仙女座Z
共生联星
仙女座Z是一对由红巨星和白矮星组合的共生联星。它是激变变星的一种，被称为共生变星，并且是这种变星的原型，所以共生变星也称为仙女座Z型变星。
| 观测资料 历元 J2000 | |
|---|---|
| 星座 | 仙女座 |
| 星官 | |
| 赤经 | 23h 33m 39.9551s[1] |
| 赤纬 | +48° 49′ 05.975″[1] |
| 视星等（V） | 7.7 - 11.3[2] |
| 特性 | |
| 光谱分类 | M2III + B1eq[3] |
| U−B 色指数 | −0.49[4] |
| B−V 色指数 | +1.35[4] |
| 变星类型 | 仙女座Z型变星[2] |
| 天体测定 | |
| 径向速度 (Rv) | -0.59[5] km/s |
| 自行 (μ) | 赤经：-1.577 ± 0.111[1] mas/yr 赤纬：-3.031 ± 0.134 [1] mas/yr |
| 视差 (π) | 0.62 ± 0.40[1] mas |
| 距离 | approx. 5,000 ly (approx. 2,000 pc) |
| 轨道 | |
| 绕行周期 (P) | 759.0±1.9[6] days |
| 偏心率 (e) | 0.0[6] |
| 倾斜角 (i) | 47±12[7]° |
| 半振幅 (K1) (primary) | 6.73±0.22[6] km/s |
| 详细资料 | |
| 红巨星 | |
| 质量 | 2[6] M☉ |
| 半径 | 85[3] R☉ |
| 亮度 | 880[8] L☉ |
| 温度 | 3,400[3] K |
| 白矮星 | |
| 质量 | 0.75[6] M☉ |
| 半径 | 0.17 - 0.36[9] R☉ |
| 亮度 | 1,500 - 9,800[9] L☉ |
| 温度 | 90,000 - 150,000[9] K |
| 其他命名 | |
| 参考数据库 | |
| SIMBAD | 资料 |
| 资料来源： | |
| 依巴谷星表、CCDM (2002)、亮星星表 | |
联星系统
仙女座Z是一对联星，这两颗星的循环轨道周期为759天[6]。 红巨星的质量大约是太阳的两倍，表面有效温度仅2800K，但它的光度是太阳的880倍。白矮星在宁静状态的光度大约是太阳的1,000倍，但在活跃阶段的光度会增加至10倍。它的温度在宁静状态时是150,000K，在活跃时下降至低于100,000K[9]。
共生变星
仙女座Z是共生变星的原型，它是激变变星的一种类型。共生变星有多种多样的群，通常分为几个子群，其中一群以仙女座Z命名[10]。
仙女座Z型变星，包括仙女座Z自身，显示出不规则的变化，在间隔几年爆发时，亮度会有数星等的改变。通常它们由一颗红巨星和一颗白矮星星组成，以数年的周期在轨道上互绕着。红巨星的恒星风会被白矮星电离，造成在轨道上不同的位置，星云的辐射强度会稍有变化。这是在宁静时的状态，活跃时白矮星的体积增大、表面温度下降，而变得更加明亮。整个联星系统的亮度会增加2-4星等 [8]。
光谱
自20世纪初以来，仙女座Z的频谱一直被认为极其奇特。在明亮阶段的早期频谱，只相对于红色的连续谱呈现明亮的发射线，对此的解释为恒星被嵌入密集的云气内[11]。当恒星的度度减弱时，光谱失去了云气被激发的谱线，并且发展出吸收谱线，就展现出天鹅座P剖面的吸收线。这样的光谱很容易确认是一颗像新兴的高温星与一颗低温恒星的组合[12]。
在MK光谱分类，通常是一颗低温的巨星，例如M4.5[3]。确切的光谱类型被证明会改变，例如在1987年是M5，在1989年是M3.5[13]。红外线观测的光谱类型是复合的M2III + B1eq。此处的光度分类III表示是一颗正常的巨星，特殊代码eq指示出有发射谱线与天鹅座P剖面型的谱线[3]。
双极喷流
2006年爆发之后，包括速度±1,150 公里/秒的微弱翼都有氢气巴耳末发射线，准直的喷流则沿着系统的轴线发射。在2000年至2002年的长期爆发中，观察到广泛的无线电波。据认为，喷流只出现在明亮的爆发 [14]。
参考资料
- ^ 1.0 1.1 1.2 1.3 1.4 Gaia Collaboration; Brown, A. G. A; Vallenari, A; Prusti, T; De Bruijne, J. H. J; Mignard, F; Drimmel, R; Babusiaux, C; Bailer-Jones, C. A. L; Bastian, U; Biermann, M; Evans, D. W; Eyer, L; Jansen, F; Jordi, C; Katz, D; Klioner, S. A; Lammers, U; Lindegren, L; Luri, X; O'Mullane, W; Panem, C; Pourbaix, D; Randich, S; Sartoretti, P; Siddiqui, H. I; Soubiran, C; Valette, V; Van Leeuwen, F; et al. Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties. Astronomy & Astrophysics. 2016, 595: A2. Bibcode:2016A&A...595A...2G. arXiv:1609.04172
. doi:10.1051/0004-6361/201629512.
