2MASS J0441+2301 (abbreviated as 2M 0441+23) is a young quadruple system hosting a

planetary-mass object A planetary-mass object (PMO), planemo, or planetary body (sometimes referred to as a world) is, by geophysical definition of celestial objects, any celestial object massive enough to achieve hydrostatic equilibrium, but not enough to sustain c ...

, a

red dwarf A red dwarf is the smallest kind of star on the main sequence. Red dwarfs are by far the most common type of fusing star in the Milky Way, at least in the neighborhood of the Sun. However, due to their low luminosity, individual red dwarfs are ...

star and two

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 ...

s, approximately 470

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 ...

(145

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, and ...

s) away. The 2MASS J04414489+2301513 Bab (abbreviated as 2M J044144) primary (a brown dwarf) has a large separation (12.4 arcseconds) companion, 2MASS J04414565+2301580 Aab (abbreviated as 2M J044145), which in turn has a nearby small separation substellar companion (separation of 0.23

arcsecond A minute of arc, arcminute (abbreviated as arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of a degree. Since one degree is of a turn, or complete rotation, one arcminute is of a tu ...

s to the northeast). 2M J044145 has similar

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 ...

to 2M J044144 and is likely physically associated with the system. The entire system of 4 objects is then a hierarchical quadruple of two binary objects orbiting each other. The primary component Aa has a spectral type of M4.5 and a red

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

of 14.2. Both components seem to be accreting mass from their stellar disks, as shown by their

emission line A spectral line is a weaker or stronger region in an otherwise uniform and continuous spectrum. It may result from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used ...

s. The four objects have a total mass of only 26% of the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

, making it the quadruple star system with the lowest mass known.

Planetary system

The primary is orbited by a companion about 5–10 times the mass of

Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...

. 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 companion object is 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 ...

or a planet. The companion is very large with respect to its parent and must have formed within 1 million years or so. This seems to be too big and too fast to form like a regular

planet A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets b ...

from a disk around the central object. It also fails the mass ratio criterion of the

IAU The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

definition of an exoplanet; the mass ratio with the primary is closer than 1/25. It is still considered a planet by the

NASA Exoplanet Archive The NASA Exoplanet Archive is an online astronomical exoplanet catalog and data service that collects and serves public data that support the search for and characterization of extra-solar planets (exoplanets) and their host stars. It is part of ...

and

Extrasolar Planets Encyclopaedia The Extrasolar Planets Encyclopaedia (also known as Encyclopaedia of exoplanetary systems and Catalogue of Exoplanets) is an astronomy website, founded in Paris, France at the Meudon Observatory by Jean Schneider in February 1995, which maintains ...

though.

References

* {{DEFAULTSORT:2MASS J04414489+2301513 4 Brown dwarfs Taurus (constellation) J04414489+2301513 M-type brown dwarfs Planetary systems with one confirmed planet TIC objects T Tauri stars

Planetary system

See also

References