WD 2359-434

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

WD 2359-434
Gliese 915 and Earth.png
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[edit]

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[edit]

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[edit]

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[edit]

  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[edit]

  1. ^ a b c d e f g h i j "GJ 915 -- White Dwarf". Centre de Données astronomiques de Strasbourg. Retrieved 2011-11-03. 
  2. ^ a b c d e f g h 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 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. 
  4. ^ a b c d e f g h i j k l m n o p q r s t 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. 
  5. ^ Pauli, E.-M.; Napiwotzki; Heber; Altmann, and Odenkirchen (2006). "3D kinematics of white dwarfs from the SPY project. II.". Astronomy and Astrophysics 447: 173–184. arXiv:astro-ph/0510494. Bibcode:2006A&A...447..173P. doi:10.1051/0004-6361:20052730.  (see Table 8)
  6. ^ a b 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. ^ a b Wood, M. A. (1992). "Constraints on the age and evolution of the Galaxy from the white dwarf luminosity function". The Astrophysical Journal 386: 539–561. Bibcode:1992ApJ...386..539W. doi:10.1086/171038. 
  12. ^ Weidemann, V. (2000). "Revision of the initial-to-final mass relation". Astronomy and Astrophysics 363: 647–656. Bibcode:2000A&A...363..647W.