Astronomy and Astrophysics Space Science in the Twenty-First Century -- Imperatives for the Decades 1995 to 2015 (1988) / Chapter Skim
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3. Astronomy and Astrophysics in 1995: Expected Status
3. Astronomy and Astrophysics in 1995: Expected Status
Pages 19-35
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From page 19... ...
Such progress will involve the principal elements of the Shuttie-based program, as well as HST, GRO, AXAF, and STRTF, which form the first family of comprehensive observatories in space and have been called "the Great Observatories." These instruments will provide a powerful capability for detailed astrophysical studies at optical, gamma-ray, x-ray, and infrared wavelengths. Thus, the next decade will see space astronomy move strongly from an era of exploration to a program of in-depth study.
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From page 20... ...
Along with this evolution of technical means and scientific aims, the task group foresees two other trends a further shift in emphasis from ground-based to space observations and a continued strengthening of the international base of space astronomy, with the realization of major European and Japanese missions, such as the Roentgen Satellite (ROSAT) , the Infrared Space Observatory (ISO)
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From page 21... ...
The relativistic jet phenomenon was clarified and shown to have alignments over scale factors differing by more than a million. Two puzzling phenomena velocities that apparently exceed the speed of light, and interstellar masers still remain unexplained; both could potentially influence our basic assumptions about physical phenomena in the universe.
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From page 22... ...
Among its major discoveries were dust systems orbiting Vega and many other nearby stars; a "cirrus" cloud component on a galactic scale extending well above and below the galactic plane; two new zodiacal dust bands straddling the ecliptic plane; hosts of infrared sources, which, because of their very Tow luminosities, appear to be solar-type stars in their earliest stages of formation; high infrared fluxes from interacting galaxies; and large numbers of galaxies that are orders of magnitude brighter at infrared wavelengths than in the optical domain and are rivaled in their energy production only by quasars. There are galaxies that at first sight might appear much like our own Milky Way-a spiral galaxy among billions of others.
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From page 23... ...
. The major shortcomings in infrared observational capabilities in the mid-1990s will be the limited angular resolution from space observatories other than HST, the lack of a major submillimeter space observatory, and the absence of milliarcsecond interferometric capability.
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From page 24... ...
If funded adequately, it will by then be equipped with second-generation instruments approaching detector quantum efficiencies of 80 percent over the spectral range 1200 ~ to 2 ,um. By 1995 the Extreme Ultraviolet Explorer (EUVE)
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From page 25... ...
In studies of brighter objects, AXAF will allow high-resolution x-ray spectra to be obtained for the first time on objects as diverse as supernova remnants, accreting neutron stars, black holes, and normal stars. Once again, the exploratory spectroscopic studies carried out with the Einstein Observatory herald the rich potential for discovery and detailed astrophysical measurements that AXAF will conduct.
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From page 26... ...
, to be launched in 1992, will extend the high time-resolution studies of such compact galactic x-ray sources and permit similar studies to still higher photon energies. The internal structure of neutron stars will be probed with sustained observations of x-ray pulsars and bursters, and physical conditior~s in accretion disks will be explored.
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From page 27... ...
and COS-B, following earlier pioneering measurements, have provided maps of the highenergy gamma-ray emission from the galactic plane and an interpretation of the origin and propagation of the cosmic rays. In addition, they have made observations of pulsars as well as other galactic objects, measured the basic properties of extragalactic diffuse gamma radiation, and discovered gamma-ray emission from a quasar.
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From page 28... ...
The field of view of the telescope need not be wide, and an appropriate goal for angular resolution is of the order of 1 to 2 arcmin. A high-resolution nuclear gamma-ray spectrometer would also be needed for the study of the gamma-ray lines from radioactivity in supernova remnants, positron annihilation in the galactic disk and in extragalactic sources, nuclear excitations caused by cosmic rays in dense matter, and nucleosyntheses in extragalactic supernovae.
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From page 29... ...
A continuing series of observations of galactic cosmic rays at higher energies is being conducted on balloons and on the Space Shuttle. These provide important exploratory data, but definitive measurements have to await the availability of spacecraft capable of carrying very large payloads for extended periods of time (years)
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From page 30... ...
The comparison between the compositions of these particle populations will therefore either reveal characteristics of the chemical evolution of the interstellar matter for instance, a continuing metal enrichment or indicate if the solar system composition is atypical, perhaps owing to the admixture of fresh supernova ejecta during its formation. Space Shuttle and Space Station A very large detector to measure elemental abundances and energy spectra of cosmic-ray nuclei at very high energies has been
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From page 31... ...
These measurements will constrain models of galactic particle acceleration by determining, for instance, the energy dependence of the relative abundances of primary cosmic rays (e.g., the iron/carbon ratio)
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From page 32... ...
Tests for the existence of at least a restricted frequency range of gravitational waves will be provided by spacecraft equipped with dual-frequency transponders in distant trajectories throughout the solar system. Passage of a gravitational wave between these spacecraft and Earth should provide a signature in the arrival time of transponder response uniquely identifying the passage of such a wave.
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From page 33... ...
A further complication is the difference between international European missions as distinct from autonomous national European missions. Lumping all these varied efforts together, we then have the following array of instruments:
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From page 34... ...
· Optical Astronomy: The ESA astrometric mission HIPPARCOS will improve optical astrometric accuracy by an order of magnitude and survey about 100,000 stars. It will provide parallaxes for a variety of astrophysical studies including a refined color-luminosity relationship and an improved distance scale based on direct measurements of a few Cepheid and RR Lyrae variables.
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From page 35... ...
. The West German ROSAT mission of 1987 will be followed by a hard x-ray mission (SAX)
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