LP 944-20

LP 944-20
Observation data; Epoch J2000 Equinox J2000
Constellation	Fornax
Right ascension	03h 39m 35.220s[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)	10.725±0.021[1]
Apparent magnitude (H)	10.017±0.021[1]
Apparent magnitude (K)	9.548±0.023[1]
Astrometry
Proper motion (μ)	RA: 317±60[1] mas/yr ; Dec.: 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 (MV)	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 an X-ray flare was detected.[5][6] 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.[7]

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 $\sigma _{X+Y}^{2}=\sigma _{X}^{2}+\sigma _{Y}^{2}$ [8]) 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 5±0.1 pc, or 16.2±0.3 ly.[9] (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 155.89±1.03 mas (6.41±0.04 pc or 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.[10]

Notes

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

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References

"SIPS J0339-3525 -- Brown Dwarf (M<0.08solMass)". Centre de Données astronomiques de Strasbourg. Retrieved 2009-12-14.
Research Consortium on Nearby Stars (1 January 2012). "The 100 nearest star systems". RECONS. Georgia State University. Retrieved 12 February 2017.
Dieterich, Sergio B.; Todd J. Henry; Wei-Chun Jao; Jennifer G. Winters; Altonio D. Hosey (2013). "The Solar Neighborhood XXXII: The Hydrogen Burning Limit". The Astronomical Journal. 147: 94. arXiv:1312.1736v1. Bibcode:2014AJ....147...94D. doi:10.1088/0004-6256/147/5/94.
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.
Rutledge, Robert E.; Basri, Gibor; Martín, Eduardo L.; Bildsten, Lars (1 August 2000). "Chandra Detection of an X-Ray Flare from the Brown Dwarf LP 944-20". The Astrophysical Journal. 538 (2): L141–L144. arXiv:astro-ph/0005559. Bibcode:2000ApJ...538L.141R. doi:10.1086/312817.
"LP 944-20". Solstation.com. Retrieved 2017-03-11.
Berger, E.; Ball, S.; Becker, K. M.; Clarke, M.; Frail, D. A.; Fukuda, T. A.; Hoffman, I. M.; Mellon, R.; Momjian, E.; Murphy, N. W.; Teng, S. H.; Woodruff, T.; Zauderer, B. A.; Zavala, R. T. (2001-03-15). "Discovery of radio emission from the brown dwarf LP944-20". Nature. 410 (6826): 338–340. arXiv:astro-ph/0102301. Bibcode:2001Natur.410..338B. doi:10.1038/35066514. PMID 11268202.
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.; Jones, H. R. A.; Martín, E. L.; Guenther, E.; Kenworthy, M. A.; Zapatero Osorio, M. R. (September 2007). "Lithium in LP944-20". Monthly Notices of the Royal Astronomical Society. 380 (3): 1285–96. 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

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[note_1-10] In RECONS' TOP100 older versions the standard deviation value was 4.20 mas, not 4.21 mas.

[SIMBAD-1] "SIPS J0339-3525 -- Brown Dwarf (M<0.08solMass)". Centre de Données astronomiques de Strasbourg. Retrieved 2009-12-14.

[RECONS_TOP100-2] Research Consortium on Nearby Stars (1 January 2012). "The 100 nearest star systems". RECONS. Georgia State University. Retrieved 12 February 2017.

[Dieterich2013-3] Dieterich, Sergio B.; Todd J. Henry; Wei-Chun Jao; Jennifer G. Winters; Altonio D. Hosey (2013). "The Solar Neighborhood XXXII: The Hydrogen Burning Limit". The Astronomical Journal. 147: 94. arXiv:1312.1736v1. Bibcode:2014AJ....147...94D. doi:10.1088/0004-6256/147/5/94.

[Lurie2014-4] 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.

[5] Rutledge, Robert E.; Basri, Gibor; Martín, Eduardo L.; Bildsten, Lars (1 August 2000). "Chandra Detection of an X-Ray Flare from the Brown Dwarf LP 944-20". The Astrophysical Journal. 538 (2): L141–L144. arXiv:astro-ph/0005559. Bibcode:2000ApJ...538L.141R. doi:10.1086/312817.

[6] "LP 944-20". Solstation.com. Retrieved 2017-03-11.

[Berger2001-7] Berger, E.; Ball, S.; Becker, K. M.; Clarke, M.; Frail, D. A.; Fukuda, T. A.; Hoffman, I. M.; Mellon, R.; Momjian, E.; Murphy, N. W.; Teng, S. H.; Woodruff, T.; Zauderer, B. A.; Zavala, R. T. (2001-03-15). "Discovery of radio emission from the brown dwarf LP944-20". Nature. 410 (6826): 338–340. arXiv:astro-ph/0102301. Bibcode:2001Natur.410..338B. doi:10.1038/35066514. PMID 11268202.

[www.stat.yale.edu/Courses/1997-98/101/rvmnvar.htm-8] Mean and Variance of Random Variables

[Tinney1996-9] 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.

[11] Pavlenko, Ya. V.; Jones, H. R. A.; Martín, E. L.; Guenther, E.; Kenworthy, M. A.; Zapatero Osorio, M. R. (September 2007). "Lithium in LP944-20". Monthly Notices of the Royal Astronomical Society. 380 (3): 1285–96. arXiv:0707.0694. Bibcode:2007MNRAS.380.1285P. doi:10.1111/j.1365-2966.2007.12182.x.