阿佩普 (恆星系統)
參考資料

註解
↑   2016年8月13日，歐洲南方天文台的甚大望遠鏡拍攝的兩張紅外影像的合成圖：儀器NACO以2.24微米的波長拍攝系統中心的一顆恆星，儀器VISIR以8.9微米的波長拍攝這一顆恆星周圍的塵埃和氣體雲。影像的寬度為0.26×0.26弧分
↑  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.
來源
Callingham, Joseph. . Nature. 20 November 2018  [26 November 2018]. （原始内容存档于26 November 2018）.
Callingham, J. R.; Tuthill, P. G.; Pope, B. J. S.; Williams, P. M.; Crowther, P. A.; Edwards, M.; Norris, B.; Kedziora-Chudczer, L.  (PDF). University of Sydney School of Physics. 24 September 2018  [20 November 2018]. （原始内容存档 (PDF)于20 November 2018）.
Plait, Phil. . Syfy Wire. 19 November 2018  [22 November 2018]. （原始内容存档于22 November 2018）.
引文
1 2 3  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."
↑  ESO staff. . 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
1 2 3  Callingham, J. R.; Crowther, P. A.; Williams, P. M.; Tuthill, P. G.; Han, Y.; Pope, B. J. S.; Marcote, B. . Monthly Notices of the Royal Astronomical Society. 2020, 495 (3): 3323–3331. Bibcode:2020MNRAS.495.3323C. S2CID 218470247. arXiv:2005.00531 . doi:10.1093/mnras/staa1244.
↑  . SIMBAD. 斯特拉斯堡天文資料中心.   [2021-12-24].
1 2  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."
1 2 3  Dvorsky, George. . 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...
1 2 3  Letzter, Rafi. . 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...
↑  XMM-Newton Survey Science Centre. . 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
1 2 3 4  Carpineti, Alfredo. . 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.
1 2  Griffin, Andrew. . 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.
↑  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..."
1 2 3  Strom, Marcus. . 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.
↑  Plait 2018，"Sometimes, if they are in a tight binary, you get a pinwheel. The most famous example of that is WR 104..."
↑  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."
1 2  Weule, Genelle. . 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.
1 2 3  Devitt, James. . 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.
↑  Clery, Daniel. . 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...
1 2  Callingham et al. 2018，page 18–19, "If we use the visual extinction AV = 11.4 [...] we need a distance of d = 7000240000000000000♠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."
1 2  Mannix, Liam. . 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.
↑  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."
↑  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)..."
↑  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."
↑  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 7001102000000000000♠10.2±0.2 and 7000960000000000000♠9.6±0.2, respectively."
1 2 3  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."
↑  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."
↑  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."
↑  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."
↑  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."
↑  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.
↑  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..."
↑  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..."
↑  Tuthill, Peter G.; Monnier, John D.; Danchi, William C. . Nature. 1 April 1999, 398 (6727): 487–489  [2023-07-30]. Bibcode:1999Natur.398..487T. ISSN 0028-0836. S2CID 4373103. arXiv:astro-ph/9904092 . doi:10.1038/19033. （原始内容存档于2023-02-22）.
↑  Tuthill, Peter. . 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.
↑  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."
↑  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..."
↑  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."