1. Cygnus X1 – The First

2. Cygnus X1 In the early Seventies scientists found an intensive X-Ray source in the Cygnus Constellation. They believe that this X-Ray source is a black hole. Cygnus X-1 is an X-ray binary in the constellation Cygnus, the swan, that was one of the first X-ray sources discovered when it was detected in 1962. It is called Cygnus X-1 because it was the first X-ray source discovered in the constellation Cygnus. The visible object HDE226868 is a 9th magnitude blue supergiant star whose radial velocity curve shows an orbital period of a little less than a week. The fact that the object is a strong X-ray emitter and that the optical and X-ray emission varies on very short time scales (as short as one one- thousandth of a second) suggest that the companion might be a black hole.

3. Cygnus X1 Cygnus X-1 is one of the most likely candidates as being a black hole. Cygnus X-1 is about 14,000 light years away from earth. So this means that what we are seeing, is many, many, years old. It is a very inconsistent source for X-ray emissions. The emissions of X-rays for Cygnus X-1 flicker in hundredth of a second bursts. It is also been proven that Cygnus X-1 is smaller than the Earth. Strangely enough, Cygnus X-1 has a companion star called HDE 226868. HDE 226868 is a supergiant with a temperature around 31,000 K. After extremely close observations of HDE 226868, it appears that its spectral lines (light given off at a certain frequency by an atom or molecule) shift back and forth it a rotation of about 5.6 days. Other images show that its mass would be about 30 times as much as the sun for its size. This would mean that Cygnus X-1 would have the mass of about 7 solar masses for its gravitational pull to exhibit the shifts in the spectral lines on HDE 226868. Because 7 solar masses is too big to be a white dwarf or neutron star, it must be a black hole. HDE 226868 and Cygnus X-1 X-ray emissions

4. Cygnus X1 Cygnus X-1 is believed to be a black hole binary, with a 20-35 solar mass black hole and a supergiant, orbiting around with a period of 5.6 days, as companion. The mass of the unseen companion, significantly larger then 5 solar masses suggests that it is a black hole. Focused wind accretion from a primary star being extremely close to filling the Roche lobe drives the powerful source of the X-ray radiation. Cygnus X-1 is one of the brightest X-ray sources in the sky.

5. Cygnus X1 Subrahmanyan Chandrasekhar first determined the upper limit to the mass of a white dwarf as 1.4 solar masses. This value, called the Chandrasekhar mass limit, is still used today. Later, J.R. Oppenheimer and G.M. Volkoff determined the upper mass of a neutron star. It is called the Oppenheimer-Volkoff mass, and has been recalculated many times since. Because we are dealing with degenerate neutron gas, which we can only make educated guesses about the exact properties of, we cannot truly determine precisely what this limit is. It is usually said to be about 2 to 3 solar masses, and generally stays well below 4 or 5.

6. Cygnus X1 Is there really a black hole in Cygnus? Scientists don't know if this is really a black hole. It could be a small star, too faint to see in optical wavelengths, or possibly a planet sized hunk of rock. But the Object is too small for a star. A better explanation is that the object is a neutron star or a white dwarf. Neutron Stars usually have very regular and distinct pulses. Cygnus X-1's emmissions, however, show no regularity or periodicity. They seem to have no repeating patterns, and vary on short and long timescales equally.

7. Cygnus X1 There is evidence that says that Cygnus X-1 is not a black hole. It could be that HDE 226868 has a low mass for its size, resulting in Cygnus X-1 having a lower mass it self. If this were the case, Cygnus X-1 may only be the mass of 3 solar masses and would be likely be a neutron star. A neutron star is a more stable body of the remains from a super nova explosion of a large star compared to a black hole. Since both neutron stars and black holes give off X-rays, this is a convincing argument on how Cygnus X-1 might not be a black hole. It has also been found in recent years, that both black holes and neutron stars give off gamma rays. The new images collected using gamma rays provides a much more clear representation of black holes and neutron stars. Gamma ray images can also can be artificially colored to a more precise scale, making them easier to understand. The discovery still doesn't answer the question rather Cygnus X-1 is a black hole or neutron star, but still should help aid the discovery of other new black holes or neutron stars