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Cygnus X-1: Still a 'Star' After All Those Years
Cygnus X-1

  • Originally discovered in 1964, Cygnus X-1 has been observed intensely since

  • In the 1970s, X-ray and optical observations led to the conclusion that Cygnus X-1 contained a black hole, the first one identified

  • Because it is only 6,000 light years from Earth, Cygnus X-1 is a very bright and therefore a good target for astronomers to study

Since its discovery 45 years ago, Cygnus X-1 has been one of the most intensively studied cosmic X-ray sources. About a decade after its discovery, Cygnus X-1 secured a place in the history of astronomy when a combination of X-ray and optical observations led to the conclusion that it was a black hole, the first such identification.

The Cygnus X-1 system consists of a black hole with a mass about 10 times that of the Sun in a close orbit with a blue supergiant star with a mass of about 20 Suns. Gas flowing away from the supergiant in a fast stellar wind is focused by the black hole, and some of this gas forms a disk that spirals into the black hole. The gravitational energy release by this infalling gas powers the X-ray emission from Cygnus X-1.

Although more than a thousand scientific articles have been published on Cygnus X-1, its status as a bright and nearby black hole continues to attract the interest of scientists seeking to understand the nature of black holes and how they affect their environment. Observations with Chandra and ESA's XMM-Newton are especially valuable for studying the property of the stellar wind that fuels Cygnus X-1, and determining its rate of spin. Recent analyses of spectra obtained from Chandra, the Rossi X-ray Timing Explorer, and the Swift, and Suzaku observatories showed that the Cygnus X-1 BH is rotating at or near its maximum spin rate.

Fast Facts for :
Release Date  August 27, 2009
Scale  Image is about 4.7 arcmin across
Category  Black Holes
Coordinates (J2000)  RA | Dec
Constellation  Cygnus
Observation Date  01/30/2001 - 04/19/2003
Observation Time  16 hours
Obs. ID  2742-2743, 3814
Instrument  ACIS
References M. Hanke et al. 2009 , Astrophys. J. 690, 330 J. Miller, 2007 Ann.Rev.Astron.Astrophys.45:441-479
Color Code  Intensity
Distance Estimate  About 6070 light years
distance arrow
Visitor Comments (13)

what about gravitational lensing observed in the universe? Can Chandra penetrate through it show further?

Posted by Xavier Joseph on Tuesday, 02.19.13 @ 19:56pm

The companion star around cygnus X-1 is a blue super-giant destined to become a black-hole itself. How long until this happens (2 black holes will be in orbit around each other)?

Posted by kb on Monday, 07.9.12 @ 00:01am

WOW. Thanks for the great pictures and information.

Posted by StarTrek74 on Wednesday, 12.30.09 @ 17:58pm

I bookmarked this link. Thank you for good job.

Posted by Umoarloi on Saturday, 10.10.09 @ 15:57pm

Dear Marvin,
Chandra detects stars as point sources, just most other telescopes. It is able to see more point sources than other X-ray telescopes because of its unprecedented spatial resolution. It can't resolve stars, but in a few cases features on the surfaces of stars can actually be resolved, e.g.
HST images of Betelgeuse.

P. Edmonds, CXC

Posted by P. Edmonds on Monday, 09.14.09 @ 14:53pm

We think a better estimate of the distance to Cygnus X-1 is 8000 light years, but in any case it's not a danger to us on Earth.

P. Edmonds, CXC

Posted by P. Edmonds on Monday, 09.14.09 @ 14:50pm

Dear Nabeel,
I suggest that you research this topic using Google and the web.
Chandra is used to do work on star forming regions, but also the Hubble Space Telescope and the Spitzer Space Telescope and many other telescopes.
There is a lot to learn if you are going to obtain data and do analysis, but there are archives available from the above telescopes for obtaining FITS images of the appropriate regions and there is a free FITS reader called
FITS Liberator.

P. Edmonds, CXC

Posted by P. Edmonds on Monday, 09.14.09 @ 14:47pm

Dear Sourav,
Cygnus X-1 has no effect on our solar system. The gravitational influence of the Sun dominates the solar system and the gravity of Cygnus X-1 is negligible (and is identical to the gravitational influence of stars with the same mass at the same distance).

P. Edmonds, CXC

Posted by P. Edmonds on Monday, 09.14.09 @ 14:44pm

I am doing a bsc project on massive star evolution, so I would like to obtain information about massive star evolution star forming regions, data based on recent observation and apparatus used to detect them.
I would also like to obtain data for analysis.

Posted by Nabeel on Friday, 09.4.09 @ 07:09am

It will be nice when in the future the instrumentation's get advanced enough to resolve the image to it's component stars BH s etc.

Posted by Chris on Wednesday, 09.2.09 @ 15:04pm

If Cygnus X-1 is 6,000 light years from Earth does that mean a pulsar or worse aimed at earth will kill all life on earth?

Posted by iuyt879 on Saturday, 08.29.09 @ 21:47pm

Thank you for this article. Knew that Cygnus X-1 is a black hole.
It is about 8000 light years away from us. Does it effect in any way the solar system?
What is the future of a black hole?


Posted by Sourav Maiti on Saturday, 08.29.09 @ 14:03pm

It is great that we can image individual stars now.

A question for you at Chandra, How is the imaging of stars done now?

Posted by Marvin L S on Thursday, 08.27.09 @ 19:13pm

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