IC 1805 – The Heart of the Heart Nebula
Key Scientific Data
Object type: Emission nebula – H II region and star-forming complex
Constellation: Cassiopeia
Other designations: IC 1805, Sh2-190, Heart Nebula
Distance from Earth: approximately 7,000–7,500 light-years
Diameter: approximately 200 light-years
Central open cluster: Melotte 15 (Collinder 26)
Cluster age: approximately 1–3 million years
Notable features: Sculpted gas pillars, ionisation fronts and dark molecular clouds
Main emissions: Hydrogen (Hα), Oxygen (OIII)
Location: Perseus Arm of the Milky Way
Right Ascension: 02h 32m
Declination: +61° 27′
Light-travel time: approximately 7,000–7,500 years
Description
IC 1805, commonly known as the Heart Nebula, is a vast emission nebula and active star-forming region in the constellation Cassiopeia, located within the Perseus Arm of the Milky Way.
This high-resolution image focuses on the central region of the nebula, dominated by the young open cluster Melotte 15, rather than the familiar heart-shaped outline visible in wide-field photographs.
The cluster contains several hot, massive O-type stars whose intense ultraviolet radiation ionises the surrounding hydrogen, producing the nebula's characteristic emission. Their powerful stellar winds also erode and compress the interstellar gas, creating the intricate pillars, ridges and cavities visible throughout the image.
Among these structures are dark molecular clouds, including LDN 1366, LDN 1367, LDN 1368 and LDN 1369. These dense concentrations of gas and dust absorb background light and may contain material from which new stars can form.
The interaction between stellar radiation and molecular clouds illustrates a fundamental process known as stellar feedback. Massive stars progressively disperse the material from which they formed, while compression along cloud boundaries can sometimes encourage further star formation.
The image combines deep Hα and OIII narrowband observations with broadband data. Hα reveals the extensive ionised hydrogen and delicate filaments, while OIII highlights regions of higher ionisation. The broadband exposures contribute additional stellar colour information.
At only 1–3 million years old, Melotte 15 is extremely young compared with our 4.6-billion-year-old Sun. Its most massive stars will evolve rapidly, and some may eventually end their lives as core-collapse supernovae, enriching the surrounding interstellar medium with heavier elements.
The nearby Soul Nebula (IC 1848) belongs to the same broader star-forming environment, making this region one of the most remarkable concentrations of young massive stars and emission nebulosity in Cassiopeia.
Looking Back in Time
The light recorded from IC 1805 began its journey approximately 7,000–7,500 years ago, between 5500 and 5000 BC, during Earth's Holocene epoch.
At that time, humanity was living through the Neolithic period in many regions. Agriculture and permanent settlements were spreading across Europe and the Near East, while hunter-gatherer communities remained widespread elsewhere.
The first great urban civilisations of Mesopotamia and ancient Egypt had not yet emerged. Writing, the Egyptian pyramids and the monumental stone structures of Stonehenge were still thousands of years in the future.
While human societies developed from early agricultural communities into modern civilisation, these photons travelled through the Milky Way before reaching Earth.
This photograph therefore reveals the central region of the Heart Nebula as it appeared more than seven millennia ago, when the first agricultural societies were transforming human life on Earth.
Image Data
Total integration time: 18h 56m 20s
Integration by filter:
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LP: 39m (117 × 20")
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Red: 48m 40s (146 × 20")
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Green: 32m 20s (97 × 20")
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Blue: 36m 20s (109 × 20")
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Hα: 9h 30m (57 × 600")
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OIII: 6h 50m (41 × 600")
Equipment:
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Telescope: Artesky ARTEC 250 Pro
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Camera: ToupTek ATR2600M
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Mount: 10Micron GM2000 HPS II
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Filters: Optolong L-Pro 2", RGB 2", H-Alpha 3nm 2", OIII 3nm 2"
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Accessories: Pegasus Astro Prodigy Microfocuser, ToupTek AFW-L 7×2", WandererAstro WandererBox Pro V3
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Software: Adobe Photoshop, Pleiades Astrophoto PixInsight, Stefan Berg Nighttime Imaging 'N' Astronomy (N.I.N.A. / NINA)
For further details and the full-resolution image, visit AstroBin: