一颗疑似系外行星的资料，不是新的
放维基的英文资料，来源：维基百科HD 188753
以下是其母星的相关资料：HD 188753 is a hierarchical triple star system approximately 151 light-years away in the constellation of Cygnus, the Swan. In 2005, an extrasolar planet was announced to be orbiting the primary star (designated HD 188753 A) in the system. Follow-up measurements by an independent group in 2007 did not confirm the planet's existence.
这显然是一个分层三重星系统，诡异的是这颗疑似行星只围绕一颗主星运转，2007年另一个独立的研究团队没有能够证实这颗疑似的类木行星，确切地讲是一颗热木星的真实存在。。。
Possible planet
In 2005 the discovery of a candidate planet orbiting the primary star of the triple star system was announced. This planet, which received the designation HD 188753 Ab, was announced by a Polish astronomer working in the United States, Dr. Maciej Konacki. This would not be the first known planet in a triple star system – for example, the planet 16 Cygni Bb had been discovered earlier, orbiting one of the components of a wide triple system also in the constellation of Cygnus.
Since HD 188753 Ab was believed to be orbiting in a multi-star system, Konacki referred to planets of this type as "Tatooine planets" after Luke Skywalker's home world. The detection of this planet has been challenged by Eggenberger et al.
The candidate planet, a hot Jupiter gas giant slightly more massive than Jupiter, was thought to orbit the star HD 188753 A once every 80 hours or so (3.3 days), at a distance of about 8 million kilometers, a twentieth of the distance between Earth and the Sun. The existence of HD 188753 Ab in a relatively close triple star system challenged the current models of planet formation. The current idea is that giant planets form in the outer reaches of their system (in orbits similar to those of Jupiter and Saturn). Once formed, some of these planets may migrate close to their stars, becoming hot Jupiters. The theoretical difficulty in understanding HD 188753 Ab is that any protoplanetary disk would have ended around 1 astronomical unit from the primary star (due to the presence of the secondary stars). A Jovian planet should not have been able to form so close to the primary, and with no disk material beyond 1 AU, a planet should not have been able to form beyond that distance to migrate inward. One of the possibilities suggested that the planet formed before the secondary stars had reached their current configuration. This suggests that the two secondary stars were once more distant than they are now.
An attempt to confirm the discovery failed. In 2007, a team at the Geneva Observatory stated that they had the precision and sampling rate sufficient to have detected the would-be planet, and that they did not detect it. Konacki responded to this, stating that the precision of the follow-up measurements was not sufficient to confirm or deny the planet's existence and that he planned to release an update in 2007. As of August 2012, no update appears to have been published.
https://upload.wikimedia.org/wikipedia/commons/thumb/7/7c/HD188753_orbit.jpg/220px-HD188753_orbit.jpg
https://upload.wikimedia.org/wikipedia/commons/thumb/9/93/HD188753-hot-jupiter-1.jpg/300px-HD188753-hot-jupiter-1.jpg
最后一张是艺术家笔下的这颗疑似行星概念图，感觉和 @SamuelHan 画的不一致哦。。。{:3_201:} 最后补充一类系外行星：脉冲星附近的系外行星，鉴于脉冲星实际上在恒星总数中所占比例很小，加上这类恒星的残骸附近存在行星的概率很小，实际上这类行星并不具有代表性，但是由于其是最早得到确认的系外行星，加之宇宙中其总数仍然不少，因此还是有必有介绍一二：
Pulsar planets are discovered through pulsar timing measurements, to detect anomalies in the pulsation period. Any bodies orbiting the pulsar will cause regular changes in its pulsation. Since pulsars normally rotate at near-constant speed, any changes can easily be detected with the help of precise timing measurements. The discovery of pulsar planets was unexpected; pulsars or neutron stars have previously gone supernova, and it was thought that any planets orbiting such stars would have been destroyed in the explosion.
In 1991, Andrew G. Lyne announced the first ever pulsar planet discovered around PSR 1829-10. However, this was later retracted, just before the first real pulsar planets were announced.
In 1992, Aleksander Wolszczan and Dale Frail announced the discovery of a multi-planet planetary system around the millisecond pulsar PSR 1257+12. These were the first two extrasolar planets confirmed to be discovered, and thus the first multi-planet extrasolar planetary system discovered, and the first pulsar planets discovered. There was doubt concerning the discovery because of the retraction of the previous pulsar planet, and questions about how pulsars could have planets. However, the planets proved to be real. Two additional planets of lower mass were later discovered by the same technique.
In 2000, the millisecond pulsar PSR B1620-26 was found to have a circumbinary planet (PSR B1620-26 b) that orbits both it and its companion white dwarf, WD B1620-26. This was announced as the oldest planet ever discovered, at 12.6 billion years old. It is currently believed to have originally been the planet of WD B1620-26 before becoming a circumbinary planet, and therefore, while discovered through the pulsar timing method, it did not form the way that PSR B1257+12's planets are thought to have.
