LP 944-20

Coordinates: 03^h 39^m 35.22^s, −35° 25′ 44.09″

LP 944-20
Observation data Epoch J2000 Equinox J2000
Constellation	Fornax
Right ascension	03^h 39^m 35.220^s^[1]
Declination	–35° 25′ 44.09″^[1]
Apparent magnitude (V)	18.69^[2]
Characteristics
Spectral type	M9^[1]
Apparent magnitude (B)	~20.17^[1]
Apparent magnitude (I)	~13.288^[1]
Apparent magnitude (J)	7001107250000000000♠10.725±0.021^[1]
Apparent magnitude (H)	7001100170000000000♠10.017±0.021^[1]
Apparent magnitude (K)	7000954800000000000♠9.548±0.023^[1]
Astrometry

Proper motion (μ)	RA: 7002317000000000000♠317±60^[1] mas/yr Dec.: 7002276000000000000♠276±52^[1] mas/yr
Parallax (π)	155.89 ± 1.03^[3]^[4] mas
Distance	20.9 ± 0.1 ly (6.41 ± 0.04 pc)
Absolute magnitude (M_V)	20.02

Details

Mass	0.07^[2] M_☉

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
Database references
SIMBAD	data

LP 944-20 is a dim brown dwarf of spectral class M9 located about 21 light-years from the Solar System in the constellation of Fornax. With a visual apparent magnitude of 18,^[2] it has one of the dimmest visual magnitudes listed on the RECONS page.

On 15 December 1999 a flare was detected.^[5]

Distance

The first parallax measurement from 1996 found that LP 944-20 (designated there as BRI 0337−3535) has a relative parallax of $\pi _{r}=200.0\pm 4.2$ mas, and its correction from relative to absolute parallax (i.e. mean parallax of the reference frame stars) is $\pi _{{ref}}=1.4\pm 0.3$ mas. This yields an absolute parallax of $\pi _{r}+\pi _{{ref}}=200.0+1.4=201.4$ mas, with a standard deviation (according to $\sigma _{{X+Y}}^{2}=\sigma _{X}^{2}+\sigma _{Y}^{2}$ ^[6]) of ${\sqrt {\sigma _{{\pi _{r}}}^{2}+\sigma _{{\pi _{{ref}}}}^{2}}}={\sqrt {4.2^{2}+0.3^{2}}}=4.21$ mas, which corresponds to a distance of 7000500000000000000♠5±0.1 pc, or 7001162000000000000♠16.2±0.3 ly.^[7] (The same values of absolute parallax and its standard deviation are in the RECONS' TOP100 list.^[2]^{[note 1]}

A newer parallax, published in 2013, is 7002155890000000000♠155.89±1.03 mas (7000641000000000000♠6.41±0.04 pc or 7001209200000000000♠20.92±0.14 ly).^[3]

Lithium and clouds

Observations published in 2007 showed that the atmosphere of LP 944-20 contains much lithium and that it has dusty clouds.^[8]

Notes

↑ In RECONS' TOP100 older versions the standard deviation value was 4.20 mas, not 4.21 mas.

References

1 2 3 4 5 6 7 8 9 10 "SIPS J0339-3525 -- Brown Dwarf (M<0.08solMass)". Centre de Données astronomiques de Strasbourg. Retrieved 2009-12-14.
1 2 3 4 Research Consortium on Nearby Stars, Georgia State University (January 1, 2012). "The 100 nearest star systems". RECONS. Retrieved 2012-06-11. External link in |journal= (help)
1 2 Dieterich, Sergio B.; Todd J. Henry; Wei-Chun Jao; Jennifer G. Winters; Altonio D. Hosey (2013). "The Solar Neighborhood XXXII: The Hydrogen Burning Limit". arXiv:1312.1736v1.
↑ Lurie, John C.; Henry, Todd J.; Jao, Wei-Chun; Quinn, Samuel N.; Winters, Jennifer G.; Ianna, Philip A.; Koerner, David W.; Riedel, Adric R.; Subasavage, John P. (2014). "The Solar Neighborhood. XXXIV. a Search for Planets Orbiting Nearby M Dwarfs Using Astrometry". The Astronomical Journal. 148 (5): 91. arXiv:1407.4820. Bibcode:2014AJ....148...91L. doi:10.1088/0004-6256/148/5/91.
↑ http://www.solstation.com/stars/lp944-20.jpg
↑ Mean and Variance of Random Variables
↑ Tinney, C. G. (1996). "CCD astrometry of southern very low-mass stars". Monthly Notices of the Royal Astronomical Society. 281 (2): 644–658. Bibcode:1996MNRAS.281..644T. doi:10.1093/mnras/281.2.644.
↑ Pavlenko, Ya. V.; et al. (September 2007). "Lithium in LP944-20". Monthly Notices of the Royal Astronomical Society. 380 (3): 1285–1296. arXiv:0707.0694. Bibcode:2007MNRAS.380.1285P. doi:10.1111/j.1365-2966.2007.12182.x.

External links

"The 100 nearest star systems", Research Consortium on Nearby Stars

Stars of Fornax

Bayer	α (Dalim) β γ¹ γ² δ ε ζ η¹ η² η³ ι¹ ι² κ λ¹ λ² μ ν π ρ σ τ υ φ χ¹ χ² χ³ ψ ω

Variable	R TY TZ UX UZ AI

HR	517 528 532 535 554 576 606 630 683 700 703 727 742 780 805 817 858 884 893 900 903 943 970 974 980 993 1013 1018 1045 1082 1093 1095

HD	12596 20781 20782 20868 22333

Other	HIP 13044 LP 944-20 2MASS J02431371-2453298 UDF 2457

List

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