Hot Jupiter

hot JupitersPuffy planetultra-short period planethothot Jupiter" planetshot planethot zoneJupiter or Neptune sized planetslow-density (puffy)pegasean planet
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 (Pwikipedia
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51 Pegasi b

Dimidium51 Peg ban exoplanet
One of the best-known hot Jupiters is 51 Pegasi b.
It is the prototype for a class of planets called hot Jupiters.

Exoplanet

extrasolar planetexoplanetsplanet
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 (P
In 1952, more than 40 years before the first hot Jupiter was discovered, Otto Struve wrote that there is no compelling reason why planets could not be much closer to their parent star than is the case in the Solar System, and proposed that Doppler spectroscopy and the transit method could detect super-Jupiters in short orbits.

Planetary migration

migrationmigrating Neptunemigrated
The planet then migrates inwards to the star where it eventually forms a stable orbit.
Planetary migration is the most likely explanation for hot Jupiters: exoplanets with Jovian masses but orbits of only a few days.

Gas giant

gas giantsgiant planetJovian
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 (P
Jupiter and Saturn are both class I. Hot Jupiters are class IV or V.

WASP-47

WASP-47bbWASP-47c
In 2015, two planets were discovered around WASP-47.
It was first noticed to have a hot Jupiter exoplanet orbiting every 4 days in 2012 by the Wide Angle Search for Planets (WASP) team.

Solar analog

solar twinSun-likeSun-like stars
Discovered in 1995, it was the first extrasolar planet found orbiting a Sun-like star.
High metallicity strongly correlates to the formation of hot Jupiters, but these are not absolute bars to life, as some gas giants end up orbiting within the habitable zone themselves, and could potentially host Earth-like moons.

HD 209458 b

HD 209458bOsirisHD209458b
It had been previously hypothesized that hot Jupiters particularly close to their parent star should exhibit this kind of inflation due to intense heating of their outer atmosphere.

Retrograde and prograde motion

retrogradeprograderetrograde orbit
It has been found that several hot Jupiters have retrograde orbits and this calls into question the theories about the formation of planetary systems, although rather than a planet's orbit having been disturbed, it may be that the star itself flipped over early in their system's formation due to interactions between the star's magnetic field and the planet-forming disc.
In 2010 the discovery of several hot Jupiters with backward orbits called into question the theories about the formation of planetary systems.

Frost line (astrophysics)

frost linesnow lineice line
In the migration hypothesis, a hot Jupiter forms beyond the frost line, from rock, ice, and gases via the core accretion method of planetary formation.
However, giant planets have been found inside the frost line around several other stars (so-called hot Jupiters).

WASP-43b

b
Confirmed transiting hot Jupiters that have orbital periods of less than one day include WASP-18b, WASP-19b, WASP-43b, and WASP-103b.
The planet is a Hot Jupiter with a mass twice that of Jupiter, but with a roughly equal radius.

Jupiter

JovianGioveplanet Jupiter
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 (P

Disrupted planet

disruptiondestroyeddisintegrating planet
According to a 2011 study, hot Jupiters may become disrupted planets while migrating inwards; this could explain an abundance of "hot" Earth-sized to Neptune-sized planets within 0.2 AU of their host star.
Examples of planets (or their related remnants), considered to have been a disrupted planet, or part of such a planet, include: 'Oumuamua and WD 1145+017 b, as well as asteroids, hot Jupiters and those that are hypothetical planets, like Fifth planet, Phaeton, Planet V and Theia.

WASP-19b

b
Confirmed transiting hot Jupiters that have orbital periods of less than one day include WASP-18b, WASP-19b, WASP-43b, and WASP-103b.
At the time of discovery it was the shortest period hot Jupiter discovered as planets with shorter orbital periods had a rocky, or metallic composition.

