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View Full Version : Discussion: Young Star Has Grown Up Quickly



Fraser
2005-Mar-02, 06:49 PM
SUMMARY: Astronomers have found an embryonic star in a stellar nursery giving off a healthy glow of X-rays, even though it's much too young. The observations were mostly made using the European Space Agency's XMM-Newton observatory, and suggest that some unknown process is superheating the star's surface to generate X-rays. Matter is falling towards the star 10 times faster than it should just with gravity, so it could be that the star's magnetic field is somehow responsible, channeling gas into the star.

View full article (http://www.universetoday.com/am/publish/young_star_grown_quickly.html)

What do you think about this story? Post your comments below.

Greg
2005-Mar-03, 02:25 AM
It seems that surprisingly little of these newly discovered effects of magnetic fields around protostars, neutron stars, and black holes have been predicted by anyone before. I wonder why that is? I guess it demonstrates how little we know about the effects of magnetism in general or at least on enormous scales such as these.

wstevenbrown
2005-Mar-03, 01:52 PM
There are two good reasons, and one bad one.

1) Computational difficulty-- one needs more "initial conditions" information, in order to calculate effectively; i.e., where are the charges, and what material with what electrical properties, lies between them?

2) Explanatory depth-- for an electric effect to occur, charges must be separated. It is difficult to reason backward to find out why they were separated. In the present article, we are told that the temperature (it should read: average temperature) is -400F. In the same breath, we are told that the X-rays are probably due to magnetic effects caused by ionization. Huh? Whuzzat? What new material ionizes at -400F ? The chain of causation is not clearly articulated, because it is not clearly understood.

And now, the baddie. Astronomers have historically had it pretty easy. If an object emits light, either it was massive enough to gravitate into a star, or else something nearby was. Clearly, gravity only attracts, and cannot be screened, so with a minimum of assumptions about where the masses are, calculations can proceed. Which brings us to:

3) Astronomers grow up listening to explanations based solely upon the influence of gravity, and it becomes a habit of thought (and exposition)-- all visible effects are created by gravity.

With our increased sensitivity and resolution and spectral range, we are beginning to realize that it isn't so, and the era of easy calculations, which painted the broad strokes, cannot be carried forward to accomplish the detail work. Best regards--Steve