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.

gollark: I imagine it would be possible to teach you it eventually, but I'm not really good at "patience" or "explaining over large inferential distances".

gollark: Yes, well.

gollark: And just randomly tries different things until I say that they look less wrong.

gollark: Oh, and he is apparently entirely incapable of generalization or remembering things from more than 15 seconds ago.

gollark: He doesn't understand some things, which is fine I guess, but he also doesn't seem to understand the things he needs to understand to understand those things either, and seems to think he's done with things when the arbitrary computer marking thing™ says so even when it's repeatedly blatantly wrong, and wants me to just give him answers so he'll apparently learn from them.

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.