New Planets Found Around Sun-like Stars
Posted by Science Oxford on December 17, 2009 | comments
Excellent, more planets found!
Visit this page »An international team of planet hunters has today announced the discovery of four new planets orbiting nearby stars like our Sun. The discoveries include both a mysterious new class of planet that is more massive than the Earth, but less massive than Uranus and Neptune, and a gas-giant planet that has a long-period orbit like that of Jupiter and could likely reside in a solar system reminiscent of our own, with the potential for life.
These new discoveries were made by British, Australian and American astronomers using the Anglo-Australian Telescope in New South Wales, Australia and the Keck Telescope in Hawaii. UK involvement comes from Hertfordshire University and is funded by the Science and Technology Facilities Council (STFC).
The long-period planet orbiting the star 23 Lib has an orbit similar to that of Jupiter which indicates that we now have the ability to detect the signatures of solar systems reminiscent of our own.
“Since Jupiter dominates the signal from our Solar System, we are now in a position to quantify how common planets like Jupiter are around stars like our Sun,” says Hugh Jones of University of Hertfordshire. “Compared to the Solar System, most extrasolar systems look odd, with planets in very small or very elliptical orbits. In contrast, this new planet has an orbit that is both large, and nearly circular – for the first time we are beginning to see systems that resemble our own.”
The Jupiter-mass planet orbits the star 23 Lib in a fourteen-year period, similar to Jupiter’s twelve-year orbit. The detection of long-period planets like this one is important. Of the planets in the Solar System, only Jupiter could be detected by current techniques. So finding a planet with an orbit like Jupiter’s suggests that astronomers are zeroing in on extrasolar planetary systems like our own.
The team also found some remarkable planets with much shorter orbital periods. “The sub-Neptune-mass planets we have found are very exciting”, said Chris Tinney of the University of New South Wales. “They suggest that a large number of nearby stars may harbour detectible planets with Neptune’s mass or less. These small planets point the way to detecting potentially habitable worlds in the near future.”
Three new planets with masses ranging from 5.3 up to 24.9 times the mass of the Earth have been found to orbit the star 61 Virginis, which at this time of year can be seen with the naked eye in the South East, in the constellation of Virgo rising in the morning ahead of the Sun. 61 Vir has long stood out amongst the hundreds of nearest stellar neighbours as being most similar to the Sun.
On one hand the 61 Vir and 23 Lib detections confirm our expectation that nearby stars like the Sun have planets like Jupiter and have multiple planets orbiting with periods less than an Earth-year. On the other hand, 61 Vir adds to a recent slew of discoveries that have upended conventional thinking regarding planet detection. “Our simulations suggest that more than a quarter of nearby stars have sub-Neptune mass planets in orbits shorter than a few weeks, in other words much closer to their stars than Mercury is to our Sun” said Simon O’Toole of the Anglo-Australian Observatory
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