Working Papers Astronomy and Astrophysics Panel Reports (1991) / Chapter Skim
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Infrared Astronomy
Infrared Astronomy
Pages 25-46
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From page 25... ...
INFRARED PANEL Report of the Infrared Pane]
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From page 26... ...
IRO, a national 8-m telescope fully optimized for infrared observations, exploits the remarkably dry and stable atmospheric conditions of the summit of Mauna Kea. Together, SOFIA and IRO span the IR at high angular resolution with more than an order of magnitude increase in sensitivity compared to current ambient temperature telescopes.
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From page 27... ...
It laid the foundation for major scientific advances, impacted all fields of astrophysical research, and made IR observations accessible to the whole astronomical community; about 70% of the IRAS data users are other than infrared astronomers. IRAS discovered disks of particles orbiting nearby mature stars.
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From page 28... ...
The last decade has resulted in an explosion in the breadth and depth of our investigations of the infrared sky, driven by the initial exploitation of infrared observations from the space environment and by advances in the technical maturity of infrared detectors and associated instrumentation. Observational infrared astronomy is now poised to revolutionize our understanding of the most fundamental questions of modern astronomy.
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From page 29... ...
Depending on the redshift of the formation epoch, near to mid-infrared observations will be required to detect the intrinsic ultraviolet luminosity from hot, young stars. IR observations have already demonstrated that extensive star formation in local galaxies is invariably accompanied by dust absorption at UV and optical wavelengths and re-emission in the IR.
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From page 30... ...
In the 1990's we will image molecular clouds with sufficient sensitivity, spatial resolution and spectral resolving power to measure the conditions throughout star-forming clouds, to detect the emission from individual embedded stars, to determine the luminosity function into the substellar range - far below the hydrogen burning limit of about 0.08Mo - and to correlate star formation rates and stellar masses with the cloud properties. The spatial and spectral resolution available at far-infrared and submillimeter wavelengths will enable the detailed study of numerous infalling cores in nearby molecular clouds.
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From page 31... ...
Infrared observations are uniquely capable of detecting thermal emission from not only substellar companions but also isolated substellar objects, which glow faintly in the infrared as their residual heat of formation diffuses away. Isolated brown dwarfs can be detected in nearby space, in molecular clouds and stellar clusters, and, possibly, in the halos of other galaxies.
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From page 32... ...
A cryogenically cooled telescope operating outside the earth's atmosphere, like IRAS, COBE and SIRTF, is free from the limitations of atmospheric and telescope emission and atmospheric absorption. The natural mid-IR background in space, which originates from interplanetary and interstellar dust grains, is at least a million times fainter than that at any groundbased observatory; SIRTF's sensitivity is limited only by the statistical fluctuations in this natural background.
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From page 33... ...
to provide our first unbiased spectroscopic view of the submm regime, while SIRTF will provide the most sensitive submm continuum measurements out to 700 ~m. Antartica offers an intriguing possibility for a ground-based astronomical site with conditions of atmospheric water vapor content and ambient temperature that are much more favorable to IR observations even than those of Mauna Kea.
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From page 34... ...
This gain, coupled with the imaging and spectroscopic power inherent in its large-format infrared detector arrays, will make SIRTF unique for the solution of key astrophysical problems ranging from the doorstep of the solar system to beyond the horizon of our current understanding. SIRTF will be equipped with instruments utilizing modern two dimensional infrared arrays providing w~de-~eld and diffraction limited imaging and spectroscopic capability over most of the IR spectral regime.
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From page 35... ...
SIRTF SCIENCE HIGHLIGHTS SIRTF will make fundamental contributions to virtually all contemporary forefront astrophysical problems. As illustrated in Figures 3 and 4, SIRTF will permit detection and identification of objects as disparate as galaxies at redshifts z>5 and brown dwarfs in the solar neighborhood; and detailed study of problems as different as the relationship between high luminosity infrared galaxies and quasars, and the nature of planetary system debris around nearby stars.
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From page 36... ...
