半人马座A
| 半人马座 A | |
|---|---|
 半人马座 A (NGC 5128) | |
| 观测资料（J2000 历元） | |
| 星座 | 半人马座 |
| 赤经 | 13h 25m 27.6s[1] |
| 赤纬 | -43° 01′ 09″[1] |
| 红移 | 547 ± 5 公里/秒[1] |
| 距离 | 1千3百70万 ± 90万光年 (420 ± 30万秒差距)[2] |
| 视星等 (V) | 6.84[3][4] |
| 特征 | |
| 类型 | S0 pec[1] |
| 角直径 (V) | 25′.7 × 20′.0[1] |
| 其他 | 异常的尘埃带 |
| 其他名称 | |
| NGC 5128,[1] Arp 153,[1] PGC 46957[1] | |
半人马座A，也称为NGC 5128，是位于半人马座内距离大约1千4百万光年远的一个透镜星系。它是最靠近地球的电波源之一，也是被专业天文学家广泛研究的活跃星系核[5]。这个星系也是全天第五亮的星系，所以即使这个星系只能在南半球和北半球的低纬度地区看见，它依然还是业余天文学家的理想目标[6]。 相对论性喷流的能量被相信是从在星系核心的超大质量黑洞附近的空间喷射出来的，辐射出X射线和无线电波的波长。以十年间隔对喷流进行的电波观察，天文学家确定喷流内侧部分的移动速度达到光速的一半。X射线则是喷流内的高能微粒在更远处与周围的气体碰撞所产生的。
如同对其他的星暴星系所做的观测，碰撞导致恒星的形成和引发强烈的爆炸。使用史匹哲太空望远镜，科学家证实了半人马座A是经由一个大型椭圆星系与一个小螺旋星系碰撞的结果。
型态（组织）
半人马座A在型态学上可能是特殊星系，因为从地球上观察，这个细看起来像是透镜星系或椭圆星系叠加上一条尘埃带[7]。这个特殊的星系在1847年首度被约翰·赫歇尔确认，并被收录在赫顿·阿普的《特殊星系图集》（1966年出版），作为"受摄"星系和尘埃吸收的最佳范例之一[8]。这个星系的奇怪型态被公认为是两个较小星系合并的结果[9]。
这个星系的核球主要由演化中的红色恒星组成[7]；然而，尘埃盘是最近的恒星形成场所[5]，已经确认的恒星形成区超过100个[10]。
超新星
在半人马座A曾经检测到一颗超新星[11]。 这颗超新星，SN 1986G，是艾文思于1986年在尘埃带内发现的[12]， 稍后被鉴定是一颗Ia超新星[13]。Ia超新星通常是有一颗白矮星的联星系统，白矮星由伴星攫取气体，使质量至足以点燃在核心的碳融合反应，引发热失控的核聚变。SN 1986G被用来演示Ia超新星的光谱并不是全都一样，Ia超新星的光谱可能会随着时间的推移，在亮度和形式上有不同的改变[13]。 2016年2月发现第二颗超新星SN 2016adj，稍后经被鉴定为是一颗Ⅱb超新星。
距离
自1980年代以来，估计NGC 5128的距离通常在3-5百万秒差距[2][14][15][16][17][18]。发现在NGC 5128的经典造父变星受到浓厚的尘埃巷道遮蔽，依据消光法的本质和考虑其他的因素，距离估计在300-350万秒差距[15][16]。在NGC 5128也发现米拉变星[18]和第二型造父变星[15][16]，而后者很少在本星系群之外被发现[19]。以一些米拉变星和行星状星云测定的距离，认为是更远的〜380万秒差距[20][17]。
邻近的星系和星系集团的资料
半人马座 A位于半人马座 A/M83星系团的两个子集团中的一个的中心位置，是一个邻近的星系集团[21]。M83 (南风车星系)在另一个集团的中心，有时这两个集团会被视为一个集团[22][23]，有时又会被视为两个集团[24]。然而，环绕着半人马座 A的星系和环绕着M83实际上是非常接近的，且这两个集团之间有着相互的运动[25]。
业余天文学的资讯
半人马座 A位于半人马座ω (一个肉眼可见的球状星团) 北方约4°的地方[6]。因为这个星系有着高表面亮度和相对较大的视角，他是业余天文观测的理想目标。明亮的核球和黑色的尘埃带在找星镜和大的双筒望远镜中就能见到[6]，而其他的结构要更大的望远镜才能看见[6]。
图片
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半人马座A的光晕 -
The radio galaxy Centaurus A, as seen by ALMA -
Image taken by the Wide Field Imager attached to the MPG/ESO 2.2-meter telescope at the La Silla Observatory. -
!["Hubble's panchromatic vision... reveals the vibrant glow of young, blue star clusters..."[26]](https://upload.wikimedia.org/wikipedia/commons/thumb/b/bb/Firestorm_of_Star_Birth_in_Galaxy_Centaurus_A.jpg/120px-Firestorm_of_Star_Birth_in_Galaxy_Centaurus_A.jpg)
"Hubble's panchromatic vision... reveals the vibrant glow of young, blue star clusters..."[26] -
A Hubble Space Telescope (HST) image of the dust disk in front of the nucleus of Centaurus A. Credit: HST/NASA/ESA. -
This image of the central parts of Centaurus A reveals the parallelogram-shaped remains of a smaller galaxy that was absorbed about 200 to 700 million years ago. -
史匹哲太空望远镜的完整盘面影像 -
Chandra X-ray view of Cen A in X-rays showing one relativistic jet from the central black hole -
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Video about Centaurus A jets.
