Beta Pictoris moving group

The Beta Pictoris Moving Group is a young moving group located relatively near Earth. A moving group, in astronomy, is a group of stars that share a common motion through space as well as a common origin.

The Beta Pictoris Moving Group is an important object for astronomical study due to its relative proximity to the Solar System as well as the young age of its component stars in terms of stellar evolution. The star Beta Pictoris is known to have a large disk of gas and dust, possibly a protoplanetary disk. There is also some evidence of a young gas giant planet around the star. [ [http://www.extrasolar.net/planettour.asp?StarCatId=&PlanetId=58 Extrasolar Visions - beta Pictoris b ] ]

The age and distance of the group makes it a prime candidate for the search for extrasolar planets as well as the study of how stellar systems might form.

Constituents

The Beta Pictoris Moving Group consists of 17 stellar systems, comprised of a total of 28 individual component stars, including identified brown dwarves. The core of the group is located some 115 light-years from Earth, and has an average estimated age of between 10 and 30 million years.

The majority of the group is made up of cool, dim K and M class stars. Most are not visible to the naked eye. Beta Pictoris is an important exception, however there are a few other visible components of the group, including :

*Eta Telescopii
*51 Eridanus
*HD 203
*HD 146624
*HD 165189
*HD 172555

The group covers a region of space largely confined to the Southern Hemisphere, and lies in the constellations Eridanus, Lepus, Pictor, Scorpius, and Telescopium.

Discovery

An early estimated age for the star Beta Pictoris at about 10 million years proved problematic due to the star's apparent isolation in space. According to current theory regarding stellar evolution, extremely young stars of this age should be located near other young stars that formed from the same region in space. It is not until significantly later that gravitational interactions with other stars causes stellar 'siblings' to disperse.

It was not until 1999 that the situation was resolved by the discovery of a pair of dim red dwarf stars were discovered to have a similar velocity and age to β Pictoris, lending credence to the estimated age of the star. [cite journal|author = Barrado y Navascués, David; Stauffer, John R.; Song, Inseok; Caillault, J.-P.|title = The Age of beta Pictoris|journal = The Astrophysical Journal|date = August 1 1999|volume = 520|issue = 2|pages = L123–L126|url = http://adsabs.harvard.edu/abs/1999ApJ...520L.123B|accessdate = 2007-05-14|doi = 10.1086/312162]

Further work published in 2001 identified a total of 17 stellar systems with a similar motion and age as the Beta Pictoris moving group, named for the primary member of the association. [http://www.journals.uchicago.edu/doi/full/10.1086/337968]

References