2MASS
Encyclopedia
Observations for the Two Micron All-Sky Survey (2MASS) began in 1997 and were completed in 2001 at two telescope
s located one each in the northern
and southern hemisphere
s (Mt. Hopkins Arizona
and Cerro Tololo/CTIO
Chile
, respectively) to ensure coverage of the entire sky. The most ambitious project to map the night sky to date, the final (post-processing) data release for 2MASS occurred in 2003. The whole sky was covered using a photometric system
of three infrared
wavebands around 2 micrometre
s (
m): J (1.25 
m), H (1.65 
m), and Ks (2.17 
m).
The goals of this survey included:
This last goal has been admirably achieved. Numerical descriptions of point sources (star
s, planet
s, asteroid
s) and extended sources (galaxies
, nebula
e) were catalogued by automated computer programs to an average limiting magnitude
of about 14. More than
300 million
point sources and 1 million extended sources were catalogued.
In November 2003, a team of scientists announced the discovery of the Canis Major Dwarf Galaxy
, at that time the closest known satellite galaxy to the Milky Way, based on analysis of 2MASS stellar data.
The resulting data and images from the survey are currently in the public domain
, and may be accessed online for free by anyone. There is also a list of 2MASS science publications with links to free pre-publication copies of the papers.
2MASS is sponsored by the University of Massachusetts
(aka UMass, and the origin of the survey name), the Infrared Processing and Analysis Center (IPAC
, run by JPL
and Caltech), NASA
, and the NSF
.
Telescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...
s located one each in the northern
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
and southern hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...
s (Mt. Hopkins Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
and Cerro Tololo/CTIO
Cerro Tololo Inter-American Observatory
The Cerro Tololo Inter-American Observatory is a complex of astronomical telescopes and instruments located at 30.169 S, 70.804 W, approximately 80 km to the East of La Serena, Chile at an altitude of 2200 metres. The complex is part of the National Optical Astronomy Observatory along with Kitt...
Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
, respectively) to ensure coverage of the entire sky. The most ambitious project to map the night sky to date, the final (post-processing) data release for 2MASS occurred in 2003. The whole sky was covered using a photometric system
Photometric system
In astronomy, a Photometric system is a set of well-defined passbands , with a known sensitivity to incident radiation. The sensitivity usually depends on the optical system, detectors and filters used. For each photometric system a set of primary standard stars is provided.The first known...
of three 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...
wavebands around 2 micrometre
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...
s (
m): J (1.25 m), H (1.65 m), and Ks (2.17 m).The goals of this survey included:
- Detection of galaxiesGalaxyA galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...
in the "Zone of AvoidanceZone of AvoidanceThe Zone of Avoidance is the area of the night sky that is obscured by our own galaxy, the Milky Way.-Term:The ZOA was originally called the "Zone of Few Nebulae" in an 1878 paper by English astronomer Richard Proctor that referred to the distribution of "nebulae" in Sir John Herschel's General...
", a strip of sky obscured in visible light by our own Galaxy, the Milky WayMilky WayThe Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
. - First detection of brown dwarfBrown dwarfBrown 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...
s such as 2MASS 0939-24482MASS 0939-24482MASS 0939-2448 is probably a binary system consisting of two brown dwarfs. The object belongs to the spectral class T8, lies in the constellation Antlia and is about 17 light years away from Earth. It was identified as a brown dwarf through analysis of data from the 2MASS survey by Tinney et al....
, 2MASS 0415-09352MASS 0415-09352MASS J04151954-0935066 is a brown dwarf in the constellation Eridanus, located about 18.7 light-years from Earth. It was discovered in 2002 by Adam J. Burgasser et al. It belongs to the spectral class T8V; its surface temperature is 600-750 Kelvin. As with other brown dwarfs of spectral type T,...
, 2M12072M12072M1207, 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...
, and 2MASS J04414489+23015132MASS J04414489+23015132MASS J04414489+2301513 is a young brown dwarf approximately 450 light years away with an orbiting companion about 5-10 times the mass of Jupiter.The mass of the primary brown dwarf is roughly 20 times the mass of Jupiter and its age is roughly one million years.It is not clear whether this...
. As of 2003, 2MASS had discovered 173 brown dwarfs. - An extensive survey of low mass starStarA star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
s, the most common type of star both in our own galaxy and others. - Cataloging of all detected stars and galaxies.
This last goal has been admirably achieved. Numerical descriptions of point sources (star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
s, planet
Planet
A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
s, asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...
s) and extended sources (galaxies
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...
, nebula
Nebula
A nebula is an interstellar cloud of dust, hydrogen gas, helium gas and other ionized gases...
e) were catalogued by automated computer programs to an average limiting magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
of about 14. More than
300 million
Million
One million or one thousand thousand, is the natural number following 999,999 and preceding 1,000,001. The word is derived from the early Italian millione , from mille, "thousand", plus the augmentative suffix -one.In scientific notation, it is written as or just 106...
point sources and 1 million extended sources were catalogued.
In November 2003, a team of scientists announced the discovery of the Canis Major Dwarf Galaxy
Canis Major Dwarf Galaxy
The Canis Major Dwarf Galaxy is located in the same part of the sky as the constellation Canis Major. The galaxy contains a relatively high percentage of red giant stars, and is thought to contain an estimated one billion stars in all....
, at that time the closest known satellite galaxy to the Milky Way, based on analysis of 2MASS stellar data.
The resulting data and images from the survey are currently in the public domain
Public domain
Works are in the public domain if the intellectual property rights have expired, if the intellectual property rights are forfeited, or if they are not covered by intellectual property rights at all...
, and may be accessed online for free by anyone. There is also a list of 2MASS science publications with links to free pre-publication copies of the papers.
2MASS is sponsored by the University of Massachusetts
University of Massachusetts
This article relates to the statewide university system. For the flagship campus often referred to as "UMass", see University of Massachusetts Amherst...
(aka UMass, and the origin of the survey name), the Infrared Processing and Analysis Center (IPAC
Infrared Processing and Analysis Center
The Infrared Processing and Analysis Center is the NASA science center responsible for the data processing, analysis, and archiving of NASA's infrared astronomy and astrophysics missions...
, run by JPL
Jet Propulsion Laboratory
Jet Propulsion Laboratory is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. The facility is headquartered in the city of Pasadena on the border of La Cañada Flintridge and Pasadena...
and Caltech), NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
, and the NSF
National Science Foundation
The National Science Foundation is a United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health...
.
External links
- 2MASS at IPAC
- 2MASS at UMass
- 2MASS Science Publications
- 2MASS Atlas Image Gallery: Miscellaneous Objects
- Low-Mass Stars and Brown Dwarfs in 2MASS
- Wikipedia :Category:2MASS objects