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Q: Viewing Black Holes from Earth ( Answered,   0 Comments )
Subject: Viewing Black Holes from Earth
Category: Science
Asked by: berford-ga
List Price: $5.00
Posted: 20 Dec 2003 02:27 PST
Expires: 19 Jan 2004 02:27 PST
Question ID: 288965
I am an exceedingly amateur astronomer, and I put to you the following
interrogative paragraph: Can an amateur astronomer like me, using a
middle-of-the-road telescope in my backyard, see a black hole--or at
least evidence thereof?

Or are huge astronomical observatory telescopes--or The Hubble--the
ONLY means through which one can view black holes (or at least
EVIDENCE of a black hole?)
Subject: Re: Viewing Black Holes from Earth
Answered By: hlabadie-ga on 20 Dec 2003 05:24 PST
The short Answer is, No.

The observational evidence for the existence of black holes can only
be gathered by very sophisticated instruments, such as the Hubble
Space Telescope or the Chandra X-Ray Observatory.

In most cases, the evidence is so subtle, or is found in a part of the
electromagnetic spectrum so distant from the visible, that only very
careful analysis of some very minutely detailed data can be advanced
for the existence of black holes. Such data can only be obtained from
the observations made through the great telescopes. It is a process of
inference that provides the evidence.

Cambridge Relativity: Black Holes
Introduction to Black Holes

"It is impossible to see a black hole directly because no light can
escape from them; they are black. But there are good reasons to think
they exist."

Observational Evidence for Black Holes

New Evidence for Black Holes

"By seeing almost nothing, astronomers say they've discovered
something extraordinary: the event horizons of black holes in space."
"NASA's two Great Observatories, the Hubble Space Telescope and the
Chandra X-ray Observatory, have independently provided what could be
the best direct evidence yet for the existence of an event horizon,
the defining feature of a black hole and one of the most bizarre
astrophysical concepts in nature."

Scientist Claims First Direct Evidence of Black Hole

"A scientist announced today what he thinks is evidence of a hot blob
of gas slipping past an event horizon, a theoretical point of no
return that surrounds a black hole
If further research supports the finding, it would be the first direct
evidence that black holes exist.

But the researcher, Joseph Dolan of NASA's Goddard Space Flight
Center, cautioned that the small amount of data used in the study
could contain a statistical error, and further research will be needed
to confirm the finding."

"Iron-Clad" Evidence For Spinning Black Hole

"Telltale X-rays from iron may reveal if black holes are spinning or
not, according to astronomers using NASA's Chandra X-ray Observatory
and the European Space Agency's XMM-Newton Observatory. The gas flows
and bizarre gravitational effects observed near stellar black holes
are similar to those seen around supermassive black holes. Stellar
black holes, in effect, are convenient `scale models' of their much
larger cousins.

Black holes come in at least two different sizes. Stellar black holes
are between five and 20 times the mass of the Sun. At the other end of
the size scale, supermassive black holes contain millions or billions
times the mass of our Sun. The Milky Way contains both a supermassive
black hole at its center, as well as a number of stellar black holes
sprinkled throughout the Galaxy."

Supermassive Black Holes

"The active galaxies appear to require a compact energy source of
enormous strength. The most plausible candidate is a rotating,
supermassive black hole
<> of order a billion
solar masses at their center. Until recently there has been strong
circumstantial evidence to support such a mechanism. In the past few
years evidence of much more direct nature has emerged. *

Evidence for a Supermassive Black Hole in M87

The left portion of the following Hubble Space Telescope
<> photograph shows the center of the
giant elliptical galaxy M87
<>, which is the 87th
entry in the famous Messier Catalog
<>. This galaxy is believed to
contain a supermassive black hole of several billion solar masses at
its center. The observations indicate that approximately 3 billion
solar masses are concentrated in a region at the galactic core that is
only about the size of the Solar System. The diagonal line across the
right image is a jet of high-speed electrons approximately 6500 light
years long that is probably being ejected from the galactic nucleus by
the black hole located there."



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