Planets Orbiting Stars (Image Credit: ESO/M. Kornmesser)

Our solar system was once thought to be unlike anything we've ever seen in terms of how ordinary it is. or instance, the Sun is average in size, none of the planets (besides Earth, of course) are particularly noteworthy, and planetary orbits, in general, are eloquent. Now, with the growing number of extrasolar planets we've cataloged, we see that it is atypical in many ways. In fact, the vast majority of alien solar systems we've encountered are much different from the one Earthlings call home; the most prevalent types contain huge planets—called hot-Jupiters—that are situated extremely close to their parent stars, others have planets with wildly erratic orbits that render life all but impossible.

A new planetary system discovered by Australian researchers takes unpleasant to a whole new level. Furthermore, the system, found just 500 light-years away from Earth, challenges the very foundation on which planetary formation theories are built.

According to George Zhou, a researcher from the Australian National University's Research School of Astrophysics and Astronomy, "We have found a small star, with a giant planet the size of Jupiter, orbiting very closely," he continued, "It must have formed further out and migrated in, but our theories can't explain how this happened."

By classification, the parent star—known as HATS-6—belongs to the M-dwarf family. Otherwise known as red dwarfs, they are believed to be the most common type of star in the universe, but given the fact that they are very small, cool and rather dim, they are far more mysterious than their larger siblings.

Artist's impression of HATS-6 (Image Credit: ANU)

Take HATS-6: it only emits roughly 1/20th of the light Sol does, which makes it very difficult to witness a transit—that is, when an exoplanet passes in front of its parent star relative to our vantage point, obstructing a tiny bit of light in the process. After first spotting the blip in light astronomers associate transits with, detected by the ANU Siding Spring Observatory, the team conducted follow-up observations with the Magellan Telescope: one of the largest and most powerful in the world.

Ultimately, Magellan and ANU learned that indeed, the blip is a planet—a rather large one at that. It orbits HATS-6 from a distance equal to 1/10th of Mercury's orbit around the Sun, and its year lasts just 3.3 days.

"The planet has a similar mass to Saturn, but its radius is similar to Jupiter, so it's quite a puffed up planet. Because its host star is so cool it's not heating the planet up so much, it's very different from the planets we have observed so far," Zhou said.

Zhou and the team hope that, in the future, they'll be able to study its atmosphere in greater detail.


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