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阿佩普 (恒星系统)

天球赤道座标：星图 16h 00m 50.5s, −51° 42′ 45″
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阿佩普

甚大望远镜拍摄的红外影像
（ ESO/Callingham等人。）[a]。
观测资料
历元 J2000.0
星座 矩尺座
星官
赤经 16h 00m 50.5s
赤纬 -51° 42′ 45″
视星等（V） 17.5
特性
演化阶段WR 联星
视星等 (J)10.2
视星等 (K)6.9
天体测定
距离2,000+400
−300[3] pc
绝对星等 (MV)-5.15 / -5.15 / -7.4[3]
其他命名
WR 70-16、2MASS J16005047-5142449[4]
参考数据库
SIMBAD资料

阿佩普 是位于矩尺座的一个三合星系统，包含沃夫–瑞叶星联星和一颗炽热的超巨星。以埃及神话中的蛇神命名，该恒星系统被恒星风和宇宙尘的巨大复合体包围，这些复合体被联星主星的高转速抛入太空，并在次星的影响下形成“风车”形状。2010年代对该系统的地面研究得出结论，该系统是银河系中最著名的伽马射线暴前身候选者。

命名法

阿佩普（英语：Apep），发音为 /ˈɑːpɛp/，由荷兰无线电天文研究所的Joseph Callingham领导的天文学家团队命名，他在2016年至2018年间研究了该系统，并发表了一篇关于他们观测结果的科学论文[5][6]。它是以埃及神话中太阳神拉的同名死敌命名的，他经常被描绘成一条巨蛇；他们的竞争被描述为“一个恰当的典故”，指的是该系统及其恒星风在红外中的外观是“一颗被龙卷包围在内的恒星”[5][7]。在由XMM-牛顿卫星太空望远镜观测到的天体物理X射线源（英语：Astrophysical X-ray source）偶然源的恒星目录中，该系统被编目为2XMM J160050.7–514245[8]。它也被称为WR 70-16。

特性

阿佩普是一个三合星系统[6][9]，包含一颗被描述为“中央发动机”，轨道周期为~100年的沃夫–瑞叶星联星 沃夫–瑞叶星联星[10]，和被描述为“北方伴星”，围绕中心发动机运行，距离约1,700天文单位，周期>10,000年的第三颗热的超巨星[11]。阿佩普中心的联星由碳（WC8）和氮序（WN4-6b）亚型的两颗经典沃夫-瑞叶星组成，使阿佩普成为银河系中经典WR+WR联星系统的最强案例[3]。碳序沃夫–瑞星通常是制造尘埃的工厂。一个巨大的恒星风和宇宙尘埃复合体围绕着这个系统[7][9][12]，类似于另一个产生风车星云的沃夫 – 瑞叶星系统WR 104[13]。恒星风的速度为12 × 106 km/h（7.5 × 106 mph）[6][12]，在系统的边缘，尘埃速度为 2 × 106 km/h（1.2 × 106 mph），表明中央发动机至少有一个部件正在快速旋转，其中其表面重力接近于由其向外的离心力平衡[9][14]。这个元件从两极产生更快的恒星风，从赤道产生较慢的风，赤道风与其次级风的相互作用产生了系统的“风车”形状[15][16]。快速旋转的沃夫–瑞叶星理论上能够在超新星期间产生伽马射线暴，该系统已被确定为伽马射线暴的前身[17]。估计阿佩普距离地球约~2.4 千秒差距[18]，或~8,000 光年[10][19]，潜在差异为+0.2和-0.5千秒差距，估计视觉消光为11.4[18]。

