极端海王星外天体
极端海王星外天体 (ETNO,extreme trans-Neptunian object)是在太阳系最外层的海王星(30AU)之外绕太阳运行,半长轴至少为150–250 AU的海王星外天体[1][2]。与所有其它已知的海王星外天体相比,极端海王星外天体的轨道受已知巨行星的影响要小得多。然而,它们可能会受到与假想的第九行星的引力相互作用的影响,将这些物体引导到同类型的类似轨道[1]。已知的极端海王星外天体在具有较小升交点和降交点距离的天体对的分布之间,表现出高度统计显著的不对称性,这可能表明受到外部扰动的响应[3][4]。
![](http://upload.wikimedia.org/wikipedia/commons/thumb/7/78/Extreme_transneptunian_object_eccentricity_vs_perihelion.png/350px-Extreme_transneptunian_object_eccentricity_vs_perihelion.png)
离散的ETNOs或ESDOs (38–45 AU)
孤立的ETNOs或EDDOs (40–45与50–60 AU)
类赛德娜天体或内欧特云天体(超过 50–60 AU)
极端海王星外天体可分为三个不同的子群。离散盘天体(或极端散射盘天体,ESDOs)的近日点大约在38–45 AU和超过0.85的异常高偏心率。与常规的离散盘天体一样,它们很可能是由海王星引力散射形成的,并且仍然与巨行星相互作用。孤立 海王星外天体(或极端分离圆盘天体,EDDO),近日点大约在40-45和50-60之间 AU受海王星的影响比离散盘天体的海王星外天体小,但仍然相对靠近海王星。类赛德娜天体或希尔斯云天体,近日点超过 50–60 AU,离海王星太远,不会受到它的强烈影响[1]。
类赛德娜天体
编辑在极端的海王星外天体中,有类赛德娜天体(英语:sednoids),这四颗天体具有非常大的近日点距离:赛德娜、2012 VP113、541132 Leleākūhonua、和2021 RR205。赛德娜和2012 VP113是近日点大于70 AU的远距离独立天体。它们的大近日点距离使它们保持足够的距离,避免了来自海王星的显著引力扰动。以前对赛德娜大近日点距离的解释包括:在遥远的轨道上与未知行星的近距离相遇,以及与随机恒星或太阳诞生星团成员的遥远相遇,该恒星或太阳诞生星团的成员在太阳系附近经过[5][6][7]。
离太阳最远的天体
编辑楚希罗和雪柏的发现
编辑外太阳系起源调查
编辑- 2013 SY99:由蜜雪儿·班尼斯特(Michele Bannister)发现,它的倾角比许多物体都低。在2016年3月由SETI协会主办的讲座上讨论过,后来在2016年10月AAS的会议也讨论过[14][15]。
- 2015 KG163:它的方向与2013 FT28相似,但有一个更大的半长轴,可能导致它的轨道穿过第九行星的轨道。
- 2015 RX245:它适合其它反对齐物件。
- 2015 GT50:既不属于反对齐天体,也不属于对齐天体;相反的,它的轨道方向与拟议的第九行星的方向成直角。它关于近日点的参数也超出了近日点参数的集群。
自2016年初以来,又发现了10个极端海王星外天体,其轨道的近日点大于30 AU 和半长轴大于 250;使非对齐天体总数达到16颗(完整清单见下表)。大多数海王星外天体(TNO)的近日点明显超出海王星绕太阳运行的 30 AU[16][17]。一般来说,近日点小于的海王星外天体会与海王星发生强烈的相遇 36 AU[18][19]。大多数海王星外天体相对较小,但因为它们在椭圆轨道上接近与太阳的最近距离,因此目前相对明亮。这些天体也包含在下面的轨道图和表格中。
TESS数据搜索
编辑Malena Rice和Gregory Laughlin应用了一种有针对性的移位堆叠搜索算法分析来自TESS扇区18和19的数据,寻找候选的太阳系外天体[20]。他们的搜索恢复了像赛德娜这样的已知海王星外天体,并产生了17个新的太阳系外天体候选者,这些天体位于80-200天文单位的地心距离范围内,需要地面望远镜资源进行后续观测才能确认。WHT旨在恢复这些遥远的海王星外天体的候选者,但未能确认其中两个[21][22]。
清单
编辑最极端的例子是2015 BP519,绰号“Caju”,它具有最高的倾角[23],和最远的节点距离;这些属性使其成为该群中可能的异常值[2]。
注解
编辑参考资料
编辑- ^ 1.0 1.1 1.2 1.3 Sheppard, Scott S.; Trujillo, Chadwick A.; Tholen, David J.; Kaib, Nathan. A New High Perihelion Trans-Plutonian Inner Oort Cloud Object: 2015 TG387. The Astronomical Journal. 2019, 157 (4): 139. Bibcode:2019AJ....157..139S. S2CID 119071596. arXiv:1810.00013 . doi:10.3847/1538-3881/ab0895 .
