The Heart Nebula, an emission nebula in Cassiopeia

IC 1805

Image Credit & Copyright: J-P Metsavainio (http://astroanarchy.zenfolio.com/)

The Heart Nebula (IC 1805, Sh2-190) is an emission nebula and star forming region of almost 200 light-years across, located within the Perseus Arm of our Milky Way galaxy, about 7500 light-years away in the northern constellation Cassiopeia. It is nicknamed the Heart Nebula because it looks like a human heart.

The very brightest part of this nebula (the knot at the bottom right) is separately classified as NGC 896 (also designated IC 1795). The Heart Nebula is the western neighbor of the Soul Nebula (NGC 1848) and together they form the Heart and Soul Nebulae. They both are part of a complex of star forming regions that lie at the edge of a large molecular cloud.

The Heart Nebula is formed by plasma of ionized hydrogen and free electrons. The image, coloured in the Hubble palette, is showing a mix of glowing interstellar gas and dark dust clouds. The nebula appears relatively devoid of stars because of the obscuring dust. However, fierce winds radiated from massive stars, in an open star cluster near the center, shaped the nebula.

This small open star cluster of about 30 light-years across and approximately 1.5 million years young, is named Melotte 15. It 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. The cluster used to contain a microquasar that was expelled over a million years ago.