Royal Astronomical Society – June 25, 2018 -- The galaxy
is rich in grease-like molecules, according to an Australian-Turkish team.
Astronomers at the University
of New South Wales in Sydney (UNSW)[Australia] and Ege
University in Turkey used a laboratory to manufacture material with the
same properties as interstellar dust and used their results to estimate the
amount of ‘space grease’ found in the Milky Way. Their results
appear in a paper in Monthly
Notices of the Royal Astronomical Society.
Organic matter of different kinds contains carbon, an element considered essential for life. There is though real uncertainty over its abundance, and only half the carbon expected is found between the stars in its pure form. The rest is chemically bound in two main forms, grease-like (aliphatic) and mothball-like (aromatic).
The UNSW / Ege team used a laboratory to create material with the same properties as interstellar dust. They mimicked the process by which organic molecules are synthesised in the outflows of carbon stars, by expanding a carbon-containing plasma into a vacuum at low temperature. The material was collected and then analysed by a combination of techniques. Using magnetic resonance and spectroscopy (splitting light into its constituent wavelengths) they were able to determine how strongly the material absorbed light with a certain infrared wavelength, a marker for aliphatic carbon.
Organic matter of different kinds contains carbon, an element considered essential for life. There is though real uncertainty over its abundance, and only half the carbon expected is found between the stars in its pure form. The rest is chemically bound in two main forms, grease-like (aliphatic) and mothball-like (aromatic).
The UNSW / Ege team used a laboratory to create material with the same properties as interstellar dust. They mimicked the process by which organic molecules are synthesised in the outflows of carbon stars, by expanding a carbon-containing plasma into a vacuum at low temperature. The material was collected and then analysed by a combination of techniques. Using magnetic resonance and spectroscopy (splitting light into its constituent wavelengths) they were able to determine how strongly the material absorbed light with a certain infrared wavelength, a marker for aliphatic carbon.
“Combining our lab results with observations from
astronomical observatories allows us to measure the amount of aliphatic carbon
between us and the stars”, explained Professor Tim
Schmidt, from the Australian
Research Council Centre of Excellence in Exciton Science in the School of
Chemistry at UNSW Sydney.
The researchers found that there are about 100
greasy carbon atoms for every million hydrogen atoms, accounting for between a
quarter and a half of the available carbon. In the Milky Way Galaxy, this
amounts to about 10 billion trillion trillion tonnes of greasy matter, or
enough for 40 trillion trillion trillion packs of butter.
Schmidt is quick to dispel the comparison with
anything edible: “This space grease is not the kind of thing you’d want to
spread on a slice of toast! It’s dirty, likely toxic and only forms in the
environment of interstellar space (and our laboratory). It’s also intriguing
that organic material of this kind – material that gets incorporated into
planetary systems – is so abundant.”
The team now
wants to determine the abundance of the mothball-like carbon, which will
involve yet more challenging work in the laboratory. By firmly establishing the
amount of each type of carbon in the dust, they will know precisely how much of
this element is available to create life.
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