Question

How are X-rays used in astrophysics and astronomy?

Answer 1

Very hot objects with very high temperature million degree K emit X- rays.

Explanation:

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.

Answer 2

See a process below

Explanation:

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 .