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LP 658-2

Coordinates: Sky map 05h 55m 09.53s, −04° 10′ 07.1″
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LP 658-2
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Orion
Right ascension 05h 55m 09.53s[1]
Declination −04° 10′ 07.1″[1]
Apparent magnitude (V) 14.488[2]
Characteristics
Spectral type DZ11.8[2]
Apparent magnitude (B) 15.49[1]
Apparent magnitude (V) 14.488[2]
Apparent magnitude (RKC) 13.99[3]
Apparent magnitude (IKC) 13.51[3]
Apparent magnitude (J) 13.05 ± 0.03[3]
Apparent magnitude (H) 12.86 ± 0.03[3]
Apparent magnitude (KS) 12.78 ± 0.03[3]
B−V color index 1.0[1][2]
Astrometry
Proper motion (μ) RA: 551[3] mas/yr
Dec.: −2311[3] mas/yr
Parallax (π)156.13 ± 0.84 mas[3]
Distance20.9 ± 0.1 ly
(6.40 ± 0.03 pc)
Absolute magnitude (MV)15.44 ± 0.03[3]
Details
Mass0.45 ± 0.01,[2] or 0.80 ± 0.01[3] M☉
Radius0.014,[2][note 1] or 0.010[3] R☉
Surface gravity (log g)7.80 ± 0.02,[2] or 8.35 ± 0.01[3] cgs
Temperature4270 ± 70,[2] or 5180 ± 70[3] K
Age6.42,[4] or 6.82 ± 0.02[3][note 2] Gyr
Other designations
GJ 223.2, GJ 9193, HL 4, LHS 32, LP 658-2, NLTT 15811, G 099-044[5] , G 99-44, G 106-12, WD 0552–041, EGGR 45.[1]
Database references
SIMBADdata

LP 658-2 is a degenerate (white dwarf) star in the constellation of Orion,[1] the single known object in its system. It has an apparent visual magnitude of approximately 14.488.[2]

Distance

According to a 2009 paper, it is the eighth closest known white dwarf to the Sun (after Sirius B, Procyon B, van Maanen's star, Gliese 440, 40 Eridani B, Stein 2051 B and GJ 1221).[6] Its trigonometric parallax from the CTIOPI (Cerro Tololo Inter-American Observatory (CTIO) Parallax Investigation) 0.9 m telescope program, published in 2009, is 0.15613 ± 0.00084 arcsec,[3] corresponding to a distance 6.40 ± 0.03 pc, or 20.89 ± 0.11 ly. Also, previous less precise parallax measurements of LP 658-2 present in YPC (Yale Parallax Catalog) and among results of CTIOPI 1.5 m telescope program:

LP 658-2 parallax measurements

Source Paper Parallax, mas Distance, pc Distance, ly Ref.
YPC van Altena et al., 1995 155.0 ± 2.1 6.45 ± 0.09 21.04 ± 0.29 [5]
CTIOPI 1.5 m TSN-14 (Costa et al., 2005) 156.93 ± 2.67 6.37 ± 0.11 20.78 ± 0.35 [7]
CTIOPI 0.9 m TSN-21 (Subasavage et al., 2009) 156.13 ± 0.84 6.40 ± 0.03 20.89 ± 0.11 [3]

Physical parameters

There are two sets of published physical parameters of LP 658-2, significantly differing from each other: one from Holberg et al. 2008 and Sion et al. 2009, the other from Subasavage et al. 2009.

Holberg et al. 2008 / Sion et al. 2009 version

Subasavage et al. 2009 version

Color

Despite it being classified as a "white" dwarf, it appears orange rather than white, due to its relatively cool temperature, comparable with that of late (according Holberg et al. 2008 / Sion et al. 2009 version), or early (according Subasavage et al. 2009 version) K-type main sequence stars.

Notes

  1. ^ a b c From surface gravity and mass.
  2. ^ a b c White dwarf cooling age, i. e. age as degenerate star (not including lifetime as main sequence star and as giant star)

References

  1. ^ a b c d e f "GJ 223.2". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2011-01-17.
  2. ^ a b c d e f g h i Holberg, J. B.; Sion, E. M.; Oswalt, T.; McCook, G. P.; Foran, S.; Subasavage, John P. (1 April 2008). "A new look at the local white dwarf population". The Astronomical Journal. 135 (4): 1225–1238. Bibcode:2008AJ....135.1225H. doi:10.1088/0004-6256/135/4/1225.
  3. ^ a b c d e f g h i j k l m n o p Subasavage, John P.; Jao, Wei-Chun; Henry, Todd J.; Bergeron, P.; Dufour, P.; Ianna, Philip A.; Costa, Edgardo; Méndez, René A. (1 June 2009). "The solar neighborhood. XXI. Parallax results from the CTIOPI 0.9 m program: 20 new members of the 25 parsec white dwarf sample". The Astronomical Journal. 137 (6): 4547–4560. arXiv:0902.0627. Bibcode:2009AJ....137.4547S. doi:10.1088/0004-6256/137/6/4547.
  4. ^ Sion, Edward M.; Holberg, J. B.; Oswalt, Terry D.; McCook, George P.; Wasatonic, Richard (1 December 2009). "The white dwarfs within 20 parsecs of the Sun: kinematics and statistics". The Astronomical Journal. 138 (6): 1681–1689. arXiv:0910.1288. Bibcode:2009AJ....138.1681S. doi:10.1088/0004-6256/138/6/1681.
  5. ^ a b van Altena, W. F.; Lee, J. T.; Hoffleit, E. D. (1995). The General Catalogue of Trigonometric [Stellar] Parallaxes (4th ed.). New Haven, CT: Yale University Observatory. Bibcode:1995gcts.book.....V. VizieR entry.
  6. ^ Table 1 in Sion et al. 2009
  7. ^ Costa, Edgardo; Méndez, René A.; Jao, W.-C.; Henry, Todd J.; Subasavage, John P.; Brown, Misty A.; Ianna, Philip A.; Bartlett, Jennifer (July 2005). "The solar neighborhood. XIV. Parallaxes from the Cerro Tololo Inter-American Observatory Parallax Investigation—First results from the 1.5 m telescope program". The Astronomical Journal. 130 (1): 337–349. Bibcode:2005AJ....130..337C. doi:10.1086/430473.
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