This picture has been a little personal challenge, as I deemed the Dolphin Head an impossible target from my location. It never goes above 18 degrees on the horizon and it appears clear among the trees for two hours per night. I gave it a try and imaged it for 6 nights in January 2024. This is actually the image of the southernmost object I have ever photographed.
The Dolphin is again a creation of a Wolf-Rayet star, which are among the most creative galactic sculptors, giving birth and shape to beautiful nebulae, like the Dolphin or, for instance, the
WR134.
Sh2-308 Dolphin Head NebulaGalactic Coordinates: (234.76°, -10.09°)
This ring nebula, also designated as RCW 11, or LBN 1052, surrounds the Wolf-Rayet star HD50896 (WR6, EZ CMa), which is one of the closest Wolf-Rayet stars to our solar system and may also partially ionize Sh 2-303 and Sh 2-304 (just out of our field).
Distance to WR6 was a matter of some controversy. The Hipparcos astrometric satellite results were used in 1997 to determine a parallax suggesting a distance of about 575 parsecs. However, other researchers strongly disagreed with this estimate and proposed distances of up to three times this amount. A revised Hipparcos analysis published in 2007 using the same data determined a very different parallax and a distance of about 1400 pc (4560 ly), much closer to other estimates.
WR6 spectral type indicates that the star is very hot and luminous. The spectrum shows that it is devoid of hydrogen at the surface. EZ Canis Majoris is expected eventually to explode in a supernova.
The nebula was formed about 70000 years ago by the WR6 throwing off its outer hydrogen layers, revealing inner layers of heavier elements. Fast stellar winds, blowing at 1700 km/s (6.1 million km/h!) 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 ionized by intense ultraviolet radiation. The nebula is approximately 60ly across at its widest point.
sources: galaxymap.org, wikipedia
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