NGC 7538, near the more famous Bubble Nebula,
is located in the constellation Cepheus. It is located about
9,100 light years away from earth. It is home to the biggest yet
discovered protostar which is about 300 times the size of our
Solar System. It is located in the Perseus Spiral 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.