Monster Black Holes. Caty Pilachowski IU Astronomy Mini-University 2014. What is a black h ole , anyway?. A black hole is…. …an object whose gravity is so intense that light cannot escape. How Big Are Black Holes?. A black hole’s size depends on its mass….
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…an object whose gravity is so intense that light cannot escape
A black hole’s size depends on its mass….
100 billion times smaller than a proton
About 1 centimeter
About 3 kilometers
At larger distances, a black hole’s gravity is exactly the same as if it were “normal” matter
from xkcd (www.xkcd.com)
What would happen to the Moon if the Earth were suddenly to collapse into a Black Hole?
The Moon would continue to orbit the Earth just as before…
Isaac Newton, 1728
A Treatise of the System of the World
Distance x Distance
In the 1930s – Chandrasekhar, Oppenheimer, Snyder predict that massive stars can collapse into something denser – a black hole
But many stars surround Sgr A*
Even though Sgr A* is 26,000 light years away, we can see stars orbiting around it
The orbits of stars around Sgr A* tell us the mass of the central object
The giant elliptical galaxy M87 contains a massive black hole
3.5 BILLION solar masses!
Hubble has examined many large galaxies and found super-massive black holes at their centers
Does the galaxy make the black hole?
Does the black hole make the galaxy?
Black holes in the center of galaxies will eventually merge together
BH Mass ~ 100 million suns
The leading edge of the cloud has whipped around Sgr A* at 10,000,000 km/hour!
High energy jets from feeding black holes may regulate star formation, gas accretion, and
Only a fraction of accreted material ends up in the black hole – most is shot back out in a jet!