女四

女四（寶瓶座κ，寶瓶座3）
女四（寶瓶座κ，寶瓶座3）的位置（紅圈）。
觀測資料
曆元 J2000
星座 寶瓶座
星官
赤經 20h 47m 44.23898s[1]
赤緯 −05° 01′ 39.7220″[1]
視星等（V） 4.429[2]
特性
演化阶段漸近巨星分支[3]
光谱分类M3 III[4]
U−B 色指数+1.914[2]
B−V 色指数+1.651[2]
变星类型Lb[5]
天体测定
徑向速度 (Rv)−22.0[6] km/s
自行 (μ) 赤经：+1.68[1] mas/yr
赤纬：−40.06[1] mas/yr
视差 (π)5.57 ± 0.28[1] mas
距离590 ± 30 ly
(180 ± 9 pc)
绝对星等 (MV)−1.83[7]
詳細資料
質量1.8[8] M☉
半徑117.59+3.98
−4.21[9] R☉
表面重力 (log g)0.25[10]
亮度1,771±128[9] L☉
溫度3,452±35[9] K
其他命名
EN Aqr、BD−05°5378、 FK5 1543、HD 198026、HIP 102624、HR 7951、SAO 144814[11]
參考資料庫
SIMBAD资料
依據依巴谷衛星的資料繪製的寶瓶座EN光變曲線[12]。數據與Koen和Eyer報告的4.57天期間合併 （2002）[13]。

女四（英語：3 Aquarii，縮寫為3 Aqr）是在天球赤道星座寶瓶座的一顆變星。「寶瓶座3」是來自佛蘭斯蒂德命名法的名稱；它的拜耳名稱是寶瓶座k，和變星名稱為寶瓶座EN。平均視星等為4.429[2]，在黑暗的天空中，肉眼可見。它的年週視差位移為5.57毫角秒，誤差範圍為5%[1]，這相當於實際距離地球約為 590光年（180秒差距）。

恆星分類為M3III[4]，這顆恆星是紅巨星，其核心的氫已經耗盡，並且演化遠離了主序星]。經過修正臨邊昏暗後，測量這顆恆星的角直徑是5.60±0.70 mas[14]。在估計的女四距離下[1]，這使得實際尺寸約為太陽半徑的108倍[15]。恆星大氣的有效溫度為3,450 K[9]，賦予這顆恆星冷且帶有M型恆星的紅色調。

最早於1960年代被注意到，女四的視星等變化可達0.06星等[16][17]。1973年正式被列為變星，並依變星命名法命名為寶瓶座EN[18]。它被歸類為不規則變星[5]，然而詳細分析顯示有多個可能的週期[19]。

脈動週期[19]
週期 (days) 20.2 24.9 27.2 35.0 36.9 143.9 197.2
振幅 (magnitudes) 0.020 0.038 0.027 0.021 0.024 0.022 0.027