SOFIA SCIENCE HIGHLIGHTS SOFIA's capability for diffraction-limited imaging beyond 30 microns and for high resolution spectroscopy over the entire 1 ,um to 1 mm infrared band will allow studies of the composition, structure, and dynamics of planetary atmospheres, comets, and interstellar gas and dust; the initial luminosity function of stars embedded in nearby molecular clouds; the infall and outflow from protostars; and the nature of the luminosity sources in nearby starburst and AGN galaxies.
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From page 37... ...
The Submillimeter Explorer utilizes a 2.5-m ambient temperature telescope with a liquid-helium cooled complement of instruments designed to obtain complete submillimeter spectra from 100 ,um to 700 ,um for a large number of galactic and extragalactic sources. SMMM will provide our first complete, unbiased spectroscopic view of the submillimeter portion of the electromagnetic spectrum.
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From page 38... ...
SMMM will observe the carbon reservoir species CO and CI and the oxygen reservoir molecules H2O and O2 in a wide variety of gas phase environments, and identify dominant large molecules and small dust grains by observations of vibration-rotation spectra of large linear-chain and polyacetylene molecules and of vibrational modes of polycyclic-aromatic-hydrocarbon dust grains, thus examing the link between the lighter molecules observed at millimeter wavelengths and the small dust grains discovered at shorter infrared wavelengths. In star formation regions, SM~M will enable thermal balance studies in dense protostellar enviroments and molecular shock regions where H2O and hydride molecules dominante the cooling process.
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From page 39... ...
We note also that, as recommended earlier, the NASA IRTF, the dedicated 3-meter infrared telescope located on Mauna Kea, is the logical location at which to take the earliest advantage of infrared optimization techniques. IRO SCIENCE HIGHLIGHTS IRO will provide a level of clarity in imaging never before achieved from the ground, with angular resolution in the near IR an order of magnitude sharper than typically obtained at optical wavelengths.
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From page 40... ...
The survey will explore large scale stellar structure of the Milky Way Galaxy and address basic stellar evolution questions by measuring luminous evolved stars throughout the Milky Way, in the Magellanic Clouds, and other galaxies in the Local Group. 2MASS will dramatically expand our current census of the coolest stars and probe the young stellar population within dozens of dense molecular clouds.
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From page 41... ...
For studies of emission extended on a scale large compared to the angular resolution, SIRTF is some three orders of magnitude more sensitive than any warm telescope. Angular Resolution ~ Figure 8 ~ SIRTF provides diffraction limited angular resolution beyond 3 ~m.
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From page 42... ...
IR imaging interferometry will provide orders of magnitude improved spatial resolution, and qualitatively new kinds of information from very high angular resolution imaging of forming stars and planetary systems, starburst galaxies, and active galaxy nuclei. Interferometric imaging will also allow progress on study of circumstellar environments (YSO's, evolved stars, novae, nebulae)
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From page 43... ...
We recommend that the NASA program for phased exploitation of the far-ir/submillimeter wavelength range be vigorously pursued. The Decade review report of the 1980s included a major 30 ,um to 1000 Am project, the Large Deployable
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From page 44... ...
Fluid dynamic modeling of the flows which occur in, for example: MOD shock waves; "turbulence" in molecular clouds; gravitational collapse of rotating, magnetized clumps in molecular clouds; accretion disks around protostars; outflows associated with star formation; and ionization-shock fronts formed when neutral clouds are exposed to ionizing radiation from newly-formed OB stars. Global models that study the interplay between stars, gas, photons, and gravity which determines the structure of the interstellar medium in a galaxy, the rate of star formation, the initial mass function, conditions in starburst, interacting and merging gas-rich galaxies, AGNs, and QSOs.
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From page 46... ...
OPTICAL/IR FROM GROUND PANEL STEPHEN STROM, University of Massachusetts, Amberst, Chair WALLACE L.W. SARGENT, California Institute of Technology, Vice-Chair SIDNEY WOLFF, National Optical Astronomy Observatories, Vice-Chair MICHAEL F
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