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New Camera Sees "First Light" on Burrell Schmidt
Telescope
Posted 12-May-2008
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Using new
instrumentation, Case Western Reserve University astronomers
can now view the night sky wider and deeper than before.
While the vast reaches of intergalactic space may appear dark and
empty, a new camera installed on the university's Burrell Schmidt
telescope at Kitt Peak National
Observatory in Tucson, AZ will bring into clear view the faint sea of
orphan stars strewn throughout the nearby Virgo cluster of galaxies.
The design and installation of the new camera system was led by Case
Western Reserve astronomer Paul Harding, who also serves as the
observatory manager. A new charge coupled device (CCD) --- a larger and
more sensitive version of the imaging technology found in everyday
digital cameras --- will enable the astronomers to determine the ages
of these stars and unravel the secrets of their origins.
This faint orphan starlight, dubbed "cintracluster light", is formed
when galaxies collide with one another inside titanic clusters of
galaxies. During these collisions, stars are ripped away from their
parent galaxies and strewn throughout the cluster by the gravitational
forces at work.
Originally discovered in the Virgo cluster three years ago by Case
astronomer Chris Mihos and his collaborators, this intracluster light
holds the key to understanding how galaxy clusters form and evolve.
The primary reason for upgrading the telescopes camera is to determine
the color of these stars, according to Mihos and Harding. "Typically
younger stars are bluer," Harding says, "so if we can measure the color
of the intracluster light, we can learn about its age."
Younger ages for the stars would suggest that the Virgo cluster formed
relatively recently, over the past few billion years. But because the
stars are very faint in the blue, to measure the stellar colors the
existing camera needed to be upgraded to be image a wider portion of
the sky with even greater sensitivity.
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Images from the new
camera can be seen below. Click on any image for a larger view.
Image of partial
moon light up
by Earthshine, showing extremely wide field of view of the camera.
Image of the Virgo
cluster, from a mosaic of images from the new camera. The total field
of view here is 3.2 degrees on a side.
Image of the new CCD sitting in the cryogenic dewar.
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The telescope's upgraded
camera images an area of the sky 1.5 degrees
on a side --- twice as big as the old camera, and enough to fit nine
full moons in the field of view. "By imaging twice as much sky, we can
collect twice as much light at once," Mihos says, "and that lets us
detect this faint starlight even in the blue where it is extremely
faint."
Harding likens the new CCD to a camera that has been retrofitted to
increase its film size from 35 mm to a large format film size of
several inches. "It's the same camera but bigger film," Harding
explained. The CCD itself, a thin wafer of silicon measuring 3" on a
side, was fabricated by the Imaging Technology Laboratory at the
University of Arizona and cost approximately $100,000.
Harding worked with astronomy graduate student Craig Rudick and
undergraduate student Colin Slater to install the CCD onto Case's
wide-field telescope at Kitt Peak. Funding for the new camera came from
a combination of research grants from the National Science Foundation
and Research Corporation to Mihos and fellow Case astronomer Heather
Morrison, as well as from departmental endowment funds.
The Burrell Schmidt Telescope of Case Western Reserve's Warner and
Swasey Observatory was first opened in 1939 and continues to be a
workhorse telescope for astronomers. Over the years, it has had several
technological upgrades to keep it at the forefront of astronomical
research, and recent discoveries made by Case astronomers using the
telescope include the discovery of the faint dwarf galaxy Andromeda
VIII by Morrison and her collaborators in 2003 and later, in 2005, the
discovery of the intracluster light in Virgo by Mihos and collaborators.
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