As it is clear the galaxies contain Halo,dust and stars,What is the source of dust and how we can observe it?

Vincent G's answer is mostly but not entirely correct. The dust is NOT primordial. Dust consists pretty much entirely of heavy elements, and thus all of it is created by having been expelled from stars, usually by supernova. Some can be expelled from novae as well, if there is carbon burning near the surface.





As stated correctly in the other answers, it blocks visible light and so can be observed by absorption in the visible and by emission in the infrared. The emission is re-radiation of absorbed starlight.As it is clear the galaxies contain Halo,dust and stars,What is the source of dust and how we can observe it?
Possible from the black hole in the center of the Galaxy.As it is clear the galaxies contain Halo,dust and stars,What is the source of dust and how we can observe it?
Cosmic dust has multiple sources, mainly two causes: matter in agglomeration or matter in dispersion. It is only observable when it forms clouds.
The dust is a mix of primordial gas that actually did not yet condense into stars plus gas that was expelled by stars going supernova.


Since the ';dust'; as such is not an energy producer, it can only be observed when it block, absorbs and reemits energy from stars around it.
Interstellar dust usually forms near stars, and is blown out into the interstellar medium with the star's solar wind. Some stars make much more dust than others.





The dust is observable in absorption in visible light, and in emission in the infrared.