In a message dated 09/14/2000 6:55:03 AM Eastern Daylight Time,
[log in to unmask] writes:
<< A black hole is an extremely dense object at the
center of a galaxy with such powerful gravitational
pull that not even light can escape. That is why black
holes are invisible to conventional telescopes that
use visible light.
Is this a grade school definition for what black holes are?
A black hole is the remnant left behind after a star of at least 3 solar
masses has gone supernova and the core has collapsed beyond solid neutron
densities. The first Black hole detected was Cygnus X-1. Many black holes
are binary companions to other stars, and orbit them as they swallow up
matter peeled off from the companion star. There does seem to be a large
black hole at the center of ours, and other galaxies, but it is not the
defining location for a black hole.
Also the gravitational pull is NOT so powerful that light can't escape, since
x-rays, which are also a form of electromagnetic radiation just as light is,
seem to escape fine on their own. How else would we see black holes.
<< X-rays can directly penetrate conventional flat
mirrors. So to catch them, telescopes must use
ultra-smooth mirrors in creative designs.>>
How does smoothness affect reflectivity for an x-ray? What is this mirror
made of? Not glass and silver I suspect.
<<The $1.5 billion Chandra observatory is the most
powerful X-ray telescope. Orbiting Earth since July,
it uses four cylindrical nesting mirrors to funnel
incoming X-rays. Computers process the data into
images.>>
That's July 1999, and in September 1999 they discovered the Van Allen belt
radiation was damaging some of the CCDs. In the ACIS camera, 8 out of 10
charge-coupled device chips, each about 1 inch across were damaged, reducing
the resolution and detail of the images. The remaining 2 can be used but it
slows down the process of capturing images.
They new x-ray telescope you mentioned is the MAXIM Pathfinder project.
Their intent is to use 33 small spacecraft with x-ray telescopes flying in
formation with a large one to coordinate and combine the interferometry data
from this 300 mile array of detectors. Ambitious, complex, but hopefully
will answer many of the questions astromoners have about black holes and
other x-ray sources in the universe.
James Hinsey
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