The Universe in the Classroom

No. 49 - Winter 2000

© 2000, Astronomical Society of the Pacific, 390 Ashton Avenue, San Francisco, CA 94112.

Stellar Evolution (a la Chez Stella)

by Michael Chabin
The Urban School

At first, you are aware of nothing, nothing at all. It is dark. You are warm and comfortable -- very comfortable -- in a dark cloud...suspended somehow in outer space.

A warm breeze is passing gently over you. In the distance you hear a sound vaguely like chalk against a blackboard. It mingles with phrases from some strange language, phrases like "epleurslaw" and "lipsis swee pingorb ts...libdical...libdical." The words are indistinct and dull, incredibly dull, but they pass, and as they do, the cloud parts and you see over the edge of a galaxy's vast spiral arm and into the endless chasm of intergalactic space beyond.

Somehow it all seems as it should.

You are above the disk of the galaxy, high above the plane, though not so high as the top of the bulge at the center. There stars of a million different colors are so densely packed together and so unspeakably brilliant that you turn away from the sloping bulge and the spiral arm. Even without the structures' intense glare, your eyes take a moment to adjust to the vast scatterings of stars dazzling as diamonds on a sea of black velvet.

The strange dry mist continues to clear. The breeze is growing quite distinct. It is coming from a particularly dark patch ahead of you.

waiterA waiter you hadn't noticed puts a menu on the table. Odd, you think, that you hadn't noticed that table before. And there is something vaguely fishy about the waiter.

"Excuse me," you say. "Is that wind I feel?"

"Oui," the waiter responds, "It is the stellar wind. The large star nearby is very bright. It is blowing this dust away quite rapidly. You should be able to see them all in another moment -- the big one first and then the others. But," he adds, holding his finger in the air for emphasis, "even though you'll see it first, I can assure you that all the stars in the cluster formed at exactly the same instant, and are exactly the same distance from this spot."

"And what do you recommend?" you ask, picking up the menu. "I think you'll find everything interesting. The largest star changes the most from start to finish, of course, and can be quite dramatic. The smaller stars take longer to develop, but there are those who prefer the subtlety."

He turns, distracted by a faint glow at the center of the dark patch from where the wind is blowing. "Ah," he smiles, "here they are."

The bright patch quickly turns orange and yellow. Details of the edge of the cloud begin to show clearly as it passes. A second later a gap appears and, just as the waiter predicted, you see a brilliant blue white star. It is alone for a moment, then joined in rapid succession by five other stars. Actually, not all of them are equally brilliant. There is a faint red one you almost miss, and the smaller ones in general are a bit harder to see against the glare of the bright ones.

"And already, they begin to change," he adds, almost wistfully.

"They are beautiful," you say. "But I wouldn't worry about these stars changing anytime soon." There is a quote you half remember. It is from Shakespeare, perhaps, and about stars being eternal, but all you can think of at the moment is "who would fardels bear to make his peace with a bare bodkin," so you let the matter drop and look at what's offered in this interstellar cafe.

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