WASP-19b, formally named Banksia, is an

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first det ...

, notable for possessing one of the shortest orbital periods of any known planetary body: days or approximately 18.932 hours. It has a mass close to 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 Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...

(1.15 Jupiter masses), but by comparison has a much larger radius (1.31 times that of Jupiter, or 0.13

Solar radii Solar may refer to: Astronomy * Of or relating to the Sun ** Solar telescope, a special purpose telescope used to observe the Sun ** A device that utilizes solar energy (e.g. "solar panels") ** Solar calendar, a calendar whose dates indicat ...

); making it nearly the size of a low-mass star. It orbits the star WASP-19 in the Vela constellation. At the time of discovery it was the shortest period

hot Jupiter Hot Jupiters (sometimes called hot Saturns) are a class of gas giant exoplanets that are inferred to be physically similar to Jupiter (i.e. Jupiter analogue, Jupiter analogues) but that have very short orbital periods (). The close proximity to t ...

discovered as planets with shorter orbital periods had a rocky, or metallic composition. A study in 2012, utilizing the Rossiter–McLaughlin effect, determined the planetary orbit is well aligned with the equatorial plane of the star, misalignment equal to -15°. In 2013, secondary eclipse and orbital phases were barely observed from the data gathered with ASTEP telescope, making it the first detection of such kind through ground-based observations. This was possible due to the large size of the planet and its small

semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longe ...

. In 2019 the planet was observed with TESS and the eclipse of the planet was measured. The broad variations caused by the changing aspect of the heated face of the planet were measured. The study deduced that the dayside has a temperature of 2240 ± 40 K (1967 ± 40 °C) and that the planet reflects 16 ± 4 percent of the light that falls on it. The last value is relatively high compared to other planets. Despite the short orbital period, orbital decay of WASP-19b was not detected as of 2019.

Nomenclature

In August 2022, this planet and its host star were included among 20 systems to be named by the third NameExoWorlds project. The approved names, proposed by a team from Brandon Park Primary School in Wheelers Hill (

Melbourne Melbourne ( , ; Boonwurrung language, Boonwurrung/ or ) is the List of Australian capital cities, capital and List of cities in Australia by population, most populous city of the States and territories of Australia, Australian state of Victori ...

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

), led by scientist Lance Kelly and teacher David Maierhofer were announced in June 2023. WASP-19b is named Banksia and its host star is named Wattle, after the '' Banksia'' and wattle plants.

Atmosphere

In December 2013, scientists working with the

Hubble Space Telescope The Hubble Space Telescope (HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the Orbiting Solar Observatory, first space telescope, but it is one of the largest and most ...

reported detecting

water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...

in the

atmosphere An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

of the

. In September 2017, astronomers using the

Very Large Telescope The Very Large Telescope (VLT) is an astronomical facility operated since 1998 by the European Southern Observatory, located on Cerro Paranal in the Atacama Desert of northern Chile. It consists of four individual telescopes, each equipped with ...

at the

European Southern Observatory The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental organization, intergovernmental research organisation made up of 16 m ...

reported the detection of titanium oxide (TiO) in WASP-19b's atmosphere. This was the first time titanium oxide had been detected in an exoplanet atmosphere. They also detected a strongly scattering haze in the atmosphere as well as the element

sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...

, and additionally confirmed the presence of water. Strong haze and barely discernible titanium oxide signal were confirmed in 2021, while no sign of water or alkali metals can be found. A study using TESS data concluded that the atmosphere of WASP-19b is moderately efficient at transporting heat from the dayside to the nightside. Clear to cloudy hot Jupiters

References

External links

{{DEFAULTSORT:WASP-19b Exoplanets discovered by WASP Exoplanets discovered in 2009 Giant planets Hot Jupiters Transiting exoplanets Vela (constellation) Exoplanets with proper names