LP 944-20

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

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 a flare was detected.[5]

Distance[edit]

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\pm4.2 mas, and its correction from relative to absolute parallax (i.e. mean parallax of the reference frame stars) is \pi_{ref}=1.4\pm0.3 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 5±0.1 pc, or 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 155.89±1.03 mas (6.41±0.04 pc or 20.92±0.14 ly).[3]

LP 944-20 distance estimates

Source Parallax, mas Distance, pc Distance, ly Distance, Pm Ref.
Tinney (1996) 201.4±4.21 4.97+0.11
−0.1
16.2±0.3 153.2+3.3
−3.1
[7]
Dieterich et al. (2013)
Lurie et al. (2014)
155.89±1.03 6.41±0.04 20.92±0.14 197.9±1.3 [3][4]

Non-trigonometric distance estimates are marked in italic. The most precise estimate is marked in bold.

Lithium and clouds[edit]

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

Notes[edit]

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

References[edit]

  1. ^ a b c d e f g h i j "SIPS J0339-3525 -- Brown Dwarf (M<0.08solMass)". Centre de Données astronomiques de Strasbourg. Retrieved 2009-12-14. 
  2. ^ a b c d Research Consortium on Nearby Stars, Georgia State University (January 1, 2012). "The 100 nearest star systems". RECONS. Retrieved 2012-06-11. 
  3. ^ a b c 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. 
  4. ^ a b 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.  edit
  5. ^ http://www.solstation.com/stars/lp944-20.jpg
  6. ^ Mean and Variance of Random Variables
  7. ^ a b 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. 
  8. ^ 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[edit]