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!["False-colour image of the nearby radio galaxy Centaurus A, showing radio (red), 24-micrometre infrared (green) and 0.5-5 keV X-ray emission (blue). The jet can be seen to emit synchrotron emission in all three wavebands. The lobes only emit in the radio frequency range, and so appear red. Gas and dust in the galaxy emits thermal radiation in the infrared. Thermal X-ray radiation from hot gas and non-thermal emission from relativistic electrons can be seen in the blue 'shells' around the lobes, particularly to the south (bottom)."[27]](https://upload.wikimedia.org/wikipedia/commons/thumb/e/e6/Centauros_a-spc.png/120px-Centauros_a-spc.png)
"False-colour image of the nearby radio galaxy Centaurus A, showing radio (red), 24-micrometre infrared (green) and 0.5-5 keV X-ray emission (blue). The jet can be seen to emit synchrotron emission in all three wavebands. The lobes only emit in the radio frequency range, and so appear red. Gas and dust in the galaxy emits thermal radiation in the infrared. Thermal X-ray radiation from hot gas and non-thermal emission from relativistic electrons can be seen in the blue 'shells' around the lobes, particularly to the south (bottom)."[27]
!["Hubble's panchromatic vision... reveals the vibrant glow of young, blue star clusters..."[26]](/zh-sg/File:Firestorm_of_Star_Birth_in_Galaxy_Centaurus_A.jpg)
!["False-colour image of the nearby radio galaxy Centaurus A, showing radio (red), 24-micrometre infrared (green) and 0.5-5 keV X-ray emission (blue). The jet can be seen to emit synchrotron emission in all three wavebands. The lobes only emit in the radio frequency range, and so appear red. Gas and dust in the galaxy emits thermal radiation in the infrared. Thermal X-ray radiation from hot gas and non-thermal emission from relativistic electrons can be seen in the blue 'shells' around the lobes, particularly to the south (bottom)."[27]](/zh-sg/File:Centauros_a-spc.png)
相关条目
外部链接
- SEDS: Peculiar Galaxy NGC 5128
- ESA/Hubble images of Centaurus A（页面存档备份，存于互联网档案馆）
- NASA's APOD: The Galaxy Within Centaurus A (3/4/06)（页面存档备份，存于互联网档案馆）
- NASA's APOD: X-Rays from an Active Galaxy (7/5/03)（页面存档备份，存于互联网档案馆）
- High-resolution image of Centaurus A（页面存档备份，存于互联网档案馆） showing the discrete elements of galactic core
- Centaurus A（页面存档备份，存于互联网档案馆） at UniverseToday.com
- NGC5128 Centaurus A
- WikiSky上关于半人马座A的内容：DSS2, SDSS, GALEX, IRAS, 氢α, X射线, 天文照片, 天图, 文章和图片
参考资料
- STScI. Hubble Provides Multiple Views of How to Feed a Black Hole（页面存档备份，存于互联网档案馆）. Press release: Space Telescope Science Institute. March 14, 1998.
- Chandra X-Ray Observatory Photo Album Centaurus A Jet（页面存档备份，存于互联网档案馆）
- ^ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 NASA/IPAC Extragalactic Database. Results for Centaurus A. [2006-12-06]. （原始内容存档于2008-12-16）.
- ^ 2.0 2.1 J. L. Tonry; A. Dressler; J. P. Blakeslee; E. A. Ajhar; et al. The SBF Survey of Galaxy Distances. IV. SBF Magnitudes, Colors, and Distances. Astrophysical Journal. 2001, 546 (2): 681–693. Bibcode:2001ApJ...546..681T. arXiv:astro-ph/0011223
. doi:10.1086/318301.
- ^ [ NAME Centaurus A] 请检查
|url=值 (帮助). SIMBAD. 斯特拉斯堡天文资料中心. - ^ Armando, Gil de Paz; Boissier; Madore; Seibert; Boselli; et al. The GALEX Ultraviolet Atlas of Nearby Galaxies. Astrophysical Journal Supplement. 2007, 173 (2): 185–255. Bibcode:2007ApJS..173..185G. S2CID 119085482. arXiv:astro-ph/0606440 . doi:10.1086/516636.
- ^ 5.0 5.1 F. P. Israel. Centaurus A - NGC 5128. Astronomy and Astrophysics Review. 1998, 8: 237–278 [2020-10-02]. doi:10.1007/s001590050011. （原始内容存档于2019-10-20）.
- ^ 6.0 6.1 6.2 6.3 D. J. Eicher. The Universe from Your Backyard. Cambridge: Cambridge University Press. 1988. ISBN 0-521-36299-7.
