The Sciences

Spitzer's hot topics

Bad AstronomyBy Phil PlaitAug 5, 2009 6:28 PM


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Y'know, when I'm really old and past my prime, I expect to watch a lot of TV and take naps. But when NASA's missions are old and having trouble, they produce images like this:

Whoa. Click to embiggenate. Spitzer Space Telescope is an infrared observatory that launched in 2003. Infrared light is emitted by warm objects: dust, stars, gas, planets, and so on. That includes the telescope itself: unless cooled, the mirror and the rest of the telescope will glow brightly in the infrared, making it impossible to do any science. It would be like shining a flashlight down the 'scope! So Spitzer uses liquid helium to cool some of its instruments down almost to absolute zero. Or, I should say it "used" liquid helium: over time, the helium warms up, and in May 2009 the last of the liquid helium boiled away. What this means is that some of the detectors on board Spitzer are no longer usable. However, Spitzer has a sun shade that keeps it passively cooled to about 30K (-400 F) , so two of the detectors are still running just fine, as evidenced by the image above! Taken with those remaining "channels" -- which see 3.6 and 4.5 micron light, roughly 4 and 6 times the wavelengths our eyes can see --it shows the star forming region DR22, a giant cloud of gas and dust with a young cluster of stars in its heart. Those stars are less than a million years old, so they're infants on a galactic scale. Winds and UV light from those stars are carving up the surrounding nebulosity, sculpting it into sheets and blowing out a cavity in the middle. I'm curious about the short diagonal streak in the upper left of the image; it doesn't look like a galaxy or a filament. I've sent a letter to the folks at Spitzer to get more info.

[Update: Word back from Spitzer is that it is a galaxy. Weird!]

Along with DR22, a pretty image of the planetary nebula NGC 4361 was released. This is a star at the end of its normal life; it is ejecting a wind of particles like the solar wind but far, far denser. Images like this from Spitzer can tell us how much warm dust is generated in the star, and give diagnostics needed to understand how stars like the Sun eventually die. You can see the star itself smack dab in the center of the nebulosity. Take a good look: that's us in about 7 billion years time. It's not entirely certain if the Sun will be hot enough to create such a beautiful nebula as seen here -- it takes a star somewhat more massive than the Sun to leave behind a hot enough corpse to get the gas to glow -- but what happens to us is not all that different than what happened to the central star of NGC 4361.

Finally, they also released this way cool shot of the spiral galaxy NGC 4145. I could go on and on about this too, but really, I'll just say it's a way cool image and that you should look at the one in full resolution. Spitzer will be used by astronomers for years to come, even though in many ways it's not up to 100% power. But these images go to show you the advantages and abilities of space-borne telescopes; even when they're down, they're definitely not out.

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