Cygnus X-1

Henry Draper Catalog	HD 226868 [1]
2MASS catalog	2MASS J19582166 + 3512057 [2]
Other names	V1357 Cyg, 1H 1956 + 350, PBC J1958.3 + 3512, UBV 17047, 3A 1956 + 350, PPM 83929, UBV M 27507, AG + 35 1910, H 1956 + 350, 1RXS J195821.9 + 351156, uvby98 100226868, ALS 10678, H 1957 + 35, SAO 69181, WEB 17338, BD + 34 3815, HIC 98298, SBC7 776, XRS 19564 + 350, CGO 548, Hilt 849, SBC9 1193, X Cyg X-1, 2E 4306, HIP 98298 , SV * SVS 1808, [AAA2018] FGL J1958.6 + 3510, 2E 1956.4 + 3503, INTEGRAL1 116, SWIFT J1958.4 + 3510, [BM83] X1956 + 350, 1FGL J1958.9 + 3459, INTREF 1001, SWIFT J1958 .3 + 3512, [KRL2007b] 370, GCRV 12319, LS II +35 8, TYC 2678-791-1, [MJD95] J195821.72 + 351205.9, GEN # +1.00226868, 1M 1956 + 350, 2U 1956 + 35, AAVSO 1954 + 34, GOS G071.34 + 03.07 01, 3U 1956 + 35, Gaia DR2 2059383668236814720, GSC 02678-00791, MCW 770, 4U 1956 + 35

Cygnus X-1 also CYG X-1 is referred to as H IgH M ass X -ray B inary ( HMXB , dt. Ray binary system with high mass) indicated, in 1972 the American US from the astronomers Tom Bolton discovered and is the first actually existing black hole that could be detected at all.

The system is located near η Cygni and is a powerful X-ray source . The name Cygnus X-1 results from the fact that it is the first X-ray object discovered in the constellation Swan.

System structure

High-Mass X-ray Binaries (HMXBs) consist of a compact object (a neutron star or a black hole) that accumulates matter from a massive OB star. These are further subdivided into the SgXBs (Supergiant X-Ray Binaries) and the BeXBs (Be / X-Ray Binaries). In the SgXBs, the massive giant star blows a slow, dense stellar wind , which is transformed by the compact object into a focused wind geometry and directly accreted, which leads to a sustained X-ray emission. They have rare type II outbreaks but no type I outbreaks.

In BeXBs, the visual companion is a Be star . Be stars are rapidly rotating stars of spectral class B and luminosity class III-V , which at a certain point in time in their development showed spectral lines in the emission, hence the qualifier "e" in their spectral types.

Some SgXBs have companion stars that cross the Roche limit, with the matter flowing over the Lagrange point to the compact partner.

The black hole

Cygnus X-1 is the only known SgXB (as of 2019) in which the mass transfer occurs through both wind accretion and the Roche limit being exceeded by the mass donating star, and contains a confirmed black hole as a compact component. The system is normally in the so-called low-state with a mass accretion rate of 3.0 × 10 ^-6 M _☉ / year, from which the luminosity in the X-ray range of L _X ∼ 5 × 10 ³¹ erg / s (corresponding to 5 × 10 ²⁴ W or 10,000 times the X-ray luminosity of the sun) can be derived. During outbreaks, very high X-ray luminosity in the order of magnitude of L _X ∼ 10 ³⁸ erg / s (corresponding to 10 ³¹ W or 100 billion times the X-ray luminosity of the sun) is emitted.

Since the compact component is a black hole, the term microquasar or Black Hole X-ray Binary (BHXB) is used in the terminology . With a mass of about 15.8 M _⊙ and an event horizon of about 50 km in diameter, Cygnus X-1 is the closest stellar black hole in the Milky Way to XTE J1118 + 480 .