In 2006, the magnetar 4U 0142+61, located 13,000 light years from Earth, was found to have a circumstellar disk. The discovery was made by a team led by Deepto Chakrabarty of MIT using the Spitzer Space Telescope. The disk is thought to have formed from metal-rich debris left over from the supernova that formed the pulsar roughly 100,000 years ago and is similar to those seen around Sun-like stars, suggesting it may be capable of forming planets in a similar fashion. Pulsar planets would be unlikely to harbour life as we know it, because the high levels of ionizing radiation emitted by the pulsar and the corresponding paucity of visible light.
In 2011, a planet that is theorized to be the remaining core of a star that orbited a pulsar was announced. It orbits millisecond pulsar PSR J1719-1438, and represents a path to planetary status by evaporation of a star. The planet is estimated to have a density of at least 23 times that of water, a diameter of 55,000 km, a mass near that of Jupiter's, and a 2hr10min orbital period at 600,000 km. It is thought to be the diamond crystal core remaining from the evaporated white dwarf, with an estimated 1031 carat weight.
There are three types of pulsar planets known so far. The PSR B1257+12 planets were formed out of the debris of a destroyed companion star that used to orbit the pulsar. In PSR J1719-1438, the planet most likely is the companion, or what's left of it after being almost entirely blasted away by the extreme irradiation from the nearby pulsar. PSR B1620-26 b is most likely a captured planet.
以下为得到确认的系外脉冲星的行星：
PSR B1620-26 b，PSR B1257+12 A，PSR B1257+12 B以及PSR B1257+12 C，还有一颗系外脉冲星行星的候选者PSR J1719-1438 b，等待进一步确认，估计质量大约是一个木星质量，半长轴只有0.004个AU，呵呵，估计是个超级热木星吧。。。 上面那颗疑似超级热木星的资料如下：
PSR J1719-1438 b is an extrasolar planet that was discovered on August 25, 2011 in orbit around PSR J1719-1438, a millisecond pulsar. The pulsar planet is most likely composed largely of crystalline carbon, but with a density far greater than diamond. PSR J1719-1438 b orbits so closely to its host star, the planet's orbit would fit inside the Sun. The existence of such carbon planets had been theoretically postulated.
PSR J1719-1438 was first observed in 2009 by a team headed by Matthew Bailes of Swinburne University of Technology in Melbourne, Australia. The orbiting planet was published in the journal Science on August 25, 2011. The planet was confirmed through pulsar timing, in which small modulations detected in the highly regular pulsar signature are measured and extrapolated. Observatories in Britain, Hawaii, and Australia were used to confirm these observations.[1
PSR J1719-1438 b was, at the time of its August 25, 2011 discovery, the densest planet ever discovered, at nearly 20 times the density of Jupiter (about 23 times the density of water). It is slightly more massive than Jupiter. It is thought to be composed of oxygen and carbon (as opposed to hydrogen and helium, the main components of gas giants like Jupiter and Saturn).
The oxygen is most likely on the surface of the planet, with increasingly higher quantities of carbon deeper inside the planet. The intense pressure acting upon the planet suggests that the carbon is crystallized, much like diamond is.
PSR J1719-1438 b orbits its host star with a period of 2.177 hours and at a distance of a little bit less than one (0.89) solar radius.
我了个去，这颗行星的轨道比地球-月球的间距远不了多少，它的一年才只有2个多小时，看来其他主序星的超短周期行星和它一比简直弱爆了。。。。 zenghan 发表于 2016-3-30 08:32
上面那颗疑似超级热木星的资料如下：
PSR J1719-1438 b is an extrasolar planet that was discovered on A ...
资料显示，这颗行星的密度大约是水的23倍，分析还显示这可能是一颗钻石星球，看来要发财的要尽快动手啊。。。。但是实际上这可能是一颗死亡恒星的残骸，其组分和表面形态与我们熟知的热木星，太阳系里的“冷木星”以及远日的冰巨星完全不同，代表了一类全新的系外行星-源自于死亡恒星内核的超致密的所谓”钻石行星或碳行星“。
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zenghan 发表于 2016-3-30 08:28
最后补充一类系外行星：脉冲星附近的系外行星，鉴于脉冲星实际上在恒星总数中所占比例很小，加上这类恒星的 ...
先掰一下这个三星系统。
A: 1.06 ± 0.07 M☉
B: 0.96 ± 0.05 M☉
C: 0.67 ± 0.05 M☉
Ab: 1Mj + ？
B、C互绕周期156天，半长轴0.67Au，偏心率0.1（还算圆）。
A（1.06M☉）与B/C（1.63M☉）互绕周期25.7年，半长轴12.3Au，偏心率0.5（轨道算长了）。
Ab绕A周期80小时，半长轴8,000,000km
B/C共有的Rrochelobe约为6.5~7Au ，而B、C距离为0.67Au，约为Rrochelobe/10
Rrochelobe/10的位置能形成恒星，哈哈哈。 zenghan 发表于 2016-3-30 08:28
最后补充一类系外行星：脉冲星附近的系外行星，鉴于脉冲星实际上在恒星总数中所占比例很小，加上这类恒星的 ...
哈哈，复错楼层了，刚才要复主楼的。
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