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WD 2359−434
	; Size of WD 2359−434 in comparison with Earth. On the left is Earth, on the right is WD 2359-434.
Observation data; Epoch J2000 Equinox J2000
Constellation	Phoenix
Right ascension	00h 02m 10.72420s
Declination	−43° 09′ 55.3906″
Apparent magnitude (V)	12.76
Characteristics
Spectral type	DAP5.8
Apparent magnitude (B)	13.12
Apparent magnitude (V)	12.76
Apparent magnitude (RKC)	12.82
Apparent magnitude (IKC)	12.66
Apparent magnitude (J)	12.60 ± 0.03
Apparent magnitude (H)	12.43 ± 0.02
Apparent magnitude (KS)	12.45 ± 0.02
Astrometry
Radial velocity (Rv)	-58.8 ± 10.8 km/s
Proper motion (μ)	RA: 613.785 mas/yr ; Dec.: -686.989 mas/yr
Parallax (π)	120.0143 ± 0.0215 mas
Distance	27.176 ± 0.005 ly ; (8.332 ± 0.001 pc)
Absolute magnitude (MV)	13.20
Details
Mass	0.85 ± 0.01 M☉
Radius	0.0097 R☉
Surface gravity (log g)	8.39 ± 0.01 cgs
Temperature	8570 ± 50 K
Age	1.82 ± 0.06 Gyr
Other designations
	GJ 915, EGGR 165, L 362-81, LAWD 96, LFT 1849, LHS 1005, LP 988-88, LTT 9857, WD 2359-434, 2MASS J00021076-4309560
Database references
SIMBAD	data
	WD 2359−434 Location of WD 2359−434 in the constellation Phoenix;

WD 2359-434 (Gliese 915, LHS 1005, L 362-81) is a nearby degenerate star (white dwarf) of spectral class DAP5.8,^[4] the single known component of the system, located in the constellation Phoenix, the nearest star in this constellation.

Distance

Currently, the most accurate distance estimate of WD 2359−434 is a trigonometric parallax from Gaia DR3:^[2] 120.0143±0.0215 mas, corresponding to a distance of 8.332±0.001 pc, or 27.176±0.005 ly. WD 2359−434 is the 13th closest white dwarf to the Sun.^[7]

Physical parameters

WD 2359−434's mass is 0.85 ± 0.01 Solar masses,^[5] its surface gravity is 10^{8.39 ± 0.01} (2.45 · 10⁸) cm·s⁻²,^[5] or approximately 250,000 of Earth's, corresponding to a radius 6780 km, or 1.06 of Earth's.

WD 2359−434 is relatively hot and young white dwarf, its temperature is 8570 ± 50 K;^[3] its cooling age, i. e. age as degenerate star (not including lifetime as main sequence star and as giant star) is 1.82 ± 0.06 Gyr.^[5] Gliese 518 should appear bluish-white, due temperature, comparable with that of A-type main sequence stars.

As all white dwarfs, WD 2359−434 is composed of very dense degenerate matter, its mean density is 1,300,000 g·cm⁻³,^[5]^{[note 4]} i.e. mass of one cubic millimetre of WD 2359−434 matter is 1.3 kg.

Unusually for a white dwarf star, WD 2359-434 has a weak, non-dipole magnetic field of 50,000 - 100,000 Gauss.^[8]

Main sequence progenitor properties

As all degenerate stars, WD 2359−434 previously existed initially as main-sequence star and then as giant star, until all the thermonuclear fuel was exhausted, after which WD 2359−434 lost most of its mass. According to the 2010 thesis for the degree of Doctor of Science,^[9] using Wood model D^[10] initial–final mass relation and WD 2359−434's white dwarf mass value 0.97 ± 0.03 M_☉ from Holberg et al. 2008,^[3] its main sequence progenitor mass was 7.09 M_☉. Using expression for pre-white dwarf lifetime 10 · (M_MS/M_☉)^2.5 (Gyr),^[10] was found WD 2359−434 main sequence age 0.07 Gyr.

White dwarf mass value 0.85 ± 0.01 M_☉ from Subasavage et al. 2009,^[5] in Wood model D yields MS (main sequence) mass 6.03 M_☉, and MS lifetime 0.11 Gyr, corresponding to B-type main sequence star.

According to initial-final mass relation from Weidemann 2000 paper,^[11] WD 2359−434's main sequence progenitor should have mass about 4.6 M_☉ and lifespan 0.22 Gyr, and, again, should be of B spectral type. There are also other models.

Notes

^ From apparent magnitude and parallax.
^ From surface gravity and mass.
^ White dwarf cooling age, i. e. age as degenerate star (not including lifetime as main sequence star and as giant star).
^ From mass and surface gravity (assuming spherical shape).