If symmetry is a sign of splendor, then the newly
discovered Red Square nebula is one of the most beautiful objects in
the universe.
Seen in the infrared, the nebula resembles a giant, glowing red box
in the sky, with a bright white inner core. A dying star called MWC 922
is located at the system’s center and spewing its innards from opposite
poles into space. (A nebula is an interstellar cloud of gas, dust and
plasma where stars can both emerge and die.)
“This spectacular event is the death of a star,” said study team member James Lloyd of Cornell University.
After MWC 922 ejects most of its material into space, it will contract into a dense stellar corpse known as a white dwarf, shrouded by clouds of its own remains.
The Red Square nebula discovery is detailed in the April 13 issue of the journal Science.
Almost perfect
What is particularly astonishing about the Red
Square, the researchers say, is the degree of symmetry seen in lines,
or “rungs,” that bisect its surface. The rungs appear as shadows, and
their makeup is uncertain.
“The high degree of regularity in this case may point
to the intriguing possibility that these bands are shadows cast by
periodic ripples or waves on the surface of an inner disk close to the
star at the heart of the system," Lloyd said.
The Red Square ranks among the most symmetrical
objects ever observed by scientists. “If you fold things across
the principle diagonal axis, you get an almost perfect reflection
symmetry,” said study leader Peter Tuthill from the University of
Sydney in Australia. “This makes the Red Square nebula the most
symmetrical object of comparable complexity ever imaged.”
The Red Square’s extreme symmetry suggests the star’s
surroundings are extremely still and not buffeted by external stellar
winds or other turbulence.
The researchers propose that similar conditions are contributing to the extreme symmetry of another system, the Red Rectangle, whose central star is cooler than that of the Red Square.
“The Red Rectangle is mostly symmetrical, but it has some asymmetries,” Lloyd told SPACE.com.
“It wasn’t clear whether it was because the outflow was very
symmetrical or whether material in the outflow was encountering some
other material” which introduced the symmetry.
The new findings suggest the system’s perfect form
results from an even outflow of gas. “The reason the Red Square remains
so symmetrical is that there is no material that has interfered with
the outflow, so it has preserved the symmetry it was born with,” Lloyd
said.
Adaptive optics
Tuthill and Lloyd spotted the Red Square using the
200-inch Hale Telescope at Caltech’s Palomar Observatory and the Keck-2
Telescope in Hawaii.
Both telescopes utilize a relatively new type of imaging called adaptive optics,
which uses a laser guide star as a reference and a rapidly deforming
mirror to correct image distortions from the Earth’s atmosphere in real
time.
Adaptive optics “acts like a myopia cure for a telescope,” Lloyd said.
advertisement
