Discovery [1] | |
---|---|
Discovered by | MEarth-South Array Team |
Discovery site | Chile |
Discovery date | May 10, 2015 (announced) [2] November 12, 2015 (confirmed) [3] |
Transit | |
Orbital characteristics [4] | |
0.0153±0.0005 AU | |
Eccentricity | <0.22 |
1.6289304(13) d [5] | |
Inclination | 86.58°±0.63° [6] |
Semi-amplitude | 2.85±0.34 m/s |
Star | GJ 1132 |
Physical characteristics [4] | |
Mean radius | 1.130±0.056 R🜨 |
Mass | 1.66±0.23 M🜨 |
Mean density | 6.3±1.3 g/cm3 |
12.9±2.2 m/s2 | |
13.6±1.0 km/s | |
GJ 1132 b (also known as Gliese 1132 b) is an exoplanet orbiting the red dwarf star GJ 1132 41 light-years (13 parsecs ) from Earth, [1] in the constellation Vela. The planet is considered uninhabitable but cool enough to possess an atmosphere. [2] GJ 1132 b was discovered by the MEarth-South array in Chile. [7]
It has been called "one of the most important planets ever discovered beyond the Solar System": Due to its relative proximity to Earth, telescopes should be able to determine the composition of its atmosphere, the speed of its winds and the color of its sunsets. [8] [9] [10] This is due in part to the small diameter of its parent star (20% that of the Sun), which increases the effect on the star's light of its transits. The planet's diameter is approximately 20% larger than that of the Earth [1] and its mass is estimated at 1.6 times that of Earth, [2] implying that it has an Earth-like rocky composition. [11] GJ 1132 b orbits its star every 1.6 days at a distance of 1.4 million miles (2.24 million kilometres). [7]
The planet receives 19 times more stellar radiation than Earth. [1] The equilibrium temperature is estimated at 529 K (256 °C; 493 °F) for an Earth-like albedo, or 409 K (136 °C; 277 °F) for a Venus-like albedo. The planet is likely to be hotter than Venus, as higher temperatures likely prevail at the surface if the planet has an atmosphere. [11] It is possible that the night side of the planet is cooler, because it is presumed to be tidally locked due to its proximity to its star; however, under most circumstances where an atmosphere is thick, it would be able to transfer heat to the far side.
In April 2017, a hydrogen-dominated atmosphere was claimed to have been detected around GJ 1132 b. [12] [6] However, subsequent, more precise work ruled out the claim. [13] Instead, in 2021 detection of a hazy hydrogen atmosphere without helium but with the admixture methane and hydrogen cyanide (implying substantial underlying free nitrogen in the mix, at around 8.9% of the atmosphere) was claimed. [14] However, two subsequent studies found no evidence for molecular absorption in the HST WFC3 Spectrum of GJ 1132 b. Instead, the spectrum was found to be flat, [15] [16] which is more consistent with our current understanding of photoevaporation.
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