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词条 WD 2359-434
释义

  1. Distance

  2. Physical parameters

  3. Main sequence progenitor properties

  4. See also

  5. Notes

  6. References

{{Sky|00|02|10.766|-|43|09|56.02|26.7}}{{Starbox begin
|name= WD 2359-434}}{{Starbox image
| image =
| caption = Size of WD 2359-434 in comparison with Earth. On the left is Earth, on the right is WD 2359-434.
}}{{Starbox observe
|epoch=J2000[1]
|equinox=J2000[1]
|constell=Phoenix
|ra={{RA|00|02|10.766}}[1]
|dec={{DEC|-43|09|56.02}}[1]
|appmag_v=12.76[2]}}{{Starbox character
|class=DAP5.8[3]
| appmag_1_passband=B
| appmag_1=13.12[1]
| appmag_2_passband=V
| appmag_2=12.76[2]
| appmag_3_passband=RKC
| appmag_3=12.82[4]
| appmag_4_passband=IKC
| appmag_4=12.66[4]
| appmag_5_passband=J
| appmag_5=12.60 ± 0.03[4]
| appmag_6_passband=H
| appmag_6=12.43 ± 0.02[4]
| appmag_7_passband=KS
| appmag_7=12.45 ± 0.02[4]}}{{Starbox astrometry
|prop_mo_ra=589[4]
|prop_mo_dec=-664[4]
|radial_v=-58.8 ± 10.8[5]
|parallax=122.27
|p_error=1.13
|parallax_footnote=[4]
| absmag_v=13.20[2][4][6]}}{{Starbox detail
| mass=0.85 ± 0.01[4]
| gravity=8.39 ± 0.01[4]
| radius=0.0097[4][7]
| temperature=8570 ± 50[2]
| age_gyr=1.82 ± 0.06[4][8]}}{{Starbox catalog
|names=Gliese 915,[2][3] LHS 1005,[2] LFT 1849,[1] LTT 9857,[1] LP 988-88,[1] L 362-81,[9] EGGR 165,[1] 2MASS J00021076-4309560[1]}}{{Starbox reference
| Simbad=Gliese+915
}}{{Starbox end}}

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[10] 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 [11]
GJ, 3rd version Gliese, Jahreiss 1991 128.2 ± 6.4 7.80 ± 0.41 25.44 ± 1.37 [12]
YPC, 4th edition van Altena et al. 1995 127.4 ± 6.8 7.85 ± 0.44 25.60 ± 1.44 [9]
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][13] 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 to the 2010 thesis for the degree of Doctor of Science,[14] using Wood model D[15] initial–final mass relation and WD 2359-434's white dwarf mass value {{Solar mass|link=y|0.97 ± 0.03}} from Holberg et al. 2008,[2] its main sequence progenitor mass was {{Solar mass|7.09}}. Using expression for pre-white dwarf lifetime 10 · (MMS/{{Solar mass}})2.5 (Gyr),[15] was found WD 2359-434 main sequence age 0.07 Gyr.

White dwarf mass value {{Solar mass|0.85 ± 0.01}} from Subasavage et al. 2009,[4] in Wood model D yields MS (main sequence) mass {{Solar mass|6.03}}, and MS lifetime 0.11 Gyr, corresponding to B-type main sequence star.

According to initial-final mass relation from Weidemann 2000 paper,[16] WD 2359-434's main sequence progenitor should have mass about {{Solar mass|4.6}} and lifespan 0.22 Gyr, and, again, should be of B spectral type. There are also other models.

See also

  • List of star systems within 25–30 light-years

Notes

1. ^1 2 3 4 5 6 7 8 9 {{cite web| url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Gliese+915| title =GJ 915 -- White Dwarf| publisher=Centre de Données astronomiques de Strasbourg| accessdate=2011-11-03}}
2. ^1 2 3 4 5 6 7 {{cite journal| last=Holberg |first=J. B.|author2=Sion |author3=Oswalt |author4=McCook |author5=Foran |author6= Subasavage | date=2008| title=A NEW LOOK AT THE LOCAL WHITE DWARF POPULATION| journal=The Astronomical Journal| volume=135 | pages=1225–1238| bibcode=2008AJ....135.1225H| doi=10.1088/0004-6256/135/4/1225}}
3. ^1 2 {{cite journal| last=Sion |first=Edward M.|author2=Holberg |author3=Oswalt |author4=McCook |author5= Wasatonic | date=2009| title=THE WHITE DWARFS WITHIN 20 PARSECS OF THE SUN: KINEMATICS AND STATISTICS| journal=The Astronomical Journal| volume=138 | pages=1681–1689| bibcode=2009AJ....138.1681S| doi=10.1088/0004-6256/138/6/1681|arxiv = 0910.1288 }}
4. ^1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 {{cite journal| last=Subasavage |first=John P.|author2=Jao |author3=Henry |author4=Bergeron |author5=Dufour |author6=Ianna |author7=Costa |author8= Mendez | date=2009| title=THE SOLAR NEIGHBORHOOD. XXI. PARALLAX RESULTS FROM THE CTIOPI 0.9 m PROGRAM: 20 NEW MEMBERS OF THE 25 PARSEC WHITE DWARF SAMPLE| journal=The Astronomical Journal| volume=137 | pages=4547–4560| bibcode=2009AJ....134.4547S| doi=10.1088/0004-6256/137/6/4547|arxiv=0902.0627}}
5. ^{{cite journal| last=Pauli |first=E.-M.|author2=Napiwotzki |author3=Heber |author4= Altmann |author5= Odenkirchen |last-author-amp= yes | date=2006| title=3D kinematics of white dwarfs from the SPY project. II| journal=Astronomy and Astrophysics| volume=447 | pages=173–184| bibcode=2006A&A...447..173P| doi=10.1051/0004-6361:20052730|arxiv = astro-ph/0510494 }} (see Table 8)
6. ^From apparent magnitude and parallax.
7. ^From surface gravity and mass.
8. ^White dwarf cooling age, i. e. age as degenerate star (not including lifetime as main sequence star and as giant star).
9. ^1 Yale Trigonometric Parallaxes, Fourth Edition (van Altena+ 1995)
10. ^The Solar Neighborhood (TSN) Series in The Astronomical Journal
11. ^Stars within 25 pc of the Sun (Woolley+ 1970)
12. ^Nearby Stars, Preliminary 3rd Version (Gliese+ 1991)
13. ^From mass and surface gravity (assuming spherical shape).
14. ^Matías Cristóbal Radiszcz Sotomayor, BINARIEDAD ESTELAR Y SUB-ESTELAR EN ENANAS BLANCAS CERCANAS{{Dead link|date=July 2018 |bot=InternetArchiveBot |fix-attempted=yes }}
15. ^1 {{cite journal| last=Wood |first=M. A.| date=1992| title=Constraints on the age and evolution of the Galaxy from the white dwarf luminosity function| journal=The Astrophysical Journal| volume=386 | pages=539–561| bibcode=1992ApJ...386..539W| doi=10.1086/171038}}
16. ^{{cite journal| last=Weidemann |first=V.| date=2000| title=Revision of the initial-to-final mass relation| journal=Astronomy and Astrophysics| volume=363 | pages=647–656| bibcode=2000A&A...363..647W}}

References

{{Stars of Phoenix}}

4 : White dwarfs|Phoenix (constellation)|Gliese and GJ objects|2MASS objects
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