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G 240-72

天球赤道座标星图 17h 48m 08.17s, +70° 52′ 35.3″
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G 240-72
观测资料
历元 J2000[1]
星座 天龙座
星官
赤经 17h 48m 08.17s[1]
赤纬 +70° 52′ 35.3″[1]
视星等(V) 14.15[2]
特性
光谱分类DQP9.0[2]
视星等 (B)14.55[1]
视星等 (V)14.15[1]
视星等 (R)13.5[1]
视星等 (I)13.1[1]
视星等 (J)12.709 ± 0.021[1]
视星等 (H)12.528 ± 0.023[1]
视星等 (K)12.507 ± 0.023[1]
天体测定
自行 (μ) 赤经:-1261[3] mas/yr
赤纬:1112[3] mas/yr
视差 (π)160.9952 ± 0.0119[4] mas
距离20.259 ± 0.001 ly
(6.2114 ± 0.0005 pc)
绝对星等 (MV)15.23[2][5][note 1]
详细资料
质量0.81 ± 0.01[2] M
半径0.00984[2][note 2] R
表面重力 (log g)8.36 ± 0.02[2]
亮度0.000085[6] L
温度5590 ± 90[2] K
自转>100 years[7]
年龄5.69[note 3][3] Gyr
其他命名
WD 1748+708,[2][3] LHS 455,[2] LP 44-113,[1] NLTT 45565,[1] GJ 1221,[5] EGGR 372,[1] 2MASS J17480817+7052353[1]
参考数据库
SIMBAD资料
G 240-72 is located in the constellation Draco
G 240-72 is located in the constellation Draco
G 240-72
G 240-72 在天龙座的位置

G 240-72 (或 WD 1748+708LHS 455GJ 1221) 是一颗位于天龙座附近的白矮星,光谱等级为 DQP9.0[2]

距离

G 240-72 是距离第七近的白矮星(仅次于天狼星B南河三B范马南星GJ 440波江座40B施泰因2051B)。

特性

G 240-72质量为0.81个太阳质量[2]

这颗白矮星的温度相对较低,为5590K[2]。由于其温度与太阳相似,因此外观呈白色。它有纯氦大气,自转非常缓慢,周期可能超过100年。[7]

参考

  1. ^ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 GJ 1221 -- White Dwarf. Centre de Données astronomiques de Strasbourg. [2011-10-23]. (原始内容存档于2023-03-22). 
  2. ^ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 Holberg, J. B.; Sion; Oswalt; McCook; Foran; Subasavage. A New Look at the Local White Dwarf Population. The Astronomical Journal. 2008, 135 (4): 1225–1238 [2023-03-22]. Bibcode:2008AJ....135.1225H. S2CID 122855486. doi:10.1088/0004-6256/135/4/1225. (原始内容存档于2023-04-20). 
  3. ^ 3.0 3.1 3.2 3.3 Sion, Edward M.; Holberg; Oswalt; McCook; Wasatonic. The White Dwarfs within 20 Parsecs of the Sun: Kinematics and Statistics. The Astronomical Journal. 2009, 138 (6): 1681–1689. Bibcode:2009AJ....138.1681S. S2CID 119284418. arXiv:0910.1288可免费查阅. doi:10.1088/0004-6256/138/6/1681. 
  4. ^ Brown, A. G. A.; et al. Gaia Early Data Release 3: Summary of the contents and survey properties. Astronomy & Astrophysics. 2021, 649: A1. Bibcode:2021A&A...649A...1G. S2CID 227254300. arXiv:2012.01533可免费查阅. doi:10.1051/0004-6361/202039657可免费查阅.  已忽略未知参数|collaboration= (帮助) (勘误: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  5. ^ 5.0 5.1 Van Altena W. F.; Lee J. T.; Hoffleit E. D. GCTP 2835.01. The General Catalogue of Trigonometric Stellar Parallaxes Fourth. 1995 [2023-03-22]. (原始内容存档于2022-05-23). 
  6. ^ Giammichele, N.; Bergeron, P.; Dufour, P., Know Your Neighborhood: A Detailed Model Atmosphere Analysis of Nearby White Dwarfs, The Astrophysical Journal Supplement, April 2012, 199 (2): 29, Bibcode:2012ApJS..199...29G, S2CID 118304737, arXiv:1202.5581可免费查阅, doi:10.1088/0067-0049/199/2/29. 
  7. ^ 7.0 7.1 MEASURING THE ROTATIONAL PERIODS OF ISOLATED MAGNETIC WHITE DWARFS. [2023-03-22]. (原始内容存档于2023-03-22). 

注释

  1. ^ From apparent magnitude and parallax.
  2. ^ From surface gravity and mass.
  3. ^ Cooling age, i. e. age as degenerate star (not counting duration of previous existence as main sequence star and as giant star)

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