观察

Map of the constellation Norma
阿佩普在矩尺座中的位置（红圈）

阿佩普位于星座矩尺座，在赤经16h 00m 50.5s和赤纬-51° 42′ 45″[1]。该系统可以解析为两个组成部分：“中央发动机”沃夫-瑞叶联星，和“北方伴星”超巨星[20]。系统的总视星等为17.5，分辨出的中央发动机和北方伴星的视星等分别为19.0和17.8[21]。它的红外光谱能量分布（SED）是独一无二的，亮度范围从2.2μm处的6.4等到22μm处的-2.4等[22]。使用欧洲南方天文台（ESO）的仪器SINFONI，在甚大望远镜上进行的调查量测到，中央发动机在红外J波段（英语：J band (infrared)）中的视星等为10.2±0.2，北方伴星的视星级为9.6±0.2[23]。SINFONI 还量测了系统在K波段中的表观星等，对于中央发动机为6.9±0.2，对C为8.1±0.2[24]， 在 L 波段（英语：L band (infrared)），对于中央发动机为4.7±0.1，北方办星为7.3±0.1[24]，和在M波段（英语：M band (infrared)）的中央发动机为4.4±0.3，北方伴星为7.0±0.2[24]。SINFONI的观测进一步详细说明，北方伴星可能是一颗传统的B1Ia+高光度恒星[25]。A和B显示了WC7恒星的典型光谱[26]，但具有额外的WN4或WN5恒星特征，理论上来自中央发动机的恒星之一；如果得到证实，这将使阿佩普成为一个罕见的WR星的联星系统[27]。另一种基于SINFONI数据的假设认为，光谱可能都来自一颗不寻常的过渡WN/WC星，而北方伴星则是一颗传统的OB恒星[28]。将WR星大犬座EZ和WR 90的光谱结合起来，将产生与WR联星观测到的光谱几乎相同的光谱。

该系统是在银河系星系中发现的第一个伽马射线爆发前身候选者[7]，尽管它在早期的观测中并不为人所知，比如使用XMM-牛顿卫星和Chandra太空望远镜的观测，早在2004年8月，它就被简单地确定为天体物理X射线源（英语：Astrophysical X-ray source）[29]。天文学家乔·卡林厄姆（Callingham）在雪梨大学的大学生研究期间首次用莫隆格罗天文台合成望远镜（英语：Molonglo Observatory Synthesis Telescope）观测到阿佩普[12][30]，并被认为是一个潜在的碰撞风联星，其射电源亮如海山二（船底座η）[31]。卡林厄姆和彼得·塔希尔 (天文学家)（英语：Peter Tuthill (astronomer)）在1998年领导了WR104的发现[32]，并在观察到阿佩普的极端红外特性后，寻求对其感兴趣[33][34]，2016年8月使用ESO的甚大望远镜进行观测[1][35]。使用英澳望远镜和澳大利亚望远镜致密阵列进行的进一步观测[19]，以及各国际机构的贡献 [b]，导致2018年11月19日在《自然·天文学》上发表了科学论文[15]。它得出的结论是，该系统是沃夫–瑞叶联星，是伽马射线暴的前身[9][36]。以前人们认为，这种系统只在比银河系年轻的星系中发现[16]。

相关条目

参考资料

注解

  1. ^ 2016年8月13日，欧洲南方天文台的甚大望远镜拍摄的两张红外影像的合成图：仪器NACO以2.24微米的波长拍摄系统中心的一颗恒星，仪器VISIR以8.9微米的波长拍摄这一颗恒星周围的尘埃和气体云。影像的宽度为0.26×0.26弧分[1][2]
  2. ^ Contributions from the University of Edinburgh, the University of New South Wales, New York University, and the University of Sheffield, and the University of Sydney.[16]

来源

  1. Callingham, Joseph. Riding the serpent: The discovery and study of Apep. Nature. 20 November 2018 [26 November 2018]. （原始内容存档于26 November 2018）. 
  2. Callingham, J. R.; Tuthill, P. G.; Pope, B. J. S.; Williams, P. M.; Crowther, P. A.; Edwards, M.; Norris, B.; Kedziora-Chudczer, L. Anisotropic winds in a Wolf–Rayet binary identify a potential gamma-ray burst progenitor (PDF). University of Sydney School of Physics. 24 September 2018 [20 November 2018]. （原始内容存档 (PDF)于20 November 2018）. 
  3. Plait, Phil. Bad Astronomy: Is this cosmic sprinkler surrounding galaxy's next gamma-ray burst?. Syfy Wire. 19 November 2018 [22 November 2018]. （原始内容存档于22 November 2018）. 

