Using the HARPS planet-hunting instrument on the 3.6-m telescope at ESO’s La Silla Observatory, Chile, astronomers have discovered a Jupiter-mass exoplanet orbiting the Sun-like star HIP 11915 at almost exactly the same distance as Jupiter.

Although many exoplanets similar to Jupiter have been found at a variety of distances from Sun-like stars, the newfound planet, HIP 11915b, in terms of both mass and distance from its host star, and in terms of the similarity between the host star and our Sun, is the most accurate analogue yet found for the Sun and Jupiter.

HIP 11915 is not only similar in mass to the Sun, but is also about the same age. To further strengthen the similarities, the composition of the star is similar to the Sun’s.

The star is located in the constellation Cetus, about 200 light-years away. It is too faint to be seen without optical aid, but can be picked up with binoculars.

“After two decades of hunting for exoplanets, we are finally beginning to see long-period gas giant planets similar to those in our own Solar System thanks to the long-term stability of planet hunting instruments like HARPS,” said Dr Megan Bedell from the University of Chicago, first author of a paper accepted for publication in the journal Astronomy and Astrophysics.

“This discovery is, in every respect, an exciting sign that other solar systems may be out there waiting to be discovered.”

Dr Jorge Melendez from the University of São Paulo in Brazil, who is a co-author on the paper, added: “the quest for an Earth 2.0, and for a complete Solar System 2.0, is one of the most exciting endeavors in astronomy. We are thrilled to be part of this cutting-edge research, made possible by the observational facilities provided by ESO.”

“Follow-up observations are needed to confirm and constrain the finding, but HIP 11915 is one of the most promising candidates so far to host a planetary system similar to our own,” the astronomers said.

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M. Bedell et al. 2015. The Solar Twin Planet Search II. A Jupiter twin around a solar twin. A&A, accepted for publication