Soul Nebula (IC 1848 / Sharpless 2-199 / Embryo Nebula)
Coordinates, Gaia DR3 distance (2.06 kpc), W5 West/East triggered star-formation bubbles, and observing guide for the Soul Nebula in Cassiopeia.
Provenance-Backed Scientific Measurements
Every measurement below preserves its unit, uncertainty interval, observational method, reference epoch, quality status, and primary catalog source. See Uncertainty & Provenance for how competing measurements are handled.
| Parameter | Value | Uncertainty | Method & Epoch | Quality Status | Source Archive |
|---|---|---|---|---|---|
| Integrated visual magnitude (V) | 6.5 mag | ± 0.2 mag | Integrated Collinder 32/34 cluster + nebular photometry | high-confidence | Revised New General Catalogue and Index Catalogue (RNGC/IC) |
| Heliocentric distance | 6720 ly | ± 160 ly | Gaia DR3 astrometric parallax of IC 1848 O-type stars (2.06 ± 0.05 kpc) (J2016.0) | definitive | ESA Gaia Archive — Data Release 3 |
| Apparent angular dimensions | 120 arcmin | ± 10 arcmin | Optical H-alpha emission complex (120′ × 60′) | high-confidence | Revised New General Catalogue and Index Catalogue (RNGC/IC) |
| Central O-star cluster age | 0.0022 Gyr | ± 0.0005 Gyr | O6–O7 V main-sequence & pre-main-sequence isochrone (2.2 ± 0.5 Myr) | high-confidence | ESA Gaia Archive — Data Release 3 |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots Soul Nebula (IC 1848 / Westerhout 5) at RA 02h 51m 18.00s, Dec +60° 26′ 00.0″ within Cassiopeia, alongside peak meridian transit altitudes for 40°N and 30°S observers. Use the RA/Dec Coordinate Converter to compute exact culmination altitude for your latitude.
Astrophysical Context & Structure
The Soul Nebula (IC 1848, Westerhout 5, Sharpless 2-199—also known as the Embryo or Baby Nebula) is a 2-degree-long H II emission complex located 6,720 light-years (2.06 ± 0.05 kiloparsecs) away in eastern Cassiopeia, sitting just 2.2 degrees southeast of the Heart Nebula (IC 1805). While Edward Emerson Barnard discovered the embedded open cluster IC 1848 visually in the 1890s, the surrounding nebulosity (containing smaller cataloged knots IC 1871, NGC 1027 on its southwestern margin, and LBN 667) spans roughly 150 by 75 light-years physically.
In infrared and radio images, Westerhout 5 is divided into two huge adjacent cavities—W5-West and W5-East—carved out by fierce stellar winds and ionizing radiation from a handful of O6 to O7 main-sequence stars: the quadruple O-star system HD 17505 and HD 17520 inside W5-West, and the O7 V binary HD 18326 inside W5-East.
Observations with the Spitzer Space Telescope made W5 a classic textbook proof of 'triggered star formation': the central O stars are ~2.2 to 5 million years old, whereas hundreds of younger (<1 million-year-old) Class I and Class II protostars are concentrated exclusively inside the compressed ionization rims and towering 10-light-year elephant-trunk pillars (such as the W5 East pillar) pointing directly back toward the central O stars.
Practical Visual Observing Guide
- Located 2.2° east-southeast of the Heart Nebula (IC 1805) along the eastern border of Cassiopeia near Camelopardalis.
- In 10×50 binoculars, the embedded cluster IC 1848 (magnitude 6.5) and neighboring open cluster NGC 1027 (magnitude 6.7, 1° southwest) appear as two distinct stellar groupings.
- Through a 100–200 mm rich-field telescope at 20×–50× with a UHC or O-III filter under dark skies, trace the bright northern ionization ridge (IC 1871) and the glowing haze enveloping the 7th-magnitude O-star quadruple HD 17505.
Catalog Cross-Identifications & Aliases
Common Aliases: IC 1848 · Westerhout 5 · Soul Nebula · Embryo Nebula · Sharpless 2-199
| Catalog Authority | Identifier |
|---|---|
| IC | IC 1848 |
| SIMBAD | IC 1848 |
| WIKIDATA | Q1078679 |
Related Objects, Comparisons & Guides
Heart Nebula (IC 1805 / Melotte 15)
Coordinates, Gaia DR3 distance (2.07 kpc), Melotte 15 O-star cluster, Fishhead Nebula IC 1795, and observing guide for IC 1805 in Cassiopeia.
Double Cluster (NGC 869 & NGC 884)
Coordinates, Gaia DR3 distance (2.29 kpc), age 14 Myr, supergiant population, and observing guide for NGC 869 and NGC 884 in Perseus.
Messier 52 (NGC 7654 Salt-and-Pepper Cluster)
Coordinates, Gaia DR3 distance (1.49 kpc), magnitude 6.9, heavy differential dust extinction, and observing guide for M52 in Cassiopeia.
Surface Brightness & Extended Objects Guide
Why surface brightness (mag/arcsec²) governs nebula and galaxy visibility more than integrated magnitude, and how exit pupil controls eyepiece contrast.
Trigonometric Parallax, Parsecs & Gaia DR3
How trigonometric parallax (d_pc = 1 / p_arcsec), the distance modulus equation, Hipparcos, and Gaia DR3 microarcsecond astrometry measure cosmic distances.
Scientific Sources & Dataset Provenance
- ESA Gaia Archive — Data Release 3 (DR3 (2022-06-13)): Gaia Collaboration, Vallenari, A., et al. 2023, A&A, 674, A1 (Gaia Data Release 3) — European Space Agency / Gaia DPAC
- Revised New General Catalogue and Index Catalogue (RNGC/IC) (2024/2026 edition): Steinicke, W. 2010, Observing and Cataloguing Nebulae and Star Clusters (Cambridge Univ. Press); Verga, M. OpenNGC (CC-BY-SA 4.0 / data tables) — Wolfgang Steinicke / OpenNGC
- SIMBAD Astronomical Database (CDS) (2026-10 release): Wenger, M., et al. 2000, A&AS, 143, 9 (The SIMBAD astronomical database) — Centre de Données astronomiques de Strasbourg