2M1207
Encyclopedia
2M1207, 2M1207A or 2MASS J12073346-3932539 is a brown dwarf
located in the constellation
Centaurus
; a companion object, 2M1207b
, 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
infrared
sky survey: hence the "2M" in its name, followed by its celestial coordinates. With a fairly early (for a brown dwarf) spectral type
of M8, it is very young, and probably a member of the TW Hydrae
association. Its estimated mass is around 25 Jupiter
masses. The companion, 2M1207b, is estimated to have a mass of 3–10 Jupiter masses. 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 Eric Mamajek reported a more accurate distance (53 ± 6 parsecs) to 2M1207 using the moving cluster method
. 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
or 172 ± 3 light years
.
Like classical T Tauri stars, many brown dwarfs are surrounded by disks of gas and dust
which accrete onto the brown dwarf. 2M1207 was first suspected to have such a disk because of its broad Hα line. This was later confirmed by ultraviolet
spectroscopy
. The existence of a dust disk has also been confirmed by infrared
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
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
(VLT) at the European Southern Observatory
. Material in the jets streams into space at a few kilometers per second.
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...
located in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Centaurus
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.-Stars:...
; a companion object, 2M1207b
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
2MASS
Observations for the Two Micron All-Sky Survey began in 1997 and were completed in 2001 at two telescopes located one each in the northern and southern hemispheres to ensure coverage of the entire sky...
infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
sky survey: hence the "2M" in its name, followed by its celestial coordinates. With a fairly early (for a brown dwarf) spectral type
Stellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...
of M8, it is very young, and probably a member of the TW Hydrae
TW Hydrae
TW Hydrae is an orange dwarf star approximately 176 light-years away in the constellation of Hydra . The star is the closest T Tauri star to the Solar System. TW Hydrae is similar in mass to the Sun, but is only about 5-10 million years old...
association. Its estimated mass is around 25 Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
masses. The companion, 2M1207b, is estimated to have a mass of 3–10 Jupiter masses. 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 Eric Mamajek reported a more accurate distance (53 ± 6 parsecs) to 2M1207 using the moving cluster method
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 the 1900s to determine distance...
. The new distance gives a fainter luminosity
Luminosity
Luminosity is a measurement of brightness.-In photometry and color imaging:In photometry, luminosity is sometimes incorrectly used to refer to luminance, which is the density of luminous intensity in a given direction. The SI unit for luminance is candela per square metre.The luminosity function...
for 2M1207. Recent trigonometric parallax
Parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines. The term is derived from the Greek παράλλαξις , meaning "alteration"...
results have confirmed this moving cluster distance, leading to a distance estimate of 53 ± 1 parsec
Parsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
or 172 ± 3 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"....
.
Like classical T Tauri stars, many brown dwarfs are surrounded by disks of gas and dust
Protoplanetary disk
A protoplanetary disk is a rotating circumstellar disk of dense gas surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star...
which accrete onto the brown dwarf. 2M1207 was first suspected to have such a disk because of its broad Hα line. This was later confirmed by ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
spectroscopy
Spectroscopy
Spectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative...
. The existence of a dust disk has also been confirmed by infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
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
Astrophysical Journal
The Astrophysical Journal is a peer-reviewed scientific journal covering astronomy and astrophysics. It was founded in 1895 by the American astronomers George Ellery Hale and James Edward Keeler. It publishes three 500-page issues per month....
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
Very Large Telescope
The Very Large Telescope is a telescope operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. The VLT consists of four individual telescopes, each with a primary mirror 8.2m across, which are generally used separately but can be used together to...
(VLT) at the European Southern Observatory
European Southern Observatory
The European Southern Observatory is an intergovernmental research organisation for astronomy, supported by fifteen countries...
. Material in the jets streams into space at a few kilometers per second.
See also
- Direct imaging of extrasolar planets
- List of extrasolar planets
External links
- Space.com - Astronomers Confident: Planet Beyond Solar System Has Been Photographed
- Space.com article on the discovery
- "A Giant Planet Candidate Near a Young Brown Dwarf" (PDF) from the European Southern ObservatoryEuropean Southern ObservatoryThe European Southern Observatory is an intergovernmental research organisation for astronomy, supported by fifteen countries...
. - "A Moving Cluster Distance to the Exoplanet 2M1207b in the TW Hydrae Association"