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危宿一（宝瓶座α）
α Aquarii
	危宿一在宝瓶座的位置
觀測資料; 曆元 J2000.0
星座	宝瓶座
星官	危宿危
赤經	22h 05m 47.03593s
赤緯	−00° 19′ 11.4568″
視星等（V）	2.942
特性
光谱分类	G2 Ib
U−B 色指数	+0.699
B−V 色指数	+0.971
R−I 色指数	+0.49
天体测定
徑向速度 (Rv)	7.5 km/s
自行 (μ)	赤经：+18.25 mas/yr ; 赤纬：−9.39 mas/yr
视差 (π)	6.23 ± 0.19 mas
距离	520 ± 20 ly ; (161 ± 5 pc)
绝对星等 (MV)	–3.882
詳細資料
質量	6.5 ± 0.3 M☉
半徑	77 ± 15 R☉
表面重力 (log g)	1.76 ± 0.04
亮度	4400 L☉
溫度	5,400 ± 100 K
自轉速度 (v sin i)	6.7 ± 1.5 km/s
年齡	53 Myr
其他命名
	El Melik, Rucbah, Saad el Melik, Sadalmelek, Sadalmelik, Sadlamulk, α Aqr, Alpha Aquarii, Alpha Aqr, 34 Aquarii, 34 Aqr, BD−01 4246, FK5 827, HD 209750, HIP 109074, HR 8414, SAO 145862.
參考資料庫
SIMBAD	资料

危宿一，即宝瓶座α（α Aqr，α Aquarii）是一颗位于宝瓶座的超巨星，距离地球约520光年。

特征

危宿一的视星等为2.94，是宝瓶座第二亮的恒星^[2]，仅次于虚宿一（宝瓶座β）。根据依巴谷卫星对恒星视差的测量，危宿一距离地球大约为520光年（160秒差距）。^[1]

危宿一的年龄约为5300万年，已经演变成一颗超巨星，恒星光谱是G2 Ib型。^[3] 恒星的质量是太阳质量的6.5倍^[3]，半径是太阳半径的77倍^[7]，亮度是太阳亮度的4400倍。^[8] 危宿一的表面有效温度约为5400K，这使得它的呈现出G型星特征的黄色色调。^[13] 钱德拉X射线天文台对危宿一的观测发现它和G-型主序星相比，辐射出的X射线显著匮乏，这也是早期G型巨星的共同特征。^[9] 危宿一和虚宿一（宝瓶座β）、离宫四（飞马座η）三颗中等质量的恒星组成一个恒星群落，它们在星际运动的方向垂直于银河面。^[9]

危宿一有一颗伴星CCDM J22058-0019B，可以通过望远镜看到，其视星等约为12.2，距离主星的角距离为110.4角秒，目前的位置角位于主星的40°方位。^[11]

命名

危宿一在西方的传统名字为Sadalmelik, 来自于阿拉伯语سعد الملك（sa‘d al-malik），意思为“帝皇的幸运星”。波斯帖木儿帝国国王、天文学家乌鲁伯格将危宿一和蓋屋一（宝瓶座ο）并称为Sadalmelik。此外，危宿一还与阁道三（仙后座δ）共用一个名字Rucbah，在阿拉伯语是“膝盖”的意思。^[12] 它是在天球赤道附近（1°之内）两颗拥有古代固有名的恒星之一，但是这两个名字的起源历史已不可考究。^[8]

在中国古代星官系统中，危宿一属于北方玄武七宿中危宿危 (星官)第一星，这也是危宿一名字的来由。^[14]“危”意思是屋顶，危星官由三颗恒星组成，另外两颗恒星分别是危宿二（飞马座θ）和危宿三（飞马座ε）。^[15]