Accretion disk

It is believed that the compact object is surrounded by a thin, flat disk of accreted matter called the accretion disk . This disk is heated up by friction between ionized gas in faster moving inner tracks and that in slower outer tracks. It is divided into a hot inner area with a relatively high degree of ionization and a cooler, less ionized outer area, which extends to an estimated 500 Schwarzschild radii or about 15,000 km.

Cygnus X-1, while highly variable, is the brightest and most consistent source of hard X-rays in the sky. The X-rays are generated as soft "seed photons" of the cold standard disk and are then converted to high energies (X-ray or gamma quanta ) by hot, ultra-relativistic electrons through inverse Compton scattering in a hot corona , which is presumably very close to the event horizon of the hole. scattered towards and cool in this way the hot plasma of the corona.

The X-ray emissions from Cygnus X-1 show quasi-periodic oscillations (QPOs) in the range of a few Hertz. The poloidal magnetic fields at the black hole heat a leptonic plasma , creating a corona in which a jet is created. It is believed that the corona is holey and sits on the accretion disk . The mass of the compact object determines the distance at which the surrounding plasma begins to emit these QPOs, with the emission radius decreasing with decreasing mass.

Jets

When accumulated matter falls on the compact object, it loses potential gravitational energy. Part of this released energy is diverted by so-called stellar jets oriented perpendicular to the accretion disk, which flow outwards at relativistic velocities (v _jet = 0.995 c ).

The jets of Cygnus X-1 give off only a small part of their energy in the visible electromagnetic spectrum , so they appear to be "dark". The estimated angle of the jets to the line of sight is 30 °, with the axis of rotation also changing due to precession movement . One of the jets collides with a relatively dense part of the interstellar medium (ISM) and seems to form a ring nebula at this point, which was observed at optical wavelengths, but can also be detected by its radio emission. To generate this fog, has the jet at least a power of 4-14 × 10 ³⁶ erg / s or (9 ± 5) × 10 ²⁹ W muster. This is more than 1,000 times the energy given off by the sun. There is no corresponding nebula in the opposite direction as this stellar jet faces a lower density area of the ISM.

In 2006, Cygnus X-1 was the first stellar black hole to show gamma-ray emission in the very high energy band above 100 GeV . The signal was observed simultaneously with a flare of hard X-rays, suggesting a relationship between the events. The X-rays could come from the base of the jet, while the gamma rays are generated where the jet hits the stellar wind from HDE 226868.

HDE 226868

The companion star is a blue and white supergiant named HDE 226868. This is of the spectral type O9.7, has an effective temperature T _e = 31,000 K , a radius of R _opt = 30 to 34 R _⊙ and a mass of M _opt = 25 to 35 M _⊙ , and thus 200,000 times the luminosity of the sun. The two components orbit each other with a period of 5.6 days. The physical distance to each other is only R = 20 R _☉ (approx. 14 million km). The total loss of mass of HDE 226868 is given as M = −2.6 × 10 ⁻⁶ M _⊙ / year.

The surface of HDE 226868 is distorted in a teardrop shape by the gravity of the black hole. This causes the star's optical brightness to fluctuate by 0.06 ^m during one orbital period . The "ellipsoidal" pattern of the change in light results from the darkening of the star's surface and the gravitational redshift .

Gas and dust between our solar system and HDE 226868 lead to a reduction in the apparent brightness of 3.3 ^m and to a redshift. Without the interstellar extinction , HDE 226868 would be a star of the fifth magnitude and thus visible to the naked eye.

observation

Cygnus X-1 was the first confirmed candidate for a black hole, but the masses of the two components of the system were long controversial. The history of its destination before 2005 was described by J. Ziółkowski. After 2005, two important observational improvements were made that were crucial for mass determination.

First, a more precise estimate of the effective surface temperature of the supergiant was achieved by carefully modeling the stellar atmosphere of the companion HDE 226868. Second, MJ Reid et al. 2011, the distance to the binary system HDE 226868 / Cyg X-1 was better estimated using radio parallax.

