LP 658-2

Coordinates: 05h 55m 09.53s, −04° 10′ 07.1″

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[3] mas
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: from Holberg et al. 2008, April[2] / Sion et al. 2009, December[4] articles, and from Subasavage et al. 2009, June[3] article:

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

Subasavage et al. 2009 version

Color

Despite it is classified as "white dwarf", it should appear orange, not white, due low 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. ↑ 1.0 1.1 1.2 From surface gravity and mass.
  2. ↑ 2.0 2.1 2.2 White dwarf cooling age, i. e. age as degenerate star (not including lifetime as main sequence star and as giant star)

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 NAME HL 4 -- White Dwarf, database entry, SIMBAD. Accessed on line January 17, 2011.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 Holberg, J. B.; Sion; Oswalt; McCook; Foran; Subasavage (2008). "A NEW LOOK AT THE LOCAL WHITE DWARF POPULATION". The Astronomical Journal 135: 1225–1238. Bibcode:2008AJ....135.1225H. doi:10.1088/0004-6256/135/4/1225.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 Subasavage, John P.; Jao; Henry; Bergeron; Dufour; Ianna; Costa; Mendez (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: 4547–4560. Bibcode:2009AJ....134.4547S. doi:10.1088/0004-6256/137/6/4547.
  4. ↑ 4.0 4.1 4.2 Sion, Edward M.; Holberg; Oswalt; McCook; Wasatonic (2009). "THE WHITE DWARFS WITHIN 20 PARSECS OF THE SUN: KINEMATICS AND STATISTICS". The Astronomical Journal 138: 1681–1689. arXiv:0910.1288. Bibcode:2009AJ....138.1681S. doi:10.1088/0004-6256/138/6/1681.
  5. ↑ 5.0 5.1 Yale Trigonometric Parallaxes, Fourth Edition (van Altena+ 1995)
  6. ↑ Table 1, "The White Dwarfs Within 20 Parsecs of the Sun: Kinematics and Statistics", Edward M. Sion et al., The Astronomical Journal 138, #6 (December 2009), pp. 1681-1689, doi:10.1088/0004-6256/138/6/1681, Bibcode: 2009AJ....138.1681S.
  7. ↑ Costa, Edgardo; Mendez; Jao; Henry; Subasavage; Brown; Ianna; Bartlett (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: 337–349. Bibcode:2005AJ....130..337C. doi:10.1086/430473.