UGPS J072227.51-054031.2
Encyclopedia
UGPS J072227.51-054031.2 (designation often abbreviated to UGPS 0722-05) is a brown dwarf
of late T type, located approximately 4.1 pc from Earth. The astronomical object
was discovered by Philip Lucas at the University of Hertfordshire
and announced in 2010. The discovery image was taken on 28 November 2006 by the UKIRT Infrared Deep Sky Survey
(UKIDSS) with a recovery image confirming the object's proper motion
on 2 March 2010. The reported distance is derived from the current measured parallax
of 246 milliarcseconds. The object was initially reported to be at an even closer distance of 2.9 parsecs, which would have placed it among the ten nearest stars to the Sun but later measurements revealed that the object was in fact located at a greater distance than initially thought, at 4.1 parsecs.
The object is roughly the volume of Jupiter, but is estimated to have 5-40 Jupiter mass
es (MJ). This would make it less massive than ε Indi Ba. Sub-brown dwarfs have a mass of less than about 13 Jupiter mass
es. Infrared spectra
shows the object contains water vapor and methane
and has a surface temperature of approximately 480–560 Kelvin
.
Ken Croswell
in the New Scientist
describes UGPS 0722-05 as a "dark sun" for any hypothetical observers, orbiting around such a cool brown dwarf, in their "daytime" sky.
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...
of late T type, located approximately 4.1 pc from Earth. The astronomical object
Astronomical object
Astronomical objects or celestial objects are naturally occurring physical entities, associations or structures that current science has demonstrated to exist in the observable universe. The term astronomical object is sometimes used interchangeably with astronomical body...
was discovered by Philip Lucas at the University of Hertfordshire
University of Hertfordshire
The University of Hertfordshire is a new university based largely in Hatfield, in the county of Hertfordshire, England, from which the university takes its name. It has more than 27,500 students, over 2500 staff, with a turnover of over £181m...
and announced in 2010. The discovery image was taken on 28 November 2006 by the UKIRT Infrared Deep Sky Survey
UKIRT Infrared Deep Sky Survey
The UKIRT Infrared Deep Sky Survey or UKIDSS is an astronomical survey conducted using the WFCAM wide field camera on the United Kingdom Infrared Telescope on Mauna Kea in Hawaii...
(UKIDSS) with a recovery image confirming the object's proper motion
Proper motion
The proper motion of a star is its angular change in position over time as seen from the center of mass of the solar system. It is measured in seconds of arc per year, arcsec/yr, where 3600 arcseconds equal one degree. This contrasts with radial velocity, which is the time rate of change in...
on 2 March 2010. The reported distance is derived from the current measured 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"...
of 246 milliarcseconds. The object was initially reported to be at an even closer distance of 2.9 parsecs, which would have placed it among the ten nearest stars to the Sun but later measurements revealed that the object was in fact located at a greater distance than initially thought, at 4.1 parsecs.
The object is roughly the volume of Jupiter, but is estimated to have 5-40 Jupiter mass
Jupiter mass
Jupiter mass , is the unit of mass equal to the total mass of the planet Jupiter . Jupiter mass is used to describe masses of the gas giants, such as the outer planets and extrasolar planets. It is also used in describing brown dwarfs....
es (MJ). This would make it less massive than ε Indi Ba. Sub-brown dwarfs have a mass of less than about 13 Jupiter mass
Jupiter mass
Jupiter mass , is the unit of mass equal to the total mass of the planet Jupiter . Jupiter mass is used to describe masses of the gas giants, such as the outer planets and extrasolar planets. It is also used in describing brown dwarfs....
es. Infrared spectra
Infrared spectroscopy
Infrared spectroscopy is the spectroscopy that deals with the infrared region of the electromagnetic spectrum, that is light with a longer wavelength and lower frequency than visible light. It covers a range of techniques, mostly based on absorption spectroscopy. As with all spectroscopic...
shows the object contains water vapor and methane
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...
and has a surface temperature of approximately 480–560 Kelvin
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...
.
Ken Croswell
Ken Croswell
Ken Croswell is an astronomer and author living in Berkeley, California. His first degree mixed science and wider interests, majoring in physics and minoring in English literature. He also got a PhD in astronomy for studying the Milky Way's halo....
in the New Scientist
New Scientist
New Scientist is a weekly non-peer-reviewed English-language international science magazine, which since 1996 has also run a website, covering recent developments in science and technology for a general audience. Founded in 1956, it is published by Reed Business Information Ltd, a subsidiary of...
describes UGPS 0722-05 as a "dark sun" for any hypothetical observers, orbiting around such a cool brown dwarf, in their "daytime" sky.