Hubble Site STSci-2010-17 - 24 May 2010
For just over a decade, astronomers have known that three Jupiter-type planets orbit the yellow-white star Upsilon Andromedae. But to their surprise it's now been discovered that not all planets orbit this star in the same plane, as the major planets in our solar system orbit the Sun. The orbits of two of the planets are inclined by 30 degrees with respect to each other. Such a strange orientation has never before been seen in any other planetary system. This surprising finding will impact theories of how planetary systems form and evolve, say researchers. It suggests that some violent events can happen to disrupt planets' orbits after a planetary system forms. The discovery was made by joint observations with the Hubble Space Telescope, the giant Hobby-Eberly Telescope, and other ground-based telescopes.
(NASA/ESA/B. McArthur (University of Texas, Austin, McDonald Observatory))
McDonald Observatory: University of Texas, Austin
Weird orbits of neighbors can make 'habitable' planets not so habitableThe discovery of a planetary system “out of whack,” where the orbits of two planets are at a steep angle to each other, was reported today (May 24) by a team of astronomers led by Barbara McArthur of The University of Texas at Austin McDonald Observatory.
This surprising finding will affect theories of how multi-planet systems evolve and shows that some violent events can happen to disrupt planets’ orbits after a planetary system forms, say researchers.
University of Washington - 24 May 2010
Astronomers hunting for planets orbiting nearby stars similar to the sun are looking for signs of rocky, Earth-like planets in a "habitable" zone, where conditions such as temperature and liquid water remain stable enough to support life.
New findings from computer modeling indicate that some of those exoplanets might fluctuate between being habitable and being inhospitable to life because of the forces exerted by giant neighbors with eccentric orbits.
A lone Earth-like, or terrestrial, planet with a generally circular orbit toward the inner edge of its sun's habitable zone could be expected to remain within that zone, said Rory Barnes, a University of Washington postdoctoral researcher in astronomy. Adding a planet comparable to Jupiter to the system, however, and giving it a highly elliptical orbit -- similar to most exoplanets discovered so far -- can cause strange things to happen to the smaller planet, possibly causing it to cycle between habitable and uninhabitable conditions.
The smaller planet's orbit will elongate and then become more circular again, all in as little as 1,000 years, and could do so repeatedly. That raises the possibility, for example, that its average yearly temperature could change significantly during each millennium.
