WASP-31b is a low-density (puffy) "

hot Jupiter Hot Jupiters (sometimes called hot Saturns) 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 temp ...

extrasolar planet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

orbiting the

metal-poor In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal physical matter in the Universe is either hydrogen or helium, and astronomers use the word ''"metals"'' as a ...

(63% of solar metallicity)

dwarf star A dwarf star is a star of relatively small size and low luminosity. Most main sequence stars are dwarf stars. The meaning of the word "dwarf" was later extended to some star-sized objects that are not stars, and compact stellar remnants which are ...

WASP-31. The exoplanet was discovered in 2010 by the

WASP A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. Th ...

project. WASP-31b is in the constellation of Crater, and is about 1305 light-years (

light travel distance Distance measures are used in physical cosmology to give a natural notion of the distance between two objects or events in the universe. They are often used to tie some ''observable'' quantity (such as the luminosity of a distant quasar, the ...

) from Earth.

Characteristics

WASP-31b is a low-density (puffy) "

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

with a mass about 0.48 times that of

Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but ...

and a radius about 1.55 times that of Jupiter. The planetary atmosphere has indeed the largest

scale height In atmospheric, earth, and planetary sciences, a scale height, usually denoted by the capital letter ''H'', is a distance (vertical or radial) over which a physical quantity decreases by a factor of e (the base of natural logarithms, approximate ...

, equal to 1150km, among exoplanets with measurable atmospheres as at 2021. The exoplanet orbits WASP-31, its host star, every 3.4 days. Clear to cloudy hot Jupiters

In 2012, it was found from the

Rossiter–McLaughlin effect The Rossiter–McLaughlin effect is a spectroscopic phenomenon observed when an object moves across the face of a star. Description The Rossiter–McLaughlin effect is a spectroscopic phenomenon observed when either an eclipsing binary's second ...

that WASP-31b is orbiting the parent star in a prograde direction, with the WASP-31 star rotational axis inclined to the planetary orbit by 2.8 degrees. The spectroscopic study in 2014 revealed that WASP-31b has a dense cloud deck overlaid by a hazy atmosphere. WASP-31b was also reported to have significant amounts of

potassium Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosphe ...

in its upper atmosphere, but the detection of potassium was refuted in 2015. The potassium detection discrepancy was resolved in 2020 with the improved cloud deck model, with the best fit being a very small amount of water over clouds and no potassium at all. Reanalysis of planetary spectroscopic data in 2020 has revealed the presence of

chromium monohydride Chromium(I) hydride, systematically named chromium hydride, is an inorganic compound with the chemical formula (also written as or CrH). It occurs naturally in some kinds of stars where it has been detected by its spectrum. However, molecular c ...

besides water.

References

External links

{{Sky, 11, 17, 45.0, -, 19, 03, 17 Exoplanets discovered by WASP Exoplanets discovered in 2010 Giant planets Hot Jupiters Crater (constellation)

Characteristics

See also

References

External links