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 is a type of giant planet with a mass similar to that of Neptune or Uranus orbiting close to its star, normally within less than 1 AU. The first hot Neptune to be discovered with certainty was Gliese 436 b (Awohali) 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 May 2024, there are 5,662 confirmed exoplanets in 4,169 planetary systems, with 896 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 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-1227 b is one of the youngest transiting exoplanets discovered, alongside K2-33b and HIP 67522 b. The exoplanet TOI-1227 b is about 11±2 million years old and currently 9.6 R🜨 large. It will become a 3-5 R🜨 planet in about 1 billion years, because the planet is still contracting. TOI-1227 b orbits its host star every 27.36 days.
TOI-4603 b is a gas giant exoplanet orbiting HD 245134, a F-type subgiant star located 731 light-years away, in the constellation of Taurus. It orbits its host star at a distance of 0.0888 astronomical units (13,280,000 km), completing one orbit every 7 days around it. With a density of 14.1 g/cm3, it is one of the densest exoplanets known. The planet is just 4% larger than Jupiter, but is 12.9 times more massive, being located in the mass limit between planets and brown dwarfs.
TOI-3235 b is a gas giant exoplanet found 237 light-years away from Earth. It was discovered in 2023 by the transit method.
Gliese 414, also known as GJ 414, is a binary system made up of an orange dwarf and a red dwarf, located about 39 light years from Earth, in the constellation Ursa Major. With an apparent magnitude of 8.31, it is not visible to the naked eye. The primary component of the system has two known exoplanets.
Gliese 414 Ac, or GJ 414 Ac, is an exoplanet orbiting Gliese 414 A, a K-type main-sequence star located 39 light-years from Earth, in the constellation Ursa Major. It is classified as a super-Neptune exoplanet, being at least 54 times more massive than the Earth and about 8.5 times larger. Gliese 414 Ac orbits its parent star at a distance of 1.4 astronomical units and completes one revolution around it every 2 years and 20 days. It is one of the two planets orbiting Gliese 414 A, the another is Gliese 414 Ab, a sub-Neptune.
Gliese 414 Ab, also known as GJ 414 Ab, is a sub-Neptune exoplanet orbiting Gliese 414 A, an orange dwarf located 39 light-years from Earth, in the constellation Ursa Major. It is at least 7.6 times more massive than the Earth and is 3 times larger, having a diameter of 37600 km. It orbits its host star at a distance of 0.24 astronomical units (36,000,000 km), completing one revolution every 51 days. The distance of Gliese 414 A b from its star makes it to be located in the inner part of the optmistic habitable zone, and the planet has a equilibrium temperature of 35.5 °C.
GJ 3929 b is a confirmed exoplanet located 52 light-years away orbiting the red dwarf star GJ 3929. It is an Earth-sized planet, having a radius only 9% larger than that of Earth. 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. 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.
HD 63433 c is a mini-Neptune exoplanet orbiting the Sun-like star HD 63433. It is the outermost planet in its planetary system, being located 0.1448 astronomical units (21,660,000 km) from its star, and completing one orbit every 21 days. Despite being the outermost planet in the system, it is still located close to its star, meaning that its temperature is hot, being estimated between 267 and 406 °C. HD 63433 c is about 2.7 times larger than Earth and 15.5 times more massive, but still smaller and less massive than Neptune. In 2022, a study showed that its atmosphere, made up of hydrogen, is being evaporated by the strong radiation from its star, causing it to slowly turn into a super-Earth planet.
