宿ㄒㄧㄡˋ,即人馬座ττ Sgr拜耳命名法)或人馬座40佛氏命名法),是位於黃道南天星座人馬座的一顆恆星

斗宿五(τ Sagittarii)
斗宿五的位置(紅圈)
觀測資料
曆元 J2000.0
星座 人馬座
星官 斗宿
赤經 19h 06m 56.40897s[1]
赤緯 –27° 40′ 13.5189″[1]
視星等(V) +3.326[2]
特性
光譜分類K1 III[3]
U−B 色指數+1.185[2]
B−V 色指數+1.170[2]
天體測定
徑向速度 (Rv)+45.4[4] km/s
自行 (μ) 赤經:–50.61[1] mas/yr
赤緯:-249.80[1] mas/yr
視差 (π)28.3195 ± 0.3134[5] mas
距離115 ± 1 ly
(35.3 ± 0.4 pc)
絕對星等 (MV)0.48[6]
詳細資料 [7]
質量1.25 M
半徑15.71 R
表面重力 (log g)2.15
亮度87.6 L
溫度4,459 K
金屬量 [Fe/H]–0.27 dex
自轉速度 (v sin i)1.04[8] km/s
年齡7.91 Gyr
其他命名
Namalsadirah 2、Rabi al Sadira、人馬座τ、τ Sgr、 Tau Sgr、40 Sagittarii、CPD−27°6617、FK5 1496、GC 26291、HD 177716、HIP 93864、HR 7234、PPM 269078、SAO 187683
參考資料庫
SIMBAD資料

描述

這是星座中較亮的成員之一,視星等為+3.3[2]。根據視差測量結果[1],這顆恆星與地球的距離大約是122光年(37秒差距)。

這是一顆光譜類型K1的巨星,質量大約是1.25 M。恆星包層比太陽略冷,有效溫度為4,590K,使恆星呈淺橙色。這顆恆星以干涉測量術測得的角直徑,在校正周邊昏暗後,為3.93 ± 0.04 mas[9],在其估計距離處,其物理半徑約為太陽半徑的16倍[10]

斗宿五疑似一顆雙星,但是尚未能確認其伴星。它的金屬含量較低(Fe與H的比值比太陽低54%),且相對太陽的本動速度(64km/s,是當地平均速度的四倍)較高,這表明該恆星是來自銀河系不同地區的訪客[11]

斗宿五是一顆紅群聚的巨星,是一顆質量與太陽相似的恆星,它耗盡了核心的氫,穿過紅巨星分支成為水平分支星,已在核心進行氦融合[12]

哇!訊號

斗宿五是距離1977年的哇!訊號起源處最近的恆星(傳統星座輪廓上的一部分)[11]

名稱和詞源

參考資料

  1. ^ 1.0 1.1 1.2 1.3 1.4 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 , doi:10.1051/0004-6361:20078357 
  2. ^ 2.0 2.1 2.2 2.3 Celis S., L., Photoelectric photometry of late-type variable stars, Astronomy and Astrophysics Supplement Series, October 1975, 22: 9–17, Bibcode:1975A&AS...22....9C 
  3. ^ Gray, R. O.; et al, Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample, The Astronomical Journal, July 2006, 132 (1): 161–170, Bibcode:2006AJ....132..161G, S2CID 119476992, arXiv:astro-ph/0603770 , doi:10.1086/504637 
  4. ^ Wilson, R. E. General Catalogue of Stellar Radial Velocities. Carnegie Institute of Washington D.C. 1953. Bibcode:1953GCRV..C......0W. 
  5. ^ 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 . doi:10.1051/0004-6361/202039657 .  已忽略未知參數|collaboration= (幫助) (勘誤: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  6. ^ Cardini, D., Mg II chromospheric radiative loss rates in cool active and quiet stars, Astronomy and Astrophysics, January 2005, 430: 303–311, Bibcode:2005A&A...430..303C, S2CID 12136256, arXiv:astro-ph/0409683 , doi:10.1051/0004-6361:20041440. 
  7. ^ Reffert, Sabine; et al. Precise radial velocities of giant stars. VII. Occurrence rate of giant extrasolar planets as a function of mass and metallicity. Astronomy & Astrophysics. 2015, 574: A116. Bibcode:2015A&A...574A.116R. S2CID 59334290. arXiv:1412.4634 . doi:10.1051/0004-6361/201322360. hdl:10722/215277. 
  8. ^ Hekker, S.; Meléndez, J. Precise radial velocities of giant stars. III. Spectroscopic stellar parameters. Astronomy and Astrophysics. 2007, 475 (3): 1003. Bibcode:2007A&A...475.1003H. S2CID 10436552. arXiv:0709.1145 . doi:10.1051/0004-6361:20078233. 
  9. ^ 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  
  10. ^ Lang, Kenneth R., Astrophysical formulae, Astronomy and astrophysics library 1 3rd, Birkhäuser, 2006 [2022-09-05], ISBN 3-540-29692-1, (原始內容存檔於2023-07-28) . The radius (R*) is given by:
     
  11. ^ 11.0 11.1 The world's biggest mysteries scientists still can't solve. 2014-09-02 [2022-10-29]. (原始內容存檔於2015-11-08). 
  12. ^ Alves, David R. K-Band Calibration of the Red Clump Luminosity. The Astrophysical Journal. 2000, 539 (2): 732–741. Bibcode:2000ApJ...539..732A. S2CID 16673121. arXiv:astro-ph/0003329 . doi:10.1086/309278. 
  13. ^ Teapot. constellation-guide.com. [2017-05-13]. (原始內容存檔於2020-07-26). 
  14. ^ 14.0 14.1 Template:Cite bok
  15. ^ Jack W. Rhoads - Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Jet Propulsion Laboratory, California Institute of Technology; November 15, 1971 (PDF). [2022-10-29]. (原始內容存檔 (PDF)於2011-08-05). 
  16. ^ (中文) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 11 日頁面存檔備份,存於網際網路檔案館