The Heart Nebula

Posted on Friday, 2 January, 2015Sunday, 20 August, 2017 by Zheluo Cai

The Heart Nebula or IC 1805, lies some 7500 light years away from Earth and is located in the Perseus Arm of the Milky Way Galaxy in the constellation Cassiopeia. This is an emission nebula showing glowing gas and darker dust lanes, formed by plasma of ionized hydrogen and free electrons. The very brightest part of this nebula (the knot at the bottom right) is separately classified as NGC 896, because it was the first part of this nebula to be discovered. Often, it is paired with the Soul Nebula (IC 1848), but for this review we will only look at the Heart Nebula.

The nebula’s intense red output and its configuration are driven by the radiation emanating from a small group of stars near the nebula’s centre (right). This open cluster of stars known as Melotte 15 contains a few bright stars nearly 50 times the mass of our Sun, and many more dim stars that are only a fraction of our Sun’s mass.

Fierce stellar winds from this cluster have blown the enormous bubble within the parent HII nebula that is the heart nebula. The winds have also sculpted the dust clouds within which other stars are forming into interesting columns and shapes, analogous to the Pillars of Creation in the Eagle Nebula.

Also visible in this image are two nearby galaxies, Maffei 1 and Maffei 2. In visible light these galaxies are hidden by dust in IC 1805, and were unknown until 1968 when Paolo Maffei found them using infra-red observations. Both galaxies contain billions of stars and are located some 10 million light-years away (well outside our own Milky Way Galaxy). Maffei 1 is the bluish elliptical object in the centre of the image. It is a Lenticular type galaxy, which has a disk-like structure and a central bulge but no spiral structure or appreciable dust content. Maffei 2 (to the upper left of Maffei 1) is a Spiral type galaxy that also has a disk shape, but with a bar-like central bulge and two prominent dusty spiral arms.