Rocky planets as small as 5 times Earth's mass have been found orbiting stars in our neighborhood. These results suggest we will find a lot more solar systems with planets closer to our own in size. Have intelligent dinosaurs developed on some and do they see us hominids as revolting enemies? Or as tasty snacks?
Washington, D.C. — Two nearby stars have been found to harbor "super-Earths"― rocky planets larger than the Earth but smaller than ice giants such as Uranus and Neptune. Unlike previously discovered stars with super-Earths, both of the stars are similar to the Sun, suggesting to scientists that low-mass planets may be common around nearby stars.
"Over the last 12 years or so nearly 400 planets have been found, and the vast majority of them have been very large―Jupiter mass or even larger," says researcher Paul Butler of the Carnegie Institution's Department of Terrestrial Magnetism. "These latest planets are part of a new trend of finding much smaller planets – planets that are more comparable to Earth."
The international team of researchers, co-led by Butler and Steven Vogt of the University of California, Santa Cruz, was able to detect the new planetary systems by combining data from observations spanning several years at the W. M. Keck Observatory in Hawaii and the Anglo-Australian Telescope in New South Wales, Australia. The researchers used the subtle "wobbling" of the stars caused by the planets' gravitational pull to determine the planets' size and orbits. Greg Henry at Tennessee State University independently monitored the brightness of the stars to rule out stellar "jitter"―roiling of gases on a star's surface that can be confused with a planet-induced wobble.
The bright star 61 Virginis, visible with the naked eye in the constellation Virgo, is only 28 light-years from Earth and closely resembles the Sun in size, age and other properties. Earlier studies had eliminated the possibility of a Jupiter-sized planet orbiting 61 Virginis. In this study, the researchers found evidence of three low-mass planets, the smallest of which is five times the mass of Earth and speeds around the star once every four days.
Will some of us live long enough to find life on other planets? Is it possible to detect life on a planet in another solar system without picking up radio signals?
Think of the possibilities. We could ask older civilizations if they overheated their planets by burning fossil fuels.
"These planets are particularly exciting," said team member Professor Chris Tinney of the University of NSW. "Neptune in our Solar System has a mass 17 times that of the Earth. It looks like there may be many Sun-like stars nearby with planets of that mass or less. They point the way to even smaller planets that could be rocky and suitable for life."
|Share |||Randall Parker, 2009 December 14 10:04 PM Space Exploration|