NGC 2404
NGC 2404 is massive H II region inside NGC 2403, a spiral galaxy in Camelopardalis. It was discovered on February 2, 1886 by Gulliaume Bigourdan. NGC 2404 is approximately ≈ 2000 ly in diameter, making it one of the largest H II regions so far known. NGC 2404 is even larger than the Tarantula Nebula, one of the largest and most active H II regions in Local Group. NGC 2404 is 83 times larger than Orion Nebula, and if it would be at same distance, it would cause visible shadows. It is the largest H II region in NGC 2403, and lies at the outskirts of the galaxy, making striking similarity with NGC 604 in M33, both in size and location in host galaxy. This H II region contains 30-40 Wolf-Rayet stars, and unlike Tarantula Nebula, but similar to NGC 604, the NGC 2404's open cluster is probably much less compact, so it probably looks like as a large stellar association. This H II region is probably only a few million years old.
