A group of researchers from the University of Montreal have announced the discovery of an exoplanet that is 115 light years away and surprisingly, was directly imaged. It also has one of the largest orbits of any known exoplanet. The discovery was published in The Astrophysical Journal.
Neptune is about thirty times further away from the Sun than Earth, around 4.5 billion kilometers away. That’s such a great distance, our minds can’t even comprehend it, and the distance from the Sun to Neptune doesn’t have anything on planet in the system of an M3 star, GU Psc, located 115 light years away in the constellation Pisces. The planet, GU Psc b, is ten times more massive than Jupiter and orbits its star at a colossal distance of 2000 AU. It takes the planet 80,000 Earth years to complete one full revolution. Neptune takes just under 165 years.
Exoplanets are typically washed out from the light of their parent star, forcing astronomers to rely on indirect methods of identification, based on how much of the star’s light is obstructed by the planet. However, the incredibly large orbit in this situation allowed them to image GU Psc b directly, based on the differing wavelengths between the planet and the star.
"The planets are much brighter when viewed in the infrared rather than visible light, because their surface temperature is lower than those of the stars, says Marie-Eve Naud. This is what has identified GU Psc b,” said lead author Marie-Eve Naud in a press release.
Another aspect that helped in identifying the exoplanet is that the host star is quite young, at only 100 million years old. The planets in the system haven’t had a chance to cool all the way, making them brighter and more easily detected. GU Psc is one of 90 young stars in the group AB Doradus and is the only one with a confirmed planet.
In order to determine some of the details GU Psc b, the researchers relied on theoretical models of how the planet may have formed. The wavelength of the light obtained from the planet indicates that it likely has a surface temperature of 800 °C (1472 °F). As a comparison, during the day on the equator of Mercury, temps only get up to about 427 °C (800 °F). They were able to use the age of the parent star to determine the mass, which is about 9-13 times more massive than Jupiter.
"GU b Psc is a true gift of nature. The great distance that separates it from its star makes possible a thorough study with a variety of instruments, allowing a better understanding of giant exoplanets in general,” co-author René Doyon said in the press release.
Researchers didn’t imagine they’d be able to directly image an exoplanet like GU Psc b with current technology, as it had been assumed that 100 light years would be the cutting-off point. Knowing that planets as distant as GU Psc b could be imaged directly may have opened more possibilities for researchers to look for exoplanets in locations they may have passed over before.
GU Psc b is definitely unique and stands out among confirmed exoplanets. Want to read more about other cool exoplanets? Check out the Earth-sized exoplanet in its star’s habitable zone, how abundant diamond planets might be, and the IFLScience list of most amazing known exoplanets!