WD 2359-434

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Coordinates: Sky map 00h 02m 10.766s, −43° 09′ 56.02″

WD 2359-434
250px
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[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) 122.27 ± 1.13[4] mas
Distance 26.7 ± 0.2 ly
(8.18 ± 0.08 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
Gliese 915,[2][3] LHS 1005,[2] LFT 1849,[1] LTT 9857,[1] LP 988-88,[1] L 362-81,[6] EGGR 165,[1] 2MASS J00021076-4309560[1]
Database references
SIMBAD data

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.

Distance

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[7] 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.

WD 2359-434 distance estimates

Source Paper Parallax, mas Distance, pc Distance, ly Ref.
Woolley Woolley et al. 1970 122 ± 8 8.2 ± 0.6 26.7 ± 1.9 [8]
GJ, 3rd version Gliese, Jahreiss 1991 128.2 ± 6.4 7.80 ± 0.41 25.44 ± 1.37 [9]
YPC, 4th edition van Altena et al. 1995 127.4 ± 6.8 7.85 ± 0.44 25.60 ± 1.44 [6]
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.

Physical parameters

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.

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 2010 thesis for the degree of Doctor of Science,[10] using Wood model D[11] 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),[11] 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 initial-final mass relation from Weidemann 2000 paper,[12] 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

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

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ 3.0 3.1 3.2 Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ Lua error in package.lua at line 80: module 'strict' not found. (see Table 8)
  6. ↑ 6.0 6.1 Yale Trigonometric Parallaxes, Fourth Edition (van Altena+ 1995)
  7. ↑ The Solar Neighborhood (TSN) Series in The Astronomical Journal
  8. ↑ Stars within 25 pc of the Sun (Woolley+ 1970)
  9. ↑ Nearby Stars, Preliminary 3rd Version (Gliese+ 1991)
  10. ↑ Matías Cristóbal Radiszcz Sotomayor, BINARIEDAD ESTELAR Y SUB-ESTELAR EN ENANAS BLANCAS CERCANAS
  11. ↑ 11.0 11.1 Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.
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