2M1207, 2M1207A or 2MASSW J12073346–3932539 is 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 ...

located in the constellation

Centaurus Centaurus is a bright constellation in the southern sky. One of the largest constellations, Centaurus was included among the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. ...

; a companion object,

2M1207b 2M1207b is a planetary-mass object orbiting the brown dwarf 2M1207, in the constellation Centaurus, approximately 170 light-years from Earth.

, may be the first extrasolar planetary-mass companion to be directly imaged, and is the first discovered orbiting a brown dwarf. 2M1207 was discovered during the course of the

2MASS The Two Micron All-Sky Survey, or 2MASS, was an astronomical survey of the whole sky in infrared light. It took place between 1997 and 2001, in two different locations: at the U.S. Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona, and ...

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

sky survey: hence the "2M" in its name, followed by its celestial coordinates. With a fairly early (for a brown dwarf)

spectral type In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the ...

of M8, it is very young, and probably a member of the

TW Hydrae TW Hydrae is a T Tauri star approximately 196 light-years away in the constellation of Hydra (the Sea Serpent). TW Hydrae is about 80% of the mass of the Sun, but is only about 5-10 million years old. The star appears to be accreting fr ...

association. Its estimated mass is around 25

Jupiter Jupiter is the fifth planet from the Sun and the 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 slightly less than one-thousandth t ...

masses. The companion, 2M1207b, is estimated to have a mass of 3–10 Jupiter masses.Star: 2M1207
, ''Extrasolar Planets Encyclopaedia''. Accessed on line June 15, 2008. Still glowing red hot, it will shrink to a size slightly smaller than Jupiter as it cools over the next few billion years. An initial photometric estimate for the distance to 2M1207 was 70 parsecs. In December 2005, American astronomer reported a more accurate distance (53 ± 6 parsecs) to 2M1207 using the

moving cluster method In astrometry, the moving-cluster method and the closely related convergent point method are means, primarily of historical interest, for determining the distance to star clusters. They were used on several nearby clusters in the first half of th ...

. The new distance gives a fainter luminosity for 2M1207. Recent trigonometric parallax results have confirmed this moving cluster distance, leading to a distance estimate of 53 ± 1

parsec The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, an ...

or 172 ± 3

light years 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 ...

."The Distance to the 2M1207 System"
, Eric Mamajek, November 8, 2007. Accessed on line June 15, 2008.

Planetary system

Like classical

T Tauri stars T Tauri stars (TTS) are a class of variable stars that are less than about ten million years old. This class is named after the prototype, T Tauri, a young star in the Taurus star-forming region. They are found near molecular clouds and iden ...

, many brown dwarfs are surrounded by disks of gas and dust which accrete onto the brown dwarf.First Ultraviolet Spectrum of a Brown Dwarf: Evidence for H₂ Fluorescence and Accretion, John E. Gizis, Harry L. Shipman, and James A. Harvin, ''Astrophysical Journal'' 630, #1 (September 2005), pp. L89–L91. . 2M1207 was first suspected to have such a disk because of its broad H_α line. This was later confirmed by

ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation ...

spectroscopy. The existence of a dust disk has also been confirmed by

observations. In general, accretion from disks is known to produce fast-moving jets, perpendicular to the disk, of ejected material. This has also been observed for 2M1207; an April 2007 paper in the ''

Astrophysical Journal ''The Astrophysical Journal'', often abbreviated ''ApJ'' (pronounced "ap jay") in references and speech, is a peer-reviewed scientific journal of astrophysics and astronomy, established in 1895 by American astronomers George Ellery Hale and ...

'' reports that this brown dwarf is spouting jets of material from its poles. The jets, which extend around 10⁹ kilometers into space, were discovered using the

Very Large Telescope The Very Large Telescope (VLT) is a telescope facility operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. It consists of four individual telescopes, each with a primary mirror 8.2 m acro ...

(VLT) at the European Southern Observatory. Material in the jets streams into space at a few kilometers per second.Small Stars Create Big Fuss
Ker Than, May 28, 2007, space.com. Accessed on line June 15, 2008.

References

External links

Space.com - Astronomers Confident: Planet Beyond Solar System Has Been Photographed

*
"A Giant Planet Candidate Near a Young Brown Dwarf" (PDF)
from the European Southern Observatory.
"A Moving Cluster Distance to the Exoplanet 2M1207b in the TW Hydrae Association"
{{DEFAULTSORT:2M1207 M-type brown dwarfs Centaurus (constellation) TW Hydrae association Planetary systems with one confirmed planet J12073346-3932539 Free-floating substellar objects

Planetary system

See also

References

External links