引文

  1. ^ 1.0 1.1 1.2 Callingham et al. 2018，page 3, "Figure 1. VISIR 8.9 μm image of Apep taken on 2016 August 13, displaying the exotic dust pattern being sculpted by the system. The 2.24 μm NACO image of the region bounded by the blue box, of dimension 1.8" × 1.8", is shown in the upper right corner."
  2. ^ ESO staff. Coils of Apep. European Southern Observatory (ESO). 19 November 2018 [6 January 2019]. （原始内容存档于6 January 2019）. Field of view: 0.26 x 0.26 arcminutes 
  3. ^ 3.0 3.1 3.2 Callingham, J. R.; Crowther, P. A.; Williams, P. M.; Tuthill, P. G.; Han, Y.; Pope, B. J. S.; Marcote, B. Two Wolf-Rayet stars at the heart of colliding-wind binary Apep. Monthly Notices of the Royal Astronomical Society. 2020, 495 (3): 3323–3331. Bibcode:2020MNRAS.495.3323C. S2CID 218470247. arXiv:2005.00531 可免费查阅. doi:10.1093/mnras/staa1244. 
  4. ^ AX J1600.9-5142. SIMBAD. 斯特拉斯堡天文资料中心. [2021-12-24]. 
  5. ^ 5.0 5.1 Callingham et al. 2018，page 3, "we here adopt the moniker "Apep" after the sinuous form of this infrared plume [...] The serpent diety from Egyptian mythology; mortal enemy of sun god Ra. We think this is an apt allusion to the image which evokes a star embattled within a dragon’s coils."
  6. ^ 6.0 6.1 6.2 Dvorsky, George. Stunning Pinwheel Nebula Is a Cosmic Cataclysm in the Making. Gizmodo. 19 November 2018 [20 November 2018]. （原始内容存档于20 November 2018）. ...but to the researchers who recently investigated this enigmatic object, it’s simply "Apep" [...] The speed of gas within the nebula was clocked at 12 million kilometers per hour [...] featuring a massive triple star system at its core—a binary pair and a lone star... 
  7. ^ 7.0 7.1 7.2 Letzter, Rafi. This Spinning, Snakelike Star System Might Blast Gamma Rays into the Milky Way When It Dies. Live Science. 19 November 2018 [20 November 2018]. （原始内容存档于20 November 2018）. For the first time, astronomers have found a star system in our galaxy that could produce a gamma-ray burst [...] the researchers nicknamed it "Apep" after the Egyptian snake-deity of chaos. [...] The name works nicely for the system, which is surrounded by long, fiery pinwheels of matter cast out into space... 
  8. ^ XMM-Newton Survey Science Centre. The XMM-Newton Serendipitous Source Catalogue: 2XMM User Guide. University of Leicester Department of Physics and Astronomy. 20 August 2008 [20 November 2018]. （原始内容存档于20 November 2018）. 2XMM is a catalogue of serendipitous X-ray sources from the European Space Agency's (ESA) XMM-Newton observatory 
  9. ^ 9.0 9.1 9.2 9.3 Carpineti, Alfredo. This 'Cosmic Serpent' Is The First System Of Its Kind To Be Discovered In Our Galaxy. IFL Science!. 19 November 2018 [20 November 2018]. （原始内容存档于20 November 2018）. Three stars are in this picture, although the two Wolf-Rayet stars look like a single one in the center [...] the winds are moving at 12 million kilometers (7.5 million miles) per hour. [...] The observations were possible thanks to the Very Large Telescope [...] the dust at the edge of the system is moving at the slower pace of 2 million kilometers (1.2 million miles) per hour. 
  10. ^ 10.0 10.1 Griffin, Andrew. Huge star system near Earth could produce one of the most spectacular explosions in the universe. The Independent. 19 November 2018 [20 November 2018]. （原始内容存档于20 November 2018）. The swirling cloud of dust is a mere 8,000 light years from Earth is a vast system made up of two shockingly bright stars. [...] The two bright stars orbit each other every hundred years or so, according to the researchers. 
  11. ^ Plait 2018，"At 250 billion kilometers out from the bright star (about ten times the distance of Neptune from the Sun), it would take more than 10,000 years to circle it once..."
