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Credit & Copyright: M. Weiss, CXC
Explanation:
Q: Why are
black holes black?
A: Because they have an
event horizon.
The event horizon is that one-way boundary predicted by
general
relativity beyond which nothing, not even light, can return.
X-ray
astronomers using the space-based Chandra Observatory now
believe they have direct for event horizons - therefore
black holes - in binary star systems which can be
detected in x-ray light.
These binaries, sometimes called x-ray novae, are
known to consist of relatively normal stars dumping
material on to massive, compact companions.
As illustrated,
the material swirls toward the companion in an
accretion disk which itself glows in x-rays.
If the compact companion is a neutron star
(right), the material ultimately smashes into the solid surface
and glows even more brightly in high energy x-rays.
But if it is indeed a
black hole with a defining event
horizon, then the x-ray hot material approaches the speed of
light as it swirls past the surface of no
return and is lost from view.
Recent
work describes observations of two classes of
x-ray binaries,
one class 100 times fainter than the other.
The results imply the presence of an event horizon in the
fainter class which causes the extreme difference in x-ray
brightness.
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NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: black hole - x-ray binary - neutron star
Publications with words: black hole - x-ray binary - neutron star
See also:
- APOD: 2024 November 24 Á Journey to the Center of the Galaxy
- APOD: 2024 October 1 Á Porphyrion: The Longest Known Black Hole Jets
- APOD: 2024 June 16 Á Animation: Black Hole Destroys Star
- Simulation: Two Black Holes Merge
- The Galaxy, the Jet, and a Famous Black Hole
- APOD: 2024 May 8 Á Visualization: A Black Hole Accretion Disk
- APOD: 2024 May 7 Á Black Hole Accreting with Jet