How are X-rays used in astrophysics and astronomy?
Very hot objects with very high temperature million degree K emit X- rays.
Stars with high temperature, matter falling into event horizon of black hole, etc emit radiation in X ray wave length. Since our atmosphere is not transparent to X rays, we have to send X ray telescopes to space or in balloons to high altitude.
See a process below
At night we see many stars, if there's a clear sky
Mostly we see them as tiny, white objects in sky .
The stars are not really so white , some are lot more red and some are blue , The thing that used to surprise me a lot was that blue stars are much hotter than the red ones .
What about X-rays , the are light waves of frequency more than ultraviolet and less than gamma rays , the are not a part of visible spectrum .
But what about their use ?
some stars do emit x-rays , showing their extremely high temperature .
satellites with x-ray detectors are used to detect such stars .