A sun-like star, which is already known to host five alien planets, may actually have nine full-fledged worlds, according to a new study. If the planetary arrangement is confirmed, it would outnumber our own solar system and set a new record for the most populated system of extrasolar planets yet found.
The sun-like star, named HD 10180, is situated nearly 127 light-years away from Earth. In an earlier study that was published in August 2010, astronomers discovered five confirmed alien worlds and two planetary candidates. Now a new study confirms both previous candidates in the HD 10180 system, and also indicates that two more planets could be orbiting the star.
This could bring the tally up to nine planets, asserted lead author Mikko Tuomi, an astronomer at the University of Hertfordshire in the UK
"The data indicates that there are not only seven but likely as many as nine planets in the system," Tuomi said.
"The two new planets appear to have orbital periods of roughly 10 and 68 days and masses of 1.9 and 5.1 times that of Earth, which enables the classification of them as hot super-Earths, i.e. planets with likely scorchingly hot rocky surfaces."
Tuomi re-analyzed observations collected between November 2003 and June 2010 by the planet-hunting HARPS spectrograph instrument, which is mounted on a 3.6-meter telescope at the European Southern Observatory in La Silla, Chile
Since the newly detected candidates are still unproven, more research is required to determine if they are bonafide planets, and not erroneous signals.
"While the existence of the larger of these two is well supported by the data, the signal corresponding to the smaller one exceeds the detection threshold only barely, which gives it a very small but non-eligible probability of being a false positive," Tuomi added.
The study has been accepted for publication in the journal Astronomy and Astrophysics.
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