Andrew Yee[_1_]
June 12th 07, 03:43 AM
McDonald Observatory
University of Texas
Contact: Rebecca Johnson
ph: 512-475-6763 fax: 512-471-5060
08 June 2007
Hobby-Eberly Telescope Helps Astronomers Learn Secrets of One of Universe's
Most Distant Objects
FORT DAVIS, Texas -- Astronomers have used the 9.2-meter Hobby-Eberly
Telescope (HET) at McDonald Observatory to confirm one of the most distant
known objects in the universe. The object is a quasar -- an extremely bright
galaxy nucleus powered by matter falling into a supermassive black hole at
its heart -- that is 12.7 billion light-years away. Because light travels at
a finite speed, we are seeing this quasar as it appeared 12.7 billion years
ago, when the universe was just 7 percent of its present age.
The object was discovered by the Canada-France High-z Quasar Survey, which
has been undertaken by an international group using the Canada-France-Hawaii
Telescope on Mauna Kea, Hawaii. The survey team, headed by Chris Willott of
the University of Ottawa, presented their results on four extremely distant
quasars, including this one, this week at the annual conference of the
Canadian Astronomical Society in Kingston, Ontario.
It is particularly important to find such distant quasars because they can
be used to probe a time in cosmic history called the "Era of Re-ionization,"
said Gary Hill, a member of the survey team and McDonald Observatory's Chief
Astronomer. During this time, he said, the earliest stars were forming and
beginning to turn the universe from mostly neutral atoms to mostly ionized
(where they have lost their electrons due to ultraviolet radiation). The era
lasted about half a billion years.
He explained that the distant quasars are seen early enough in the history
of the universe that they shine through regions of space that were not yet
fully ionized. Some of the quasar's light is absorbed by any clouds of
still-neutral hydrogen. So, by studying the quasar's light today,
astronomers can gauge what types of gas clouds the light has passed through
on its way to Earth -- providing a record of when in time and where in space
these gas clouds lived.
Fewer than 10 such distant quasars were previously known, Hill said, so
"every one of these counts. Every one you add gives you another line of
sight," -- a way to probe a different part of the universe and study the
inhomogeneous re-ionization process.
Follow-up observations of this specific quasar (with the somewhat difficult
moniker "CFHQS 1641+3755") were first made in the infrared with the
2.7-meter Harlan J. Smith Telescope at McDonald Observatory to indicate that
it is probably a quasar, and not a brown dwarf (both objects are point-like
and red in color in photos).
That accomplished, it was then sent to be studied by HET. The large
light-gathering power of this telescope, the world's fourth-largest,
combined with its Marcario Low Resolution Spectrograph, allowed astronomers
to measure a spectrum of the quasar and calculate its distance of 12.7
billion light-years (in astronomical jargon, this equates to a redshift of z
= 6.04).
The difficult HET observation was carried out by Michael Gully-Santiago, a
college student astronomer from Boston University spending the summer at
McDonald Observatory. Gully-Santiago was taking part in the observatory's
Research Experiences for Undergraduates program, which is funded by the
National Science Foundation.
The group plans to continue following up quasars from the Canada-France
survey with HET, Hill said. They have submitted their results to the
Astronomical Journal for publication. A copy of this paper is available
online at
http://arxiv.org/abs/0706.0914
The Hobby-Eberly Telescope is a joint project of The University of Texas at
Austin, The Pennsylvania State University, Stanford University,
Ludwig-Maximilians-Universitat Munchen and Georg-August-Unversitat Gottingen.
-- END --
Note to Editors : For more information contact Gary Hill at 512-471-1477.
IMAGE CAPTIONS:
[Image 1:
http://mcdonaldobservatory.org/news/gallery/image.php?id=108]
Spectrum of a Distant Quasar
This chart shows the light given off by superheated material spiraling into
a black hole at the heart of a galaxy 12.7 billion light-years away. This
active galaxy, called a quasar, is known as CFHQS 1641+3755. Because its
light has traveled so far to us, it has lost energy, causing wavelengths to
stretch. The light from neutral hydrogen gas, indicated by the label Ly
alpha here, has stretched from a wavelength of 1216 Angstroms all the way to
8500 Angstroms. (For comparison, the human eye can only see light of
wavelengths up to 6500 Angstroms.) The magnitude of this stretch, or
redshift, is what allows astronomers to calculate the quasars distance. This
quasar is one of only a handful known at such a great distance. This
spectrum was taken with Marcario Low Resolution Spectrograph on the
Hobby-Eberly Telescope at McDonald Observatory. Credit: Gary Hill/Tim
Jones/McDonald Observatory. Credit: Gary Hill/Tim Jones/McDonald Obs.
[Image 2:
http://mcdonaldobservatory.org/news/gallery/image.php?id=36]
Hobby-Eberly Telescope, Aerial View. Credit: Marty Harris/McDonald
Observatory.