  12. ^ 12.0 12.1 12.2 Strom, Marcus. Doomed star in Milky Way threatens rare gamma-ray burst. University of Sydney. 20 November 2018 [20 November 2018]. （原始内容存档于20 November 2018）. ...the astronomers have measured the velocity of the stellar winds as fast as 12 million kilometres an hour, about 1 percent the speed of light. [...] We discovered this star as an outlier in a survey with a radio telescope operated by the University of Sydney. 
  13. ^ Plait 2018，"Sometimes, if they are in a tight binary, you get a pinwheel. The most famous example of that is WR 104..."
  14. ^ Plait 2018，"The astronomers who observed it think that the primary (brighter) one is spinning extremely rapidly, so fast it's nearly at the breakup rate — in other words, spinning so fast that the gravity of the star at the surface is nearly balanced by the centrifugal force outwards."
  15. ^ 15.0 15.1 Weule, Genelle. Spectacular cosmic pinwheel is a 'ticking bomb' set to blast gamma rays across the Milky Way. ABC News Australia. 20 November 2018 [20 November 2018]. （原始内容存档于20 November 2018）. Writing in the journal Nature Astronomy [...] the most violent star is creating stellar winds at two speeds — fast at the poles, slow at the equator [...] the beautiful pinwheel of blazing dust is created not by the fast polar winds, but by the turbulence that arises when the second star in the central engine passes through that first star's slow-moving equatorial wind. 
  16. ^ 16.0 16.1 16.2 Devitt, James. Scientists Discover New "Pinwheel" Star System. New York University. 19 November 2018 [20 November 2018]. （原始内容存档于20 November 2018）. "It was not expected such a system would be found in our galaxy—only in younger galaxies much further away," [...] The discovery of the system [...] also included scientists from the Netherlands Institute for Radio Astronomy, the University of Sydney, the University of Edinburgh, the University of Sheffield, and the University of New South Wales. [...] is adorned with a dust "pinwheel"— whose strangely slow motion suggests current theories on star deaths may be incomplete. 
  17. ^ Clery, Daniel. Massive star system primed for intense explosion. Science. 20 November 2018 [20 November 2018]. （原始内容存档于20 November 2018）. One of stars is an unusually massive sun known as a Wolf-Rayet star. When such stars run out of fuel, they collapse, causing a supernova explosion. Theorists believe that if the Wolf-Rayet star is also spinning fast, the explosion will produce intense jets of gamma rays out of either pole... 
  18. ^ 18.0 18.1 Callingham et al. 2018，page 18–19, "If we use the visual extinction AV = 11.4 [...] we need a distance of d = 2.4+0.2
    −0.5     to get realistic absolute magnitudes for the components. [...] Despite these uncertainties, all lines of evidence suggest that Apep is located [less-than around] 4.5 kpc, and likely around d ≈ 2.4 kpc."
  19. ^ 19.0 19.1 Mannix, Liam. Super-powerful interstellar 'ticking time bomb' found not far from Earth. The Sydney Morning Herald. 20 November 2018 [20 November 2018]. （原始内容存档于20 November 2018）. In a part of the Milky Way 8000-odd light-years away [...] The system was spotted by PhD student Dr Joe Callingham while he was sorting through data, and later confirmed using the Anglo-Australian Telescope at Coonabarabran in regional NSW. 
  20. ^ Callingham et al. 2018，page 2, "The 2.24μm NACO observation (Figure 1, inset) resolves Apep into a 0.739" ± 0.002" binary with a fainter companion to the North."
  21. ^ Callingham et al. 2018，page 18, "...the known visual magnitude V = 17.5 for Apep (V = 17.8 for the OB supergiant that is the northern companion and V = 19.0 for the Central Engine)..."
  22. ^ Callingham et al. 2018，page 18–19, "...was first noted as a high-luminosity outlier in our Galactic plane X-ray and radio survey, and revealed as an exceptional object on considering its infra-red spectral energy distribution (SED), where it brightens from an apparent magnitude of 6.4 at 2.2μm to −2.4 at 22μm, with both measurements on the Vega system."
