LP 658-2

LP 658-2 is a degenerate (white dwarf) star in the constellation of Orion,^[3] the single known object in its system. It has an apparent visual magnitude of approximately 14.488.^[2]

LP 658-2

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Orion
Right ascension	05h 55m 09.53049s[1]
Declination	−04° 10′ 07.0653″[1]
Apparent magnitude (V)	14.488[2]
Characteristics
Spectral type	DZ11.8[2]
Apparent magnitude (B)	15.49[3]
Apparent magnitude (V)	14.488[2]
Apparent magnitude (RKC)	13.99[4]
Apparent magnitude (IKC)	13.51[4]
Apparent magnitude (J)	13.05 ± 0.03[4]
Apparent magnitude (H)	12.86 ± 0.03[4]
Apparent magnitude (KS)	12.78 ± 0.03[4]
B−V color index	1.0[3][2]
Astrometry
Proper motion (μ)	RA: 535.249 mas/yr[1] Dec.: −2,317.011 mas/yr[1]
Parallax (π)	155.2373±0.0175 mas[1]
Distance	21.010 ± 0.002 ly (6.4418 ± 0.0007 pc)
Absolute magnitude (MV)	15.44 ± 0.03[4]
Details[2]
From Holberg etal. (2008)
Mass	0.45±0.01 M☉
Radius	0.014[2][note 1] R☉
Surface gravity (log g)	7.80±0.02[2] cgs
Temperature	4,270±70,[2] K
Age	6.42[5][note 2] Gyr
Details[4]
From Subasavage etal. (2009)
Mass	0.80±0.01 M☉
Radius	0.010 R☉
Surface gravity (log g)	8.35±0.01 cgs
Temperature	5,180±70 K
Age	6.82±0.02[note 2] Gyr
Other designations
HL 4, GJ 223.2, GJ 9193, EGGR 45, G 99-44, G 106-12, LHS 32, LP 658-2, NLTT 15811, WD 0552-041[3]
Database references
SIMBAD	data

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,^[4] 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	[7]
CTIOPI 1.5 m	TSN-14 (Costa et al., 2005)	156.93 ± 2.67	6.37 ± 0.11	20.78 ± 0.35	[8]
CTIOPI 0.9 m	TSN-21 (Subasavage et al., 2009)	156.13 ± 0.84	6.40 ± 0.03	20.89 ± 0.11	[4]

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.

Color

Despite it being classified as a "white" dwarf, it appears yellowish white rather than white, due to temperature, cooler than the Sun's and comparable with that of a K-type main sequence star.

Notes

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