IC 1396 in Ha

May 10, 2022

IC 1396 is a large circular emission nebula and star cluster in the constellation Cepheus. (If this general shape looks familiar, compare IC 1396 to the Rosette Nebula in Monoceros in terms of the roughly circular structure and that central bowl being carved out by the radiation from a batch of overenthusiastic core stars). The brightest star in the frame, on the right, is the Garnet Star (mu Cephei), which is actually farther away than most of the gas, dust, and other material in the frame, and is one of the largest known stars (1,650 times the size of the Sun). The bright star in the center of IC 1396 is HD 206267, a variable double star. It is the intense radiation and stellar wind from the core star cluster, including HD 206267, that drives the expansion of the circular shell of dust and ionized hydrogen. This bright circular structure is over a hundred lightyears across. The "Elephant's Trunk Nebula" (VdB 142, Van den Bergh 142, IC 1396A) is the towering structure running up the center from the bottom of IC1396. There are a bunch of Barnard Catalogue dark nebulae in the region, including Barnard 161, above and to the right of the Elephant's Trunk, with B 163, 160, and 365 along the left. To give you a sense of the size of IC 1396, you're looking at roughly 600 trillion miles from top to bottom (965 trillion kilometers). 

Imaging Notes: 64 x 240 second subs in Hydrogen-alpha, stacked in DSS, over 4 hours of data. Gear: William Optics SpaceCat51 Apo Refractor, ZWO ASI1600MM-Pro mono camera, Antlia Pro 3nm Ha filter, Sky-Watcher EQ6R Pro equatorial mount.