G 99-47

G 99-47 (V1201 Orionis) is a nearby degenerate star (white dwarf) of spectral class DAP8 (DAP8.9,[3] or DAP8.7[2]), the single known component of the system, located in the constellation Orion.

G 99-47
Observation data
Epoch J2000[1]      Equinox J2000[1]
Constellation Orion
Right ascension  05h 56m 25.47s[1]
Declination +05° 21′ 48.6″[1]
Apparent magnitude (V) 14.105[2]
Characteristics
Spectral type DAP8.9[3]
Apparent magnitude (B) 14.69[1]
Apparent magnitude (V) 14.10[1]
Apparent magnitude (R) 14.0[1]
Apparent magnitude (I) 13.6[1]
Apparent magnitude (J) 12.930 ± 0.022[1]
Apparent magnitude (H) 12.720 ± 0.025[1]
Apparent magnitude (K) 12.653 ± 0.024[1]
Astrometry
Proper motion (μ) RA: -434[3] mas/yr
Dec.: -931[3] mas/yr
Parallax (π)125.0 ± 3.6[4] mas
Distance26.1 ± 0.8 ly
(8.0 ± 0.2 pc)
Absolute magnitude (MV)14.59[2][4][note 1]
Details
Mass0.71 ± 0.03[2] M☉
Radius0.011[2][note 2] R☉
Surface gravity (log g)8.20 ± 0.05[2] cgs
Temperature5790 ± 110[2] K
Age3.97[3][note 3] Gyr
Other designations
WD 0553+053,[2][3] V1201 Ori,[1] LHS 212,[2] LTT 17891,[1] NLTT 15834,[1] G 099-047,[4] GJ 1087,[1] G 102-40,[1] G 106-15,[1] EGGR 290,[1] 2MASS J05562547+0521486,[1] USNO-B1.0 0953-00073703[1]
Database references
SIMBADdata

Distance

G 99-47 is probably the tenth closest white dwarf (or possibly the 9th–12th: see Gliese 293, Gliese 518 and Gliese 915). Its trigonometric parallax from the Yale Parallax Catalog is 0.1250 ± 0.0036 arcsec,[4] corresponding to a distance 8.00 ± 0.23 pc, or 26.09 ± 0.75 ly.

Parallax data
SourcePaperParallax, masDistance, pcDistance, lyRef.
Nearby Stars, 3rd ed. prelim., 3rd versionGliese, Jahreiss, 1991125.1 ± 4.17.99 ± 0.2626.07 ± 0.85[5]
YPC, 4th editionvan Altena et al., 1995125.0 ± 3.68.00 ± 0.2326.09 ± 0.75[4]

Physical parameters

G 99-47's mass is 0.71 ± 0.03 Solar masses;[2] its surface gravity is 108.20 ± 0.05 (1.58 · 108) cm·s−2,[2] or approximately 162 000 of Earth's, corresponding to a radius 7711 km, or 121% of Earth's.

Its temperature is 5790 ± 110 K,[2] almost like the Sun's; its cooling age, i. e. age as degenerate star (not including lifetime as main sequence star and as giant star) is 3.97 Gyr.[3] Due almost equal to the Sun's temperature, GJ 1087 should appear almost the same color as the Sun.

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)

See also

References
  1. "V* V1201 Ori -- White Dwarf". Centre de Données astronomiques de Strasbourg. Retrieved 2011-11-01.
  2. Holberg, J. B.; Sion; Oswalt; McCook; Foran; Subasavage (2008). "A New Look at the Local White Dwarf Population". The Astronomical Journal. 135 (4): 1225–1238. Bibcode:2008AJ....135.1225H. doi:10.1088/0004-6256/135/4/1225.
  3. Sion, Edward M.; Holberg; Oswalt; McCook; Wasatonic (2009). "The White Dwarfs within 20 Parsecs of the Sun: Kinematics and Statistics". The Astronomical Journal. 138 (6): 1681–1689. arXiv:0910.1288. Bibcode:2009AJ....138.1681S. doi:10.1088/0004-6256/138/6/1681.
  4. Yale Trigonometric Parallaxes, Fourth Edition (van Altena+ 1995)
  5. Nearby Stars, Preliminary 3rd Version (Gliese+ 1991)
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