Cygnus X1 The First

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Cygnus X1 The First
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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.
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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
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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.
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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.
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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.
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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