Paris, Aug 25 (IANS) Astronomers have found a new solar system, the largest ever detected, which is believed to have up to seven planets orbiting a sun-like star 127 light years away from the earth.
The new planetary system contains at least five planets orbiting the sun-like star HD 10180. The researchers also have tantalising evidence that two other planets may be present, one of which would have the lowest mass ever found, Europe’s astronomical observatory centre European Southern Observatory (ESO) has said.
The team also found evidence that the distances of the planets from their star follow a regular pattern, similar to our solar System, the ESO said in a press release.
‘We have found what is most likely the system with the most planets yet discovered,’ says Christophe Lovis, lead author of the paper reporting the result.
‘This remarkable discovery also highlights the fact that we are now entering a new era in exoplanet research: the study of complex planetary systems and not just of individual planets.
‘Studies of planetary motions in the new system reveal complex gravitational interactions between the planets and give us insights into the long-term evolution of the system,’ Lovis added.
The astronomers used HARPS spectrograph, attached to ESO’s 3.6-metre telescope at La Silla, Chile, for a six-year-long study of the Sun-like star HD 10180, located 127 light-years away in the southern constellation of Hydrus.
The team detected the tiny back and forth motions of the star caused by the complex gravitational attractions from five or more planets. The five signals correspond to planets with Neptune-like masses – between 13 and 25 Earth masses – which orbit the star with periods ranging from about 6 to 600 days.
These planets are located between 0.06 and 1.4 times the Earth-Sun distance from their central star, the statement said.
‘We also have good reasons to believe that two other planets are present,’ says Lovis. One would be a Saturn-like planet (with a minimum mass of 65 Earth masses) orbiting in 2200 days. The other would be the least massive exoplanet ever discovered, with a mass of about 1.4 times that of the Earth.
It is very close to its host star, at just 2 percent of the Earth-Sun distance. One ‘year’ on this planet would last only 1.18 Earth-days.
‘This object causes a wobble of its star of only about 3 km/hour- slower than walking speed – and this motion is very hard to measure,’ says team member Damien Segransan.
So far, astronomers know of fifteen systems with at least three planets. The last record-holder was 55 Cancri, which contains five planets, two of them being giant planets. ‘Systems of low-mass planets like the one around HD 10180 appear to be quite common, but their formation history remains a puzzle,’ says Lovis.
