quasars.
The largest and brightest galaxies contain more stars compared to other galaxies. Stars are sources of light and therefore make the galaxy brighter.
The largest and brightest galaxy contains quasars.
quasars.
quasars.
Smaller galaxies do. Larger galaxies contain billions or even trillions of stars.
None. Galaxies on the other hand do contain planets
ummmm, galaxies can have galaxies in them unless they combine, also, we don't know, the universe is infinite and we have ye to see beyond our local galaxy cluster... sorry but that is an impossible question (although if the universe is infinite then nothing is quite impossible...)
Spiral and irregular galaxies.
yes
Galaxy
Yes. Some spiral galaxies do contain at least 1 trillion stars.
Red giant is the largest and the brightest.
Yes. Some dwarf galaxies contain at least 1 billion stars.
The center is crowded with stars, and the number of stars decreases farther out.