Clear evidence in a Chinese meteorite for the past presence of chlorine-36, a
short-lived radioactive isotope, lends further support to the controversial
concept that a nearby supernova blast was involved in the formation of our solar
system, according to a report forthcoming in the February 1 issue and published
online Jan. 24, of the Proceedings of the National Academy of Sciences.
Known as the Ningqiang carbonaceous chondrite, the primitive meteorite is a
space relic that formed shortly after the solar system’s creation. It contains
pockets of still older materials or “inclusions” that contain that contain
calcium, aluminum and sodalite, a chlorine-rich mineral.
A Chinese-American team of scientists including Yangting Lin, Ziyuan Ouyang and
Daode Wang from the Chinese Academy of Sciences, and Yunbin Guan and Laurie
Leshin from Arizona State University found the rare isotope sulfur-36 in
association with the sodalite. Though it can be formed in various ways,
sulfur-36 is a natural decay product of chlorine-36. Its association with the
chlorine in the sodalite is strong evidence for the past presence of
chlorine-36, which has a half-life of only 300,000 years, in the early solar system.
The solar system’s chlorine-36 could have formed in two different ways — either
in the explosion of a supernova or in the irradiation of a nebular cloud near
the forming Sun. The irradiation explanation is unlikely in this case, however,
since the mineral the chlorine-36 was discovered in must have formed a
significant distance from the sun.
“There is no ancient live chlorine-36 in the solar system now,” said Leshin, who
is director of ASU’s Center for Meteorite Studies. “But this is direct evidence
that it was here in the early solar system.
“We have now discovered the first solid evidence for two different short-lived
radionuclides in the GeoSIMS Lab at ASU — iron-60 and chlorine-36 — and both
of them provide evidence for where the solar system’s short-lived radionuclides
came from. It’s producing a really strong argument that these radionuclides were
produced in a supernova that exploded near the forming solar system and seeded
the solar system with these isotopes.”
In a “Perspectives” article in the journal Science last spring, Leshin and
others argued that the presence of iron-60 was evidence that the solar system
formed as a result of violent star-creation processes in a dense nebula rife
with short-lived, high-mass stars and supernovas — a very different creation
story than the traditional view that the solar system formed from a slowly
condensing molecular cloud. (To see the release on the Science paper, see
http://www.asu.edu/asunews/research/sun_earth_creation.htm )
Leshin points out that the current paper is part of a growing collaboration
between space sciences at ASU and the Chinese science community, in this case
being driven by Guan, a native of China , and manager of the ASU GeoSIMS Lab.
“Lin, the first author on this paper, was a visiting fellow in our lab for six
months. We’ve published several papers on meteorites with groups in China —
it’s a very fruitful relationship,” she said.
“There is no ancient live chlorine-36 in the solar system now,” said Leshin, who
is director of ASU’s Center for Meteorite Studies. “But this is direct evidence
that it was here in the early solar system.
“We have now discovered the first solid evidence for two different short-lived
radionuclides in the GeoSIMS Lab at ASU — iron-60 and chlorine-36 — and both
of them provide evidence for where the solar system’s short-lived radionuclides
came from. It’s producing a really strong argument that these radionuclides were
produced in a supernova that exploded near the forming solar system and seeded
the solar system with these isotopes.”
In a “Perspectives” article in the journal Science last spring, Leshin and
others argued that the presence of iron-60 was evidence that the solar system
formed as a result of violent star-creation processes in a dense nebula rife
with short-lived, high-mass stars and supernovas — a very different creation
story than the traditional view that the solar system formed from a slowly
condensing molecular cloud. (To see the release on the Science paper, see
http://www.asu.edu/asunews/research/sun_earth_creation.htm )
Leshin points out that the current paper is part of a growing collaboration
between space sciences at ASU and the Chinese science community, in this case
being driven by Guan, a native of China , and manager of the ASU GeoSIMS Lab.
“Lin, the first author on this paper, was a visiting fellow in our lab for six
months. We’ve published several papers on meteorites with groups in China —
it’s a very fruitful relationship,” she said.
