zh %E6%96%97%E5%AE%BF%E4%BA%94

**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（斗宿）
赤經	19h 06m 56.40897s
赤緯	–27° 40′ 13.5189″
視星等（V）	+3.326
特性
光谱分类	K1 III
U−B 色指数	+1.185
B−V 色指数	+1.170
天体测定
徑向速度 (Rv)	+45.4 km/s
自行 (μ)	赤经：–50.61 mas/yr ; 赤纬：-249.80 mas/yr
视差 (π)	28.3195 ± 0.3134 mas
距离	115 ± 1 ly ; (35.3 ± 0.4 pc)
绝对星等 (MV)	0.48
詳細資料
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
金属量 [Fe/H]	–0.27 dex
自轉速度 (v sin i)	1.04 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	资料

斗（dǒu）宿（xiù）五，即人馬座τ（τ 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恒星。

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

這顆恆星其它一些恆星構成了幾個簡單的星群：
- 茶壺：由人馬座γ、斗宿五、人馬座δ、人馬座ε 、人馬座ζ、人馬座λ、人馬座σ和人馬座φ組成^[13]。
- 歸來的鴕鳥（"the Returning Ostriches"）：由人馬座φ、人馬座λ、人馬座σ、斗宿五、人馬座ζ和人馬座χ（雙星）組成。在阿拉伯語中是Al Naʽām al Ṣādirah，經常翻譯為 Namalsadirah（لنعم السادرة）^[14]。
  - 起初以數值順序排列的四顆星：人馬座φ、斗宿五、人馬座χ¹和 and 人馬座χ²^[15]。
- 鴕鳥窩（"Ostrich's Nest"，Al Udḥiyy）：由人馬座ν、斗宿五、人馬座φ、人馬座ω、人馬座60和人馬座ζ組成^[14]。
- 在完全獨立的中國傳統中的斗宿：斗宿五屬於斗（Dǒu），意思是斗宿的第五顆星。斗宿由斗宿一（人馬座φ）、斗宿二（人馬座λ）、斗宿三（人馬座μ）、斗宿四（人馬座σ）、斗宿五（人馬座τ）、斗宿六（人馬座ζ）組成，也稱為南斗六星 ^[16]。

参考资料

^ ^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
^ ^2.0 ^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
^ 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
^ Wilson, R. E. General Catalogue of Stellar Radial Velocities. Carnegie Institute of Washington D.C. 1953. Bibcode:1953GCRV..C......0W.
^ 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 . 已忽略未知参数|collaboration= (帮助) (勘误: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
^ 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.
^ 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.
^ 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.
^ 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 
^ Lang, Kenneth R., Astrophysical formulae, Astronomy and astrophysics library 1 3rd, Birkhäuser, 2006 [2022-09-05], ISBN 3-540-29692-1, （原始内容存档于2023-07-28） . The radius (R_*) is given by:
${\begin{aligned}2\cdot R_{*}&={\frac {(10^{-3}\cdot 37\cdot 3.93)\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 31.3\cdot R_{\bigodot }\end{aligned}}$
^ ^11.0 ^11.1 The world's biggest mysteries scientists still can't solve. 2014-09-02 [2022-10-29]. （原始内容存档于2015-11-08）.
^ 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.
^ Teapot. constellation-guide.com. [2017-05-13]. （原始内容存档于2020-07-26）.
^ ^14.0 ^14.1 Template:Cite bok
^ 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]. （原始内容存档 (PDF)于2011-08-05）.
^ （中文） AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 11 日（页面存档备份，存于互联网档案馆）

[aaa474_2_653-1] 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

[aaass22_9-2] 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

[aj132_1_161-3] 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

[gcsrv-4] Wilson, R. E. General Catalogue of Stellar Radial Velocities. Carnegie Institute of Washington D.C. 1953. Bibcode:1953GCRV..C......0W.

[Gaia3-5] 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 . 已忽略未知参数|collaboration= (帮助) (勘误: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.

[Cardini2005-6] 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.

[reffert-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.

[hekker-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.

[aaa431_773-9] 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 

[lang2006-10] Lang, Kenneth R., Astrophysical formulae, Astronomy and astrophysics library 1 3rd, Birkhäuser, 2006 [2022-09-05], ISBN 3-540-29692-1, （原始内容存档于2023-07-28） . The radius (R_*) is given by:
${\begin{aligned}2\cdot R_{*}&={\frac {(10^{-3}\cdot 37\cdot 3.93)\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 31.3\cdot R_{\bigodot }\end{aligned}}$

[:0-11] 11.0 ^11.1 The world's biggest mysteries scientists still can't solve. 2014-09-02 [2022-10-29]. （原始内容存档于2015-11-08）.

[alves-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.

[teapot-13] Teapot. constellation-guide.com. [2017-05-13]. （原始内容存档于2020-07-26）.

[allen1899-14] 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]. （原始内容存档 (PDF)于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（页面存档备份，存于互联网档案馆）

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