参考资料

^ ^1.0 ^1.1 ^1.2 ^1.3 ^1.4 ^1.5 van Leeuwen, F., Validation of the new Hipparcos reduction, Astronomy and Astrophysics, November 2007, 474 (2): 653–664, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357
^ ^2.0 ^2.1 ^2.2 ^2.3 Cousins, A. W. J., Standardization of Broadband Photometry of Equatorial Standards, South African Astronomical Observatory Circulars, 1984, 8: 59, Bibcode:1984SAAOC...8...59C
^ ^3.0 ^3.1 ^3.2 ^3.3 ^3.4 ^3.5 ^3.6 Lyubimkov, Leonid S.; et al, Accurate fundamental parameters for A-, F- and G-type Supergiants in the solar neighbourhood, Monthly Notices of the Royal Astronomical Society, February 2010, 402 (2): 1369–1379, Bibcode:2010MNRAS.402.1369L, doi:10.1111/j.1365-2966.2009.15979.x
^ ^4.0 ^4.1 HR 8414 （页面存档备份，存于互联网档案馆）, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50 （页面存档备份，存于互联网档案馆）. Accessed on line October 3, 2008.
^ Wielen, R.; et al, Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions (35), Astronomisches Rechen-Institut Heidelberg, 1999, Bibcode:1999VeARI..35....1W
^ Soubiran, C.; et al. Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants. Astronomy and Astrophysics. 2008, 480 (1): 91–101. Bibcode:2008A&A...480...91S. doi:10.1051/0004-6361:20078788.
^ ^7.0 ^7.1 Nordgren, Tyler E.; et al, Stellar Angular Diameters of Late-Type Giants and Supergiants Measured with the Navy Prototype Optical Interferometer, The Astronomical Journal, December 1999, 118 (6): 3032–3038, Bibcode:1999AJ....118.3032N, doi:10.1086/301114
^ ^8.0 ^8.1 ^8.2 Sadalmelik （页面存档备份，存于互联网档案馆）, Stars, Jim Kaler. Accessed on line October 3, 2008.
^ ^9.0 ^9.1 ^9.2 Ayres, Thomas R.; Brown, Alexander; Harper, Graham M., Chandra Observations of Coronal Emission from the Early G Supergiants α and β Aquarii, The Astrophysical Journal, July 2005, 627 (1): L53–L56, Bibcode:2005ApJ...627L..53A, doi:10.1086/431977
^ NAME SADALMELIK -- Star in double system, database entry, SIMBAD. Accessed on line October 3, 2008.
^ ^11.0 ^11.1 Entry 22058-0019, The Washington Double Star Catalog （页面存档备份，存于互联网档案馆）, United States Naval Observatory. Accessed on line November 18, 2008.
^ ^12.0 ^12.1 pp. 51, 148, Star-names and Their Meanings （页面存档备份，存于互联网档案馆）, Richard Hinckley Allen, New York: G. E. Stechert, 1899.
^ The Colour of Stars, Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004 [2012-01-16], （原始内容存档于2012-03-10）
^ 香港太空館 - 研究資源 - 亮星中英對照表. [2012-03-29]. （原始内容存档于2010-08-18）.
^ 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.

外部链接

[aaa474_2_653-1] 1.0 ^1.1 ^1.2 ^1.3 ^1.4 ^1.5 van Leeuwen, F., Validation of the new Hipparcos reduction, Astronomy and Astrophysics, November 2007, 474 (2): 653–664, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357

[saoc8_59-2] 2.0 ^2.1 ^2.2 ^2.3 Cousins, A. W. J., Standardization of Broadband Photometry of Equatorial Standards, South African Astronomical Observatory Circulars, 1984, 8: 59, Bibcode:1984SAAOC...8...59C

[mnras402_2_1369-3] 3.0 ^3.1 ^3.2 ^3.3 ^3.4 ^3.5 ^3.6 Lyubimkov, Leonid S.; et al, Accurate fundamental parameters for A-, F- and G-type Supergiants in the solar neighbourhood, Monthly Notices of the Royal Astronomical Society, February 2010, 402 (2): 1369–1379, Bibcode:2010MNRAS.402.1369L, doi:10.1111/j.1365-2966.2009.15979.x

[bsc1-4] 4.0 ^4.1 HR 8414 （页面存档备份，存于互联网档案馆）, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50 （页面存档备份，存于互联网档案馆）. Accessed on line October 3, 2008.

[scfs-5] Wielen, R.; et al, Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions (35), Astronomisches Rechen-Institut Heidelberg, 1999, Bibcode:1999VeARI..35....1W

[aaa480_1_91-6] Soubiran, C.; et al. Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants. Astronomy and Astrophysics. 2008, 480 (1): 91–101. Bibcode:2008A&A...480...91S. doi:10.1051/0004-6361:20078788.

[aj118_6_3032-7] 7.0 ^7.1 Nordgren, Tyler E.; et al, Stellar Angular Diameters of Late-Type Giants and Supergiants Measured with the Navy Prototype Optical Interferometer, The Astronomical Journal, December 1999, 118 (6): 3032–3038, Bibcode:1999AJ....118.3032N, doi:10.1086/301114

[kaler-8] 8.0 ^8.1 ^8.2 Sadalmelik （页面存档备份，存于互联网档案馆）, Stars, Jim Kaler. Accessed on line October 3, 2008.

[apj627_1_L53-9] 9.0 ^9.1 ^9.2 Ayres, Thomas R.; Brown, Alexander; Harper, Graham M., Chandra Observations of Coronal Emission from the Early G Supergiants α and β Aquarii, The Astrophysical Journal, July 2005, 627 (1): L53–L56, Bibcode:2005ApJ...627L..53A, doi:10.1086/431977

[sb0-10] NAME SADALMELIK -- Star in double system, database entry, SIMBAD. Accessed on line October 3, 2008.

[wds-11] 11.0 ^11.1 Entry 22058-0019, The Washington Double Star Catalog （页面存档备份，存于互联网档案馆）, United States Naval Observatory. Accessed on line November 18, 2008.

[allen-12] 12.0 ^12.1 pp. 51, 148, Star-names and Their Meanings （页面存档备份，存于互联网档案馆）, Richard Hinckley Allen, New York: G. E. Stechert, 1899.

[csiro-13] The Colour of Stars, Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004 [2012-01-16], （原始内容存档于2012-03-10）

[14] 香港太空館 - 研究資源 - 亮星中英對照表. [2012-03-29]. （原始内容存档于2010-08-18）.

[15] 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.

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危宿一

特征

命名

参考资料

外部链接

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