IC 1805 THE HEART NEBULA

IC 1805 (also known as the Heart Nebula or by the abbreviation W4) is a nebula scattered in association with an open cluster, visible in the constellation Cassiopeia, towards the border with the Giraffe. It can be detected about 6 degrees southeast of the star ε Cassiopeiae, but it can also be detected starting from the Perseus Double Cluster and moving about 4-5 degrees in a north-northeast direction; it pairs with another vast nebula, known as IC 1848. To be able to locate it, you need a telescope with a large diameter, not so much because of its size, since the nebula is quite large, but because of its weakness. A long-exposure photo or a CCD camera, on the other hand, reveals the object with some ease. The entire complex of nebulae visible in this area is circumpolar from most regions of the northern hemisphere; The best months for its observation are from October to April. It is a very large HII region, whose distance is estimated at 7500 light years from us; Its main feature is the presence of two large, apparently empty areas, of different sizes, which make the nebula similar to a "heart". Inside there is a system of small, loosely concentrated open clusters, responsible for the ionization of the nebula. The most notable of these is Melotte 15, which contains some stars about 50 times more massive than the Sun, plus others smaller and a microquasar ejected millions of years ago.

This and nearby IC 1848 form a large nebulous complex known as the W3/W4/W5 or "Heart and Soul" complex; the "heart" is IC 1805, while the "soul" is represented by IC 1848.