There are several crowded stars in the northern winter night, which are very close to each other. They appeared in the sky around 9 pm. What constellation is it? Is it a nebula?

It is considered as the Pleiades, a combination of Taurus nebula and cluster, and the 45th celestial body in the messier catalog, namely M45.

If you look through a telescope, you can easily distinguish dozens of stars inside, and new stars are constantly forming in this area, but you must use a large-caliber telescope to see the nebula.