M52 & NGC7635

In the constellation of Cassiopeia, on the border with the neighbouring constellation of Cepheus. In this area we can admire (even with binoculars) an open star cluster known as M52 or NGC 7654, about 4,500 light-years away: a “young” cluster, roughly 160 million years old, containing several massive blue stars. Very close by lies an H II region and a nebula discovered by William Herschel in 1787, NGC 7635, known as the Bubble Nebula. The nebula is actually much farther from us than M52 (11,000 light-years) and measures 7 light-years across. At its centre sits the star responsible for its distinctive shape, a blue giant thousands of times more luminous than the Sun and about 45 times more massive, whose powerful stellar wind “inflates” it like a balloon.