2MASS J11263991−5003550 (2MASS J1126−5003) is a

brown dwarf Brown dwarfs are substellar objects that have more mass than the biggest gas giant planets, but less than the least massive main sequence, main-sequence stars. Their mass is approximately 13 to 80 Jupiter mass, times that of Jupiter ()not big en ...

about 53

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. The brown dwarf is notable for an unusual blue

near-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 of ...

color. This brown dwarf does not show

subdwarf A subdwarf, sometimes denoted by "sd", is a star with luminosity class VI under the Yerkes spectral classification system. They are defined as stars with luminosity 1.5 to 2 magnitudes lower than that of main-sequence stars of the same ...

features and the blue color cannot be explained by an unresolved

binary Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two values (0 and 1) for each digit * Binary function, a function that takes two arguments * Binary operation, a mathematical op ...

. Instead the blue color is explained by patchy

cloud In meteorology, a cloud is an aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles, suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may ...

s. The patchy cloud model allows thick clouds and a cloud coverage of 50% to explain the spectra of 2MASS J1126−5003. Other blue L-dwarfs exist, but are quite rare. 2MASS J1126−5003 has a deep

water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...

(H₂O) absorption feature in its spectra, which is comparable with late L-dwarfs and early T-dwarfs. It also shows weak

carbon monoxide Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...

(CO) features. It lacks any

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth makes ...

(CH₄) feature and is therefore not a T-dwarf. Based on near-infrared spectra this brown dwarf was therefore classified as an L9 spectral type brown dwarf. The optical spectrum is on the other hand more similar to a mid-type L-dwarf. Here a spectral type of L4.5 fits the optical spectrum. This optical spectral type is a more reliable estimate as the near-infrared spectrum does not fit spectra from other L-dwarfs. Lower

metallicity In astronomy, metallicity is the Abundance of the chemical elements, abundance of Chemical element, elements present in an object that are heavier than hydrogen and helium. Most of the normal currently detectable (i.e. non-Dark matter, dark) matt ...

and higher

surface gravity The surface gravity, ''g'', of an astronomical object is the gravitational acceleration experienced at its surface at the equator, including the effects of rotation. The surface gravity may be thought of as the acceleration due to gravity experi ...

might play a role in the formation of the weather on 2MASS J1126−5003. Lower metallicity reduces the available metal species to form cloud condensates. The higher surface gravity might cause an increased

sedimentation Sedimentation is the deposition of sediments. It takes place when particles in suspension settle out of the fluid in which they are entrained and come to rest against a barrier. This is due to their motion through the fluid in response to th ...

of cloud condensates, resulting in thinner clouds. Other factors, like

rotation Rotation or rotational/rotary motion is the circular movement of an object around a central line, known as an ''axis of rotation''. A plane figure can rotate in either a clockwise or counterclockwise sense around a perpendicular axis intersect ...

, vertical

upwelling Upwelling is an physical oceanography, oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water from deep water towards the ocean surface. It replaces the warmer and usually nutrient-depleted sur ...

and

magnetic field A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular ...

s might play a role as well. Previously one suggested scenario were thinner clouds. This brown dwarf shows variations in the J-band and at mid-infrared wavelengths with a period of 3.2 ± 0.3 hours. This is a clear indication of patchy clouds.

References

Centaurus L-type brown dwarfs Brown dwarfs J11263991−5003550 {{Centaurus