2MASS 0939−2448

2MASS 0939−2448 (full designation is 2MASS J09393548−2448279)[3] is a probable system of two nearby T-type brown dwarfs, located in constellation Antlia at 17.4 light-years from Earth.[2]

2MASS 0939−2448

Observation data Epoch J2000      Equinox J2000
Constellation	Antlia
Right ascension	09^h 39^m 35.48^s
Declination	−24° 48′ 27.9″
Characteristics
Spectral type	T8[1]
Apparent magnitude (J)	15.61 ± 0.09[1]
Apparent magnitude (H)	15.96 ± 0.09[1]
Apparent magnitude (K)	16.83 ± 0.09[1]
Astrometry
Proper motion (μ)	RA: +573.4 ± 2.3[2] mas/yr Dec.: −1044.7 ± 2.5[2] mas/yr
Parallax (π)	187.3 ± 4.6[2] mas
Distance	17.4 ± 0.4 ly (5.3 ± 0.1 pc)
Details
2MASS 0939-2448 A
Mass	20–50[1] MJup
Radius	0.08 – 0.09[1] R☉
Temperature	600–700[1] K
Metallicity	−0.3–0.0[1]
Age	2–10[1] Gyr
2MASS 0939-2448 B
Mass	20–40[1] MJup
Radius	0.09[1] R☉
Temperature	600–700[1] K
Metallicity	−0.3–0.0[1]
Age	2–10[1] Gyr
Other designations
2MASS J09393548−2448279[3]
Database references
SIMBAD	data

Discovery

2MASS 0939−2448 was identified as a brown dwarf through analysis of data from the 2MASS survey by Tinney et al. The discovery was published in 2005.[3]

Properties

Model calculations suggest that 2MASS 0939−2448 is a system of two brown dwarfs with effective temperatures of about 500 and 700 K and masses of about 25 and 40 Jupiter masses; it is also possible that it is a pair of identical objects with temperatures of 600 K and 30 Jupiter masses.[1]

Dimmest known brown dwarf

From publication of the discovery in 2005 till at least 2008, 2MASS 0939−2448, or its dimmer component, was the dimmest brown dwarf known.[4] Later dimmer objects, including (sub)brown dwarfs and rogue planets of new spectral class Y, were discovered, using data from WISE and from other surveys. In 2011–2014, the dimmest known of these objects was WISE 1828+2650, and from 2014 the dimmest one is WISE 0855−0714.

References

1. Leggett, S. K.; Cushing, Michael C.; Saumon, D.; Marley, M. S.; Roellig, T. L.; Warren, S. J.; Burningham, Ben; Jones, H. R. A.; Kirkpatrick, J. D.; Lodieu, N.; Lucas, P. W.; Mainzer, A. K.; Martín, E. L.; McCaughrean, M. J.; Pinfield, D. J.; Sloan, G. C.; Smart, R. L.; Tamura, M.; Van Cleve, J. (2009). "The Physical Properties of Four ~600 K T Dwarfs". The Astrophysical Journal. 695 (2): 1517–1526. arXiv:0901.4093. Bibcode:2009ApJ...695.1517L. doi:10.1088/0004-637X/695/2/1517.
2. Burgasser, Adam J.; Tinney, C. G.; Cushing, Michael C.; Saumon, Didier; Marley, Mark S.; Bennett, Clara S.; Kirkpatrick, J. Davy (2008). "2MASS J09393548-2448279: The Coldest and Least Luminous Brown Dwarf Binary Known?" (PDF). The Astrophysical Journal. 689 (1): L53–L56. Bibcode:2008ApJ...689L..53B. doi:10.1086/595747.
3. Tinney, C. G.; Burgasser, Adam J.; Kirkpatrick, J. Davy; McElwain, Michael W. (2005). "The 2MASS Wide-Field T Dwarf Search. IV. Hunting Out T Dwarfs with Methane Imaging". The Astronomical Journal. 130 (5): 2326–2346. arXiv:astro-ph/0508150. Bibcode:2005AJ....130.2326T. doi:10.1086/491734.
4. "Astronomers Find the Two Dimmest Stellar Bulbs" (Press release). NASA/JPL. 2008-12-10. Retrieved 2008-12-20.

• Faherty, Jacqueline K.; Burgasser, Adam J.; Walter, Frederick M.; Van der Bliek, Nicole; Shara, Michael M.; Cruz, Kelle L.; West, Andrew A.; Vrba, Frederick J.; Anglada-Escud, Guillem (2012). "The Brown Dwarf Kinematics Project (BDKP). III. Parallaxes for 70 Ultracool Dwarfs". The Astrophysical Journal. 752 (1): 56. arXiv:1203.5543. Bibcode:2012ApJ...752...56F. doi:10.1088/0004-637X/752/1/56.
• Smart, R. L.; Tinney, C. G.; Bucciarelli, B.; Marocco, F.; Abbas, U.; Andrei, A.; Bernardi, G.; Burningham, B.; Cardoso, C.; Costa, E.; Crosta, M. T.; Daprá, M.; Day-Jones, A.; Goldman, B.; Jones, H. R. A.; Lattanzi, M. G.; Leggett, S. K.; Lucas, P.; Mendez, R.; Penna, J. L.; Pinfield, D.; Smith, L.; Sozzetti, A.; Vecchiato, A. (2013). "NPARSEC: NTT Parallaxes of Southern Extremely Cool objects. Goals, targets, procedures and first results". Monthly Notices of the Royal Astronomical Society. 433 (3): 2054–2063. arXiv:1306.4527. Bibcode:2013MNRAS.433.2054S. doi:10.1093/mnras/stt876.