Sh 2-308, also designated as Sharpless 308, RCW 11, or LBN 1052, and commonly known as the Dolphin-Head Nebula, is an H II region located near the center of the constellation Canis Major, composed of ionised hydrogen. The nebula is bubble-like and surrounds a Wolf–Rayet star named EZ Canis Majoris. This star is in the brief, pre-supernova phase of its stellar evolution.
The nebula was formed about 70,000 years ago by the star EZ Canis Majoris throwing off its outer hydrogen layers, revealing inner layers of heavier elements. Fast stellar winds, blowing at 1,700 km/s (3.8 million mph) from this star, create the bubble-shaped nebula as they sweep up slower moving material from an earlier phase of the star's evolution. The hydrogen composing the nebula is ionised by intense ultraviolet radiation.
| Object | Sh2-308 Dolphin Nebula |
| Constellation: | Canis Major |
| Position: | RA 06h 54m 13s Dec -23° 55' 42'' |
| Apparent Size: | 35′ x 35′ |
| Apparent Magnitude: | 7.0 |
| Distance in light years: | 4530 ly |
| Photo Data | |
| Date: | 10./11./13.10.2021 |
| Location: |
El Sauce Observatory Chile (2500m ASL) GPS: 47°36’13“ N, 10°11’24“ E |
| Telescope: | CHI-4-CCD: ASA500N f3.8/1900mm |
| Camera: | FLI PL16803 / 9μm 4096x4096px @ T sensor = -35.0°C |
| Field of View: | 1.1° x 1.1° |
| Pixel Scale/Resolution: | 0.98 arcsec/px |
| Expose frames/times: | H 6x600s, O 6x600s |
| Total expose: | 2h 0min |
| Filter: | Astrodon Ha (3nm), OIII (3nm) |
| Mount: | ASA DDM85 equatorial mount with direct drives |
| Software: | Siril 1.4, Photoshop CC |
| Remarks: |
© 2025 Peter Cerveny