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Superbubble of supernova remnants
caught in act of forming
James E.
Kloeppel, Physical Sciences Editor
217-244-1073; kloeppel@illinois.edu
Released
1/9/07
|
CHAMPAIGN, Ill. —
A superbubble in space, caught in the act of forming, can help scientists
better understand the life and death of massive stars, say researchers at
the University of Illinois at Urbana-Champaign.
Found within the Small Magellanic Cloud – a galactic neighbor
of the Milky Way – the large region of ionized hydrogen gas is
designated “LHa115-N19,” and “contains a number of
massive stars and overlapping supernova remnants,” said Rosa Williams,
an astronomer at the
U. of I.
“We can tell there has been a fair amount of stellar activity
going on.”
From birth to death, massive stars have a tremendous impact on their
surroundings. While alive, these stars generate stellar winds that push
away nearby gas and dust, forming low-density cavities inside expanding
bubbles. When the stars die, shock waves from their death throes can
enlarge those bubbles into huge supernova remnants.
“In N19, we have not one star, but a number of massive stars blowing
bubbles and we have several supernova remnants,” Williams said.
“Some of these cavities may overlap with one another. Eventually,
these bubbles could merge into one enormous cavity, called a superbubble.”
To identify the locations of massive stars, stellar-wind bubbles and
supernova remnants in N19, Williams and colleagues combined optical
images, X-ray data and spectroscopic measurements.
“We caught this particular region of N19 at a neat moment in time,”
Williams said. “The stars are just dispersed enough that their
stellar winds and supernova blasts are working together, but have not
yet carved out a full cavity. We are witnessing the birth of a superbubble.”
The behavior of matter and energy within a superbubble has implications
for the formation of planetary systems, said Williams, who will present
her team’s findings at the American Astronomical Society meeting
in Seattle, on Tuesday (Jan. 9).
During its life and death, a massive star forges the heavy elements
that enrich the interstellar medium and form planets. “Our own
solar system may have formed within the confines of a superbubble,”
said Williams, who uses an analogy with people to help explain her interest
in superbubbles.
“Some people live pretty independently in isolated country houses,
while others live in large cities that require a centralized structure,”
Williams said. “In N19, we are looking at a possible bridge between
an individual star living its life and dying its death, and a community
of stars, where living and dying affects other stars and planets, and
creates a structure around them.”
Collaborators on the project with Williams are You-Hua Chu, Rosie Chen
and Robert Gruendl at Illinois, and Sean Points and Chris Smith at the
Cerro-Tololo Inter-American Observatory in Chile.
The work was funded by NASA and the Smithsonian Astrophysical Observatory.
Editor’s note: To reach Rosa Williams,
call 217-244-4209; e-mail: rosanina@illinois.edu.
