2MASS J11263991−5003550

2MASS J11263991−5003550
Observation data; Epoch J2000.0 Equinox J2000.0
Constellation	Centaurus
Right ascension	11h 26m 39.80353s
Declination	−50° 03′ 54.8495″
Characteristics
Evolutionary stage	brown dwarf
Spectral type	L4.5
Variable type	Rotational
Astrometry
Radial velocity (Rv)	49.3±1.1 km/s
Proper motion (μ)	RA: -1589.17 ± 0.494 mas/yr ; Dec.: 450.986 ± 0.415 mas/yr
Parallax (π)	61.6319 ± 0.3273 mas
Distance	52.9 ± 0.3 ly ; (16.23 ± 0.09 pc)
Details
Radius	0.8−1.2 RJup
Surface gravity (log g)	3.7+0.5; −0.1 cgs
Temperature	1270+60; −20 K
Rotation	3.2 ± 0.3 hours
Rotational velocity (v sin i)	22.8+1.6; −2.4 km/s
Other designations
	DENIS J112639.9-500355, WISEA J112638.07-500350.1, Gaia DR2 5372923621096443008
Database references
SIMBAD	data

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.^[6]^[2] 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.^[2]^[7]^[3] The patchy cloud model allows thick clouds and a cloud coverage of 50% to explain the spectra of 2MASS J1126−5003.^[7] Other blue L-dwarfs exist, but are quite rare.^[8]

2MASS J1126−5003 has a deep water (H₂O) absorption feature in its spectra,^[6] which is comparable with late L-dwarfs and early T-dwarfs. It also shows weak carbon monoxide (CO) features. It lacks any methane (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.^[2]

Lower metallicity and higher surface gravity 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 of cloud condensates, resulting in thinner clouds. Other factors, like rotation, vertical upwelling and magnetic fields might play a role as well.^[2]

Previously one suggested scenario were thinner clouds. This brown dwarf shows variations in the J-band^[3] and at mid-infrared wavelengths with a period of 3.2 ± 0.3 hours.^[5] This is a clear indication of patchy clouds.

References

^ ^a ^b ^c ^d ^e Gaia Collaboration (2018-08-01). "Gaia Data Release 2 - Summary of the contents and survey properties". Astronomy & Astrophysics. 616: A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. ISSN 0004-6361. S2CID 49211658.
^ ^a ^b ^c ^d ^e Burgasser, Adam J.; Looper, Dagny L.; Kirkpatrick, J. Davy; Cruz, Kelle L.; Swift, Brandon J. (February 2008). "Clouds, Gravity, and Metallicity in Blue L Dwarfs: The Case of 2MASS J11263991-5003550". Astrophysical Journal. 674 (1): 451–465. arXiv:0710.1123. Bibcode:2008ApJ...674..451B. doi:10.1086/524726. ISSN 0004-637X. S2CID 6111840.
^ ^a ^b ^c Radigan, Jacqueline; Lafrenière, David; Jayawardhana, Ray; Artigau, Étienne (October 2014). "Strong Brightness Variations Signal Cloudy-to-clear Transition of Brown Dwarfs". Astrophysical Journal. 793 (2): 75. arXiv:1404.3247. Bibcode:2014ApJ...793...75R. doi:10.1088/0004-637X/793/2/75. ISSN 0004-637X. S2CID 118357522.
^ ^a ^b ^c ^d ^e Vos, Johanna M.; Allers, Katelyn N.; Biller, Beth A. (June 2017). "The Viewing Geometry of Brown Dwarfs Influences Their Observed Colors and Variability Amplitudes". Astrophysical Journal. 842 (2): 78. arXiv:1705.06045. Bibcode:2017ApJ...842...78V. doi:10.3847/1538-4357/aa73cf. ISSN 0004-637X.
^ ^a ^b Metchev, Stanimir A.; Heinze, Aren; Apai, Dániel; Flateau, Davin; Radigan, Jacqueline; Burgasser, Adam; Marley, Mark S.; Artigau, Étienne; Plavchan, Peter; Goldman, Bertrand (February 2015). "Weather on Other Worlds. II. Survey Results: Spots are Ubiquitous on L and T Dwarfs". Astrophysical Journal. 799 (2): 154. arXiv:1411.3051. Bibcode:2015ApJ...799..154M. doi:10.1088/0004-637X/799/2/154. ISSN 0004-637X.
^ ^a ^b Folkes, S. L.; Pinfield, D. J.; Kendall, T. R.; Jones, H. R. A. (July 2007). "Discovery of a nearby L-T transition object in the Southern Galactic plane". MNRAS. 378 (3): 901–909. arXiv:astro-ph/0703808. Bibcode:2007MNRAS.378..901F. doi:10.1111/j.1365-2966.2007.11789.x. ISSN 0035-8711.
^ ^a ^b Marley, Mark S.; Saumon, Didier; Goldblatt, Colin (November 2010). "A Patchy Cloud Model for the L to T Dwarf Transition". Astrophysical Journal Letters. 723 (1): L117–L121. arXiv:1009.6217. Bibcode:2010ApJ...723L.117M. doi:10.1088/2041-8205/723/1/L117. ISSN 0004-637X. S2CID 56286093.
^ Kirkpatrick, J. Davy; Looper, Dagny L.; Burgasser, Adam J.; Schurr, Steven D.; Cutri, Roc M.; Cushing, Michael C.; Cruz, Kelle L.; Sweet, Anne C.; Knapp, Gillian R.; Barman, Travis S.; Bochanski, John J. (September 2010). "Discoveries from a Near-infrared Proper Motion Survey Using Multi-epoch Two Micron All-Sky Survey Data". Astrophysical Journal Supplement Series. 190 (1): 100–146. arXiv:1008.3591. Bibcode:2010ApJS..190..100K. doi:10.1088/0067-0049/190/1/100. ISSN 0067-0049.