Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Fornax |
Right ascension | 03h 39m 35.252s [1] |
Declination | –35° 25′ 43.64″ [1] |
Apparent magnitude (V) | 18.69 |
Characteristics | |
Spectral type | M9β [2] |
Apparent magnitude (g) | 19.7263±0.0083 [3] |
Apparent magnitude (r) | 17.1191±0.0010 [3] |
Apparent magnitude (i) | 16.8189±0.0014 [3] |
Apparent magnitude (z) | 15.6215±0.0011 [3] |
Apparent magnitude (Y) | 14.5973±0.0014 [3] |
Apparent magnitude (J) | 10.725±0.021 [4] |
Apparent magnitude (H) | 10.017±0.021 [4] |
Apparent magnitude (K) | 9.548±0.023 [4] |
Astrometry | |
Radial velocity (Rv) | 7.43±0.72 [2] km/s |
Proper motion (μ) | RA: 309.001(50) mas/yr [1] Dec.: 269.058(64) mas/yr [1] |
Parallax (π) | 155.5982 ± 0.0522 mas [1] |
Distance | 20.961 ± 0.007 ly (6.427 ± 0.002 pc) |
Absolute magnitude (MV) | 20.02 |
Details [5] | |
Mass | 29.62±16.67 [2] MJup |
Temperature | 2,650 ± 30 K (2,376.8 ± 30.0 °C; 4,310.3 ± 54.0 °F) K |
Rotation | 3.8291±0.0084 h [6] |
Rotational velocity (v sin i) | 28±4 km/s |
Age | 320 ±80 million years |
Other designations | |
LP 944-20, SIPS J0339−3525, LEHPM 3451, 2MASSI J0339352−352544, [B2006] J033935.2−352544, APMPM J0340−3526, 2MASS J03393521-3525440, 2MASSW J0339352−352544, BRI B0337−3535, BRI 0337−3535, 2MUCD 10201, Gaia DR2 4860376345833699840 | |
Database references | |
SIMBAD | data |
Location of LP 944-20 in the constellation Fornax |
LP 944-20 is a dim brown dwarf of spectral class M9 located 21 light-years from the Solar System in the constellation of Fornax. With a visual apparent magnitude of 18.69, it has one of the dimmest visual magnitudes listed on the RECONS page. It is one of the brightest brown dwarfs, if not the brightest at JMKO=10.68±0.03 mag. [7]
LP 944-20 was discovered in the Luyten-Palomar Survey. It appears as a star with R=17.5 mag with a proper motion of 334 mas/yr in a catalog from 1979. [8] It was however first published in 1975 by Luyten & Kowal. [9] [10] It was re-discovered in the APM survey, a quasar survey, in which the red color was noticed. The first spectrum was published in 1997 by Kirkpatrick, Henry & Irwin. A spectral type of M9 or later was assigned in this work and a distance of around 5 parsec was established thanks to the parallax being measured. [10] In 1998 Tinney discovered that this M-dwarf shows the 6708 Å Lithium absorption line and H-alpha emission line, which helped to constrain the age to around 500 million years and established it as a brown dwarf with a mass of around 60 MJ. [11]
Short after LP 944-20 was established as a brown dwarf, the fast rotation was detected in 1998. [12] Later a work in 1999 claimed to have detected variability in LP 944-20. [13] A search for dust around LP 944-20 has shown that it has no disk. [14]
Due to short rotational period, this young brown dwarf is displaying strong and frequent X-ray flares, and possessing a strong magnetic field reaching 135 G at the photosphere level. [5] On 15 December 1999, an X-ray flare was detected. [15] [16] On 27 July 2000, radio emission (in flare and quiescence) was detected from this brown dwarf by a team of students at the Very Large Array. [17]
Observations published in 2007 showed that the atmosphere of LP 944-20 contains much lithium and that it has dusty clouds. [18] A search for planets was carried out in 2006 using the radial velocity method. No planets were found, but variability with an amplitude of 3.5 km/s was detected. This variability is likely due to weather effects and the rotation of the brown dwarf. [19]
In 2015 high resolution Doppler images were taken of LP 944-20 and GJ 791.2A. The time series spectra show line profile distortions, which were interpreted as starspots. These starspots were reconstructed and found to be concentrated at high latitudes. The modelling produces a better fit of ΔT=200 K (−73 °C ; −100 °F ) between starspots (Tspot=2,100 K (1,830 °C; 3,320 °F)) and photosphere (Tphot=2,300 K (2,030 °C; 3,680 °F)). [20]
In a large program in 2016 the spectral type was established to be M9β in the optical and L0β in the infrared. The beta stands for a surface gravity intermediate between normal and low. The mass was calculated to be 29.62±16.67 MJ. [2]
Observations with TESS found that LP 944-20 is variable with a period of around 3.8 hours and an amplitude of 1760±100 ppm . [6] This is in agreement with previous estimates of a period of less than 4.5 hours. [5]
Brown dwarfs are substellar objects that have more mass than the biggest gas giant planets, but less than the least massive main-sequence stars. Their mass is approximately 13 to 80 times that of Jupiter (MJ)—not big enough to sustain nuclear fusion of ordinary hydrogen (1H) into helium in their cores, but massive enough to emit some light and heat from the fusion of deuterium (2H). The most massive ones can fuse lithium (7Li).
