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] 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,
2MUCD 10201
Database references
SIMBAD data

LP 944-20 is a dim brown dwarf of spectral class M9, located about 16 light-years distant 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.

Distance[edit]

According C. G. Tinney's 1996 paper "CCD astrometry of southern very low-mass stars",[4] LP 944-20 (designated there as BRI 0337-3535) has relative parallax \pi_r=200.0\pm4.2 mas, and correction from relative to absolute parallax (i. e. mean parallax of the reference frame stars) \pi_{ref}=1.4\pm0.3 mas. This yields absolute parallax \pi_r+\pi_{ref}=200.0+1.4=201.4 mas, and standard deviation of absolute parallax (according formula \sigma_{X+Y}^2=\sigma_X^2+\sigma_Y^2[5]) \sqrt{\sigma_{\pi_r}^2+\sigma_{\pi_{ref}}^2}=\sqrt{4.2^2+0.3^2}=4.21 mas, and this corresponds to a distance of 5\pm0.1 pc, or 16.2\pm0.3 ly. (The same values of absolute parallax and its standard deviation are in RECONS' TOP100 list,[2] which is referenced to the aforementioned Tinney's article.)[note 1]

Parallax, published in 2013: 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 Ref.
Tinney (1996) 201.4 ± 4.21 4.97+0.11
−0.1
16.2 ± 0.3 [4]
Dieterich et al. (2013) 155.89 ± 1.03 6.41 ± 0.04 20.92 ± 0.14 [3]

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

Lithium and clouds[edit]

Observations published in 2007 showed that this object has an atmosphere high in lithium that also features dusty clouds.[6]

See also[edit]

Notes[edit]

  1. ^ In RECONS' TOP100 older versions 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 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. 
  5. ^ Mean and Variance of Random Variables
  6. ^ 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]