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Strange, Slow-Spinning Stars Might Harbor Planets
By SPACE.com Staff
posted: 10:15 am ET
03 May 2002
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Headline: Strange, Slow-Spinning Stars Might Harbor Planets While most stars spin more rapidly as they consolidate during their birth and early years, some do not, according to a new study that suggests newborn planets may be stealing some of the spin. A star gets smaller during its early evolution as gravity pulls gas and dust in toward its center. Like a skater pulling her arms in, the star spins faster. In the new research, Luisa Rebull of NASA's Jet Propulsion Laboratory watched giant red regions, akin to sunspots, on distant stars to measure their rotation. Rebull said the stars' spin, governed by a phenomenon called angular momentum, might be carried away in great winds of material that would shoot out into interstellar space. These stellar winds are common to all stars at some level of intensity or another. Or the star's own magnetic field, tied to a disk of dust around the star could be slowing the rotation. Some of the stars appear redder than expected, hinting that they have dust disks around them, Rebull said. Other astronomers say newborn stars should typically have such disks, out of which planets might form. Our solar system is thought to have evolved in this manner. More intriguing is the possibility that young planets have already formed in these dust disks and sopped up some of the angular momentum themselves. In our solar system, Jupiter is a good example of a large planet that has stolen a notable amount of star spin and applied it to its own rotation. Managers of future space missions might be interested in these slower spinning stars that Rebull has investigated. The Space Infrared Telescope Facility, set to launch early next year, would among other things look for planet-forming disks around other stars. The Space Interferometry Mission, not yet fully planned, would test Rebull's ideas directly by looking directly for planets around young stars. Rebull and her team studied more than 9,000 stars in the Orion Nebula. They observed about 500 stars with large spots. The spots are darker than the stars' main surface, so researchers detect them by noting an overall dip in starlight as the spots rotate across the surface. Monitoring this activity over time allows for a calculation of a star's spin rate. The research was done with the 30-inch (.76-meter) telescope at the McDonald Observatory in Texas. Other data came from the National Optical Astronomy Observatory. A paper on the results will appear in the July 2002 issue of the Astronomical Journal. More Exoplanet News | Astronomy News Briefs
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