Birth Given to New Stars
UCLA astronomers and colleagues believe that after all the millions or maybe billions of years after planets formed around two unusual stars, another wave of planetesional and planet formation appears to be happening. “This is a new class of stars, ones that display conditions now ripe for formation of a 2nd generation of planets, long, long after the stars themselves form”, said UCLA astronomy graduate student, Carl Melis, who reported the findings at the American Astronomical Society meeting in Austin, Texas.
“If we took a rocket to one of these stars and discovered there were two totally distinct ages for their planets and more minor bodies like asteroids, that would blow scientists’ minds away”, said Benjamin Zuckerman, UCLA professor of physics and astronomy and co-author of the research, which has not been published. “We’re seeing stars with characteristics that have never been seen before”.
Melis says that the stars have “amazing properties for their age, are known as BP Piscium, in the constellation Pisces, and Tycho 41443292, in the constellation Ursa Major. Melis adds that these two stars have many characteristics of very young stars including rapid accretion of gas, extended orbiting disks of dust and gas, a large infrared excess emission and, in the case of BP Piscium, jets of gas that are being shot into space. Gas and dust particles that orbit young stars from planetesimals, such as comets and asteroids as well as planets. “With all these characteristics that match so closely with young stars, we would expect that our two stars would also be young” Melis said. “As we gathered more data, however, things just did not add up”.
For example, because stars burn lithium as they get older, young stars should have large quantities of lithium. The astronomers found, however, that the spectroscopic signature of lithium in BP Piscium is seven times weaker than expected for a young star of its mass. “There is no known way to account for this small amount of lithium if BP Piscium is a young star, “Melis said. “Rather, lithium has been heavily processed, as appropriate for old stars. Other spectral measurements also indicate it is a much older star”.
About 75% of BP Piscium’s radiant energy is being converted by dust particles into infrared light and about 12% of Tycho 41443292’s. These are unusually high amounts, which Melis describe as “spectacular” in comparing it to other stars that are known to be not young. Astronomers continue to study these stars with a variety of equipment.
This entry was posted on Saturday, January 26th, 2008 at 5:03 am and is filed under Space Agency News. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
