WASP-18b
Encyclopedia
WASP-18b is an extrasolar planet
that is notable for having an orbital period of less than one day. It has a mass equal to 10 Jupiter mass
es, just below the boundary line between planets and brown dwarf
s, about 13 Jupiter masses. Due to tidal deceleration, it is expected to spiral towards and eventually merge with its host star, WASP-18
, in less than a million years. The planet is approximately 3.1 million kilometres (1.9 million miles) from its star, which is about 325 light years
from Earth. It was discovered by Coel Hellier, a professor of astrophysics at Keele University
in England.
Scientists at Keele and at the University of Maryland
are working to understand whether the discovery of this planet so shortly before its expected demise (with less than 0.1% of its lifetime remaining) was fortuitous, or whether tidal dissipation by WASP-18 is actually much less efficient than astrophysicists typically assume. Observations made over the next decade should yield a measurement of the rate at which WASP-18b's orbit is decaying.
The closest example of a similar situation in our own solar system is Mars
' moon, Phobos
. Phobos orbits Mars at a distance of only about 9000 km (5,592.4 mi), 40 times closer than our moon is to the Earth, and is expected to be destroyed in about eleven million years.
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...
that is notable for having an orbital period of less than one day. It has a mass equal to 10 Jupiter mass
Jupiter mass
Jupiter mass , is the unit of mass equal to the total mass of the planet Jupiter . Jupiter mass is used to describe masses of the gas giants, such as the outer planets and extrasolar planets. It is also used in describing brown dwarfs....
es, just below the boundary line between planets and brown dwarf
Brown dwarf
Brown dwarfs are sub-stellar objects which are too low in mass to sustain hydrogen-1 fusion reactions in their cores, which is characteristic of stars on the main sequence. Brown dwarfs have fully convective surfaces and interiors, with no chemical differentiation by depth...
s, about 13 Jupiter masses. Due to tidal deceleration, it is expected to spiral towards and eventually merge with its host star, WASP-18
WASP-18
WASP-18 is a magnitude 9 star located in the Phoenix constellation of the southern hemisphere. It has a mass of 1.25 solar masses.-Planetary system:...
, in less than a million years. The planet is approximately 3.1 million kilometres (1.9 million miles) from its star, which is about 325 light years
Light Years
Light Years is the seventh studio album by Australian recording artist Kylie Minogue. It was released on 25 September 2000 by Parlophone and Mushroom Records. The album's style was indicative of her return to "mainstream pop dance tunes"....
from Earth. It was discovered by Coel Hellier, a professor of astrophysics at Keele University
Keele University
Keele University is a campus university near Newcastle-under-Lyme in Staffordshire, England. Founded in 1949 as an experimental college dedicated to a broad curriculum and interdisciplinary study, Keele is most notable for pioneering the dual honours degree in Britain...
in England.
Scientists at Keele and at the University of Maryland
University of Maryland
When the term "University of Maryland" is used without any qualification, it generally refers to the University of Maryland, College Park.University of Maryland may refer to the following:...
are working to understand whether the discovery of this planet so shortly before its expected demise (with less than 0.1% of its lifetime remaining) was fortuitous, or whether tidal dissipation by WASP-18 is actually much less efficient than astrophysicists typically assume. Observations made over the next decade should yield a measurement of the rate at which WASP-18b's orbit is decaying.
The closest example of a similar situation in our own solar system is Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
' moon, Phobos
Phobos (moon)
Phobos is the larger and closer of the two natural satellites of Mars. Both moons were discovered in 1877. With a mean radius of , Phobos is 7.24 times as massive as Deimos...
. Phobos orbits Mars at a distance of only about 9000 km (5,592.4 mi), 40 times closer than our moon is to the Earth, and is expected to be destroyed in about eleven million years.