Kozai mechanism

Kozai resonanceKozai-Lidov mechanismKozai instability
A hot Jupiter's orbit could also have been altered via the Kozai mechanism, causing an exchange of inclination for eccentricity resulting in a high eccentricity low perihelion orbit, in combination with tidal friction.
The Lidov-Kozai mechanism, in combination with tidal friction, is able to produce Hot Jupiters, which are gas giant exoplanets orbiting their stars on tight orbits.

Kepler-7b

7bb
In order of discovery they are: HAT-P-1b, COROT-1b, TrES-4, WASP-12b, WASP-17b, and Kepler-7b.
Kepler-7b is a hot Jupiter that is about half the mass of Jupiter, but is nearly 1.5 times its size; at the time of its discovery, Kepler-7b was the second most diffuse planet known, surpassed only by WASP-17b.

WASP-17b

about twice as large as Jupiterb
In order of discovery they are: HAT-P-1b, COROT-1b, TrES-4, WASP-12b, WASP-17b, and Kepler-7b.
In terms of diameter, WASP-17b is one of the largest exoplanets discovered and at half Jupiter's mass, this made it the most puffy planet known in 2010.

Super-Earth

super-EarthsSuper EarthEarthlike planets
Instead of being gas giants that migrated inward, in an alternate hypothesis the cores of the hot Jupiters began as more common super-Earths which accreted their gas envelopes at their current locations, becoming gas giants in situ.
In February 2018, K2-141b, a rocky ultra-short period planet (USP) Super-Earth, with a period of 0.28 days orbiting the host star K2-141 (EPIC 246393474) was reported.

Hydrodynamic escape

hydrodynamic mass loss
If the atmosphere of a hot Jupiter is stripped away via hydrodynamic escape, its core may become a chthonian planet.
Exoplanets that are extremely close to their parent star, such as hot Jupiters can experience significant hydrodynamic escape to the point where the star "burns off" their atmosphere upon which they cease to be gas giants and are left with just the core, at which point they would be called Chthonian planets.

Nebular hypothesis

planet formationplanetary formationformation
In the migration hypothesis, a hot Jupiter forms beyond the frost line, from rock, ice, and gases via the core accretion method of planetary formation.
The latter case corresponds to the so-called hot Jupiters, which are likely to have stopped their migration when they reached the inner hole in the protoplanetary disk.

Chthonian planet

Chthonianremaining rocky cores
If the atmosphere of a hot Jupiter is stripped away via hydrodynamic escape, its core may become a chthonian planet.

WASP-12b

bWASP-12 b
In order of discovery they are: HAT-P-1b, COROT-1b, TrES-4, WASP-12b, WASP-17b, and Kepler-7b.
As a result, the exoplanet has been described as "black as asphalt", and as a "pitch black" and is a type of planet known as a hot Jupiter.

HD 189733 b

HD 189733bbHD189733b
In 2008, a team of astronomers first described how as HD 189733 b reaches a certain place in its orbit, it causes increased stellar flaring in its host star.
With a mass 13% higher than that of Jupiter, HD 189733 b orbits its host star once every 2.2 days at an orbital speed of 152.5 km/s, making it a hot Jupiter with poor prospects for extraterrestrial life.

HAT-P-1b

In order of discovery they are: HAT-P-1b, COROT-1b, TrES-4, WASP-12b, WASP-17b, and Kepler-7b.
It therefore falls into the category of hot Jupiters.

Internal heating

internal heat
Puffy planets orbit close to their stars so that the intense heat from the star combined with internal heating within the planet will help inflate the atmosphere.
A combination of external and internal heating (which may be a combination of tidal heating and electromagnetic heating) is thought to make giant planets that orbit very close to their stars (hot Jupiters) into "puffy planets" (external heating is not thought to be sufficient by itself).

COROT-1b

bThe first exoplanet
In order of discovery they are: HAT-P-1b, COROT-1b, TrES-4, WASP-12b, WASP-17b, and Kepler-7b.
The planet is a large hot Jupiter, about 1.49 times the radius of Jupiter and approximately 1.03 times as massive, based on ground observations of the star.