TOI-849 b

TOI-849 b is an exoplanet orbiting the late G-type star TOI-849. It is a candidate chthonian planet, the exposed core of a gas giant that had its atmosphere stripped away by stellar radiation.

TOI-849 b

Discovery
Discovered by	TESS
Discovery date	2020
Detection method	Transit
Orbital characteristics
Semi-major axis	0.01598 AU
Eccentricity	0
Orbital period (sidereal)	0.76552414 +0.00000262 -0.00000279 d
Inclination	86.8 +2.1 -2.4
Star	TOI-849
Physical characteristics
Mean radius	0.3073 +0.0140 -0.0103 RJ
Mass	39.09 ME
Mean density	5.2 +0.7 -0.8 (g/cm3)

Characteristics

TOI-849 b is claimed to be a high-density planet more massive than Neptune, nearly forty times the mass of Earth. It was found very close to its host star, within the Neptunian desert, so it may well be classified as a chthonian planet.

Compared to other exoplanets that orbit very close to their stars, this planet seems to be quite unusual. It is nearly 40 times the mass of Earth, but only about three times as big in radius. The gravity of such massive worlds should attract large amounts of gas from the disk of material out of which planets form, causing them to become gas giants. If TOI-849 b is Chthonian, it will have had its atmosphere stripped away by stellar radiation, leaving just the core behind. Planets with similar masses to TOI-849 b are usually 5 to 10 times as wide as Earth, but TOI-849 b has a much smaller radius, providing evidence that it lacks a substantial atmosphere. This makes it likely a rocky planet. If this exoplanet is indeed a rocky planet, it is one of the largest terrestrial exoplanets known.