WISE 2150–7520 AB (abbreviated W2150AB) is a binary brown dwarf 78.9

light-years A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astro ...

distant from Earth in the southern constellation

Octans Octans is a faint constellation located in the deep southern celestial hemisphere, Southern Sky. Its name is Latin for the eighth part of a circle, but it is named after the octant (instrument), octant, a navigational instrument. Devised by kingd ...

. The system is a wide binary with a separation of 341

astronomical units The astronomical unit (symbol: au or AU) is a unit of length defined to be exactly equal to . Historically, the astronomical unit was conceived as the average Earth-Sun distance (the average of Earth's aphelion and perihelion), before its mode ...

. The primary of the system was discovered in 2005 as an

infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...

object with high

proper motion Proper motion is the astrometric measure of changes in the apparent places of stars or other celestial objects as they move relative to the center of mass of the Solar System. It is measured relative to the distant stars or a stable referenc ...

and in 2008 was found to be an ultracool dwarf with a spectral type of L. The secondary, a much cooler

T dwarf An object with the spectral type T (also called T dwarf or methane brown dwarf) is either a brown dwarf or young free-floating planetary-mass object. A directly imaged exoplanet with a young age can also be a T-dwarf. T dwarfs are colder than L ...

, was discovered by volunteers of the

citizen science The term citizen science (synonymous to terms like community science, crowd science, crowd-sourced science, civic science, participatory monitoring, or volunteer monitoring) is research conducted with participation from the general public, or am ...

project Backyard Worlds: Planet 9, using data from the

Wide-field Infrared Survey Explorer Wide-field Infrared Survey Explorer (WISE, List of observatory codes, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy Space observatory, space telescope in the Explorers Program launched in December 2009.. . WISE L ...

(WISE). The system was followed up by the project scientists with

Magellan Ferdinand Magellan ( – 27 April 1521) was a Portuguese people, Portuguese explorer best known for having planned and led the Magellan expedition, 1519–22 Spanish expedition to the East Indies. During this expedition, he also discovered t ...

and Spitzer and a scientific paper describing the binary was published in the

Astrophysical Journal ''The Astrophysical Journal'' (''ApJ'') is a peer-reviewed scientific journal of astrophysics and astronomy, established in 1895 by American astronomers George Ellery Hale and James Edward Keeler. The journal discontinued its print edition and ...

in 2020. The system belongs to only a few brown dwarf binaries that can be easily resolved by ground-based

telescope A telescope is a device used to observe distant objects by their emission, Absorption (electromagnetic radiation), absorption, or Reflection (physics), reflection of electromagnetic radiation. Originally, it was an optical instrument using len ...

s. Another example is

SDSS J1416+1348 SDSS may refer to: * Sloan Digital Sky Survey, a major multi-filter imaging and spectroscopic redshift survey * Social Democratic Party of Slovakia * Spatial Decision Support System, a GIS based decision aiding system * Independent Democratic Serb ...

Brown dwarf system

The system consists out of a L1 primary with a

mass Mass is an Intrinsic and extrinsic properties, intrinsic property of a physical body, body. It was traditionally believed to be related to the physical quantity, quantity of matter in a body, until the discovery of the atom and particle physi ...

of and a T8 secondary with a mass of . The brown dwarfs are separated by 341

. Other brown dwarfs show a similar wide binary configuration, like Oph 162225-240515, but most of them are young or have a higher total mass. W2150AB is unusual as it does not show signs of youth. The age of the system was estimated between 0.5 and 10

billion years A year is a unit of time based on how long it takes the Earth to orbit the Sun. In scientific use, the tropical year (approximately 365 solar days, 5 hours, 48 minutes, 45 seconds) and the sidereal year (about 20 minutes longer) are more exa ...

. The combination of low total mass and large separation results in a low

gravitational binding energy The gravitational binding energy of a system is the minimum energy which must be added to it in order for the system to cease being in a gravitationally bound state. A gravitationally bound system has a lower (''i.e.'', more negative) gravitatio ...

for the system. The researchers compared the binding energy and the mass ratio of the system with other brown dwarf binaries and found

2M1101AB M11 or M-11 may refer to: Aviation * Miles M.11 Whitney Straight, a 1936 two-seater light aircraft * Shvetsov M-11, an aircraft engine produced in the Soviet Union Science * Messier 11 (M11), an open star cluster also known as the Wild Duck Cl ...

as a younger sibling. W2150AB must have formed like other brown dwarf binaries in a more crowded region and left this natal region surviving any interactions with nearby

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

s or giant

molecular cloud A molecular cloud—sometimes called a stellar nursery if star formation is occurring within—is a type of interstellar cloud of which the density and size permit absorption nebulae, the formation of molecules (most commonly molecular hydrogen, ...

s that could easily perturb this pair, leaving only two single brown dwarfs.

Gallery

File:W2150AB.jpg, Image of the system taken with the

Spitzer Space Telescope The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003, that was deactivated when operations ended on 30 January 2020. Spitzer was the third space telescope dedicate ...

File:WISE2150-7520-B2.jpg, Artist's impression of the WISE 2150–7520 (W2150AB) system. The colder secondary W2150B is seen in front of the image over the

Milky Way The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the #Appearance, galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galax ...

. The primary W2150A is seen as a bright star to the right of W2150B. Credit:

SpaceEngine SpaceEngine is an interactive 3D planetarium and astronomy software initially developed by Russian astronomer and programmer Vladimir Romanyuk. Development is now continued by Cosmographic Software, an American company founded by Romanyuk and th ...

PRO, Kvasyrr

References

External links

W2150AB in wiseview
tool created by Backyard Worlds volunteers
W2150B
in The Extrasolar Planets Encyclopaedia {{DEFAULTSORT:W2150AB Octans Brown dwarfs Binary stars L-type brown dwarfs T-type brown dwarfs J215018.25-752039.7 WISE objects

Brown dwarf system

Gallery

See also

References

External links