Heart Nebula

The Heart Nebula is a large emission nebula in Cassiopeia, shaped by the stellar winds and radiation from a small open cluster at its center called Melotte 15. This cluster contains a handful of very massive stars — some up to 50 times the mass of the Sun — whose powerful radiation is the primary driver of the nebula’s complex structure.

The “heart” shape is clearly visible in wide-field images, with two large cavities carved out by the central cluster’s stellar winds. Near the center, Melotte 15 itself stands out as a concentration of hot blue stars against the glowing gas.

IC 1805 is often imaged in narrowband wavelengths that isolate hydrogen-alpha, oxygen, and sulfur emissions. The resulting “Hubble Palette” (SHO mapping) reveals subtle variations in ionization structure — where the hot radiation front has swept gas clean of hydrogen, cooler sulfur emissions take over at the periphery.

The Heart and nearby Soul Nebula (IC 1848) form a connected complex of star formation spanning several hundred light-years, collectively known as the Heart and Soul Nebulae.