- ^ 2.0 2.1 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.
- ^ 4.0 4.1 Martel, M. T; Gravina, R. UBV Observations of Symbiotic Stars in July and October 1982. Information Bulletin on Variable Stars. 1985, 2750: 1. Bibcode:1985IBVS.2750....1M.
- ^ Pourbaix, D; Tokovinin, A. A; Batten, A. H; Fekel, F. C; Hartkopf, W. I; Levato, H; Morrell, N. I; Torres, G; Udry, S. SB9: The ninth catalogue of spectroscopic binary orbits. Astronomy and Astrophysics. 2004, 424 (2): 727. Bibcode:2004A&A...424..727P. arXiv:astro-ph/0406573 . doi:10.1051/0004-6361:20041213.
- ^ 6.0 6.1 6.2 6.3 6.4 6.5 Fekel, Francis C; Hinkle, Kenneth H; Joyce, Richard R; Skrutskie, Michael F. Infrared Spectroscopy of Symbiotic Stars. II. Orbits for Five S-Type Systems with Two-Year Periods. The Astronomical Journal. 2000, 120 (6): 3255. Bibcode:2000AJ....120.3255F. doi:10.1086/316872.
- ^ Leibowitz, Elia M; Formiggini, Liliana. Activity cycle of the giant star of Z Andromedae and its spin period. Mon. Not. R. Astron. Soc. 2008, 385: 445. Bibcode:2008MNRAS.385..445L. arXiv:0712.2120 . doi:10.1111/j.1365-2966.2008.12847.x.
- ^ 8.0 8.1 Skopal, A. Discovery of the eclipse in the symbiotic binary Z Andromedae. The Astrophysical Journal. 2003, 401 (3): L17. Bibcode:2003A&A...401L..17S. arXiv:astro-ph/0304046 . doi:10.1051/0004-6361:20030332.
- ^ 9.0 9.1 9.2 9.3 Sokoloski, J. L; Kenyon, S. J; Espey, B. R; Keyes, Charles D; McCandliss, S. R; Kong, A. K. H; Aufdenberg, J. P; Filippenko, A. V; Li, W; Brocksopp, C; Kaiser, Christian R; Charles, P. A; Rupen, M. P; Stone, R. P. S. A Combination Nova Outburst in Z Andromedae: Nuclear Shell Burning Triggered by a Disk Instability. The Astrophysical Journal. 2006, 636 (2): 1002. Bibcode:2006ApJ...636.1002S. arXiv:astro-ph/0509638 . doi:10.1086/498206.
- ^ Z Andromedae star. [2018-01-16]. （原始内容存档于2012-07-06）.
- ^ Plaskett, J. S. The composite stellar and nebular spectrum of Z Andromedae. Publications of the Dominion Astrophysical Observatory Victoria. 1928, 4: 119. Bibcode:1928PDAO....4..119P.
- ^ Swings, P; Struve, O. The Evolution of a Peculiar Stellar Spectrum: Z Andromedae. Astrophysical Journal. 1941, 93: 356. Bibcode:1941ApJ....93..356S. doi:10.1086/144272.
- ^ Mürset, U; Schmid, H. M. Spectral classification of the cool giants in symbiotic systems. Astronomy and Astrophysics Supplement. 1999, 137 (3): 473. Bibcode:1999A&AS..137..473M. doi:10.1051/aas:1999105.
- ^ Burmeister, M; Leedjärv, L. Evidence for bipolar jets from the optical spectra of the prototypical symbiotic star Z Andromedae. The Astrophysical Journal. 2006, 461: L5. Bibcode:2007A&A...461L...5B. arXiv:astro-ph/0611475 . doi:10.1051/0004-6361:20066630.
进阶读物
- Tomov, N. A; Tomova, M. T; Taranova, O. G. Broad-band multicolour observations of the symbiotic binary Z And during quiescence and its activity at the end of 2002. The Astrophysical Journal. 2004, 428 (3): 985. Bibcode:2004A&A...428..985T. doi:10.1051/0004-6361:20041065.