  23. ^ Callingham et al. 2018，page 14, "Apep was resolved by SINFONI [...] We summed the J-band data over the Central Engine and northern companion to derive the J-band magnitudes of 10.2±0.2 and 9.6±0.2, respectively."
  24. ^ 24.0 24.1 24.2 Callingham et al. 2018，page 22, "Supplementary Information Table 2. Summary of the NACO observations of Apep. Separation refers to the angular separation between the Central Engine and northern companion, identified in the inset of Figure 1. The uncertainties reported are for 90% confidence."
  25. ^ Callingham et al. 2018，page 21, "Despite this, we favour the northern companion being an B1 Ia+ supergiant but further observations, particularly optical spectra, are necessary to confirm this spectral type."
  26. ^ Callingham et al. 2018，page 20, "...the spectrum of Apep shows stronger He II and weaker C IV line emission than is stereotypical for a WC7 star."
  27. ^ Callingham et al. 2018，page 20, "The weakness in the J-band, where dust emission is negligible [...] points to the additional continuum from a companion star. The abnormal strength of the He II lines for a WC7 star suggests an early WN sub-type companion. The absence of N V and relative weakness of He I, and with comparison to WN spectra, implies the presence of a subtype WN4 or WN5 star. Double WR binaries are, however, rare, with very few known."
  28. ^ Callingham et al. 2018，page 21, "An alternative spectral subtype classification to the WC7+WN4-5 model, that equally well describes the spectra shown in Figure 2, is that of a WR star in the brief transitory phase between WN and WC (WN/WC) with an unseen OB-type companion."
  29. ^ Callingham et al. 2018，page 25, "Supplementary Information Table 3. Summary of the 0.2 and 10.0 keV observations of Apep. ObsID corresponds to the unique identification number assigned to each observation by the respective X-ray observatory.
  30. ^ Callingham 2018，"The path that led to the discovery of Apep started with a relatively simple crossmatch between X-ray and radio surveys in the last year of my undergraduate study at the University of Sydney..."
  31. ^ Callingham 2018，"Momentum was behind the idea that Apep was a new colliding-wind binary but the radio emission would make it the brightest radio colliding-wind binary discovered outside of the unique object Eta Carinae..."
  32. ^ Tuthill, Peter G.; Monnier, John D.; Danchi, William C. A dusty pinwheel nebula around the massive star WR104. Nature. 1 April 1999, 398 (6727): 487–489 [2023-07-30]. Bibcode:1999Natur.398..487T. ISSN 0028-0836. S2CID 4373103. arXiv:astro-ph/9904092 可免费查阅. doi:10.1038/19033. （原始内容存档于2023-02-22）. 
  33. ^ Tuthill, Peter. The Twisted Tale of Wolf-Rayet 104 First of the Pinwheel Nebulae. University of Sydney School of Physics. 1999 [26 November 2018]. （原始内容存档于26 November 2018）. These results are further described in our letter in Nature "A dusty pinwheel nebula around the massive star wr 104" by Peter Tuthill, John Monnier and William Danchi Volume 398, pp. 487–489, April 8, 1999. 
  34. ^ Callingham 2018，"This is where the imaging guru Peter Tuthill (University of Sydney) comes into the story as the extreme infrared properties of Apep particularly caught his attention. [...] It immediately brought to mind the so-called "Pinwheel Nebulae" that Peter had discovered 20 years ago, but this was larger and with more complicated structure than the clean Archimedean spiral observed in those systems."
  35. ^ Callingham 2018，"We wrote a proposal to use a mid-infrared camera on the European Southern Observatory’s Very Large Telescope (VLT) to image the source in the middle of my PhD..."
  36. ^ Callingham et al. 2018，page 1, "Near-critical stellar rotation is known to drive such winds, suggesting this Wolf-Rayet system as a potential Galactic progenitor system to long-duration gamma-ray bursts."

外部链接

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