This enabled a significantly better determination of the effective surface temperature of HDE 226868 and a more precise estimate of the masses of both components. With the current evolution models the distance with 1.86 k pc (6.064 Lj ), the effective temperature of the super giant with T _e = 31,000 K, the luminance L = 204.000 L _⊙ , the mass of HDE 226868 M _opt = 27 M _⊙ , and the mass of the black hole with M _BH = 15.8 M _{⊙ is} calculated.

Artist's impression of a black hole with an accretion disk and a hot plasma jet.

The suspicion that it is at Cygnus X-1 is a strong X-ray source, already existed since 1962 and was finally in 1970 with the help of Uhuru - X-ray telescope detected. From 1974, due to the extremely short-term variations in X-ray intensity and other properties, it was assumed that Cygnus X-1 was a binary star with an extremely compact object. Due to the high mass, a neutron star was no longer an option, so everything pointed to a black hole. Furthermore, the impact of the matter on a neutron star would be visible as a separate X-ray burst. The X-ray radiation is produced by the fact that the mass of the companion star is drawn to the black hole, where it forms an accretion disk , which heats up to a few million degrees due to the friction and thereby emits X-rays.

Above: This illustration shows how matter is drawn onto a black hole. As the gas approaches the event horizon, it becomes redder and darker due to strong gravitational redshift. When the gas crosses the event horizon, it disappears from view. Bottom: As the gas approaches a neutron star, a similar gravitational redshift makes the gas appear redder and darker. However, when the gas hits the solid surface of the neutron star, it glows brightly.

In 2001, the Hubble and Chandra space telescopes were used to demonstrate that matter suddenly disappears. This can be explained by diving into the event horizon. Combined observations with the help of Chandra and XMM-Newton initially showed that the black hole rotates either immeasurably or unusually slowly. Later research found a very fast revolution of 790 s ⁻¹ .

The distance from Cygnus X-1 was initially difficult to determine precisely because at such great distances the parallax of the object was in the order of magnitude of the possible measurement error. Initially, between 6,500 and 8,200 light years were assumed; Closer studies in 2011 put the distance at about 6,100 light years. Parallax data from the Gaia mission , on the other hand, again indicate a somewhat greater distance of almost 8,000 light years.

development

Cygnus X-1 is moving towards the galactic plane in a manner similar to the Cygnus OB3 association. This supports the hypothesis that Cygnus X-1 belongs to Cygnus-OB3. Relative to Cygnus-OB3, the speed of Cygnus X-1 is v _rel = (9 ± 2) km / s, which corresponds to a typical speed of stars in expanding associations. It can be concluded from this that the HMXB will have reached a predicted distance of ∼ 60 pc from the center of Cyg OB3 in (7 ± 2) × 10 ⁶ years. Cygnus X-1 is estimated to be around 5 million years old.

A lower limit for the initial mass of the precursor star of Cygnus X-1 can be estimated by assuming that all massive stars of the Cygnus-OB3 association were formed on an astronomical scale within a short period of time. The main sequence star with the highest mass in Cyg OB3 is of the spectral type O7 V and has a mass M = 40 M _⊙ .

Since more massive stars evolve faster, the lower limit for the initial mass of the precursor for Cygnus X-1 is M _UG ∼ (40 ± 5) M _⊙ . The upper mass limit could have been up to M _OG ∼ 100 M _⊙ . As could be deduced from current models of stellar evolution, Cygnus-OB3 and thus also the precursor star of Cygnus X-1 arose (5 ± 1.5) × 10 ⁶ years ago, which is in accordance with the time span that Cygnus X- It took 1 to move from the center of Cyg OB3 to its current location.

The properties of Cygnus X-1 indicate that in the core collapse of the massive precursor no more than (1 ± 0.3) M _{⊙ was} ejected to accelerate the system to a speed of (9 ± 2 km / s). Indeed, there are no observational results for a supernova remnant in the region where Cygnus X-1 was most likely formed.