- ^ 2.0 2.1 de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl. A Fruit of a Different Kind: 2015 BP519 as an Outlier among the Extreme Trans-Neptunian Objects. Research Notes of the AAS. 12 September 2018, 2 (3): 167. Bibcode:2018RNAAS...2..167D. S2CID 119433944. arXiv:1809.02571 . doi:10.3847/2515-5172/aadfec .
- ^ de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl. Peculiar orbits and asymmetries in extreme trans-Neptunian space. Monthly Notices of the Royal Astronomical Society. 1 September 2021, 506 (1): 633–649. Bibcode:2021MNRAS.506..633D. arXiv:2106.08369 . doi:10.1093/mnras/stab1756.
- ^ de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl. Twisted extreme trans-Neptunian orbital parameter space: statistically significant asymmetries confirmed. Monthly Notices of the Royal Astronomical Society Letters. 1 May 2022, 512 (1): L6–L10. Bibcode:2022MNRAS.512L...6D. arXiv:2202.01693 . doi:10.1093/mnrasl/slac012.
- ^ Wall, Mike. A Conversation With Pluto's Killer: Q & A With Astronomer Mike Brown. Space.com. 24 August 2011 [7 February 2016].
- ^ Brown, Michael E.; Trujillo, Chadwick; Rabinowitz, David. Discovery of a Candidate Inner Oort Cloud Planetoid. The Astrophysical Journal. 2004, 617 (1): 645–649. Bibcode:2004ApJ...617..645B. S2CID 7738201. arXiv:astro-ph/0404456 . doi:10.1086/422095.
- ^ Brown, Michael E. There's something out there – part 2. Mike Brown's Planets. 28 October 2010 [18 July 2016].
- ^ 8.0 8.1 Objects beyond Neptune provide fresh evidence for Planet Nine. 2016-10-25.
The new evidence leaves astronomer Scott Sheppard of the Carnegie Institution for Science in Washington, D.C., "probably 90% sure there's a planet out there." But others say the clues are sparse and unconvincing. "I give it about a 1% chance of turning out to be real," says astronomer JJ Kavelaars, of the Dominion Astrophysical Observatory in Victoria, Canada.
- ^ PLANET 9 SEARCH TURNING UP WEALTH OF NEW OBJECTS. 2016-08-30.
- ^ Extreme New Objects Found At The Edge of The Solar System.
- ^ The Search for Planet Nine: New Finds Boost Case for Distant World. Space.com. 29 August 2016.
- ^ HUNT FOR NINTH PLANET REVEALS NEW EXTREMELY DISTANT SOLAR SYSTEM OBJECTS. 2016-08-29.
- ^ Shankman, Cory; et al. OSSOS VI. Striking Biases in the detection of large semimajor axis Trans-Neptunian Objects. The Astronomical Journal. 2017, 154 (4): 50. Bibcode:2017AJ....154...50S. S2CID 3535702. arXiv:1706.05348 . doi:10.3847/1538-3881/aa7aed . hdl:10150/625487.
