AB Pictoris (abbreviated AB Pic, also catalogued as HD 44627) is a K-type

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

, approximately 163

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s away in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Pictor Pictor is a constellation in the Southern Celestial Hemisphere, located between the star Canopus and the Large Magellanic Cloud. Its name is Latin for Painting, painter, and is an abbreviation of the older name Equuleus Pictoris (the "painter's ...

. It has been identified as a member of the young (30 million years old) Tucana–Horologium association.New Members of the TW Hydrae Association, β Pictoris Moving Group, and Tucana/Horologium Association, Inseok Song, B. Zuckerman, and M. S. Bessell, ''The Astrophysical Journal'' 599, #1 (December 2003), pp. 342–350, , . The star has also been classified as a

BY Draconis variable BY Draconis variables are variable stars of late spectral types, usually K or M, and typically belong to the main sequence. The name comes from the archetype for this category of variable star system, BY Draconis. They exhibit variations in the ...

. In 2005 it was announced that an astronomical object (AB Pictoris b, abbreviated AB Pic b) had been imaged in 2003 and 2004 close to and apparently in orbit around the star. Its mass suggests that it is at the borderline between being a

brown dwarf Brown dwarfs (also called failed stars) are substellar objects that are not massive enough to sustain nuclear fusion of ordinary hydrogen ( 1H) into helium in their cores, unlike a main-sequence star. Instead, they have a mass between the most ...

or a

planet A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...

Possible planetary system

In 2003 and 2004, an object (now catalogued as ''AB Pictoris b'') was observed close to the star by a team of astronomers 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 mem ...

. Since it had

common proper motion This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of celestial objects and phenomena that originate outsid ...

with AB Pictoris, it was concluded that it was physically close to the star. Its

spectral type In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction grati ...

was estimated as between L0V and L3V. Using evolutionary models, its mass was estimated as from 13 to 14

Jupiter masses Jupiter mass, also called Jovian mass, is the unit of mass equal to the total mass of the planet Jupiter. This value may refer to the mass of the planet alone, or the mass of the entire Jovian system to include the moons of Jupiter. Jupiter is b ...

.A companion to AB Pic at the planet/brown dwarf boundary, G. Chauvin, A.-M. Lagrange, B. Zuckerman, C. Dumas, D. Mouillet, I. Song, J.-L. Beuzit, P. Lowrance, and M. S. Bessell, ''Astronomy and Astrophysics'' 438, #3 (August 2005), pp. L29–L32, , , . However, because modelling such young objects is difficult, this estimate is very uncertain; some models give masses as low as 11 Jupiter masses or as high as 70 Jupiter masses. Temperature estimates range from 1600 K to 2400 K.Homogeneous comparison of directly detected planet candidates: GQ Lup, 2M1207, AB Pic, Ralph Neuhaeuser, ''ESO Workshop Proceedings on Multiple Stars'', , . As it is not known if the mass of the object exceeds the

deuterium burning Deuterium fusion, also called deuterium burning, is a nuclear fusion reaction that occurs in stars and some substellar objects, in which a deuterium nucleus and a proton combine to form a helium-3 nucleus. It occurs as the second stage of the p ...

limit of 13 Jupiter masses, it is not clear whether the object should be classified as an

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 ...

or a

. The planetary orbit is significantly misaligned with its spin axis orientation (obliquity), possibly due to gravitational interactions with the additional inner planet.

References

External links

* * Homogeneous comparison of directly detected planet candidates: GQ Lup, 2M1207, AB Pic, Ralph Neuhaeuser, ''ESO Workshop Proceedings on Multiple Stars'', , . * {{DEFAULTSORT:AB Pictoris K-type main-sequence stars Pictor (constellation) 030034 044627 Pictoris, AB CD-58 01409 BY Draconis variables Planetary systems with one confirmed planet

Possible planetary system

See also

References

External links