| NGC 7538 | |
| Epoch: | J2000.0 |
| Type: | diffuse |
| Subtype: | emission or reflection |
| Constellation: | Cepheus |
| Ra: | [1] |
| Dist Ly: | 9,100[2] |
| Dist Pc: | 2,800 |
| Size V: | 9′.00 × 6′.0 |
| Notes: | Contains largest known protostar |
| Names: | Dreyer's Object, Sharpless 158 |
NGC 7538, near the more famous Bubble Nebula, is located in the constellation Cepheus. It is located about 9,100 light-years from Earth. It is home to the biggest yet discovered protostar which is about 300 times the size of the Solar System.[3] It is located in the Perseus Arm of the Milky Way and is probably part of the Cassiopeia OB2 complex. It is a region of active star formation including several luminous near-IR and far-IR sources. Stars in NGC 7538 are mainly low-mass pre-main-sequence stars.[4]