天門二
天門二（室女座69，69 Virginis）是室女座的一顆[10]恆星，距離地球約259光年。它可以用肉眼看見，是微弱的橙色恆星，視星等 4.76，[2]但它疑似是變星，視星等從4.75到4.79之間變化。[11]天門二以 -13 km/s 的日心徑向速度向地球靠近。[5]由於宇宙塵埃，天門二發出的光受到偏振。[12]
| 觀測資料 曆元 J2000.0 | |
|---|---|
| 星座 | 室女座 |
| 星官 | 天門 （角宿） |
| 赤經 | 13h 27m 27.16348s[1] |
| 赤緯 | −15° 58′ 24.8980″[1] |
| 視星等（V） | 4.76[2] |
| 特性 | |
| 演化階段 | 水平分支 |
| 光譜分類 | K0 III-IIIb CN1.5 CH0.5[3] |
| U−B 色指數 | +1.06[4] |
| B−V 色指數 | +1.09[4] |
| 天體測定 | |
| 徑向速度 (Rv) | −12.9±0.5[5] km/s |
| 自行 (μ) | 赤經：−121.016[1] mas/yr 赤緯：+21.197[1] mas/yr |
| 視差 (π) | 12.5871 ± 0.2367[1] mas |
| 距離 | 259 ± 5 ly (79 ± 1 pc) |
| 絕對星等 (MV) | 0.09[2] |
| 詳細資料 [6] | |
| 質量 | 3.51±0.94 M☉ |
| 半徑 | 15[7] R☉ |
| 表面重力 (log g) | 2.70±0.11 |
| 亮度 | 87.1[7] L☉ |
| 溫度 | 4,909±92 K |
| 金屬量 [Fe/H] | 0.11[8] dex |
| 自轉速度 (v sin i) | 4.3[7] km/s |
| 年齡 | 288+343 −156 Myr |
| 其他命名 | |
| 參考資料庫 | |
| SIMBAD | 資料 |
天門二是演化了的K型巨星，恆星分類為K0 III-IIIb CN1.5 CH0.5，[3]顯示其恆星光譜中有過多的CN和CH分子。它是一個紅群聚巨星，表明它在水平分支的核心通過氦聚變產生能量。[13]天門二的年齡約2.88億年，質量是太陽的3.5倍[6]，半徑是太陽的15倍[7]。它從擴大的光球輻射出的光是太陽的87倍[7]，有效溫度 4,909 K。[6]
參考資料
- ^ 1.0 1.1 1.2 1.3 1.4 Brown, A. G. A.; Vallenari, A.; Prusti, T.; de Bruijne, J. H. J.; et al. Gaia Data Release 2. Summary of the contents and survey properties. Astronomy & Astrophysics. 2018. Bibcode:2018A&A...616A...1G. arXiv:1804.09365
. doi:10.1051/0004-6361/201833051. VizieR中此天體在蓋亞望遠鏡第二批數據發布的記錄
- ^ 2.0 2.1 2.2 Anderson, E.; Francis, Ch., XHIP: An extended hipparcos compilation, Astronomy Letters, 2012, 38 (5): 331, Bibcode:2012AstL...38..331A, S2CID 119257644, arXiv:1108.4971 , doi:10.1134/S1063773712050015.
- ^ 3.0 3.1 Keenan, Philip C.; McNeil, Raymond C., The Perkins catalog of revised MK types for the cooler stars, Astrophysical Journal Supplement Series, 1989, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
- ^ 4.0 4.1 Hoffleit, Dorrit; Jaschek, Carlos, The Bright star catalogue, New Haven, 1991, Bibcode:1991bsc..book.....H
- ^ 5.0 5.1 de Bruijne, J. H. J.; Eilers, A.-C., Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project, Astronomy & Astrophysics, October 2012, 546: 14, Bibcode:2012A&A...546A..61D, S2CID 59451347, arXiv:1208.3048 , doi:10.1051/0004-6361/201219219, A61.
- ^ 6.0 6.1 6.2 Feuillet, Diane K.; et al, Determining Ages of APOGEE Giants with Known Distances, The Astrophysical Journal, 2016, 817 (1): 40, Bibcode:2016ApJ...817...40F, S2CID 118675933, arXiv:1511.04088 , doi:10.3847/0004-637x/817/1/40.
- ^ 7.0 7.1 7.2 7.3 7.4 Massarotti, Alessandro; et al, Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity, The Astronomical Journal, January 2008, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209.
- ^ Meléndez, J.; et al, Chemical similarities between Galactic bulge and local thick disk red giant stars, Astronomy and Astrophysics, June 2008, 484 (3): L21–L25, Bibcode:2008A&A...484L..21M, S2CID 3201679, arXiv:0804.4124 , doi:10.1051/0004-6361:200809398.
- ^ 69 Vir. SIMBAD. 斯特拉斯堡天文資料中心.
- ^ Eggleton, P. P.; Tokovinin, A. A., A catalogue of multiplicity among bright stellar systems, Monthly Notices of the Royal Astronomical Society, September 2008, 389 (2): 869–879, Bibcode:2008MNRAS.389..869E, S2CID 14878976, arXiv:0806.2878 , doi:10.1111/j.1365-2966.2008.13596.x.
- ^ Samus, N. N.; et al, General Catalogue of Variable Stars, Astronomy Reports, 5.1, 2017, 61 (1): 80–88, Bibcode:2017ARep...61...80S, S2CID 125853869, doi:10.1134/s1063772917010085.
- ^ Leroy, J. L., A Polarimetric Investigation on Interstellar Dust Within 50-PARSECS from the Sun, Astronomy and Astrophysics, July 1993, 274 (1): 203, Bibcode:1993A&A...274..203L.
- ^ Alves, David R., K-Band Calibration of the Red Clump Luminosity, The Astrophysical Journal, August 2000, 539 (2): 732–741, Bibcode:2000ApJ...539..732A, S2CID 16673121, arXiv:astro-ph/0003329 , doi:10.1086/309278.
