Planetary system
In 2022, two exoplanets were detected orbiting around GJ 3929. [4] The innermost, GJ 3929 b, is a rocky planet just 9% larger than Earth, while the outermost, GJ 3929 c, is a sub-Neptune with 5.7 times the mass of Earth. [3] Both planets orbit below the star's habitable zone. [6]
GJ 3929 b
The innermost planet, GJ 3929 b (TOI-2013 b), is an Earth-sized planet discovered by the transit method. [4] Orbiting its star at a distance of 0.0252 astronomical units (3,770,000 km), the planet is located in its star's Venus zone, and completes a revolution every 2 days and 15 hours. [3] The planet's equilibrium temperature is calculated at 568 K (295 °C), and it receives a planetary insolation 17 times greater than what the Earth receives from the Sun. [3]
The planet's mass is calculated at 1.75±0.45 M🜨 according to photometric observations using the NEID spectrometer. [3] Observations using the ARCTIC imager, plus photometry from TESS and LCOGT, constrained the planet's radius to 1.09±0.04 R🜨 . [3] This radius makes GJ 3929 b very similar to Earth in terms of size.
Due to the apparent brightness of the host star, and its small size, GJ 3929 b is an excellent planet for atmospheric study with the James Webb Space Telescope. [3] [4]
It was discovered by a team of astronomers led by Jonas Kemmer. [7] They reported an planetary transit signal in the host star's light curve. [7] Subsequent observations, mainly with the CARMENES spectrograph, revealed that this transit signal is an orbiting exoplanet. [7] [4]
GJ 3929 c
The outermost planet, GJ 3929 c (TOI-2013 c) is a Sub-Neptune discovered using the radial velocity method. [4] It orbits its star at a distance of 0.081 astronomical units (12,100,000 km), 3 times further away than GJ 3929 b, but still below GJ 3929's habitable zone, [6] completing an orbit every 15 days. [3]
Its minimum mass is 5.71±0.94 M🜨 , while its radius is unknown. [3] Estimates using mass-radius relationship derive a radius of 2.26 R🜨. [3] Its equilibrium temperature is calculated at 317 K (44 °C), and it receives a planetary insolation 68% greater than what the Earth receives from the Sun. [3]
GJ 3929 c was first identified in radial velocity data, which indicated the existence of another planet besides GJ 3929 b. [4] [8] Initially, it was just an exoplanet candidate, but it was later confirmed by a team led by Corey Beard. [3] [8] Because its orbital period (15 days) is far from its star's rotation period (122 days), it is unlikely that the radial velocity signal is actually an artifact of its parent star's activity and rotation. [4]
Gliese 436 is a red dwarf located 31.9 light-years away in the zodiac constellation of Leo. It has an apparent visual magnitude of 10.67, which is much too faint to be seen with the naked eye. However, it can be viewed with even a modest telescope of 2.4 in (6 cm) aperture. In 2004, the existence of an extrasolar planet, Gliese 436 b, was verified as orbiting the star. This planet was later discovered to transit its host star.
Gliese 876 d is an exoplanet 15.2 light-years away in the constellation of Aquarius. The planet was the third planet discovered orbiting the red dwarf Gliese 876, and is the innermost planet in the system. It was the lowest-mass known exoplanet apart from the pulsar planets orbiting PSR B1257+12 at the time of its discovery. Due to its low mass, it can be categorized as a super-Earth.
Gliese 436 b is a Neptune-sized exoplanet orbiting the red dwarf Gliese 436. It was the first hot Neptune discovered with certainty and was among the smallest-known transiting planets in mass and radius, until the much smaller Kepler exoplanet discoveries began circa 2010.
A Super-Earth is a type of exoplanet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17 times Earth's, respectively. The term "super-Earth" refers only to the mass of the planet, and so does not imply anything about the surface conditions or habitability. The alternative term "gas dwarfs" may be more accurate for those at the higher end of the mass scale, although "mini-Neptunes" is a more common term.
A hot Neptune or Hoptune is a type of giant planet with a mass similar to that of Uranus or Neptune orbiting close to its star, normally within less than 1 AU. The first hot Neptune to be discovered with certainty was Gliese 436 b in 2007, an exoplanet about 33 light years away. Recent observations have revealed a larger potential population of hot Neptunes in the Milky Way than was previously thought. Hot Neptunes may have formed either in situ or ex situ.
GJ 1214 b is an exoplanet that orbits the star GJ 1214, and was discovered in December 2009. Its parent star is 48 light-years from the Sun, in the constellation Ophiuchus. As of 2017, GJ 1214 b is the most likely known candidate for being an ocean planet. For that reason, scientists often call the planet a "waterworld".
