2MASS J0441+2301

2MASS J0441+2301 (abbreviated as 2M 0441+23) is a young quadruple system hosting a planetary-mass object, a red dwarf star and two brown dwarfs, approximately 470 light years (145 parsecs) away.

2MASS J0441+2301

2MASS J04414489+2301513 is a brown dwarf with a companion about 5–10 times the mass of Jupiter.
Observation data Epoch J2000      Equinox J2000
Constellation	Taurus
2MASS J04414489+2301513 (2M J044144 B)
Right ascension	04h 41m 44.898s[1]
Declination	+23° 01′ 51.39″[1]
2MASS J04414565+2301580 (2M J044145 A)
Right ascension	04h 41m 45.652s[1]
Declination	+23° 01′ 58.07″[1]
Apparent magnitude (V)	15.20[2]
Characteristics
Spectral type	M4.5[3]/M8.5[4]
Variable type	T Tau[5]
Astrometry
2MASS J04414489+2301513 (2M 044144)
Proper motion (μ)	RA: 7.918[6] mas/yr Dec.: -20.152[6] mas/yr
Parallax (π)	8.1822±0.3044 mas[6]
Distance	400 ± 10 ly (122 ± 5 pc)
2MASS J04414565+2301580 (2M 044145)
Proper motion (μ)	RA: 7.914[7] mas/yr Dec.: -22.086[7] mas/yr
Parallax (π)	8.0887 ± 0.0713 mas[7]
Distance	403 ± 4 ly (124 ± 1 pc)
Details
2MASS J04414489+2301513 (2M 044144)
Mass	19 ± 3 / 9.8 ± 1.8[3] MJup
Luminosity	0.00347 / 0.00093[3] L☉
Temperature	2100 / 1800[3] K
Age	1-3[4][3] Myr
2MASS J04414565+2301580 (2M 044145)
Mass	0.191+0.095 −0.048 M☉ / 35 ± 5[3] MJup
Luminosity	0.14 / 0.00741[3] L☉
Temperature	3400 / 2800[3] K
Age	1-3[4][3] Myr
Other designations
WDS J04417+2302AB
2MASS J04414565+2301580: ATO J070.4402+23.0326, TIC 118893901, UCAC2 39972132, UCAC4 566-011236, UGCS J044145.65+230158.0, WISE J044145.65+230157.8, WISEA J044145.65+230157.7, Gaia DR3 146487560507840768, Gaia DR2 146487560507840768
2MASS J04414489+2301513: Gaia DR3 146487556211644544, Gaia DR2 146487556211644544, UGCS J044144.89+230151.3, USNO-B1.0 1130-00071517, TIC 118893899
Database references
SIMBAD	2M J044144
	2M J044145

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 arcseconds to the northeast). 2M J044145 has similar proper motion to 2M J044144 and is likely physically associated with the system.^[8] The entire system of 4 objects is then a hierarchical quadruple of two binary objects orbiting each other.^[8] The primary component Aa has a spectral type of M4.5 and a red apparent magnitude of 14.2.^[3] Both components seem to be accreting mass from their stellar disks, as shown by their emission lines.^[3] The four objects have a total mass of only 26% of the Sun, making it the quadruple star system with the lowest mass known.^[3]

Planetary system

Artist's impression of the 2M 0441+23 system

The primary is orbited by a companion about 5–10 times the mass of Jupiter.^[9] The mass of the primary brown dwarf is roughly 20 times the mass of Jupiter and its age is roughly one million years.^[4] It is not clear whether this companion object is a sub-brown dwarf 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 from a disk around the central object.^[4] It also fails the mass ratio criterion of the IAU definition of an exoplanet; the mass ratio with the primary is closer than 1/25.^[10] It is still considered a planet by the NASA Exoplanet Archive and Extrasolar Planets Encyclopaedia though.^[11][12]

The 2MASS J04414489+2301513 planetary system^[3]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (years)	Eccentricity	Inclination	Radius
b	9.8±1.8 MJ	15±0.6	411	—	—	3.05 RJ

See also

• 2MASS
• SCR 1845−6357
• 2M1207
• HR 8799