參考文獻

  1. ^ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 van Leeuwen, F., Validation of the new Hipparcos reduction, Astronomy and Astrophysics, November 2007, 474 (2): 653–664, Bibcode:2007A&A...474..653V, S2CID 18759600, arXiv:0708.1752 可免费查阅, doi:10.1051/0004-6361:20078357. 
  2. ^ 2.0 2.1 2.2 2.3 Gutierrez-Moreno, Adelina; et al. A System of photometric standards. Publ. Dept. Astron. Univ. Chile (Publicaciones Universidad de Chile, Department de Astronomy). 1966, 1: 1–17. Bibcode:1966PDAUC...1....1G. 
  3. ^ Eggen, Olin J. Asymptotic Giant Branch Stars Near the Sun. The Astronomical Journal. 1992, 104: 275. Bibcode:1992AJ....104..275E. doi:10.1086/116239. 
  4. ^ 4.0 4.1 Morgan, W. W.; et al. Spectral Classification. Annual Review of Astronomy and Astrophysics. 1973, 11: 29. Bibcode:1973ARA&A..11...29M. doi:10.1146/annurev.aa.11.090173.000333. 
  5. ^ 5.0 5.1 Samus, N. N.; Durlevich, O. V.; et al. VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013). VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 2009, 1. Bibcode:2009yCat....102025S. 
  6. ^ Wielen, R.; et al, Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions, Veröff. Astron. Rechen-Inst. Heidelb (Astronomisches Rechen-Institut Heidelberg), 1999, 35 (35): 1, Bibcode:1999VeARI..35....1W. 
  7. ^ Anderson, E.; Francis, Ch. XHIP: An extended hipparcos compilation. Astronomy Letters. 2012, 38 (5): 331. Bibcode:2012AstL...38..331A. S2CID 119257644. arXiv:1108.4971 可免费查阅. doi:10.1134/S1063773712050015.  Vizier catalog entry
  8. ^ Kervella, Pierre; Arenou, Frédéric; Thévenin, Frédéric. Stellar and substellar companions from Gaia EDR3. Proper-motion anomaly and resolved common proper-motion pairs. Astronomy and Astrophysics. 2022, 657: 657. Bibcode:2022A&A...657A...7K. S2CID 237605138. arXiv:2109.10912 可免费查阅. doi:10.1051/0004-6361/202142146. 
  9. ^ 9.0 9.1 9.2 9.3 Baines, Ellyn K.; Thomas Armstrong, J.; Clark, James H.; Gorney, Jim; Hutter, Donald J.; Jorgensen, Anders M.; Kyte, Casey; Mozurkewich, David; Nisley, Ishara; Sanborn, Jason; Schmitt, Henrique R. Angular Diameters and Fundamental Parameters of Forty-four Stars from the Navy Precision Optical Interferometer. The Astronomical Journal. November 2021, 162 (5): 198. Bibcode:2021AJ....162..198B. ISSN 0004-6256. S2CID 238998021. arXiv:2211.09030 可免费查阅. doi:10.3847/1538-3881/ac2431 可免费查阅. 
  10. ^ McDonald, I.; Zijlstra, A. A.; Watson, R. A. Fundamental parameters and infrared excesses of Tycho–Gaia stars. Monthly Notices of the Royal Astronomical Society. 15 June 2017, 471 (1): 770–791. Bibcode:2017MNRAS.471..770M. ISSN 0035-8711. arXiv:1706.02208 可免费查阅. doi:10.1093/mnras/stx1433 可免费查阅. eISSN 1365-2966. 
  11. ^ * k Aqr. SIMBAD. 斯特拉斯堡天文資料中心. 
  12. ^ /ftp/cats/more/HIP/cdroms/cats. Centre de Données astronomiques de Strasbourg. Strasbourg astronomical Data Center. [15 October 2022]. 
  13. ^ Koen, Chris; Eyer, Laurent. New periodic variables from the Hipparcos epoch photometry. Monthly Notices of the Royal Astronomical Society. March 2002, 331 (1): 45–59. Bibcode:2002MNRAS.331...45K. S2CID 10505995. arXiv:astro-ph/0112194 可免费查阅. doi:10.1046/j.1365-8711.2002.05150.x 可免费查阅. 
  14. ^ Richichi, A.; et al, CHARM2: An updated Catalog of High Angular Resolution Measurements, Astronomy and Astrophysics, February 2005, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039 可免费查阅. 
  15. ^ Lang, Kenneth R., Astrophysical formulae, Astronomy and astrophysics library 1 3rd, Birkhäuser, 2006, ISBN 3-540-29692-1. . The radius (R*) is given by:
  16. ^ A. W. J. Cousins. Fabry photometry of bright southern stars. Royal Greenwich Observatory Bulletins. 1966, 122: 59. Bibcode:1966RGOB..122...59C. 
  17. ^ Eggen, Olin J. Narrow-and Broad-Band Photometry of Red Stars.IV. Population Separation in Giant Stars. The Astrophysical Journal. 1969, 158: 225. Bibcode:1969ApJ...158..225E. doi:10.1086/150186 可免费查阅. 
  18. ^ Kukarkin, B. V.; Kholopov, P. N.; Kukarkina, N. P.; Perova, N. B. 59th Name-List of Variable Stars. Information Bulletin on Variable Stars. 1973, 834: 1. Bibcode:1973IBVS..834....1K. 
  19. ^ 19.0 19.1 Tabur, V.; Bedding, T. R.; Kiss, L. L.; Moon, T. T.; Szeidl, B.; Kjeldsen, H. Long-term photometry and periods for 261 nearby pulsating M giants. Monthly Notices of the Royal Astronomical Society. December 2009, 400 (4): 1945–1961. Bibcode:2009MNRAS.400.1945T. arXiv:0908.3228 可免费查阅. doi:10.1111/j.1365-2966.2009.15588.x 可免费查阅. 

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