An exoplanet is a planet located outside the Solar System. The first evidence of an exoplanet was noted as early as 1917, but was not recognized as such until 2016; no planet discovery has yet come from that evidence. What turned out to be the first detection of an exoplanet was published among a list of possible candidates in 1988, though not confirmed until 2003. The first confirmed detection came in 1992, with the discovery of terrestrial-mass planets orbiting the pulsar PSR B1257+12. The first confirmation of an exoplanet orbiting a main-sequence star was made in 1995, when a giant planet was found in a four-day orbit around the nearby star 51 Pegasi. Some exoplanets have been imaged directly by telescopes, but the vast majority have been detected through indirect methods, such as the transit method and the radial-velocity method. As of 1 January 2024, there are 5,576 confirmed exoplanets in 4,113 planetary systems, with 887 systems having more than one planet. This is a list of the most notable discoveries.
GJ 3634 b is a super-Earth exoplanet in the orbit of the nearby red dwarf GJ 3634 at approximately 64.5 light-years in constellation Hydra. The planet is approximately eight times the mass of Earth, and orbits its star every two and a half days at a distance of 0.0287 AU. The planet was the first to be discovered by a group of astronomers searching for exoplanets in the orbit of very-low-mass stars after the team reorganized their strategy, choosing to search for targets that they could also confirm using the transit method. However, a transit event associated with GJ 3634 b was not detected. The planet's discovery was published in Astronomy and Astrophysics on February 8, 2011.
Gliese 667 Cc is an exoplanet orbiting within the habitable zone of the red dwarf star Gliese 667 C, which is a member of the Gliese 667 triple star system, approximately 23.62 light-years away in the constellation of Scorpius. The exoplanet was found by using the radial velocity method, from radial-velocity measurements via observation of Doppler shifts in the spectrum of the planet's parent star.
Gliese 15 Ab, also commonly called Groombridge 34 Ab, rarely called GX Andromedae b is an extrasolar planet approximately 11 light-years away in the constellation of Andromeda. It is found in the night sky orbiting the star Gliese 15 A, which is at right ascension 00h 18m 22.89s and declination +44° 01′ 22.6″.
Luyten b is a confirmed exoplanet, likely rocky, orbiting within the habitable zone of the nearby red dwarf Luyten's Star. It is the fourth-closest potentially habitable exoplanet known, at a distance of 12 light-years. Only Proxima Centauri b, Ross 128 b, and GJ 1061 d are closer. Discovered alongside Gliese 273c in June 2017, Luyten b is a super-Earth of around 2.89 times the mass of Earth and receives only 6% more starlight than Earth, making it one of the best candidates for habitability.
GJ 3470 is a red dwarf star located in the constellation of Cancer, 96 light-years away from Earth. With a faint apparent magnitude of 12.3, it is not visible to the naked eye. It hosts one known exoplanet.
TOI-561 is an old, metal-poor, Sun-like star, known to have multiple small planets. It is an orange dwarf, estimated to be 10.5 billion years old, and about 79% the mass and 85% the radius of Sol, Earth's sun.
Kepler-737b is a super-Earth exoplanet 669 light years away. There is a chance it could be on the inner edge of the habitable zone.
Gliese 367 is a red dwarf star 30.7 light-years from Earth in the constellation of Vela. It is suspected to be a variable with amplitude 0.012 stellar magnitude and period 5.16 years. A stellar multiplicity survey in 2015 failed to detect any stellar companions to Gliese 367. It hosts three known exoplanets, Gliese 367 b, c & d.
HD 260655 is a relatively bright and cool M0 V red dwarf star located 33 light-years away from the Solar System in the constellation of Gemini. HD 260655 has two confirmed rocky planets, named HD 260655 b and HD 260655 c, that were discovered in 2022. Both planets were detected by the TESS mission and confirmed independently with archival and new precise radial velocity data obtained with the HIRES observatory since 1998, and the CARMENES survey instruments since 2016.
TOI-3235 b is a Neptune-like exoplanet found 237 light-years away from Earth. The exoplanet was discovered in 2023.
GJ 3929 b is an Earth-sized exoplanet orbiting the red dwarf GJ 3929. It is located 51.6 light-years from Earth, in the constellation Corona Borealis, and orbits its host star at a distance of 0.0252 astronomical units (3,770,000 km), completing one orbit every 2 days and 15 hours. Because it orbits very close to its star, it is classified as a Venus-like planet.
