2M1207b is a planetary-mass object orbiting the

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 ...

2M1207, 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. ...

, approximately 170

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distance, astronomical distances and is equivalent to about 9.46 Orders of magnitude (numbers)#1012, trillion kilometers (), or 5.88 ...

s from Earth."The Distance to the 2M1207 System"
, Eric Mamajek, November 8, 2007. Accessed on line June 15, 2008. It is one of the first candidate

exoplanet 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 ...

s to be directly observed (by

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

imaging). It was discovered in April 2004 by 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 Paranal Observatory in

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the eas ...

by a team from 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 research organisation made up of 16 member states for ground-based ast ...

led by Gaël Chauvin.A giant planet candidate near a young brown dwarf. Direct VLT/NACO observations using IR wavefront sensing, G. Chauvin, A.-M. Lagrange, C. Dumas, B. Zuckerman, D. Mouillet, I. Song, J.-L. Beuzit, P. Lowrance, ''Astronomy and Astrophysics'', 425 (October 2004), pp. L29–L32. . It is believed to be from 3 to 10 times the

mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different ele ...

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-thousand ...

and may orbit 2M1207 at a distance roughly as far from the brown dwarf as

Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the S ...

is from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

.Star: 2M1207
, ''Extrasolar Planets Encyclopaedia''. Accessed on line June 15, 2008. The object is a very hot

gas giant A gas giant is a giant planet composed mainly of hydrogen and helium. Gas giants are also called failed stars because they contain the same basic elements as a star. Jupiter and Saturn are the gas giants of the Solar System. The term "gas giant" ...

; the estimated surface

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

is roughly 1600 K (1300 °C or 2400 °F), mostly due to gravitational contraction.The Planetary Mass Companion 2MASS 1207-3932B: Temperature, Mass, and Evidence for an Edge-on Disk, Subhanjoy Mohanty, Ray Jayawardhana, Nuria Huelamo, and Eric Mamajek, ''Astrophysical Journal'' 657, #2 (March 2007), pp. 1064–1091. . Its

is well below the calculated limit for deuterium fusion in brown dwarfs, which is 13

Jupiter mass 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 by ...

es. The projected

distance Distance is a numerical or occasionally qualitative measurement of how far apart objects or points are. In physics or everyday usage, distance may refer to a physical length or an estimation based on other criteria (e.g. "two counties over"). ...

between 2M1207b and its primary is around 40 AU (similar to the mean distance between

and the

).Estimated observed projected separation from observed angular separation and estimated distance. Its

spectrum indicates the presence of

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...

molecules in its atmosphere. The object is not a likely candidate to support

life Life is a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from that which does not, and is defined by the capacity for growth, reaction to stimuli, metabolism, energy ...

, either on its surface or on any

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioiso ...

Catalog views: Aladin Lite

DSS colorDSS near IRsDSS red (high res)

Discovery and identification

2M1207b is around 100 times fainter in the sky than its companion. It was first spotted as a "faint reddish speck of light" in 2004 by the VLT. After the initial observation, there was some question as to whether the objects might be merely an

optical double In observational astronomy, a double star or visual double is a pair of stars that appear close to each other as viewed from Earth, especially with the aid of optical telescopes. This occurs because the pair either forms a binary star (i.e. a bi ...

, but subsequent observations by the ''

Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most vers ...

'' and the VLT have shown that the objects move together and are therefore presumably a

binary system A binary system is a system of two astronomical bodies which are close enough that their gravitational attraction causes them to orbit each other around a barycenter ''(also see animated examples)''. More restrictive definitions require that th ...

.Yes, it is the Image of an Exoplanet: Astronomers Confirm the First Image of a Planet Outside of Our Solar System
ESO Press Release 12/05, April 30, 2005,

. Accessed on line July 10, 2010. An initial photometric estimate for the distance to 2M1207b was 70

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 ...

s. In December 2005, American astronomer Eric Mamajek reported a more accurate distance (53 ± 6 parsecs) to 2M1207b using the moving-cluster method. Recent trigonometric

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. Due to foreshortening, nearby object ...

results have confirmed this moving-cluster distance, leading to a distance estimate of 52.75 parsecs 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 ...

