Researchers found a gigantic planet in the Pisces constellation that could help them gain insight into the formation of extrasolar planets.

The planet resides in a one-star system, which is unusual compared to the high rate of multiple-star systems in the region of space, a San Francisco State University news release reported.

"There is a great interest in these stars that are known to host planets," SF State astronomer Stephen Kane said in the news release.

"[A multiple star system may] have not one but two planetary disks [where planets are born]", Kane said. "Or it could be that having an extra star would be disruptive, and its gravity could cause any protoplanets to pull apart."

Extrasolar planets are rarely found in multiple-star systems, but researchers have long-suspected their existence. Four systems studies by the researchers were found to contain exoplanets.

The team used optical imaging data to observe these star systems, and noticed what appeared to be second stars; instead they the mysterious objects turned out to be exoplanets. The team used the radial velocity technique (measuring the variations in speed as a star moves back and forth getting closer and farther away from Earth; and how nearby objects' gravitational pulls cause it to "wobble") to pinpoint the exoplanets. The researchers are able to determine if the "wobble" is caused by a star or planet.

The team noticed a radial velocity measurement in the star systems that couldn't be from a regular planet. The team was also confused because the known planets in the star systems followed erratic "elliptical" orbits; which was not the case of the suspected object.

The team's first instinct was to see if the object could be another star in the system, but they eventually ruled out this theory.

"I thought we were likely to find stellar companions, and when all four didn't have a binary star, that did surprise me," Kane said.

In the Pisces' HD 4230 system the "wobble" is believed to be a result of a giant planet. The team used "additional radial velocity data" to make their finding. The team believes the same may be true in the other star systems included in the study.