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Multi-wavelength images help astronomers study star birth, death(Forwarded)



 
 
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Old January 14th 06, 06:19 PM posted to sci.space.news
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Default Multi-wavelength images help astronomers study star birth, death(Forwarded)

News Bureau
University of Illinois at Urbana-Champaign
807 South Wright Street, Suite 520 East
Champaign, Illinois 61820-6219
Telephone 217 333-1085, Fax 217 244-0161

Contact:
James E. Kloeppel, Physical Sciences Editor
217-244-1073

1/11/06

Multi-wavelength images help astronomers study star birth, death

CHAMPAIGN, Ill. -- Black and white reproductions of Vincent van Gogh's
"The Starry Night" lack the beauty and depth of the original oil painting.
In a similar fashion, images of stars and galaxies composed of a single
wavelength band cannot convey the wealth of information now accessible to
astronomers.

In recent years, a number of ground-based optical and radio surveys of the
Large and Small Magellanic Clouds -- Earth's nearest neighboring galaxies
-- have become available. New composite images of optical, radio,
infrared, ultraviolet and X-ray wavelengths are giving astronomers at the
University of Illinois at Urbana-Champaign a clearer picture of the birth,
life and death of massive stars, and their effect on the gas and dust of
the interstellar medium surrounding them.

From their birth to their death, massive stars have a tremendous impact on
their galactic surroundings. While alive, these stars energize and enrich
the interstellar medium with their strong ultraviolet radiation and their
fast stellar winds. As they die, shock waves from their death throes
inject vast quantities of mechanical energy into the interstellar medium
and can lead to the formation of future stars.

"Comparing images at different wavelengths lets us create a more complete
picture, rather than seeing only a few features in isolation," said
You-Hua Chu, chair of the astronomy department at Illinois. "Using
multi-spectral data sets, we can examine the physical structure of the
interstellar medium and study the conditions that lead to star formation."

Massive stars interact with the interstellar medium in many ways. Their
fast stellar winds and supernova blasts can sweep up the surrounding
medium into expanding shells filled with hot gas.

"The expanding shells produce conditions that may start a new wave of star
births," said Robert Gruendl, an Illinois astronomer who uses Spitzer
Space Telescope observations to search for proto-stars. "The combination
of X-ray, optical and infrared observations allow us to determine whether
the pressure of the hot gas or compression by a passing shock wave is
responsible for triggering star formation."

In related work, Illinois astronomer Rosa Williams has added data from a
new wavelength regime to her growing database on stellar graveyards in the
Magellanic Clouds. Comparing infrared images obtained with the Spitzer
Space Telescope, Williams explored the distribution of matter caught in
the expanding shells of supernova remnants.

"We expected significant infrared emission to be generated by dust
particles," Williams said. "Instead, most of the emission from these
remnants came from heated gas."

Strong ultraviolet radiation from nearby star-forming regions may have
ionized the gas and torn apart the dust particles consisting of
hydrocarbon molecules, Williams said. "Other dust particles could have
been shattered by shock waves from the supernova."

To solve the missing dust mystery, Williams said, "We are investigating
the nature and amount of dust in regions surrounding the supernova
remnants to see whether the deficiency in dust is inherent in the
environment or created by the remnant."

Chu, Gruendl and Williams will present their latest findings at the
American Astronomical Society meeting in Washington, D.C., on Wednesday
(Jan. 11).

The National Aeronautics and Space Administration funded their work.

Editor's note:

To reach You-Hua Chu, call 217-333-5535
To reach Rosa Williams, call 217-244-4209
To reach Robert Gruendl, call 217-244-4209

IMAGE CAPTIONS:

[Image 1:
http://www.news.uiuc.edu/WebsandThum...1n51.4hx_b.jpg
(114KB)]
This false-color image shows infrared (red), optical (green), and X-ray
(blue) views of the large star-forming complex N51. The warm ionized gas
is shown in green, the hot ionized gas is in blue, and the proto-stars are
primarily in red. This color image reveals the relative position of the
expanding shell N51D and the recently formed proto-stars, allowing
astronomers to determine whether the star formation is triggered by
pressure from hot gas or by compression by a passing shock wave.

The infrared image was taken with the Spitzer Space Telescope's Infrared
Array Camera (IRAC) at a wavelength of 8 microns. The optical image of
hydrogen emission was taken as part of the Magellanic Cloud Emission-Line
Survey (MCELS) with the Curtis-Schmidt Telescope at Cerro Tololo
Inter-American Observatory in Chile. The X-ray image was taken with the
European Space Agency's satellite, XMM-Newton, using its European Photon
Imaging Camera (EPIC) camera.

Credit: NASA/SSC/MCELS/ESA/U.Illinois (Y.-H. Chu and R. A. Gruendl)

[Image 2:
http://www.news.uiuc.edu/WebsandThum...1chandra_b.jpg
(104KB)]
This false-color image shows infrared (red), optical (green), and X-ray
(blue) views of the N49 supernova remnant. This object, the remains of an
exploded star, has million-degree gas in the center, with much cooler gas
at the outer parts of the remnant. While astronomers expected that dust
particles were generating most of the infrared emission, the study of this
object indicates that much of the infrared is instead generated in heated
gas.

Images forming this composite were taken with NASA's three Great
Observatories. The infrared image was taken with the Spitzer Space
Telescope's Multiband Imaging Photometer for Spitzer (MIPS) at a
wavelength of 24 microns. The optical image was taken with the Hubble
Space Telescope's Wide Field Planetary Camera 2 (WFPC2) of hydrogen
emission. The X-ray image was taken with the Chandra X-ray Observatory's
Advanced CCD Imaging Spectrometer.

Credit: NASA (SSC/HST/CXC), U.Illinois (R.Williams & Y.-H.Chu)


 




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