Properties

Estimates for the mass, size, and temperature of 2M1207b are still uncertain. Although spectroscopic evidence is consistent with a mass of 8 ± 2 Jupiter masses and a surface temperature of 1600 ± 100

kelvin The kelvin, symbol K, is the primary unit of temperature in the International System of Units (SI), used alongside its prefixed forms and the degree Celsius. It is named after the Belfast-born and University of Glasgow-based engineer and ...

s, theoretical models for such an object predict a

luminosity Luminosity is an absolute measure of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object over time. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a st ...

10 times greater than observed. Because of this, lower estimates for the mass and temperature have been proposed. Alternatively, 2M1207b might be dimmed by a surrounding disk of dust and gas. As an unlikely possibility, Mamajek and Michael Meyer have suggested that the planet is actually much smaller, but is radiating away heat generated by a recent collision. Although the mass of 2M1207b is less than that required for deuterium fusion to occur, some 13 times the mass of Jupiter, and the image of 2M1207b has been widely hailed as the first direct image of an exoplanet, it may be questioned whether 2M1207b is actually a planet. Some definitions of the term ''planet'' require a planet to have formed in the same way as the planets in the

Solar System The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...

did, by secondary accretion in a

protoplanetary disk A protoplanetary disk is a rotating circumstellar disc of dense gas and dust surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star. The protoplanetary disk may also be considered an accretion disk for the star itself, be ...

. With such a definition, if 2M1207b formed by direct

gravitational collapse Gravitational collapse is the contraction of an astronomical object due to the influence of its own gravity, which tends to draw matter inward toward the center of gravity. Gravitational collapse is a fundamental mechanism for structure formatio ...

of a gaseous

nebula A nebula ('cloud' or 'fog' in Latin; pl. nebulae, nebulæ or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regio ...

, it would be a

sub-brown dwarf A sub-brown dwarf or planetary-mass brown dwarf is an astronomical object that formed in the same manner as stars and brown dwarfs (i.e. through the collapse of a gas cloud) but that has a planetary mass, therefore by definition below the limi ...

rather than a planet. A similar debate exists regarding the identity of

GQ Lupi b GQ Lupi b, or GQ Lupi B, is a possible extrasolar planet, brown dwarf or sub-brown dwarf orbiting the star GQ Lupi. Its discovery was announced in April 2005. Along with 2M1207b, this was one of the first extrasolar planet candidates to be dir ...

, also first imaged in 2004. On the other hand, the discovery of marginal cases like Cha 110913-773444—a free-floating, planetary-mass object—raises the question of whether distinction by formation is a reliable dividing line between stars/brown dwarfs and planets. As of 2006, the

International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...

Working Group on Extrasolar Planets described 2M1207b as a "possible planetary-mass companion to a brown dwarf."Lists of Extrasolar Planets
, IAU Working Group on Extrasolar Planets, August 28, 2006. Accessed on line June 15, 2008.

References

External links

ESO Press Release 12/05:Yes, it is the Image of an Exoplanet

BBC: Planet 'seen' around distant sun

* ttp://www.space.com/scienceastronomy/planet_photo_040910.html Space.com article on the discovery*
"A Giant Planet Candidate Near a Young Brown Dwarf" (PDF)
from the

.
Space.com: Fresh Debate over First Photo of Extrasolar Planet

"A Moving Cluster Distance to the Exoplanet 2M1207 B in the TW Hydrae Association"

"The Planetary Mass Companion 2MASS 1207-3932B: Temperature, Mass, and Evidence for an Edge-on Disk"

{{DEFAULTSORT:2m1207b 2M1207 Centaurus (constellation) TW Hydrae association Giant planets Exoplanets discovered in 2004 Exoplanets detected by direct imaging

Catalog views: Aladin Lite

Discovery and identification

Properties

See also

References

External links