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A giant planet, sometimes referred to as a jovian planet, is a diverse type of planet much larger than Earth. Giant planets are usually primarily composed of low-boiling point materials (volatiles), rather than rock or other solid matter, but massive solid planets can also exist. There are four such planets in the Solar System: Jupiter, Saturn, Uranus, and Neptune. Many extrasolar giant planets have been identified.
A super-Jupiter is a gas giant exoplanet that is more massive than the planet Jupiter. For example, companions at the planet–brown dwarf borderline have been called super-Jupiters, such as around the star Kappa Andromedae.
Chthonian planets are a hypothetical class of celestial objects resulting from the stripping away of a gas giant's hydrogen and helium atmosphere and outer layers, which is called hydrodynamic escape. Such atmospheric stripping is a likely result of proximity to a star. The remaining rocky or metallic core would resemble a terrestrial planet in many respects.
Hot Jupiters are a class of gas giant exoplanets that are inferred to be physically similar to Jupiter but that have very short orbital periods. The close proximity to their stars and high surface-atmosphere temperatures resulted in their informal name "hot Jupiters".
Planetary migration occurs when a planet or other body in orbit around a star interacts with a disk of gas or planetesimals, resulting in the alteration of its orbital parameters, especially its semi-major axis. Planetary migration is the most likely explanation for hot Jupiters. The generally accepted theory of planet formation from a protoplanetary disk predicts that such planets cannot form so close to their stars, as there is insufficient mass at such small radii and the temperature is too high to allow the formation of rocky or icy planetesimals.
An ice giant is a giant planet composed mainly of elements heavier than hydrogen and helium, such as oxygen, carbon, nitrogen, and sulfur. There are two ice giants in the Solar System: Uranus and Neptune.
Mu Arae c, also known as HD 160691 c, formally named Dulcinea, is an extrasolar planet orbiting the star Mu Arae of the constellation Ara. It was the first 'hot Neptune' to be discovered.
A Super-Earth or super-terran 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.
This page describes exoplanet orbital and physical parameters.
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 24 July 2024, there are 7,026 confirmed exoplanets in 4,949 planetary systems, with 1007 systems having more than one planet. This is a list of the most notable discoveries.
A Mini-Neptune is a planet less massive than Neptune but resembling Neptune in that it has a thick hydrogen-helium atmosphere, probably with deep layers of ice, rock or liquid oceans.
A gas giant is a giant planet composed mainly of hydrogen and helium. Jupiter and Saturn are the gas giants of the Solar System. The term "gas giant" was originally synonymous with "giant planet". However, in the 1990s, it became known that Uranus and Neptune are really a distinct class of giant planets, being composed mainly of heavier volatile substances. For this reason, Uranus and Neptune are now often classified in the separate category of ice giants.
The Next-Generation Transit Survey (NGTS) is a ground-based robotic search for exoplanets. The facility is located at Paranal Observatory in the Atacama Desert in northern Chile, about 2 km from ESO's Very Large Telescope and 0.5 km from the VISTA Survey Telescope. Science operations began in early 2015. The astronomical survey is managed by a consortium of seven European universities and other academic institutions from Chile, Germany, Switzerland, and the United Kingdom. Prototypes of the array were tested in 2009 and 2010 on La Palma, and from 2012 to 2014 at Geneva Observatory.
K2-3b, also known as EPIC 201367065 b, is an exoplanet orbiting the red dwarf K2-3 every 10 days. It is the largest and most massive planet of the K2-3 system, with about 2.1 times the radius of Earth and about 5 times the mass. Its density of about 3.1 g/cm3 may indicate a composition of almost entirely water, or a hydrogen envelope comprising about 0.7% of the planet's mass.
K2-66b is a confirmed mega-Earth orbiting the subgiant K2-66, about 520 parsecs (1,700 ly) from Earth in the direction of Aquarius. It is an extremely hot and dense planet heavier than Neptune, but with only about half its radius.
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. It is located in the constellation Sextans, near the border with Leo.
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.
References
- 1 2 3 4 5 6 7 Armstrong, David J.; Lopez, Théo A.; Adibekyan, Vardan; et al. (June 1, 2020). "A remnant planetary core in the hot-Neptune desert". Nature. 583 (7814): 39–42. arXiv: 2003.10314 . Bibcode:2020Natur.583...39A. doi:10.1038/s41586-020-2421-7. PMID 32612222. S2CID 214612138.
- ↑ Mr. DeMaio (Mr. DeMaio) (2024-01-06). The Ghost Planet! . Retrieved 2024-11-01– via YouTube.
- ↑ "The Extrasolar Planet Encyclopaedia — TOI-849 b". Extrasolar Planets Encyclopaedia . Retrieved 11 September 2023.
- ↑ Pezzotti, C.; Attia, O.; et al. (October 2021). "The key impact of the host star's rotational history on the evolution of TOI-849b". Astronomy & Astrophysics . 654: L5. arXiv: 2110.09364 . Bibcode:2021A&A...654L...5P. doi:10.1051/0004-6361/202141734.
