[meteorite-list] Astronomers Discover Complex Organic Matter in the Universe

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 26 Oct 2011 12:00:33 -0700 (PDT)
Message-ID: <201110261900.p9QJ0XhH005935_at_zagami.jpl.nasa.gov>

http://www.eurekalert.org/pub_releases/2011-10/tuoh-adc102511.php

Public release date: 26-Oct-2011

Contact: Ms Trinni Choy
pychoy at hku.hk
852-285-92606
The University of Hong Kong

Astronomers discover complex organic matter in the universe

In today's issue of the journal Nature, astronomers report that
organic compounds of unexpected complexity exist throughout the
Universe. The results suggest that complex organic compounds are not the
sole domain of life but can be made naturally by stars.

Prof. Sun Kwok and Dr. Yong Zhang of the University of Hong Kong show
that an organic substance commonly found throughout the Universe
contains a mixture of aromatic (ring-like) and aliphatic (chain-like)
components. The compounds are so complex that their chemical structures
resemble those of coal and petroleum. Since coal and oil are remnants of
ancient life, this type of organic matter was thought to arise only from
living organisms. The team's discovery suggests that complex organic
compounds can be synthesized in space even when no life forms are present.

The researchers investigated an unsolved phenomenon: a set of infrared
emissions detected in stars, interstellar space, and galaxies. These
spectral signatures are known as "Unidentified Infrared Emission
features". For over two decades, the most commonly accepted theory on
the origin of these signatures has been that they come from simple
organic molecules made of carbon and hydrogen atoms, called polycyclic
aromatic hydrocarbon (PAH) molecules. From observations taken by the
Infrared Space Observatory and the Spitzer Space Telescope, Kwok and
Zhang showed that the astronomical spectra have features that cannot be
explained by PAH molecules. Instead, the team proposes that the
substances generating these infrared emissions have chemical structures
that are much more complex. By analyzing spectra of star dust formed in
exploding stars called novae, they show that stars are making these
complex organic compounds on extremely short time scales of weeks.

Not only are stars producing this complex organic matter, they are also
ejecting it into the general interstellar space, the region between
stars. The work supports an earlier idea proposed by Kwok that old stars
are molecular factories capable of manufacturing organic compounds. "Our
work has shown that stars have no problem making complex organic
compounds under near-vacuum conditions," says Kwok. "Theoretically, this
is impossible, but observationally we can see it happening."

Most interestingly, this organic star dust is similar in structure to
complex organic compounds found in meteorites. Since meteorites are
remnants of the early Solar System, the findings raise the possibility
that stars enriched the early Solar System with organic compounds. The
early Earth was subjected to severe bombardments by comets and
asteroids, which potentially could have carried organic star dust.
Whether these delivered organic compounds played any role in the
development of life on Earth remains an open question.

###

Prof. Sun Kwok is the Dean of Science and Chair Professor of Physics of
the University of Hong Kong. He serves as Vice President of Division VI
(interstellar matter) of the International Astronomical Union, and is
the incoming Vice President of Commission 51 (bioastronomy) of the
International Astronomical Union. He has published many books, including
the recent book "Organic Matter in the Universe" (Wiley, 2011).

Dr. Yong Zhang is a Research Assistant Professor at the University of
Hong Kong.

This work was supported by the Research Grants Council of Hong Kong.

Prof. Sun Kwok is available for interview. Please contact him via email
at sunkwok at hku.hk .
Received on Wed 26 Oct 2011 03:00:33 PM PDT