An illustration of the
structure of a greasy carbon molecule, set against an image of the
galactic centre, where this material has been detected. Carbon is
represented as grey spheres and hydrogen as white spheres. - Image
Credit: D. Young (2011), The Galactic Center. Flickr – CreativeCommons
Over
the course of many centuries, scientists learned a great deal about the
types of conditions and elements that make life possible here on Earth.
Thanks to the advent of modern astronomy, scientists have since learned
that these elements are not only abundant in other star systems and
parts of the galaxy, but also in the medium known as interstellar space.
Consider carbon, the element that is essential to all organic matter and life as we know it. This life-bearing element is also present in interstellar dust, though astronomers are not sure how abundant it is. According to new research by a team of astronomers from Australia and Turkey, much of the carbon in our galaxy exists in the form of grease-like molecules.
Their study, “Aliphatic Hydrocarbon Content of Interstellar Dust“, recently appeared in the Monthly Notices of the Royal Astronomical Society. The
study was led by Gunay Banihan, a professor from the Department of
Astronomy and Space Sciences of Erge University in Turkey, and included
members from multiple departments from the University of New South Wales
in Sydney (UNSW).
A
new study by a team of Turkish and Australian astronomers has found
evidence of grease-like molecules in interstellar dust. - Image Credit:
ESO/R. Fosbury (ST-ECF)
For
the sake of their study, the team sought to determine exactly how much
of our galaxy’s carbon is bound up in grease-like molecules. At present,
it is believed that half of the interstellar carbon exists in pure
form, whereas the rest in bound up in either grease-like aliphatic
molecules (carbon atoms that form open chains) and mothball-like
aromatic molecules (carbon atoms that form planar unsaturated rings).
To
determine how plentiful grease-like molecules are compared to aromatic
ones, the team created material with the same properties as interstellar
dust in a laboratory. This consisted of recreating the process where
aliphatic compounds are synthesized in the outflows of carbon stars.
They then followed up on this by expanding the carbon-containing plasma
into a vacuum at low temperatures to simulate interstellar space.
As Prof. Tim Schmidt, from the Australian Research Council Centre of Excellence in Exciton Science in the School of Chemistry at UNSW Sydney and a co-author on the paper, explained:
“Combining our lab results with observations from astronomical observatories allows us to measure the amount of aliphatic carbon between us and the stars.”Using magnetic resonance and spectroscopy, they were then able to determine how strongly the material absorbed light with a certain infrared wavelength. From this, the team found that there are about 100 greasy carbon atoms for every million hydrogen atoms, which works out to about half of the available carbon between stars. Expanding that to include all of the Milky Way, they determined that about 10 billion trillion trillion tonnes of greasy matter exists.
Artist’s impression of the Milky Way Galaxy. - Image Credit: NASA/JPL-Caltech/R. Hurt (SSC-Caltech)
To
put that in perspective, that’s enough grease to fill about 40 trillion
trillion trillion packs of butter. But as Schmidt indicated, this
grease is far from being 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.”Looking ahead, the team now wants to determine the abundance of the other type of non-pure carbon, which is the mothball-like aromatic molecules. Here too, the team will be recreating the molecules in a laboratory environment using simulations. By establishing the amount of each type of carbon in interstellar dust, they will be able to place constraints on how much of this elements is available in our galaxy.
This
in turn will allow astronomers to determine exactly how much of this
life-giving element is available, and could also help shed light on how
and where life can take hold!
Source: Universe Today - Further Reading: RAS, MNRAS
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