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Black hole Reference Libraries

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X-Ray Astronomy
2004-10-19 04:45:44

X-Ray Astronomy -- Although the more energetic X-rays (E > 30 keV) can penetrate the air at least for distances of a few meters (they would never have been detected and medical X-ray machines would not work if this was not the case) the Earth's atmosphere is thick enough that virtually none are able to penetrate from outer space all the way to the Earth's surface. X-rays in the 0.5 - 5 keV...

Quasar
2004-10-19 04:45:42

Quasar -- A quasar (from quasi-stellar radio source) is an astronomical object that looks like a star in optical telescopes (i.e. it is a point source), but has a very high redshift. The general consensus is that this high redshift is cosmological, the result of Hubble's law and that their redshift indicates that they are typically very distant from Earth; we observe them as they were...

Cygnus X-1
2004-10-19 04:45:40

Cygnus X-1 -- Cygnus X-1 (often abbreviated to Cyg X-1) is an X-ray source in the Cygnus constellation considered to be one of the most likely black hole candidates. The optical counterpart (HDE 226868) is a variable 8.9 magnitude star (visible with good binoculars in good observing conditions.) at right ascension 19 h 56.5 min and declination of 35 deg 4 min (for 1950 epoch). Cyg X-1...

Word of the Day
bawbee
  • A coin originally worth six pennies Scots, and later three; held equivalent to an English halfpenny.
  • (in plural) Money; cash.
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