[meteorite-list] Arizona Radio Observatory Team Discovers Supergiant Star Spews Molecules Needed for Life

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon, 23 Jul 2007 12:55:28 -0700 (PDT)
Message-ID: <200707231955.MAA06505_at_zagami.jpl.nasa.gov>

ARIZONA RADIO OBSERVATORY TEAM DISCOVERS
SUPERGIANT STAR SPEWS MOLECULES NEEDED FOR LIFE
 (From Lori Stiles, University Communications, 520-626-4402)

- Monday, July 23, 2007

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Contact information, Web sites listed at the end
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University of Arizona astronomers who are probing the oxygen-rich
environment around a supergiant star with one of the world's most sensitive
radio telescopes have discovered a score of molecules that include compounds
needed for life.

"I don't think anyone would have predicted that VY Canis Majoris is a
molecular factory. It was really unexpected," said Arizona Radio Observatory
(ARO) Director Lucy Ziurys, UA professor of astronomy and of chemistry.
"Everyone thought that the interesting chemistry in gas clouds around old
stars was happening in envelopes around nearer, carbon-rich stars," Ziurys
said. "But when we started looking closely for the first time at an
oxygen-rich object, we began finding all these interesting things that
weren't supposed to be there."

VY Canis Majoris, one of the most luminous infrared objects in the sky, is
an old star about 5,000 light years away. It's a half million times more
luminous than the sun, but glows mostly in the infrared because it's a cool
star. It truly is "supergiant" -- 25 times as massive as the sun and so huge
that it would fill the orbit of Jupiter. But the star is losing mass so fast
that in a million years -- an astronomical eyeblink -- it will be gone. The
star already has blown away a large part of its atmosphere, creating its
surrounding envelope that contains about twice as much oxygen as carbon.

Ziurys and her colleagues are not yet halfway through their survey of VY
Canis Majoris, but they've already published in the journal, Nature (June 28
issue), about their observations of a score of chemical compounds. These
include some molecules that astronomers have never detected around stars and
are needed for life.

Among the molecules Ziurys and her team reported in Nature are table salt
(NaCl); a compound called phosphorus nitride (PN), which contains two of the
five most necessary ingredients for life; molecules of HNC, which is a
variant form of the organic molecule, hydrogen cyanide; and an ion molecule
form of carbon monoxide that comes with a proton attached (HCO+).
Astronomers have found very little phosphorus or ion molecule chemistry in
outflows from cool stars until now.

"We think these molecules eventually flow from the star into the
interstellar medium, which is the diffuse gas between stars. The diffuse gas
eventually collapses into denser molecular clouds, and from these solar
systems eventually form," Ziurys said.

Comets and meteorites dump about 40,000 tons of interstellar dust on Earth
each year. We wouldn't be carbon-based life forms otherwise, Ziurys noted,
because early Earth lost all of its original carbon in the form of a methane
atmosphere.

"The origin of organic material on Earth -- the chemical compounds that
make up you and me -- probably came from interstellar space. So one can say
that life's origins really begin in chemistry around objects like VY Canis
Majoris."

Astronomers previously studied VY Canis Majoris with optical and infrared
telescopes. "But that's kind of like diving in with a butcher knife to look
at what's there, when what you need is an oyster fork," Ziurys said.

The Arizona Radio Observatory's 10-meter Submillimeter Telescope (SMT) on
Mount Graham, Ariz., excels as a sensitive stellar "oyster fork." Chemical
molecules each possess their own unique radio frequencies. The astronomers
identify the unique radio signatures of chemical compounds in laboratory
work, enabling them to identify the molecules in space.

The ARO team recently began testing a new receiver in collaboration with
the National Radio Astronomy Observatory. The receiver was developed as a
prototype for the Atacama Large Millimeter Array, a telescope under
construction in Chile. The state-of-the-art receiver has given the SMT 10
times more sensitivity at millimeter wavelengths than any other radio
telescope. The SMT can now detect emission weaker than a typical light bulb
from distant space at very precise frequencies.

The UA team has discovered that the molecules aren't just flowing out as a
gas sphere around VY Canis Majoris, but also are blasting out as jets
through the spherical envelope.

"The signals we receive show not only which molecules are seen, but how the
molecules are moving toward and away from us," said Stefanie Milam, a recent
doctoral graduate on the ARO team.

The molecules flowing out from VY Canis Majoris trace complex winds in
three outflows: the general, spherical outflow from the star, a jet of
material blasting out towards Earth, and another jet shooting out a 45
degree angle away from Earth.

Astronomers have seen bipolar outflows from stars before, but not two,
unconnected, asymmetric and apparently random outflows, Ziurys said.

Ziurys said she believes the two random jets are evidence for what
astronomers earlier proposed are "supergranules" that form in very massive
stars, and has been seen in Betelgeuse. Supergranules are huge cells of gas
that form inside the star, then float to the surface and are ejected out of
the star, where they cool in space and form molecules, creating jet outflows
with certain molecular compositions.

Back in the 1960s, no one believed molecules could survive the harsh
environment of space. Ultraviolet radiation supposedly reduced matter to
atoms and atomic ions. Now scientists conclude that at least half of the gas
in space between the stars within the 33-light-year inner galaxy is
molecular, Ziurys said. "Our results are more evidence that we live in a
really molecular universe, as opposed to an atomic one," Ziurys said.

The Arizona Radio Observatory (ARO) owns and operates two radio telescopes
in southern Arizona: The former NRAO 12 Meter (KP12m) Telescope located 50
miles southwest of Tucson on Kitt Peak and the Submillimeter Telescope (SMT)
located on Mount Graham near Safford, Ariz. The telescopes are operated
around-the-clock for about nine to 10 months per year for a combined 10,000
hours per observing season. About 1,500 hours are dedicated to sub-mm
wavelengths at the SMT. The ARO offices are centrally located in the Steward
Observatory building on the UA campus in Tucson.

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Contact Information
 Lucy Ziurys (520) 621-6525 lziurys at as.arizona.edu
 Stefanie Milam (520) 977-5149 smilam at as.arizona.edu
 Aldo Apponi (520) 621-2553 aapponi at as.arizona.edu
 Nick Woolf (520) 621-3234 nwoolf at as.arizona.edu

Related Web sites
UA Astrochemistry Group -
http://www.chem.arizona.edu/faculty/ziur/ziur-group.html
Arizona Radio Observatory - http://aro.as.arizona.edu/
Life and Planets Astrobiology Center - http://www.laplace.arizona.edu/
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Received on Mon 23 Jul 2007 03:55:28 PM PDT