[meteorite-list] Red Dust in Planet-Forming Disk May Harbor Precursors to Life

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 4 Jan 2008 15:18:25 -0800 (PST)
Message-ID: <200801042318.PAA18423_at_zagami.jpl.nasa.gov>

http://www.ciw.edu/news/red_dust_planet_forming_disk_may_harbor_precursors_life

For Immediate Release January 3, 2008
Contact:
John Debes
1-202-478-8862, debes at dtm.ciw.edu

PIO Source:
Alan Cutler
1-202-939-1142
acutler at ciw.edu

For copies of the paper go to http://arxiv.org/abs/0712.3283

Red Dust in Planet-Forming Disk May Harbor Precursors to Life

Washington, DC - Astronomers at the Carnegie Institution have found the
first indications of highly complex organic molecules in the disk of red
dust surrounding a distant star. The eight-million-year-old star, known as
HR 4796A, is inferred to be in the late stages of planet formation,
suggesting that the basic building blocks of life may be common in planetary
systems.

In a study published in the current Astrophysical Journal Letters, John
Debes and Alycia Weinberger of the Carnegie Institution???s Department of
Terrestrial Magnetism with Glenn Schneider of the University of Arizona
report observations of infrared light from HR 4796A using the Near-Infrared
Multi-Object Spectrometer aboard the Hubble Space Telescope. The researchers
found that the spectrum of visible and infrared light scattered by the
star???s dust disk looks very red, the color produced by large organic
carbon molecules called tholins. The spectrum does not match those of other
red substances, such as iron oxide.

Tholins do not form naturally on present-day Earth because oxygen in the
atmosphere would quickly destroy them, but they are hypothesized to have
existed on the primitive Earth billions of years ago and may have been
precursors to the biomolecules that make up living organisms. Tholins have
been detected elsewhere in the solar system, such as in comets and on
Saturn???s moon Titan, where they give the atmosphere a red tinge. This
study is the first report of tholins outside the solar system.

"Until recently it???s been hard to know what makes up the dust in a disk
from scattered light, so to find tholins this way represents a great leap in
our understanding," says Debes.

HR 4796A is located in the constellation Centaurus, visible primarily form
the southern hemisphere. It is about 220 light years from Earth. The
discovery of its dust disk in 1991 generated excitement among astronomers,
who consider it a prime example of a planetary system caught in the act of
formation. The dust is generated by collisions of small bodies, perhaps
similar to the comets or asteroids in our solar system, and which may be
coated by the organics. These planetesimals can deliver these building
blocks for life to any planets that may also be circling the star.

"Astronomers are just beginning to look for planets around stars much
different from the Sun. HR 4796A is twice as massive, nearly twice as hot as
the sun, and twenty times more luminous than the Sun," says Debes.
"Studying this system provides new clues to understanding the different
conditions under which planets form and, perhaps, life can evolve."

This research is based on observations with the NASA/ESA Hubble Space
Telescope and was supported by NASA and the NASA Astrobiology Institute.

The Carnegie Institution (www.CIW.edu) has been a pioneering force in basic
scientific research since 1902. It is a private, nonprofit organization with
six research departments throughout the U.S. Carnegie scientists are leaders
in plant biology, developmental biology, astronomy, materials science,
global ecology, and Earth and planetary science.
Received on Fri 04 Jan 2008 06:18:25 PM PST