Monday, November 30, 2009

Pair of Brown Dwarfs Found: Forming the Way Stars Do

"Clue Found to Origin of Cosmic Misfits " (November 30, 2009)

"A class of cosmic oddballs exists that doesn't fit in with either stars or planets, instead occupying a murky middle ground.

"Known as brown dwarfs, these misfits fall somewhere between planets and stars in terms of their temperature and mass. They are cooler and more lightweight than stars and more massive (and normally warmer) than planets.

"This has generated a debate among astronomers: Do brown dwarfs form like planets or like stars?

"Scientists now have an additional clue – a baby brown dwarf was discovered by NASA's Spitzer Space Telescope – that suggests brown dwarfs develop like light-weight stars...."

I get the impression that scientists are a little more willing to admit that they don't know everything - or journalists are getting more savvy. These days, not every pronouncement by an astronomer or other scientist is the sort that inspired me to write "Once it Was Believed / Now We Know." (Don't let the 2003 copyright fool you: that's a re-write of a probably-lost piece I wrote sometime in the late sixties or early seventies.)

Where was I? Brown dwarfs. Hydrogen clouds. Stellar physics. Right.

What's happened is that, now that we've got observatories operating above this pea soup of an atmosphere, astronomers are able to get a better look at what's above the clouds. What they've found is lots and lots of stars.

And stuff that's turning into stars. And, occasionally, into something else. At least, that's a reasonable conclusion.

At issue in this article is SSTB213 J041757. Don't try to pronounce that. It's a catalog number for a "baby brown dwarf."

Brown dwarf? For now, that's what some astronomers are calling objects that aren't dense and heavy enough to support a hydrogen fusion reaction. So, they're cooler than the coolest objects that do have fusion going on inside: the things we call stars.

Planets, like Jupiter, don't have fusion going on inside - and are warmer than their surroundings. But (for now) we're calling Jupiter a planet, and the more-massive things that aren't stars, but aren't orbiting other stars "brown dwarfs."

Partly, I think, because it's easier to say "brown dwarf," than it is to say "object-which-is-insufficiently-massive-to-sustain-fusion-but-still-pretty-big-but-not-orbiting-another-star-but-isn't-a-star-because-stars-are-hotter-and-heavier."

A lot easier.

That Taurus-Auriga complex is something like 150 or 140 parsecs (parallax-seconds) away - 490 or 457 light years.

On a galactic scale, that's pretty close. On the other hand, light from those brown dwarfs started out around the time Henry VIII of England died. The Taurus-Auriga complex isn't exactly close, either.

Actually, what the Spitzer observatory picked up wasn't visible light. The observations were in longer wavelengths: infrared.

SSTB213 J041757 is a pretty big deal, since it's a pair of these "brown dwarfs" that were caught very early in their development. And, it looks like they formed the way stars do.

Which seems to show that brown dwarfs are objects that are essentially like stars, but didn't have enough mass to get fusion reactions going.


"Spitzer Telescope Observes Baby Brown Dwarf"
Spitzer Mission News, NASA (November 23, 2009)

Not-entirely-unrelated news:

"Presto! Black Hole Creates a Galaxy " (November 30, 2009)

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