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Interstellar Dust Bunnies in Taurus:
Using sensitive radio cameras on two telescopes, the 15-m James Clerk Maxwell Telescope (JCMT) and 10-m Caltech Submillimeter Observatory (CSO), at Mauna Kea Observatories in Hawaii, graduate student Sean Andrews and Dr. Jonathan Williams of the Institute for Astronomy examined the swirling disks of gas and dust that surround young stars in the Taurus region of the sky to determine how the dust changes as disks evolve. They found that the disks rapidly disappear and concluded that stars have only a few million years to get started on making planets, a far shorter time than conventional theories require.
"We expected that disks would not disappear so quickly at radio wavelengths," said Andrews, "but this was not the case in general. The dust is either being dispersed, dumped onto the star, or growing into large clumps that are difficult to detect." On a scale in which a typical star's 10-billion-year lifetime is compressed to the average human lifespan, the disks would disappear within the first week.
Previous work at shorter, infrared wavelengths had shown that the innermost regions of disks disappear rapidly, but it was thought that the outer parts, where the planets in our solar system reside and which are most visible at longer, radio wavelengths, would last substantially longer.
The work, which is published in The Astrophysical Journal and funded by the National Science Foundation (NSF) and NASA, also showed that the dust around the stars emits more efficiently at longer wavelengths as the disks evolve.
"This suggests that the dust particles are sticking together, much as dust bunnies form under a bed," said Williams. He added, "This is the first, albeit tiny, step toward forming new solar systems."
The observations were made at a range of frequencies from 350 GHz to 860 GHz, in three relatively transparent windows in the sky, which allow the total mass of the planet-forming region in the disks to be measured.
The Institute for Astronomy at the University of Hawaii conducts research into galaxies, cosmology, stars, planets, and the sun. Its faculty and staff are also involved in astronomy education, deep space missions, and in the development and management of the observatories on Haleakala and Mauna Kea.
Established in 1907 and fully accredited by the Western Association of Schools and Colleges, the University of Hawaii is the state’s sole public system of higher education. The UH System provides an array of undergraduate, graduate, and professional degrees and community programs on 10 campuses and through educational, training, and research centers across the state. UH enrolls more than 50,000 students from Hawaii, the U.S. mainland, and around the world.