- Taranova, O. G; Tomov, N. A; Tomova, M. T; Shenavrin, V. I. The symbiotic system Z Andromedae during the flare of 2000–2002. Astronomy Reports. 2004, 48 (9): 742. Bibcode:2004ARep...48..742T. doi:10.1134/1.1800174.
- Ikeda, Yuji; Akitaya, Hiroshi; Matsuda, Kentaro; Homma, Ken'Ichi; Seki, Munezo; Kawabata, Koji S; Hirata, Ryuko; Okazaki, Akira. Polarized Hα Wings in the Symbiotic Stars AG Draconis and Z Andromedae. The Astrophysical Journal. 2004, 604: 357. Bibcode:2004ApJ...604..357I. doi:10.1086/381877.
- Tomov, N. A; Taranova, O. G; Tomova, M. T. Mass ejection by the symbiotic binary Z And during its 2000–2002 outburst. The Astrophysical Journal. 2003, 401 (2): 669. Bibcode:2003A&A...401..669T. doi:10.1051/0004-6361:20030140.
- Sokoloski, J. L; Brocksopp, C; Kaiser, C; Seymour, N. A Radio "Jet" in the Prototypical Symbiotic Star Z Andromedae?. American Astron. Soc. Meeting. 2002, 201: 17.12. Bibcode:2002AAS...201.1712S.
- Bisikalo, D. V; Boyarchuk, A. A; Kilpio, E. Yu; Kuznetsov, O. A. Structure of gas flows in Z and in quiescence and during outbursts. Astronomy Reports. 2002, 46 (12): 1022. Bibcode:2002ARep...46.1022B. doi:10.1134/1.1529260.
- Gallego, M. C; Garcia, J. A; Vaquero, J. M; Sanchez Bajo, F. A Strange Attractor on a Daily Timescale in the Visual Observations of Z And?. Acta Astron. 1999, 49: 171. Bibcode:1999AcA....49..171G.
- Sokoloski, J. L; Bildsten, Lars. Discovery of a Magnetic White Dwarf in the Symbiotic Binary Z Andromedae. The Astrophysical Journal. 1999, 517 (2): 919. Bibcode:1999ApJ...517..919S. arXiv:astro-ph/9812294 . doi:10.1086/307234.
- Birriel, Jennifer J; Espey, Brian R; Schulte-Ladbeck, Regina E. Near-simultaneous Observations of Direct and Raman-scattered Linesin the Symbiotic Star Z Andromedae. The Astrophysical Journal. 1998, 507: L75. Bibcode:1998ApJ...507L..75B. doi:10.1086/311673.
- Schmid, H. M; Schild, H. The polarimetric orbit of Z Andromedae. Astronomy & Astrophysics. 1997, 327: 219. Bibcode:1997A&A...327..219S.
- Skopal, A; Vittone, A. A; Errico, L; Otsuka, M; Tamura, S; Wolf, M; Elkin, V. G. Structure of the hot object in the symbiotic prototype Z Andromedae during its 2000–03 active phase. The Astrophysical Journal. 2006, 453: 279. Bibcode:2006A&A...453..279S. arXiv:astro-ph/0603718 . doi:10.1051/0004-6361:20052917.
- Skopal, A; Pribulla, T. The first detection of the bipolar jets from the symbiotic prototype Z and. The Astronomer's Telegram. 2006, 882. Bibcode:2006ATel..882....1S.
- Sokoloski, J. L; Kenyon, S. J; Espey, B. R; Keyes, Charles D; McCandliss, S. R; Kong, A. K. H; Aufdenberg, J. P; Filippenko, A. V; Li, W; Brocksopp, C; Kaiser, Christian R; Charles, P. A; Rupen, M. P; Stone, R. P. S. A "Combination Nova" Outburst in Z Andromedae: Nuclear Shell Burning Triggered by a Disk Instability. The Astrophysical Journal. 2006, 636 (2): 1002. Bibcode:2006ApJ...636.1002S. arXiv:astro-ph/0509638 . doi:10.1086/498206.
- Tomov, N. A; Tomova, M. T; Bisikalo, D. V. Bipolar ejection by the symbiotic binary system Z and during its 2006 outburst. Mon. Not. R. Astron. Soc. 2007, 376: L16. Bibcode:2007MNRAS.376L..16T. arXiv:astro-ph/0612502 . doi:10.1111/j.1745-3933.2007.00277.x.
- Iudin, B. F. Choice of a model for Z Andromedae. Astronomicheskii Zhurnal. 1986, 63: 137. Bibcode:1986AZh....63..137I.