A rogue planet, also termed a free-floating planet (FFP) or an isolated planetary-mass object (iPMO), is an interstellar object of planetary mass which is not gravitationally bound to any star or brown dwarf.
The Hungarian Automated Telescope Network (HATNet) project is a network of six small fully automated "HAT" telescopes. The scientific goal of the project is to detect and characterize extrasolar planets using the transit method. This network is used also to find and follow bright variable stars. The network is maintained by the Center for Astrophysics | Harvard & Smithsonian.
Gliese 440, also known as LP 145-141 or LAWD 37, is an isolated white dwarf located 15.1 light-years from the Solar System in the constellation Musca. It is the fourth closest known white dwarf to the Sun, after Sirius B, Procyon B, and van Maanen's star.
SIMP J013656.5+093347 is a brown dwarf or planetary mass object at 19.9 light-years from Earth in the constellation Pisces. It belongs to the spectral class T2.5 and its position shifts due to its proper motion annually by about 1.24 arcsec in the right ascension.
WISE J071322.55−291751.9 is a brown dwarf of spectral class Y0, located in constellation Canis Major at approximately 30 light-years from Earth.
2MASS J11145133−2618235, or 2M1114−26, or 2M1114−2618, or 2MASS 1114−26, or 2MASS J1114−2618) is a nearby brown dwarf of spectral class T7.5, located in constellation Hydra at approximately 18 light-years from Earth.
WISE J163940.83−684738.6 is a brown dwarf of spectral class Y0 pec, located in constellation Triangulum Australe at 15.5 light-years from Earth. It is the second closest Y-dwarf as of February 2024.
GD 165 is a binary white dwarf and brown dwarf system located in the Boötes constellation, roughly 109 light-years from Earth. Neither of the stars have any known exoplanets.
2MASS J15031961+2525196 is a nearby brown dwarf of spectral type T5.5, located in the constellation of Boötes at approximately 20.7 light-years from Earth.
PSO J318.5−22 is an extrasolar object of planetary mass that does not orbit a parent star, it is an analog to directly imaged young gas giants. There is no consensus yet among astronomers whether the object should be referred to as a sub-brown dwarf, as a rogue planet or as a young brown dwarf. It is approximately 80 light-years away and belongs to the Beta Pictoris moving group. The object was discovered in 2013 in images taken by the Pan-STARRS PS1 wide-field telescope. PSO J318.5-22's age is inferred to be 23 million years, the same age as the Beta Pictoris moving group. Based on its calculated temperature and age, it is classified under the brown dwarf spectral type L7.
LP 816-60 is a single red dwarf star of spectral type M4, located in constellation Capricornus at 18.6 light-years from Earth.
2MASS J11263991−5003550(2MASS J1126−5003) is a brown dwarf about 53 light-years distant from earth. The brown dwarf is notable for an unusual blue near-infrared color. This brown dwarf does not show subdwarf features and the blue color cannot be explained by an unresolved binary. Instead the blue color is explained by patchy clouds. 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.