To collapse to black holes must the precursor star above (30 ± 5) M _⊙ have lost because the initial mass of the precursor larger (40 ± 5) M _⊙ was, and the estimated mass of the black hole (10 ± 5) M _⊙ is . Part of the missing mass may have been transferred to the companion HDE 226868, but since it has a mass of over 18 M _⊙ , about 12 M _{⊙ must have} been lost to stellar winds . In such a case, the precursor to the black hole in Cygnus X-1 could have been a Wolf-Rayet star .

Formation of the black hole

Cygnus X-1's black hole was not formed by a Type II supernova that blows away hydrogen shells and has ejected mass in the range of 10 to 50 _MΩ , which is well above the upper limit of mass found in Cygnus X-1 could suddenly have been ejected. Alternatively, the core collapse could have occurred in a precursor star that has lost its hydrogen-rich shell ( SN Ib ) and even most of its helium shell ( SN Ic ). Recent observations suggest that the energy and luminosity of a type Ib or Ic supernova increases with an increasing amount of ejected mass, so that the core collapse of Cygnus X-1 compared to typical supernovae was either very faint or took place without an explosion at all.

For example, stellar black holes like in Cygnus X-1 could form without a supernova without an explosion in a so-called un-nova, quasi in the dark. The maximum linear momentum and kinetic energy that could have been imparted to Cygnus X-1 by the momentum of a supernova would be (2 ± 0.5) × 10 ⁴⁶ erg . The maximum linear impulse for Cygnus X-1 is 2.5 times smaller than the linear impulse transmitted to GRO J1655-40 . The upper limit for the kinetic energy of Cygnus X-1 is at least 20 times smaller than that estimated for GRO J1655-40, and less than 2 × 10 ⁻⁵ the typical amount of energy released by a supernova of 10 ⁵¹ ergs or one Foe .

The movements of Cygnus X-1 and GRO J1655-40 suggest that the black holes in these two X-ray binary star systems originated on different evolutionary paths. The black hole in GRO J1655-40 has a mass of (7.02 ± 0.22) M _⊙ and was created by a supernova explosion and the subsequent collapse of the shells on a neutron star. The black hole in Cygnus X-1 with a mass of (10 ± 5) M _⊙ was formed by a low-energy explosion or even by an instant implosion without a supernova.

These observations are consistent with the theoretical model in which the energy of the explosion in the core collapse of massive stars decreases as a function of the increasing mass of the precursor and the black hole.

A weakly luminous (or dark) formation of black holes should also take place in massive single stars and appear as type II supernovae with low luminosity. This mode of formation of stellar black holes can be used as an approach to gain insight into the physics of long-duration gamma-ray bursts , believed to originate from relativistic jets created by black holes in distant galaxies. The nature of these so-called “dark gamma ray bursts” (dark jet model), ie those without X-rays and / or optical afterglow , have not yet been clarified.

Gamma-ray bursts usually produce an afterglow in the X-ray spectrum as well as in the visible spectrum, which is caused by the jets' shocks with circumstellar material, which consists of the stellar wind from the precursor and / or the ejection of a supernova explosion.

Analysis of the observations suggests that some gamma-ray bursts may be inherently dark. Since the metal abundance decreases with increasing redshift , and massive stars in the distant universe only generate weak stellar winds, these could immediately collapse into massive black holes without a preceding supernova explosion. Since there are no strong stellar winds or ejected material from a supernova that could be shocked by the jets, no afterglow can be observed in the X-ray or optical spectrum of such GRBs . Thus, some dark GRB jets could have originated from massive stellar black holes that formed in the dark, like the black hole in Cygnus X-1.

Stephen Hawking and Kip Thorne

Cygnus X-1 was the subject of a bet between physicists Stephen Hawking and Kip Thorne in which Hawking bet against the existence of black holes. Hawking later referred to this as a kind of "insurance policy".

