![[NGC6934]](/image_gallery/images/d5/01g02cb.jpg)
A comparison of optical and infrared images of the globular cluster NGC6934, taken by the Gemini North telescope.
Downloadable versions (see
NOAO Conditions of Use):
These images are of the central region of NGC 6934, a globular cluster located
50,000 light-years from Earth. Although this star cluster is very distant,
it is still well within our Galaxy, the Milky Way.
Observations of globular clusters teach us how the first generation of stars
in our Galaxy formed some 12 to 15 billion years ago and how they have evolved
ever since. Globular clusters are extremely dense stellar environments that
typically contain between one hundred thousand to one million stars.
The density of these star cities presents us with a wealth of information on
stars of all sizes but also presents a great challenge - how can we peer into
the very heart of such a dense star cluster?
Gemini, with its excellent image quality, can provide extremely sharp pictures
that deblur and deblend the star images and allow observations right into the
very heart of these oldest stellar environments.
The optical picture on the left is sharp and clear because of the good
atmospheric conditions on Mauna Kea and the excellent optical quality of the
Gemini telescope. Yet NGC 6934 contains so many stars that even the thin
atmosphere above Mauna Kea blurs the starlight enough that the stars overlap
and can no longer be studied individually. The infrared picture on the right
was made with Gemini and the University of Hawaii's Hokupa'a Adaptive Optics
System. Hokupa'a, derived from the Hawaiian name for the north star,
compensates for the remaining blurring of starlight by the atmosphere above
Mauna Kea. The resulting picture is so sharp that individual stars can
easily be seen and studied in detail even in the very heart of this globular
cluster. The resolution of the image on the right is comparable to resolving
the separation between two automobile headlights at 2000 miles!
Adaptive Optics systems use deformable mirrors to correct for the effects of
atmospheric distortions to starlight, resulting in significantly sharper
images. Adaptive Optics will allow Gemini to at times produce sharper
images than is possible with the Hubble Space Telescope. The United States
National Science Foundation has provided significant financial support to
the University of Hawai'i Adaptive Optics Program to obtain these images.
For further information about the Gemini Observatory, please visit
the Gemini WWW site.
Photo Credit: Gemini Observatory, US National Science Foundation, and
the University of Hawaii Institute for Astronomy.
Minimum credit line: Gemini Observatory, US National Science Foundation, and the University of Hawaii Institute for Astronomy.
(for details see Conditions of Use)
584 x 400 38 kb color JPEG
1494 x 1024 192 kb color JPEG
4134 x 2835 1.1 Mb color JPEG
4134 x 2835 11.4 Mb 8-bit color TIFF
4134 x 2835 34.3 Mb 24-bit color TIFF
This picture of the central region of NGC6934 compares the Gemini North
optical image WITHOUT Adaptive Optics (resolution = 0.6 arc seconds FWHM),
to the Gemini North infrared image WITH Adaptive Optics
(resolution = 0.09 arc seconds FWHM).
The second image approaches the theoretical limit for an 8 meter telescope.
The optical image
and the infrared image
are available separately without the graphics added to this picture.
Other examples of the quality of Gemini North can be found in
this image of BD+303639,
and
this image of G45.45+0.06.
Return to:
stars page,
Gemini stars page.
Comments by e-mail to images@noao.edu