University of Texas
Contact: Rebecca Johnson
ph: 512-475-6763 fax: 512-471-5060
08 June 2007
Hobby-Eberly Telescope Helps Astronomers Learn Secrets of One of Universe's
Most Distant Objects
FORT DAVIS, Texas -- Astronomers have used the 9.2-meter Hobby-Eberly
Telescope (HET) at McDonald Observatory to confirm one of the most distant
known objects in the universe. The object is a quasar -- an extremely bright
galaxy nucleus powered by matter falling into a supermassive black hole at
its heart -- that is 12.7 billion light-years away. Because light travels at
a finite speed, we are seeing this quasar as it appeared 12.7 billion years
ago, when the universe was just 7 percent of its present age.
The object was discovered by the Canada-France High-z Quasar Survey, which
has been undertaken by an international group using the Canada-France-Hawaii
Telescope on Mauna Kea, Hawaii. The survey team, headed by Chris Willott of
the University of Ottawa, presented their results on four extremely distant
quasars, including this one, this week at the annual conference of the
Canadian Astronomical Society in Kingston, Ontario.
It is particularly important to find such distant quasars because they can
be used to probe a time in cosmic history called the "Era of Re-ionization,"
said Gary Hill, a member of the survey team and McDonald Observatory's Chief
Astronomer. During this time, he said, the earliest stars were forming and
beginning to turn the universe from mostly neutral atoms to mostly ionized
(where they have lost their electrons due to ultraviolet radiation). The era
lasted about half a billion years.
He explained that the distant quasars are seen early enough in the history
of the universe that they shine through regions of space that were not yet
fully ionized. Some of the quasar's light is absorbed by any clouds of
still-neutral hydrogen. So, by studying the quasar's light today,
astronomers can gauge what types of gas clouds the light has passed through
on its way to Earth -- providing a record of when in time and where in space
these gas clouds lived.
Fewer than 10 such distant quasars were previously known, Hill said, so
"every one of these counts. Every one you add gives you another line of
sight," -- a way to probe a different part of the universe and study the
inhomogeneous re-ionization process.
Follow-up observations of this specific quasar (with the somewhat difficult
moniker "CFHQS 1641+3755") were first made in the infrared with the
2.7-meter Harlan J. Smith Telescope at McDonald Observatory to indicate that
it is probably a quasar, and not a brown dwarf (both objects are point-like
and red in color in photos).
That accomplished, it was then sent to be studied by HET. The large
light-gathering power of this telescope, the world's fourth-largest,
combined with its Marcario Low Resolution Spectrograph, allowed astronomers
to measure a spectrum of the quasar and calculate its distance of 12.7
billion light-years (in astronomical jargon, this equates to a redshift of z
= 6.04).
The difficult HET observation was carried out by Michael Gully-Santiago, a
college student astronomer from Boston University spending the summer at
McDonald Observatory. Gully-Santiago was taking part in the observatory's
Research Experiences for Undergraduates program, which is funded by the
National Science Foundation.
The group plans to continue following up quasars from the Canada-France
survey with HET, Hill said. They have submitted their results to the
Astronomical Journal for publication. A copy of this paper is available
online at
http://arxiv.org/abs/0706.0914
The Hobby-Eberly Telescope is a joint project of The University of Texas at
Austin, The Pennsylvania State University, Stanford University,
Ludwig-Maximilians-Universitat Munchen and Georg-August-Unversitat Gottingen.
-- END --
Note to Editors : For more information contact Gary Hill at 512-471-1477.
IMAGE CAPTIONS:
[Image 1:
http://mcdonaldobservatory.org/news/gallery/image.php?id=108]
Spectrum of a Distant Quasar
This chart shows the light given off by superheated material spiraling into
a black hole at the heart of a galaxy 12.7 billion light-years away. This
active galaxy, called a quasar, is known as CFHQS 1641+3755. Because its
light has traveled so far to us, it has lost energy, causing wavelengths to
stretch. The light from neutral hydrogen gas, indicated by the label Ly
alpha here, has stretched from a wavelength of 1216 Angstroms all the way to
8500 Angstroms. (For comparison, the human eye can only see light of
wavelengths up to 6500 Angstroms.) The magnitude of this stretch, or
redshift, is what allows astronomers to calculate the quasars distance. This
quasar is one of only a handful known at such a great distance. This
spectrum was taken with Marcario Low Resolution Spectrograph on the
Hobby-Eberly Telescope at McDonald Observatory. Credit: Gary Hill/Tim
Jones/McDonald Observatory. Credit: Gary Hill/Tim Jones/McDonald Obs.
[Image 2:
http://mcdonaldobservatory.org/news/gallery/image.php?id=36]
Hobby-Eberly Telescope, Aerial View. Credit: Marty Harris/McDonald
Observatory.