| NGC 2404 | |
| Type: | H II region |
| Epoch: | J2000 |
| Ra: | [1] |
| Dist Ly: | 9,650,000 |
| Dist Pc: | 2,960,000[2] |
| Appmag V: | +16.9 |
| Size V: | 20 arcsecs[3] |
| Constellation: | Camelopardalis |
| Radius Ly: | 470 (estimated)[4] |
| Absmag V: | -14.5 |
| Notes: | Massive H II region, the largest one in NGC 2403. |
NGC 2404 is a 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 940 ly in diameter, making it one of the largest H II regions so far known. It is the largest H II region in NGC 2403, and lies at the outskirts of the galaxy, making for a striking similarity with NGC 604 in M33, both in size and location in the host galaxy. This H II region contains 30-40 Wolf-Rayet stars,[5] and unlike the Tarantula Nebula, but similar to NGC 604, NGC 2404's open cluster is probably much less compact, so it probably looks like a large stellar association. This H II region is probably only a few million years old.