LHS 3844 b is an exoplanet orbiting the red dwarf LHS 3844, about 15 parsecs (49 ly) away in the constellation Indus,[5] discovered using the Transiting Exoplanet Survey Satellite. It orbits its parent star once every 11 hours, and its radius is 1.32 times that of Earth.[1] It has a low albedo, indicating that its surface may resemble that of the Moon or Mercury. LHS 3844 b probably does not have an atmosphere as almost no heat goes to its night side, and it has a dayside temperature of 1,040 K (770 °C; 1,410 °F).[4][6] The presence of cloudy atmosphere with cloud tops above pressure level of 0.1 bar cannot be excluded though.[7]

LHS 3844 b

Artist’s illustration of LHS 3844 b
Discovery[1]
Discovered by	Vanderspek et al.
Discovery date	September 2018
Detection method	Transit
Designations
Alternative names	TOI-136.01, TIC 410153553 b[2][3]
Orbital characteristics
Semi-major axis	0.00622±0.00017 AU[2][3]
Orbital period (sidereal)	0.46292913±0.00000190 d[2][3]
Inclination	88.50±0.51[3]
Star	LHS 3844
Physical characteristics
Mean radius	1.303±0.022 REarth[2][3]
Albedo	<0.2[4]
Temperature	1,040 K (770 °C; 1,410 °F) (day side)[4]

In order to explain the lack of atmosphere, it has been proposed that the planet was formed interior to the star system's snow-line, because if it formed beyond the snow-line it would have carried volatiles, on the surface and in a thick atmosphere, that according to models on atmospheric loss should have been enough to sustain an atmosphere to the present.[8] The planet probably also formed with a volatile-poor outgassing mantle, in a stagnant lid regime, because if the mantle was similar in constitution to Earth's, with plate tectonics, then it should still have a thick atmosphere, unless the red dwarf consistently flared at an uncharacteristically extreme rate not yet considered in atmospheric loss models.[8] An alternative explanation for the lack of atmosphere could be through a large impact event, one with enough momentum to strip the planet of its atmosphere and a large portion of its mantle.[8] In order to explain the non replenishment of volatiles via comets back onto the planet, it is also proposed that perhaps there is an outer gas giant in the star system.[8]

In August 2022, this planet and its host star were included among 20 systems to be named by the third NameExoWorlds project.[9]

See also

• List of exoplanets discovered in 2019

References