The Red Square Nebula is a celestial object located in the area of the sky occupied by star MWC 922 in the constellation

Constellation

In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....

 Serpens

Serpens

Serpens is a constellation of the northern hemisphere. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy and it remains one of the 88 modern constellations defined by the International Astronomical Union....

. The first images of this bipolar nebula

Bipolar nebula

A bipolar nebula is a distinctive nebular formation characterized by an axially symmetric bi-lobed appearance.Many, but not all, planetary nebulae exhibit an observed bipolar structure...

, taken using the Mt. Palomar

Palomar Observatory

Palomar Observatory is a privately owned observatory located in San Diego County, California, southeast of Pasadena's Mount Wilson Observatory, in the Palomar Mountain Range. At approximately elevation, it is owned and operated by the California Institute of Technology...

 Hale telescope

Hale telescope

The Hale Telescope is a , 3.3 reflecting telescope at the Palomar Observatory in California, named after astronomer George Ellery Hale. With funding from the Rockefeller Foundation, he orchestrated the planning, design, and construction of the observatory, but did not live to see its commissioning...

 in California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, 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

Cornell University

Cornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...

 claims that the shape arises from two cone shapes placed tip-to-tip. This also explains the "double-ring" structure seen in SN 1987A

SN 1987A

SN 1987A was a supernova in the outskirts of the Tarantula Nebula in the Large Magellanic Cloud, a nearby dwarf galaxy. It occurred approximately 51.4 kiloparsecs from Earth, approximately 168,000 light-years, close enough that it was visible to the naked eye. It could be seen from the Southern...

.

There is no clear understanding 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."

External links

• "Near-Perfect Symmetry Revealed in Red Cosmic Square" space.com (12 April 2007)
• "Astronomers Obtain Highly Detailed Image of the 'Red Square'" physorg.com (13 April 2007)
• Abstract of "A symmetric bipolar nebula around MWC 922" by Peter Tuthill, in Science (13 April 2007)
• APOD – MWC 922: The Red Square Nebula (2007-04-16)
• APOD – MWC 922: The Red Square Nebula (2011-03-23)