The Heart Nebula (IC 1805, Sharpless 2-190) is a large emission nebula in the constellation Cassiopeia, about 7,500 light-years away, known for its bright red hydrogen glow and complex dark dust lanes.
Location and Structure
- • The Heart Nebula is found in Cassiopeia, near the Perseus Arm of the Milky Way, and is often paired with the adjacent Soul Nebula (IC 1848) as the “Heart and Soul Nebulae”.
- • Its coordinates are right ascension 02h 33m 00s, declination +61° 27′ 00″.
- • The nebula spans about 2 degrees of sky, roughly four times the diameter of the Moon, and physically over 300 light-years across.
Features
- • The nebula’s center hosts the open star cluster Melotte 15 (Collinder 26), which has some stars about 50 times the mass of the Sun.
- • Ionized hydrogen (HII), oxygen, and sulfur gases give the nebula its rich red, blue, and orange coloration visible in narrowband imaging.
- • The brightest portion, NGC 896, was the first discovered and lies at the nebula’s western edge.
- • The Heart Nebula forms part of a larger star-forming complex (W3/W4/W5 or “Heart and Soul” complex) with the nearby Soul Nebula.
Observing and Imaging
- • The nebula has low surface brightness, making it easy to photograph but challenging to observe visually except under dark skies with a wide-field scope or large telescope.
- • Astrophotographers favor this region for its structure and color, often imaging both the Heart and Soul Nebulae together.
Scientific Interest
- • The nebula is an active star-forming region; young, massive stars and their stellar winds shape the gas and dust structures.
- • The radiation from these stars ionizes the surrounding hydrogen, causing the nebula’s characteristic glow and ongoing stellar formation.
Alternate Names and Catalog Numbers
- • IC 1805 (common designation)
- • Sharpless 2-190 (SH2-190)
- • NGC 896 (brightest portion)
- • Running Dog Nebula (nickname)
- • W4 (radio astronomy designation)
The Heart Nebula, with its rich colors, open star clusters, and active star formation, remains a favorite deep-sky target for both astronomers and astrophotographers.
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