In his book A Brief History of Time , he wrote:

"This was a kind of insurance for me. I've worked a lot on black holes and it would all have been in vain if it turned out that there were no black holes. But in that case I would at least have had the consolation to make my bet win which would have given me four years of Private Eye magazine . If there were black holes, Kip got a year of penthouse . When we made the bet in 1975, we were 80% sure that Cygnus X-1 was a black hole. In the meantime (1988) we are 95% sure but the bet has yet to be clarified. "

In the updated 10-year edition of A Brief History of Time (1998), Hawking admitted the bet as lost based on later black hole observations.

reception

The Cygnus-X-1 dilogy by the Canadian progressive rock band Rush is a story about the black hole.

In the 1979 Disney film The Black Hole , the protagonists discover a black hole with a mysterious spaceship circling directly in front of the event horizon. The name of the spaceship is "USS Cygnus".

Web links

Commons : Cygnus X-1 - Collection of images, videos and audio files

What is Cygnus X1? from the alpha-Centauri television series(approx. 15 minutes). First broadcast on June 23, 2004.

Individual evidence

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↑ ^a ^b Gaia DR2 in VizieR. In: VizieR. Université de Strasbourg / CNRS, accessed on June 11, 2019 .
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↑ Cygnus X-1. In: Compact Objects of the Sky. Andreas Müller (astronomer) , accessed June 13, 2019 .
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↑ JC Ling et al 1997 ApJ 484 375: Gamma-Ray Spectra and Variability of Cygnus X-1 Observed by BATSE . In: The Astrophysical Journal, Volume 484, Issue 1, pp. 375-382. . February 10, 1997. bibcode : 1997ApJ ... 484..375L . doi : 10.1086 / 304323 .
↑ Titarchuk, Lev, et al .: On the Nature of the Variability Power Decay toward Soft Spectral States in X-Ray Binaries: Case Study in Cygnus X-1 . In: The Astrophysical Journal, Volume 678, Issue 2, pp. 1230-1236 (2008). . 2008. arxiv : 0802.1278 . bibcode : 2008ApJ ... 678.1230T . doi : 10.1086 / 587124 .
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↑ Torres, Diego F., et al .: Probing the Precession of the Inner Accretion Disk in Cygnus X-1 . In: The Astrophysical Journal, Volume 626, Issue 2, pp. 1015-1019. . June 2005. arxiv : astro-ph / 0503186 . bibcode : 2005ApJ ... 626.1015T . doi : 10.1086 / 430125 .
^ Russell, DM, et al .: The jet-powered optical nebula of Cygnus X-1 . In: MNRAS, Volume 376, Issue 3, pp. 1341-1349. . April 2007. arxiv : astro-ph / 0701645 . bibcode : 2007MNRAS.376.1341R . doi : 10.1111 / j.1365-2966.2007.11539.x .
^ Sackmann, I.-Juliana, et al .: Our Sun. III. Present and Future . In: Astrophysical Journal v.418, p.457 . November 1993. bibcode : 1993ApJ ... 418..457S . doi : 10.1086 / 173407 .
^ Albert, J., et al .: Very High Energy Gamma-Ray Radiation from the Stellar Mass Black Hole Binary Cygnus X-1 . In: The Astrophysical Journal, Volume 665, Issue 1, pp. L51-L54. . August 2007. arxiv : 0706.1505 . bibcode : 2007ApJ ... 665L..51A . doi : 10.1086 / 521145 .
↑ Caballero, MD: OMC-INTEGRAL: Optical Observations of X-Ray Sources . In: Proceedings of the 5th INTEGRAL Workshop on the INTEGRAL Universe (ESA SP-552). 16-20 February 2004, Munich, Germany. Scientific Editors: V. Schönfelder, G. Lichti & C. Winkler, p.875 . October 2004. bibcode : 2004ESASP.552..875C .
↑ Cygnus X-1. In: James B. Kaler, University of Illinois. 2002, accessed July 5, 2019 .
↑ CT BOLTON: Identification of Cygnus X-1 with HDE 226868 . In: Naturevolume 235, pages 271-273 (1972) . February 4, 1972. doi : 10.1038 / 235271b0 .
↑ Janusz Ziolkowski: Evolutionary constraints on the masses of the components of the HDE 226868 / Cyg X-1 binary system . In: MNRAS, Volume 358, Issue 3, April 11, 2005, Pages 851-859 . April 11, 2005. doi : 10.1111 / j.1365-2966.2005.08796.x .
↑ Caballero-Nieves SM, et al .: The Ultraviolet Spectrum and Physical Properties of the Mass Donor Star in HD 226868 = Cygnus X-1 . In: The Astrophysical Journal, Volume 701, Number 2 . August 6, 2009. doi : 10.1088 / 0004-637X / 701/2/1895 .
↑ Mark J. Reid, et al .: The Trigonometric Parallax of Cygnus X-1 . In: The Astrophysical Journal, Volume 742, Number 2 . November 9, 2011. doi : 10.1088 / 0004-637X / 742/2/83 .
↑ astris.de - Chandra examines Cygnus X-1
↑ Gou, Lijun et al. (November 9, 2011), "The Extreme Spin of the Black Hole in Cygnus X-1"
↑ Mark J. Reid, Jeffrey E. McClintock, Ramesh Narayan, Lijun Gou, Ronald A. Remillard, and Jerome A. Orosz: The Trigonometric Parallax of Cygnus X-1 . In: Astrophysics. Solar and Stellar Astrophysics . 2011, arxiv : 1106.3688v1 .
^ Philip Massey, et al .: The Initial Mass Function and Massive Star Evolution in the OB Associations of the Northern Milky Way . In: Astrophysical Journal v.454, p.151 . November 1995. bibcode : 1995ApJ ... 454..151M . doi : 10.1086 / 176474 .
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↑ Optical Observations of GRO J1655-40 in Quiescence. I. A Precise Mass for the Black Hole Primary. In: Jerome A. Orosz, et al. The Astrophysical Journal, Volume 477, Number 2, accessed July 1, 2019 .
↑ ^a ^b Fryer, Chris L .; Kalogera, Vassiliki: Theoretical Black Hole Mass Distributions . In: The Astrophysical Journal, Volume 554, Issue 1, pp. 548-560. . June 2001. arxiv : astro-ph / 9911312 . bibcode : 2001ApJ ... 554..548F . doi : 10.1086 / 321359 .
↑ Stephen Hawking's Most Provocative Moments, From Evil Aliens To Black Hole Wagers. In: Michael Greshko, National Geographic. Retrieved July 5, 2019 .

