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"One of the most important programs in astrophysical cosmology is
the determination of the sequence of events which has led to the large
scale structure of the Universe as we know it today. The typical
galaxies which will be observed in the deepest exposures with the
Gemini telescopes emitted their light when the Universe was less than
half its present age and, in many cases, at much earlier times. For
many of the galaxies, multi-object spectrographs will enable their
spectra and redshifts to be determined. The wide spectral coverage
afforded by the Gemini telescopes from the ultraviolet through the
optical to the infrared wavebands will enable detailed studies of the
stellar populations of the faintest galaxies to be obtained. Furthermore,
because of the high angular resolution of the telescopes in optical
and infarared wavebands, the detailed internal structures of galaxies
at these very great distances can be obesrved. These images will
provide crucial evidence about the processes responsible fo the
evolution of sprial and elliptical galaxies and why the galaxies seem
to come in these distinct populations. The Gemini telescopes will
enable the large scale structure of the distribution of galaxies to be
determined at epochs significantly earlier than the present. According
to some theories of the origin of the large-scale structure of the
Universe, the distribution of galaxies should be significantly less
clumpy in the distant past than it is now and we should be able to test this
idea by studying the distribution of faint galaxies. Such studies
should give a definitive answer to the question of whether the galaxies were
formed by a process of hierarchal clustering of low mass objects, of
whether they formed with roughly their present masses in the process
of condensation from the intergalactic gas."
-Dr. Malcolm S. Longair, Chair of the Gemini Board 1994-1995
How did galaxies form and evolve in the Universe? Optical observations
of the individual stars and star clusters in the Milky Way and nearby
galaxies will provide the key to understanding the relation between
stellar populations, chemical enrichment history, and the dynamical
history of present day galaxies in the Universe. The Gemini telescopes
will enable observations of extremely distant galaxies at IR wavelengths,
covering the same rest wavelength range as optical observations of
nearby galaxies. With the light gathering power and excellent image quality
of the telescopes, it will be possible to make direct observations of
the morphology, content, and composition of nascent and adolescent
galaxies. Optical observations will reveal properties of the youngest
stars in such systems. For cases where dust is present, much of the
short wavelength energy emitted by young stars is absorbed and re-radiated
in the thermal infrared.
This program is an example of one that requires broad band spectral
coverage from the ultraviolet to the infrared. It requires excellent
image quality and spectroscopic capability at optical and infrared
wavelengths. It requires wide-field, multi-object capability for
optical spectroscopy. Full sky coverage is also required. For example,
the Magellanic Clouds, the nearest external galaxies, and the center of
our own galaxy are in the southern hemisphere, while M31 and M33, the
nearest spiral galaxies, are in the northern hemisphere.
Image Credits: 1:HST 2:INT 3:HST
Ruth A. Kneale / web@gemini.edu / February 27, 1998