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Saturday, April 17, 2010

Hotter Than White-Hot

black hole can be formed when a star comes to the end of its life and collapses in on itself.  Its size is small but its mass is quite large.  But even more amazing is that its gravitational pull is so strong that not even light can escape. Did you know that light can be affected by gravity?  So it is called a black hole because it looks like nothing is there.  No light reflects from it. 

Here is a little clip of a renowned astrophysicist named Neil deGrasse Tyson talking about black holes.

Sgr is the abbreviation for the constellation Sagittarius. Here is a picture taken in the direction of Sagittarius.

This is a picture of Sgr A* (pronounced A-star) which is a supermassive black hole in the middle of our Milky Way galaxy. The light shown is not visible light, but by a very long x-ray exposure.  This image was taken by the Chandra X-Ray Observatory.  The red gas on the upper right and lower left part of the image is of 20 million-degree Centigrade gas that is extending over dozens of light years away from the black hole. It is the remnant of a "meal" the black hole had dozens of years ago.  So the light has had time to travel dozens of light years away

This supermassive black hole has a mass of 3 million times that of the sun.  Mass does not refer to the size, but rather the weight an object.  A block of gold has a greater mass than the same size block of styrofoam.
Black holes can not be directly observed, but rather the evidence around them infers their presence.  For 16 years, scientist have been tracking 28 stars as they orbit an invisible point. 

The event horizon of a black hole is basically the point of no return.  Past that, there is no escaping the gravitational pull, even for light.  When matter falls or is pulled into a black hole, it gets hotter and hotter and when it reaches a few million degrees Kelvin (another temperature scale) it emits x-rays. Click here for a more detailed explanation.

The spectrum of light, when put in order by wavelength from longest to shortest, goes like this: radio, microwave, infrared, the visible region we perceive as light, ultraviolet, X-rays and gamma rays.

So you could say that it isn't red hot, or white hot, but x-ray hot!

Now you have heard something interesting.

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