- ^ SETI Institute. Exploring the outer Solar System: now in vivid colour - Michele Bannister (SETI Talks). YouTube. 28:17. 18 March 2016 [18 July 2016].
- ^ Bannister, Michele T.; et al. A new high-perihelion a ~700 AU object in the distant Solar System. American Astronomical Society, DPS Meeting #48, Id. 113.08. 2016, 48: 113.08. Bibcode:2016DPS....4811308B.
- ^ Hand, Eric. Astronomers say a Neptune-sized planet lurks beyond Pluto. Science. 20 January 2016 [20 January 2016]. doi:10.1126/science.aae0237.
- ^ Grush, Loren. Our solar system may have a ninth planet after all — but not all evidence is in (We still haven't seen it yet). The Verge. 20 January 2016 [18 July 2016].
The statistics do sound promising, at first. The researchers say there's a 1 in 15,000 chance that the movements of these objects are coincidental and don't indicate a planetary presence at all. ... 'When we usually consider something as clinched and air tight, it usually has odds with a much lower probability of failure than what they have,' says Sara Seager, a planetary scientist at MIT. For a study to be a slam dunk, the odds of failure are usually 1 in 1,744,278 . ... But researchers often publish before they get the slam-dunk odds, in order to avoid getting scooped by a competing team, Seager says. Most outside experts agree that the researchers' models are strong. And Neptune was originally detected in a similar fashion — by researching observed anomalies in the movement of Uranus. Additionally, the idea of a large planet at such a distance from the Sun isn't actually that unlikely, according to Bruce Macintosh, a planetary scientist at Stanford University.
- ^ Batygin, Konstantin; Brown, Michael E. Evidence for a distant giant planet in the Solar system. The Astronomical Journal. 2016, 151 (2): 22. Bibcode:2016AJ....151...22B. S2CID 2701020. arXiv:1601.05438 . doi:10.3847/0004-6256/151/2/22 .
- ^ Koponyás, Barbara. Near-Earth asteroids and the Kozai mechanism (PDF). 5th Austrian-Hungarian Workshop in Vienna. 10 April 2010 [18 July 2016].
- ^ Rice, Malena; Laughlin, Gregory. Exploring Trans-Neptunian Space with TESS: A Targeted Shift-stacking Search for Planet Nine and Distant TNOs in the Galactic Plane. The Planetary Science Journal. December 2020, 1 (3): 81 (18 pp.). Bibcode:2020PSJ.....1...81R. S2CID 225075671. arXiv:2010.13791 . doi:10.3847/PSJ/abc42c .
- ^ de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl; Vaduvescu, Ovidiu; Stanescu, Malin. Distant trans-Neptunian object candidates from NASA's TESS mission scrutinized: fainter than predicted or false positives?. Monthly Notices of the Royal Astronomical Society Letters. June 2022, 513 (1): L78–L82. Bibcode:2022MNRAS.513L..78D. arXiv:2204.02230 . doi:10.1093/mnrasl/slac036.
- ^ Distant Trans-Neptunian Object Candidates: Fainter Than Predicted or False Positives?. 20 May 2022.
- ^ Becker, J. C.; et al. Discovery and Dynamical Analysis of an Extreme Trans-Neptunian Object with a High Orbital Inclination. The Astronomical Journal. 2018, 156 (2): 81. Bibcode:2018AJ....156...81B. S2CID 55163842. arXiv:1805.05355 . doi:10.3847/1538-3881/aad042 . 已忽略未知参数
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外部链接
编辑- Known extreme outer solar system objects, Scott Sheppard, Carnegie Science Center
- Hunt for Ninth Planet Reveals New Extremely Distant Solar System Objects, Scott Sheppard, Carnegie Science Center
- List of Known Trans-Neptunian Objects (including ESDOs and EDDOs), Robert Johnston, Johnston's Archive