Observation data Epoch J2000 [1] Equinox J2000 [1] | |
---|---|
Constellation | Phoenix |
Right ascension | 00h 02m 10.766s [1] |
Declination | −43° 09′ 56.02″ [1] |
Apparent magnitude (V) | 12.76 [2] |
Characteristics | |
Spectral type | DAP5.8 [3] |
Apparent magnitude (B) | 13.12 [1] |
Apparent magnitude (V) | 12.76 [2] |
Apparent magnitude (RKC) | 12.82 [4] |
Apparent magnitude (IKC) | 12.66 [4] |
Apparent magnitude (J) | 12.60 ± 0.03 [4] |
Apparent magnitude (H) | 12.43 ± 0.02 [4] |
Apparent magnitude (KS) | 12.45 ± 0.02 [4] |
Astrometry | |
Radial velocity (Rv) | -58.8 ± 10.8 [5] km/s |
Proper motion (μ) | RA: 589 [4] mas/yr Dec.: -664 [4] mas/yr |
Parallax (π) | 120.0143 ± 0.0215 mas [6] |
Distance | 27.176 ± 0.005 ly (8.332 ± 0.001 pc) |
Absolute magnitude (MV) | 13.20 [2] [4] [note 1] |
Details | |
Mass | 0.85 ± 0.01 [4] M☉ |
Radius | 0.0097 [4] [note 2] R☉ |
Surface gravity (log g) | 8.39 ± 0.01 [4] cgs |
Temperature | 8570 ± 50 [2] K |
Age | 1.82 ± 0.06 [4] [note 3] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
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, [3] the single known component of the system, located in the constellation Phoenix, the nearest star in this constellation.
WD 2359−434, probably, is the 11th closest white dwarf, or, possibly, 9th, 10th, or 12th (see Gliese 293, GJ 1087 and Gliese 518). Currently, the most accurate distance estimate of WD 2359−434 is trigonometric parallax from CTIOPI (Cerro Tololo Inter-American Observatory Parallax Investigation) 0.9 m telescope program, published in 2009 in the 21st paper of RECONS's The Solar Neighborhood (TSN) series [8] Subasavage et al. 2009: [4] 122.27 ± 1.13 mas, corresponding to a distance 8.18 ± 0.08 pc, or 26.68 ± 0.25 ly.
Source | Paper | Parallax, mas | Distance, pc | Distance, ly | Ref. |
---|---|---|---|---|---|
Woolley | Woolley et al. 1970 | 122 ± 8 | 8.2 ± 0.6 | 26.7 ± 1.9 | [9] |
GJ, 3rd version | Gliese, Jahreiss 1991 | 128.2 ± 6.4 | 7.80 ± 0.41 | 25.44 ± 1.37 | [10] |
YPC, 4th edition | van Altena et al. 1995 | 127.4 ± 6.8 | 7.85 ± 0.44 | 25.60 ± 1.44 | [7] |
CTIOPI 0.9 m | TSN 21 (Subasavage et al. 2009) | 122.27 ± 1.13 | 8.18 ± 0.08 | 26.68 ± 0.25 | [4] |
The most accurate estimate is marked in bold.
WD 2359−434's mass is 0.85 ± 0.01 Solar masses, [4] its surface gravity is 108.39 ± 0.01 (2.45 · 108) cm·s −2, [4] 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; [2] 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. [4] 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, [4] [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. [11]
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, [12] using Wood model D [13] initial–final mass relation and WD 2359−434's white dwarf mass value 0.97 ± 0.03 M☉ from Holberg et al. 2008, [2] its main sequence progenitor mass was 7.09 M☉. Using expression for pre-white dwarf lifetime 10 · (MMS/M☉)2.5 (Gyr), [13] 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, [4] 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, [14] 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.
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