Red Square Nebula
Not to be confused with a similar nebula, the Red Rectangle Nebula.
The Red Square Nebula is a celestial object located in the area of the sky occupied by star MWC 922 in the constellation Serpens. The first images of this bipolar nebula, taken using the Mt. Palomar Hale telescope in California, were released in April 2007. It is notable for its square shape, which according to Sydney University astrophysicist Peter Tuthill, makes it one of the most symmetrical celestial objects ever discovered.
The explanation proposed by Tuthill and his collaborator James Lloyd of Cornell University claims that the square shape arises from two cone shapes placed tip-to-tip, as seen from the side. This also explains the "double-ring" structure seen in SN 1987A.
There is no clear explanation of how the central star could produce the nebula's shape:
Towards the end of their lives, many low-mass stars, like the Sun, slough off their outer layers to produce striking 'planetary' nebulae. But the hot star at the heart of the Red Square nebula, called MWC 922, appears to be relatively massive, suggesting another process formed its signature shape. "How did all this beautiful, crisp structure form?" asks Peter Tuthill of the University of Sydney in Australia. "This is the million dollar question."
One possible explanation is that these two outer faint radial spokes are shadows cast by periodic ripples or waves on the surface of an inner disk close to the central star.
- Than, Ker (12 April 2007). "Near-Perfect Symmetry Revealed in Red Cosmic Square". Space.com.
- "Astronomers Obtain Highly Detailed Image of the 'Red Square'". Phys.Org. 13 April 2007.
- Tuthill, Peter G.; Lloyd, J. P. (April 2007). "A Symmetric Bipolar Nebula Around MWC 922". Science 316 (5822): 247. Bibcode:2007Sci...316..247T. doi:10.1126/science.1135950. PMID 17431173.
- APOD – MWC 922: The Red Square Nebula (2007-04-16)
- APOD – MWC 922: The Red Square Nebula (2011-03-23)