MWC 922: The Red Square
Nebula
From NASA’s Astronomy Picture of the Day
From NASA’s Astronomy Picture of the Day
What could cause a
nebula to appear square? No one is quite sure. The hot star system known
as MWC 922,
however, appears to be embedded in a nebula with just such a shape.
The image below combines infrared exposures from the Hale
Telescope on Mt.
Palomar in California, and the Keck-2
Telescope on Mauna
Kea in Hawaii.
A leading progenitor
hypothesis for the square nebula is that the central star or stars somehow expelled cones of
gas during a late developmental
stage.
For MWC
922, these cones happen to
incorporate nearly right
angles and be visible
from the sides. Supporting evidence for the cone hypothesis includes radial spokes in the
image that might run along the cone walls.
Researchers speculate
that the cones viewed from another angle would appear similar to the gigantic
rings of supernova 1987A, possibly indicating that a star in MWC 922 might one day itself
explode in a similar supernova.