- ^ 7.0 7.1 A. Sandage; J. Bedke. Carnegie Atlas of Galaxies. Washington, D.C.: Carnegie Institution of Washington. 1994. ISBN 0-87279-667-1.
- ^ H. Arp. Atlas of Peculiar Galaxies. Astrophysical Journal Supplement. 1966, 14: 1–20. Bibcode:1966ApJS...14....1A. doi:10.1086/190147.
- ^ W. Baade; R. Minkowski. On the Identification of Radio Sources. Astrophysical Journal. 1954, 119: 215–231. Bibcode:1954ApJ...119..215B. doi:10.1086/145813.
- ^ P. W. Hodge; R. C. Kennicutt Jr. An atlas of H II regions in 125 galaxies. Astrophysical Journal. 1982, 88: 296–328. Bibcode:1983AJ.....88..296H. doi:10.1086/113318.
- ^ NASA/IPAC Extragalactic Database. Results for extended name search on Centaurus A. [2007-03-07]. （原始内容存档于2008-12-16）.
- ^ R. Evans; R. H. McNaught; C. Humphries. Supernova 1986G in NGC 5128. IAU Circular. 1986, 4208: 1. Bibcode:1986IAUC.4208....1E.
- ^ 13.0 13.1 M. M. Phillips; A. C. Phillips; S. R. Heathcote; V. M. Blanco; et al. The type 1a supernova 1986G in NGC 5128 – Optical photometry and spectra. Publications of the Astronomical Society of the Pacific. 1987, 99: 592–605. Bibcode:1987PASP...99..592P. doi:10.1086/132020.
- ^ Distance Results for NGC 5128. NASA/IPAC Extragalactic Database. [2010-04-26]. （原始内容存档于2019-10-18）.
- ^ 15.0 15.1 15.2 Ferrarese Laura; Mould Jeremy R.; Stetson Peter B.; Tonry John L.; et al. The Discovery of Cepheids and a Distance to NGC 5128. The Astrophysical Journal. 2007, 654: 186. Bibcode:2007ApJ...654..186F. arXiv:astro-ph/0605707 . doi:10.1086/506612.
- ^ 16.0 16.1 16.2 Majaess, D. The Cepheids of Centaurus A (NGC 5128) and Implications for H0. Acta Astronomica. 2010, 60: 121. Bibcode:2010AcA....60..121M. arXiv:1006.2458 .
- ^ 17.0 17.1 Harris, Gretchen L. H.; Rejkuba, Marina; Harris, William E. The Distance to NGC 5128 (Centaurus A). Publications of the Astronomical Society of Australia. 2010, 27 (4): 457–462. Bibcode:2010PASA...27..457H. arXiv:0911.3180 . doi:10.1071/AS09061.
- ^ 18.0 18.1 Rejkuba, M. The distance to the giant elliptical galaxy NGC 5128. Astronomy and Astrophysics. 2004, 413 (3): 903. Bibcode:2004A&A...413..903R. arXiv:astro-ph/0310639 . doi:10.1051/0004-6361:20034031.
- ^ Majaess, D.; Turner, D.; Lane, D. Type II Cepheids as Extragalactic Distance Candles. Acta Astronomica. 2009, 59: 403. Bibcode:2009AcA....59..403M. arXiv:0909.0181 .
- ^ Harris, Gretchen L. H. NGC 5128: The Giant Beneath. Publications of the Astronomical Society of Australia. 2010, 27 (4): 475. Bibcode:2010PASA...27..475H. arXiv:1004.4907 . doi:10.1071/AS09063.
- ^ I. D. Karachentsev, M. E. Sharina, A. E. Dolphin, E. K. Grebel, D. Geisler, P. Guhathakurta, P. W. Hodge, V. E. Karachetseva, A. Sarajedini, P. Seitzer. New distances to galaxies in the Centaurus A group. Astronomy and Astrophysics. 2002, 385: 21–31 [2020-10-02]. doi:10.1051/0004-6361:20020042. （原始内容存档于2018-11-22）.
- ^ R. B. Tully. Nearby Galaxies Catalog. Cambridge: Cambridge University Press. 1988. ISBN 0-521-35299-1.
- ^ P. Fouque, E. Gourgoulhon, P. Chamaraux, G. Paturel. Groups of galaxies within 80 Mpc. II - The catalogue of groups and group members. Astronomy and Astrophysics Supplement. 1992, 93: 211–233 [2020-10-02]. （原始内容存档于2019-12-13）.
- ^ A. Garcia. General study of group membership. II - Determination of nearby groups. Astronomy and Astrophysics Supplement. 1993, 100: 47–90 [2020-10-02]. （原始内容存档于2019-12-13）.
- ^ I. D. Karachentsev. The Local Group and Other Neighboring Galaxy Groups. Astronomical Journal. 2005, 129: 178–188 [2008-07-01]. doi:10.1086/426368. （原始内容存档于2008-02-21）.
- ^ Firestorm of Star Birth in Galaxy Centaurus A. NASA. [27 September 2012]. （原始内容存档于2015-06-05）.
- ^ Radio Galaxy. English Wikipedia. Wikimedia Foundation. [25 November 2012]. （原始内容存档于2015-05-30）.
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