| Discovery[1] | |
|---|---|
| Discovered by | Kemmer et al.[2] |
| Discovery date | 2022 |
| Transit | |
| Designations | |
| Gliese 3929 b, TOI 2013 b, G 180-18 b[3] | |
| Orbital characteristics[4] | |
| 0.0252±0.0005 AU | |
| Eccentricity | 0 (fixed) |
| 2.616 d | |
| Inclination | 88.442°±0.008° |
| Star | GJ 3929 |
| Physical characteristics[4] | |
| 1.09±0.04 R🜨 | |
| Mass | 1.75+0.44 −0.45 M🜨 |
Mean density | 7.3±2.0 g/cm3 |
| Temperature | 568±6 K (295 °C) |
GJ 3929 b (Gliese 3929 b, TOI-2013 b) is a confirmed exoplanet located 52 light-years away orbiting the red dwarf star GJ 3929.[3] It is an Earth-sized planet, having a radius only 9% larger than that of Earth.[4] It orbits its star at a distance of 0.0252 astronomical units (3,770,000 km), being located in the Venus zone of its star, and completes one orbit around it every 2 days and 15 hours.[4] Because of the proximity of its star, and its low mass, GJ 3929 b is classified as a Venus-like planet, having an equilibrium temperature of around 300 °C and receiving planetary insolation 17 times more intense than Earth receives from the Sun.[4]
Initially, the radius of GJ 3929 b was calculated at 1.15±0.04 R🜨, and its mass at 1.21±0.42 M🜨, giving a density of 4.4±1.6 g/cm3.[5] Later, observations using the NEID spectrometer on the WIYN 3.5 m Telescope measured the planet's mass to be 1.75±0.45 M🜨; and observations using the ARCTIC imager, plus photometry from TESS and LCOGT, constrained the planet's radius to 1.09±0.04 R🜨, this time giving a higher density of 7.3±2 g/cm3 (about 33% larger than Earth's[a]).[4] The characteristics of this planet make it similar to Earth in terms of mass and radius.
GJ 3929 b orbits its star at a distance of 0.0252 astronomical units (3,770,000 km), which makes it located in its host star's Venus zone, a region where rocky planets would have runaway greenhouse conditions like Venus.[4] GJ 3929 b completes an orbit around its star every 2 days, 14 hours and 47 minutes (2.616 days).[4]
As a terrestrial planet that orbits in the Venus zone of its star, GJ 3929 b classifies as a Venus-like planet, having a planetary equilibrium temperature of 295 °C and receiving planetary insolation 17 times greater than that of Earth receives from the Sun.[4]
The high density of GJ 3929 b does not suggest a dense atmosphere.[4] Atmospheric scenarios such as a thin atmosphere of volatiles, a thin atmosphere of silicate enriched in refractory elements, or even no atmosphere at all are plausible.[4] Due to its proximity to its star, GJ 3929 b has probably already lost much of its atmosphere since its formation.[4]
GJ 3929 b is an excellent planet for atmospheric study with the James Webb Space Telescope.[4][5] The study of this planet's atmosphere can help reveal the evolutionary history of its planetary system, and provide more information about planetary formation models.[4]
GJ 3929 b was discovered by a team of astronomers led by Jonas Kermer, from the Heidelberg UniversityinGermany.[2] They reported a transit signal identified in the host star (GJ 3929)'s light curve detected by NASA's Transiting Exoplanet Survey Satellite (TESS).[2] Afterwards, the planetary nature of this transit signal was confirmed using radial velocity observations with the CARMENES spectrograph, in addition to transit observations made with SAINT-EX and LCOGT.[5][2] The discovery was announced in 2022.[1]
The radial velocity observation with CARMENES also helped discover another planet in the planetary system, GJ 3929 c, a sub-Neptune detected by radial velocity.[5]
GJ 3929 is a red dwarfofspectral type M3.5V[7] that is located 51.6 light years from Earth, in the constellation Corona Borealis.[3][note 1] This star is smaller, cooler and less luminous than the Sun, having a radius of 0.32 R☉, an effective temperature of 3,384 K (3,111 °C) and a luminosity equivalent to 1% of solar luminosity.[4] Its age is estimated between 2.2 and 11 billion years.[4]
The star also hosts another planet, called GJ 3929 c, a sub-Neptune orbits 3 times further than the innermost planet, at a distance of 0.081 astronomical units (12,100,000 km),[5] but still below the habitable zone.[8]
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