An international team of astronomers has discovered a new hot Jupiter exoplanet orbiting a distant G-type star. The newly discovered alien world, called TOI-4515 b, is similar in size to Jupiter but roughly twice as large. The discovery was detailed in an article published on the preprocessing server on November 20. arXiv.

TESS is currently surveying approximately 200,000 of the brightest nearby stars in search of transiting exoplanets. Nearly 7,000 candidate exoplanets (TESS Objects of Interest, or TOIs) have been identified so far, of which 402 have been confirmed.

Hot Jupiters are gas giant planets with orbital periods ranging from 10 to 200 days. This makes them difficult targets for transit detection and subsequent radial velocity (RV) studies compared to their shorter-orbit counterparts, called hot Jupiters.

Now, a team of astronomers led by Ilaria Carleo of the University of La Laguna, Spain, reports the discovery of a new hot Jupiter with an orbital period of about 15.26 days. Using TESS, they detected a transition signal in the light curve of TOI-4515, a G star slightly smaller and less massive than the Sun, located about 632 light-years away.

The planetary nature of this signal was confirmed by subsequent radial velocity measurements with the HARPS-N spectrograph on the Galileo National Telescope located on the island of La Palma in Spain’s Canary Islands.

The recently discovered exoplanet TOI-4515 b has a radius of 1.09 Jupiter radii and a mass of about 2.01 Jupiter, with a density of about 1.95 g/cm.³. This planet takes 15 days and 6 hours to orbit its host in an eccentric orbit (with an eccentricity of 0.46) at a distance of almost 0.12 AU. The equilibrium temperature of TOI-4515 b is estimated to be 705 K.

As for the parent star TOI-4515, it has the G8/G9 spectral type and is about 1.2 billion years old. The radius of the star is equal to 0.875 of the radius of the Sun, and its mass is equal to 0.92 of the mass of the Sun. The effective temperature of TOI-4515 is estimated to be approximately 5400 K, and its metallicity has been found to be 10 percent higher than solar metallicity.

Trying to explain the high eccentricity of TOI-4515 b’s orbit and the relatively high density of the planet, astronomers suggest that it may be the result of a turbulent dynamic history characterized by planetary collisions.

“It is likely that many gas giants were formed in the system. After the gas disk dispersed, these gas giants may have been subjected to interactions such as interplanetary scattering or age interactions that led to the excitation of TOI-4515 b’s eccentric orbit,” the researchers explained.