars, but it’s still pretty neat that we can detect their light at all.
  • You’d think we’d know about a cluster of stars in our own Galaxy that masses 100,000 times that of the Sun, and has stars so bright they’re literally a million times the Sun’s brightness. However, sometimes nature is sneaky. There is so much floating crud in our Galaxy (astronomers politely call it the “interstellar medium”) that it can hide even tremendously bright objects. Such is Westerlund 1, a cluster of super-giant stars located just 10,000 light years away (a hop and a jump in galactic terms). Its light is dimmed by a factor of 100,00 due to the dust between us and it, so it’s hard to see at all. Astronomers have recently been able to investigate it, and find that it is chock full of monster stars, some so bright that if we were inside that cluster, they’d outshine the full Moon!
  • This one’s more gee-whiz than anything else. A gamma ray is basically normal light on steroids; a very high-energy beefed up form of light. It takes a lot of energy to make a gamma ray, and that energy comes from seriously violent stuff like exploding stars, black holes, matter-antimatter collisions (yes, seriously) and stuff like that. The Earth is bombarded by gamma rays all the time, but usually there aren’t enough to do any damage to us. Astronomers have observatories orbiting the Earth to look for gamma rays (none built by Bruce Banner, don’t fret). One of these, the Compton Gamma-Ray Observatory, orbited the Earth for many years peering into the cosmos. But it also looked down, and over the years it was able to see quite a few gamma rays coming from the Earth. An astronomer collected that data and created an image of the Earth in gamma rays. He says it will help us understand the Earth’s environment in space and all that, which is probably true, but I just think it’s kinda neat and worth looking at.

Phew! That’s more of a blog than I intended, but what the heck, it makes up for a few days of silence from me. I still have plenty to say about other things, including some rants about stuff that has me good and ticked off. Stay Tuned.’


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