[Simbad-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h HD 226868. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed June 11, 2019 .

[VSXEntry-2] V1357 Cyg. In: VSX. AAVSO , accessed June 11, 2019 .

[VizieR01-3] Gaia DR2 in VizieR. In: VizieR. Université de Strasbourg / CNRS, accessed on June 11, 2019 .

[Janusz_Ziolkowski-4] ↑ ^a ^b ^c ^d ^e ^f ^g Janusz Ziolkowski: Masses of the components of the HDE 226868 / Cyg X-1 binary system . In: MNRASL, Volume 440, Issue 1, 01 May 2014, Pages L61 – L65 . February 14, 2014. arxiv : 1401.1035 . doi : 10.1093 / mnrasl / slu002 .

[Mirabel,_F.,_Rodrigues,_I.-5] Mirabel, F., Rodrigues, I .: Formation of a Black Hole in the Dark . In: Science 300 (2003) 1119-1120 . May 12, 2003. arxiv : astro-ph / 0305205 . doi : 10.1126 / science.1083451 .

[Porter_&_Rivinius_2003-6] Porter, John M .; Rivinius, Thomas: Classical Be Stars . In: The Publications of the Astronomical Society of the Pacific, Volume 115, Issue 812, pp. 1153-1170 . October 2003. bibcode : 2003PASP..115.1153P . doi : 10.1086 / 378307 .

