Using data from NASA’s Transiting Exoplanet Survey Satellite (TESS) and Spitzer Space Telescope, astronomers have discovered a transiting hot-Jupiter exoplanet orbiting a very young star called HIP 67522.
An artist’s impression of a hot-Jupiter exoplanet. Image credit: Sci-News.com.
HIP 67522 is a G0-type star located about 417 light-years away in the constellation of Centaurus.
Otherwise known as HD 120411, 2MASS J13500627-4050090 and TYC 7794-2268-1, the star is a member of a young group of stars called the Scorpius-Centaurus association.
HIP 67522 is about 17 million years old, meaning the newfound hot Jupiter is likely only a few million years younger.
Named HIP 67522b, the planet orbits the star once every 7 days and is about 10 times the diameter of Earth, or close to that of Jupiter.
University of Texas at Austin astronomer Aaron Rizzuto and colleagues spotted the signature of the alien world in the TESS data.
They then used archival data from the Spitzer Space Telescope to confirm that the transit signal was from a planet.
“We can learn a lot about our Solar System and its history by studying the planets and other things orbiting the Sun,” Dr. Rizzuto said.
“But we will never know how unique or how common the Solar System is unless we’re out there looking for exoplanets. Exoplanet scientists are finding out how our Solar System fits in the bigger picture of planet formation in the Universe.”
According to the astronomers, there are three main hypotheses for how hot Jupiters get so close to their parent stars.
“One is that they simply form there and stay put,” they explained.
“But it’s hard to imagine planets forming in such an intense environment. Not only would the scorching heat vaporize most materials, but young stars frequently erupt with massive explosions and stellar winds, potentially dispersing any newly emerging planets.”
“It seems more likely that gas giants develop farther from their parent star, past a boundary called the snow line, where it’s cool enough for ice and other solid materials to form. Jupiter-like planets are composed almost entirely of gas, but they contain solid cores. It would be easier for those cores to form past the snow line, where frozen materials could cling together like a growing snowball.”
“The other two hypotheses assume this is the case, and that hot Jupiters then wander closer to their stars. But what would be the cause and timing of the migration?”
“One idea posits that hot Jupiters begin their journey early in the planetary system’s history while the star is still surrounded by the disk of gas and dust from which both it and the planet formed,” they said.
“In this scenario, the gravity of the disk interacting with the mass of the planet could interrupt the gas giant’s orbit and cause it to migrate inward.”
“The third hypothesis maintains that hot Jupiters get close to their star later, when the gravity of other planets around the star can drive the migration.”
The fact that HIP 67522b is already so close to its host star so early after its formation indicates that this third hypothesis probably doesn’t apply in this case.
“But one young hot Jupiter isn’t enough to settle the debate on how they all form,” the researchers said.
The discovery is reported in the Astronomical Journal.
_____
Aaron C. Rizzuto et al. 2020. TESS Hunt for Young and Maturing Exoplanets (THYME). II. A 17 Myr Old Transiting Hot Jupiter in the Sco-Cen Association. AJ 160, 33; doi: 10.3847/1538-3881/ab94b7
