|Observation data: J2000 epoch|
|Right ascension||18h 21m 16.060s|
|Declination||−13° 01′ 25.69″|
|Distance||5000 ly (1500 pc)|
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 nearly discrete-symmetrical celestial objects ever imaged.
The explanation proposed by Tuthill and his collaborator James Lloyd of Cornell University is 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.
A series of faint spokes radiate from the center of the structure. One possible explanation is that these spokes are shadows cast by periodic ripples or waves on the surface of an inner disk close to the central star.
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."
- 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. (13 April 2007). "A Symmetric Bipolar Nebula Around MWC 922". Science. 316 (5822): 247. Bibcode:2007Sci...316..247T. doi:10.1126/science.1135950. PMID 17431173. S2CID 15439363.
- NASA Astronomy Picture of the Day: MWC 922: The Red Square Nebula (16 April 2007)
- NASA Astronomy Picture of the Day: MWC 922: The Red Square Nebula (23 March 2011)