IC 1805 — The Heart Nebula
The Heart Nebula (IC 1805) lies about 7,500 light-years away in the constellation Cassiopeia, inside our own Milky Way Galaxy. This vast H II region glows in deep crimson H-alpha light, sculpted by fierce winds from the massive stars of Melotte 15—a young cluster at its center. The nebula’s sweeping filaments and dark dust channels trace a heart-shaped outline spanning nearly 200 light-years across. Astronomers often call it a “stellar nursery with a heartbeat.”
Fun Fact: The name “Heart Nebula” comes from its unmistakable shape in wide-field images. Its smaller companion, the Soul Nebula (IC 1848), lies just to the east—together forming the well-known “Heart and Soul” pair often captured in astrophotography mosaics.
| Parameter | Approximate Value |
|---|---|
| Distance from Earth | ≈ 7,500 light-years |
| Apparent Size | ≈ 2° × 2° (4 × Moon) |
| Physical Diameter | ≈ 200 light-years |
| Central Cluster | Melotte 15 (open cluster) |
| Dominant Emissions | H-α, [O III], [S II] |
| Estimated Age | ≈ 1.5 – 3 million years |
| Number of Known YSOs | > 400 (infrared surveys) |
IC 1795 — Star-forming Region near the Heart
IC 1795, just northwest of the Heart Nebula, is a smaller yet powerful star-forming region about 7,500 light-years away in the Milky Way Galaxy. Its energetic young stars illuminate dense hydrogen clouds with vivid red and teal glow, while dark dust lanes reveal the raw material of ongoing star birth.
Fun Fact: IC 1795’s nickname, the “Fish Head Nebula,” comes from its curved ridge and bright core that resembles the profile of a fish in long-exposure images.
| Parameter | Approximate Value |
|---|---|
| Distance from Earth | ≈ 7,500 light-years |
| Region Type | Emission nebula / H II region |
| Physical Extent | ≈ 50 light-years across |
| Dominant Emissions | H-α, [O III], [S II] |
| Age of Embedded Stars | ≈ 3 – 5 million years |
NGC 896 — Bright Western Region of the Heart Nebula
NGC 896 marks the bright western tip of the Heart Nebula (IC 1805) in Cassiopeia, about 7,500 light-years away within the Milky Way. It was the first part of the Heart Nebula ever discovered, shining in deep red hydrogen light with blue-green [O III] accents.
| Parameter | Approximate Value |
|---|---|
| Distance from Earth | ≈ 7,500 light-years |
| Association | Western edge of IC 1805 (Heart Nebula) |
| Physical Size | ≈ 25 light-years across |
| Dominant Emissions | H-α, [O III], [S II] |
| Discovered by | William Herschel (1787) |
Targets & WCS
Mapping & Constellations
Equipment & Integration
Imaging Setup
- Scope: William Optics GRAN-TURISMO 81 IV
- Camera: ZWO ASI2600MC Pro
- Filters: Baader 3.5 / 4 nm Ultra-Narrowband Filter-Set – CMOS-optimized (H-alpha / O-III / S-II)
- Mount: iOptron CEM120EC2
- Guiding: ZWO ASI290MM Mini Camera, WO UniGuide 50 mm f/4.0 scope
Integration
- Hα: 45 × 300 s = 3 h 45 m
- O III: 45 × 300 s = 3 h 45 m
- S II: 45 × 300 s = 3 h 45 m
- Total: 11 h 15 m
Notes / Processing
Stacking was performed using Astro Pixel Processor, which handled calibration and initial integration of the data while producing individual stretched channels for H-alpha, S II, and O III. Star reduction was completed with StarNet v2 to isolate nebular detail and better emphasize the main structures. The combined processing was carried out in Affinity Photo using its dedicated astrophotography tools, along with James Riston’s macro toolset for enhanced workflow control. The three channels were merged and color-mapped in the Hubble Palette (SHO), followed by additional stretching and refinement of each channel. Final steps included targeted noise reduction, sharpening, and overall tonal balancing—adjusting brightness, contrast, and color balance—to produce the finished image.
IC 1805 — Detailed Description & Further Reading
The Heart Nebula (IC 1805) is one of the largest and most luminous H II regions in the Milky Way. Located in the Perseus spiral arm, it spans about 200 light-years and glows primarily in H-alpha, with secondary emissions from [O III] and [S II]. At its core lies the open cluster Melotte 15, whose massive O- and B-type stars are only a few million years old. Their ultraviolet radiation ionizes surrounding gas and drives strong stellar winds that sculpt the intricate pillars and cavities visible in narrowband images.
The Heart Nebula is part of a larger star-forming complex that includes the nearby IC 1795 and NGC 896 regions. Together they form an extended cloud nearly 300 light-years wide. Observations with Spitzer and Herschel have revealed hundreds of young stellar objects (YSOs), showing that the nebula’s next generation of stars is already forming along its glowing ridges.
IC 1795 — Detailed Description & Further Reading
IC 1795 is an emission nebula and star-forming region bordering the western side of the Heart Nebula (IC 1805). Also known as the “Fish Head Nebula,” it is energized by hot O-type stars whose ultraviolet radiation ionizes surrounding hydrogen gas. The area contains several compact H II pockets and embedded young stellar objects, representing a slightly older generation than the Heart’s cluster.
Fun Fact: IC 1795’s nickname, the “Fish Head Nebula,” comes from its curved ridge and bright core that resembles the profile of a fish in long-exposure images.
NGC 896 — Detailed Description & Further Reading
NGC 896 is the luminous western lobe of the Heart Nebula complex and the first portion cataloged in the 19th century. It is a region of intense star formation where radiation from young hot stars ionizes dense gas clouds, creating bright H-alpha filaments. Infrared and radio observations show shock fronts and molecular knots where new protostars continue to emerge.
Fun Fact: NGC 896 was discovered before the rest of the Heart Nebula and originally thought to be an isolated object; only later imaging revealed it as part of the larger IC 1805 complex.