[Müller,_A.-7] Cygnus X-1. In: Compact Objects of the Sky. Andreas Müller (astronomer) , accessed June 13, 2019 .

[A._J._Young,_et_al.-8] AJ Young, et al .: A Complete Relativistic Ionized Accretion Disc in Cygnus X-1 . In: MNRAS, Volume 325, Issue 3, pp. 1045-1052. . March 14, 2001. arxiv : astro-ph / 0103214 . doi : 10.1046 / j.1365-8711.2001.04498.x .

[C.Z.Liu,_et_al.-9] CZLiu, et al .: X-Ray Spectral Variability in Cygnus X-1 . In: The Astrophysical Journal, Volume 611, Number 2 . May 13, 2004. arxiv : astro-ph / 0405246 . doi : 10.1086 / 422209 .

[J._C._Ling,_et_al.-10] JC Ling et al 1997 ApJ 484 375: Gamma-Ray Spectra and Variability of Cygnus X-1 Observed by BATSE . In: The Astrophysical Journal, Volume 484, Issue 1, pp. 375-382. . February 10, 1997. bibcode : 1997ApJ ... 484..375L . doi : 10.1086 / 304323 .

[Titarchuk,_Lev,_et_al.-11] Titarchuk, Lev, et al .: On the Nature of the Variability Power Decay toward Soft Spectral States in X-Ray Binaries: Case Study in Cygnus X-1 . In: The Astrophysical Journal, Volume 678, Issue 2, pp. 1230-1236 (2008). . 2008. arxiv : 0802.1278 . bibcode : 2008ApJ ... 678.1230T . doi : 10.1086 / 587124 .

[Begelman,_et_al.-12] Begelman, et al .: Evidence for Black Holes . In: Science, Volume 300, Issue 5627, pp. 1898-1904 (2003). . June 2003. bibcode : 2003Sci ... 300.1898B . doi : 10.1126 / science.1085334 .

[Torres,_Diego_F.,_et_al.-13] Torres, Diego F., et al .: Probing the Precession of the Inner Accretion Disk in Cygnus X-1 . In: The Astrophysical Journal, Volume 626, Issue 2, pp. 1015-1019. . June 2005. arxiv : astro-ph / 0503186 . bibcode : 2005ApJ ... 626.1015T . doi : 10.1086 / 430125 .

[Russell,_D._M.,_et_al.-14] Russell, DM, et al .: The jet-powered optical nebula of Cygnus X-1 . In: MNRAS, Volume 376, Issue 3, pp. 1341-1349. . April 2007. arxiv : astro-ph / 0701645 . bibcode : 2007MNRAS.376.1341R . doi : 10.1111 / j.1365-2966.2007.11539.x .

[Sackmann,_I.-Juliana,_et_al.-15] Sackmann, I.-Juliana, et al .: Our Sun. III. Present and Future . In: Astrophysical Journal v.418, p.457 . November 1993. bibcode : 1993ApJ ... 418..457S . doi : 10.1086 / 173407 .

[Albert,_J.,_et_al.-16] Albert, J., et al .: Very High Energy Gamma-Ray Radiation from the Stellar Mass Black Hole Binary Cygnus X-1 . In: The Astrophysical Journal, Volume 665, Issue 1, pp. L51-L54. . August 2007. arxiv : 0706.1505 . bibcode : 2007ApJ ... 665L..51A . doi : 10.1086 / 521145 .

[Caballero,_M._D.-17] Caballero, MD: OMC-INTEGRAL: Optical Observations of X-Ray Sources . In: Proceedings of the 5th INTEGRAL Workshop on the INTEGRAL Universe (ESA SP-552). 16-20 February 2004, Munich, Germany. Scientific Editors: V. Schönfelder, G. Lichti & C. Winkler, p.875 . October 2004. bibcode : 2004ESASP.552..875C .

[18] Cygnus X-1. In: James B. Kaler, University of Illinois. 2002, accessed July 5, 2019 .

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