大熊座SU

大熊座SU （SU UMa）是北天拱極星座大熊座的密接聯星。它是一顆週期性的激變變星，其幅度從峰值的10.8等至基值14.96等不等。依據視差位移，該系統與地球的距離是6992219620597542620♠4.53 mas，相當於719光年。它正以相對於地心每秒27公里的徑向速度遠離地球。 這顆變星是莫斯科天文台的利迪亞·采拉斯卡亞（英语：Lidiya Tseraskaya）（L. Ceraski）在1908年發現的。它被分類為雙子座U型變星或矮新星。自1926年以來的觀測顯示，這顆變星經歷了兩種不同類型的噴發：亮度範圍在11.6－12.9星等的短週期，最大值持續約兩天，亮度範圍在10.4－11.8的長週期，最大值延長至13天。後者的事件被稱為"超級最大化" 。後續發現類似的矮新星，因此大熊座SU現在是這一子類變星的原型。 這是單譜線的光譜聯星，軌道週期1.83小時。它由白矮星組成，通過吸積盤從伴星那裏獲取物質。這個吸積盤不穩定，會定期的爆發，增加系統的亮度。對於大熊座SU，來自伴星的吸積率是6987980000000000000♠9.8×10−13 M☉·yr−1。在白矮星附近發現X射線發射，在爆發時會下降4倍。理論認為這種發射來自白矮星與其吸積盤間的邊界層。 超峰 Brown, A. G. A.; Vallenari, A.; Prusti, T.; de Bruijne, J. H. J.; et al. Gaia Data Release 2. Summary of the contents and survey properties. Astronomy & Astrophysics. 2018. Bibcode:2018A&A...616A...1G. arXiv:1804.09365 . doi:10.1051/0004-6361/201833051.  VizieR中此天体在盖亚望远镜第二批数据发布的记录 Samus', N. N; Kazarovets, E. V; Durlevich, O. V; Kireeva, N. N; Pastukhova, E. N. General catalogue of variable stars: Version GCVS 5.1. Astronomy Reports. 2017, 61 (1): 80. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085.  Duflot, M.; et al. Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Radial velocities: The Wilson-Evans-Batten catalogue. Astronomy and Astrophysics Supplement. December 1995, 114: 269. Bibcode:1995A&AS..114..269D.  Patterson, Joseph. Distances and absolute magnitudes of dwarf novae: Murmurs of period bounce. Monthly Notices of the Royal Astronomical Society. 2011, 411 (4): 2695–2716. doi:10.1111/j.1365-2966.2010.17881.x .  Thorstensen, John R.; et al. A Spectroscopic Study of the Cataclysmic Binary Star SU Ursae Majoris. Astrophysical Journal. October 1986, 309: 721. Bibcode:1986ApJ...309..721T. doi:10.1086/164641.  Urban, Joel A; Sion, Edward M. The Dwarf Novae during Quiescence. The Astrophysical Journal. 2006, 642 (2): 1029–1041. Bibcode:2006ApJ...642.1029U. arXiv:astro-ph/0602126 . doi:10.1086/501430.  Knigge, Christian; Sion, Edward M. The donor stars of cataclysmic variables. Monthly Notices of the Royal Astronomical Society. 2006, 373 (2): 484–502. Bibcode:2006MNRAS.373..484K. arXiv:astro-ph/0609671 . doi:10.1111/j.1365-2966.2006.11096.x.  SU UMa. SIMBAD. 斯特拉斯堡天文資料中心.  Ceraski, W. Une variable nouvelle 5.1908 Ursae majoris. Astronomische Nachrichten. February 1908, 177 (11): 173. Bibcode:1908AN....177..173C. doi:10.1002/asna.19081771105.  Kraft, Robert P.; Luyten, Willem J. Binary Stars among Cataclysmic Variables. VI. on the Mean Absolute Magnitude of U Geminorum Variables. The Astrophysical Journal. October 1965, 142: 1041. Bibcode:1965ApJ...142.1041K. doi:10.1086/148374.  Isles, J. E. SU UMa, 1926-54. Journal of the British Astronomical Association. 1974, 84: 365–373. Bibcode:1974JBAA...84..365I.  van Paradijs, J. Superoutburst : a general phenomenon in dwarf novae. Astronomy and Astrophysics. September 1983, 125: L16–L18. Bibcode:1983A&A...125L..16V.  Collins, David J.; Wheatley, Peter J. X-ray observations of SU UMa throughout six outbursts. Monthly Notices of the Royal Astronomical Society. March 2010, 402 (3): 1816–1823. Bibcode:2010MNRAS.402.1816C. arXiv:0911.2711 . doi:10.1111/j.1365-2966.2009.16009.x.  Zead, I.; et al. Spectral and photometric behavior of SU UMa during quiescence and outburst states. New Astronomy. April 2017, 52: 122–132. Bibcode:2017NewA...52..122Z. doi:10.1016/j.newast.2016.10.010.  Imada, Akira; et al. Discovery of Superhumps during a Normal Outburst of SU Ursae Majoris. Publications of the Astronomical Society of Japan. October 2012, 64 (5, Letter No.5): 4. Bibcode:2012PASJ...64L...5I. arXiv:1210.1087 . doi:10.1093/pasj/64.5.L5.  Udalski, A. SU Ursae Majoris: The Perfect Prototype of SU UMa Subclass of Dwarf Novae. Astronomical Journal. July 1990, 100: 226. Bibcode:1990AJ....100..226U. doi:10.1086/115508.