Astronomers Discover New, Massive Planet in Pisces Star System

Astronomers have discovered a new giant planet in a star system within the Pisces constellation. About twice the mass of Jupiter, the new planet could help researchers learn a bit more about how extrasolar planets are formed.

The new planet was actually discovered as part of a study that examined four systems. The researchers used optical imaging data collected at the Gemini North observatory in Hawaii. This allowed them to see that the star system harboring the new planet contains just one star, as do the three other systems with extrasolar planets. This, in particular, was a surprising finding due to the high rate of multiple-star systems in our solar neighborhood.

In each system, the extrasolar planets were discovered by the radial velocity technique. This method measures variations in the speed at which a star moves away and toward Earth perturbed or "wobbled" by the gravitational pull of a nearby cosmic body. Depending on the radial velocity signature, astronomers calculated whether the wobble came from a planet or star.

In this case, the researchers found that there was a part of the radial velocity data that couldn't be explained entirely by the pull of an orbiting planet. At the same time, the planets that had already been discovered in these systems followed eccentric orbits, swinging away from their stars in a less circular and more elliptical fashion. That's what made them take a closer look at the systems and allowed them to rule out the possibility that another star was perturbing the system.

In the end, the researchers found a planet around the star, Pisces' HD 4230. In fact, this star and the others the researchers examined may also have additional planets due to the fact that the scientists did not find any stellar companions.

The findings reveal a bit more about these stellar systems and could help researchers better understand planet formation.

The findings are published in the Astrophysical Journal.