LP 658-2

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Coordinates: Sky map 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
Distance 20.9 ± 0.1 ly
(6.40 ± 0.03 pc)
Absolute magnitude (MV) 15.44 ± 0.03[3]
Details
Mass 0.45 ± 0.01,[2] or 0.80 ± 0.01[3] M
Radius 0.014,[2][note 1] or 0.010[3] R
Surface gravity (log g) 7.80 ± 0.02,[2] or 8.35 ± 0.01[3] cgs
Temperature 4270 ± 70,[2] or 5180 ± 70[3] K
Age 6.42,[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
SIMBAD data

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[edit]

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[edit]

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[edit]

Subasavage et al. 2009 version[edit]

Color[edit]

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[edit]

  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[edit]

  1. ^ a b c d e f NAME HL 4 -- White Dwarf, database entry, SIMBAD. Accessed on line January 17, 2011.
  2. ^ a b c d e f g h i j 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. ^ a b c d e f g h i j k l m n o p q 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. ^ a b c 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. ^ a b 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, Bibcode2009AJ....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.