Skip to comments.Planet-Forming Disks Might Put the Brakes on Stars
Posted on 07/30/2006 10:04:39 PM PDT by SunkenCiv
Astronomers using NASA's Spitzer Space Telescope have found evidence that dusty disks of planet-forming material tug on and slow down the young, whirling stars they surround. Young stars are full of energy, spinning around like tops in half a day or less. They would spin even faster, but something puts on the brakes. While scientists had theorized that planet-forming disks might be at least part of the answer, demonstrating this had been hard to do until now... Stars begin life as collapsing balls of gas that spin faster and faster as they shrink, like twirling ice skaters pulling in their arms. As the stars whip around, excess gas and dust flatten into surrounding pancake-like disks. The dust and gas in the disks are believed to eventually clump together to form planets. Developing stars spin so fast that, left unchecked, they would never fully contract and become stars. Prior to the new study, astronomers had theorized that disks might be slowing the super speedy stars by yanking on their magnetic fields. When a star's fields pass through a disk, they are thought to get bogged down like a spoon in molasses. This locks a star's rotation to the slower-turning disk, so the shrinking star can't spin faster... If planet-forming disks slow down stars, does that mean stars with planets spin more slowly than stars without planets? Not necessarily, according to Rebull, who said slowly spinning stars might simply take more time than other stars to clear their disks and develop planets. Such late-blooming stars would, in effect, give their disks more time to put on the brakes and slow them down.
(Excerpt) Read more at jpl.nasa.gov ...
This artist's concept shows a dusty planet-forming disk in orbit around a whirling young star. Image credit: NASA/JPL-Caltech
"Planemos" May Give Rise to Planets, Moons
Scientific American | June 06, 2006 | David Biello
Posted on 06/06/2006 2:08:11 AM EDT by SunkenCiv
Last I saw an article about this the scientists were basically admitting they ain't got a clue to whats happening in the universe
It is very hard to catch up with Astronomy these days. New things are coming out every day.
Tom Cruise to take pay cut.
Are Debris Disks and Massive Planets Correlated? [abstract]Using data from the Spitzer Space Telescope Legacy Science Program "Formation and Evolution of Planetary Systems" (FEPS), we have searched for debris disks around 9 FGK stars (2-10 Gyr), known from radial velocity (RV) studies to have one or more massive planets. Only one of the sources, HD 38529, has excess emission above the stellar photosphere; at 70 micron the signal-to-noise ratio in the excess is 4.7 while at wavelengths < 30 micron there is no evidence of excess. The remaining sources show no excesses at any Spitzer wavelengths. Applying survival tests to the FEPS sample and the results for the FGK survey published in Bryden et al. (2006), we do not find a significant correlation between the frequency and properties of debris disks and the presence of close-in planets. We discuss possible reasons for the lack of a correlation.
Amaya Moro-Martin, John M. Carpenter, Michael R. Meyer,
Lynne A. Hillenbrand, Renu Malhotra, David Hollenbach,
Joan Najita, Thomas Henning, Jinyoung S. Kim,
Jeroen Bouwman, Murray D. Silverstone, Dean C. Hines,
Sebastian Wolf, Illaria Pascucci, Eric E. Mamajek,
Note: this topic is from 07/30/2006.
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