New method to determine the origin of stardust in meteorites

Date:
August 11, 2020
Source:
University of Surrey
Summary:
Scientists have made a key discovery thanks to stardust found
in meteorites, shedding light on the origin of crucial chemical
elements.



FULL STORY ========================================================================== Scientists have made a key discovery thanks to stardust found in
meteorites, shedding light on the origin of crucial chemical elements.


========================================================================== Meteorites are critical to understanding the beginning of our solar
system and how it has evolved over time. However, some meteorites contain grains of stardust that predate the formation of our solar system and
are now providing important information about how the elements in the
universe formed.

In a study published by Physical Review Letters, researchers from the University of Surrey detail how they made a key discovery connected to
the "pre-solar grains" found in primitive meteorites. This discovery
has provided new insights into the nature of stellar explosions and the
origin of the chemical elements. It has also provided a new method for astronomical research.

Dr Gavin Lotay, Nuclear Astrophysicist and Director of Learning and
Teaching at the University of Surrey, said: "Tiny pre-solar grains, about
one micron in size, are the residuals of stellar explosions that occurred
in the distant past, long before our solar system existed. Stellar debris eventually became wedged into meteorites that, in turn, crashed into
the Earth." One of the most frequent stellar explosions to occur in our
galaxy is called a nova, which involves a binary star system consisting
of a main sequence star orbiting a white dwarf star -- an extremely dense
star that can be the size of Earth but has the mass of our Sun. Matter
from the main star is continually pulled away by the white dwarf because
of its intense gravitational field. This deposited material initiates
a thermonuclear explosion every 1,000 to 100,000 years and the white
dwarf ejects the equivalent of the mass of more than thirty Earths into interstellar space. In contrast, a supernova involves a single collapsing
star and, when it explodes, it ejects almost all of its mass.

As novae continually enrich our galaxy with chemical elements, they have
been the subject of intense astronomical investigations for decades. Much
has been learned from them about the origin of the heavier elements,
for example.

However, a number of key puzzles remain.

Dr Lotay continues: "A new way of studying these phenomena is by
analysing the chemical and isotopic composition of the pre-solar grains
in meteorites. Of particular importance to our research is a specific
nuclear reaction that occurs in novae and supernovae -- proton capture
on an isotope of chlorine - - which we can only indirectly study in
the laboratory." In conducting their experiment, the team, led by
Dr Lotay and Surrey PhD student Adam Kennington (also a former Surrey undergraduate), pioneered a new research approach. It involves the use
of the Gamma-Ray Energy Tracking In-beam Array (GRETINA) coupled to the Fragment Mass Analyzer at the Argonne Tandem Linac Accelerator System
(ATLAS), USA. GRETINA is a state-of-the-art detection system able to trace
the path of gamma rays (g-ray) emitted from nuclear reactions. It is one
of only two such systems in the world that utilise this novel technology.

Using GRETINA, the team completed the first detailed g-ray spectroscopy
study of an astronomically important nucleus, argon-34, and were able
to calculate the expected abundance of sulfur isotopes produced in
nova explosions.

Adam Kennington said: "It's extremely exciting to think that, by studying
the microscopic nuclear properties of argon-34, it may now be possible
to determine whether a particular grain of stardust comes from a nova
or a supernova."

========================================================================== Story Source: Materials provided by University_of_Surrey. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. A. R. L. Kennington, G. Lotay, D. T. Doherty,
D.

Seweryniak, C. Andreoiu, K. Auranen, M. P. Carpenter,
W. N.

Catford, C. M. Deibel, K. Hadyńska-Klęk,
S. Hallam, D. E. M. Hoff, T. Huang,
R. V. F. Janssens, S. Jazrawi, J. Jose',
F. G. Kondev, T. Lauritsen, J. Li, A. M. Rogers,
J. Saiz, G. Savard, S. Stolze, G. L. Wilson, S. Zhu. Search
for Nova Presolar Grains: g-Ray Spectroscopy of Ar34 and its
Relevance for the Astrophysical Cl33(p,g) Reaction. Physical Review
Letters, 2020; 124 (25) DOI: 10.1103/PhysRevLett.124.252702 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200811120111.htm

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