Astronomy and Astrophysics for the 1980's, Volume 2 Reports of the Panels (1983) / Chapter Skim
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II. Theoretical Astrophysics
II. Theoretical Astrophysics
Pages 262-285
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From page 262... ...
6. A number of visiting fellowships should be created to encourage astronomers and laboratory astrophysicists to visit institutions where research relevant to astronomy can be pursued.
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From page 263... ...
reciprocal: astronomical observations have provided information on atomic and molecular processes that has not been obtained experimentally and indeed have discovered molecules never seen in the laboratory. There are many such relationships: nuclear matter theory and low-temperature physics and the structure and formation of neutron stars, particle physics and cosmology, and controlled thermonuclear fusion research and spectral .
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From page 264... ...
Other paradigms exist, such as stars powered by accretion onto a neutron star core and the radiative decay of low-mass black holes, which are not strongly indicated by present observations but which we believe to be important issues for the next decade. Often theory lags observations.
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From page 265... ...
Another kind of model building involves attempts to synthesize our understanding of diverse phenomena into global models. m us we use our knowledge of stellar evolution, mass loss from stars, supernova explosions, and interstellar gas dynamics to model our Galaxy as an ecosystem, in which the observed distributions of stars and interstellar matter result from cyclic flows of mass and energy.
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From page 266... ...
The new theoretical principles provide a common ground for such different phenomena as the sPe tra of hot stars, supernovae, ana one emission spectra or quasars. Extensions of radiative transfer theory are also needed to interpret the observations of maser emission from interstellar and circumstellar molecules.
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From page 267... ...
. By the end of the 1970's we knew with some confidence that, for example, black holes are dynamically stable and uniquely described by the Kerr metric, that their collisions produce new black holes and radiate gravitational waves, and that quantum processes cause very small black holes to explode into a shower of photons and other particles.
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From page 268... ...
The binary pulsar has provided the first test of General Relativity ever made on an object outside the solar system and has provided striking evidence for the existence of the quadrupole gravitational radiation predicted by the theory. Shocks in Interstellar Gas.
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From page 269... ...
The x-ray emitting regions of these sources are some of the most exotic environments known to physics; to understand them requires consideration of gas dynamics and new radiative processes in relativistic flows -- for the case of neutron stars, in magnetic fields greater than 1012 gauss. The x-ray burst phenomenon was interpreted as thermonuclear explosions on neutron star surfaces.
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From page 270... ...
This is leading to a quantitative understanding of the major features of observed supernovae in terms of models of an exploding star and to quantitative examination of the sites of and yield from stellar nucleosynthesis. For the 1980's many further problems can be studied, for example, nonspherical collapse, the continued exploration of possible explosion mechanisms, and the nature of the gravitational radiation.
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From page 271... ...
What accounts for the isotopic anomalies in meteorites, interstellar gas, and cosmic rays? What physical processes set the characteristic masses and radii of galaxies?
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From page 272... ...
What powers the winds in the T-Tauri stars? How much energy is liberated as gravitational radiation during gravitational collapse?
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From page 273... ...
What mechanism produces gamma-ray bursts? Are stellar black holes formed only in binaries or from some mass range of isolated stars also?
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From page 274... ...
As we have argued earlier, theory should not be treated as equivalent to one of a group of observational programs but rather as a parallel and interdependent component of scientific research. From a budgetary point of view there must always be theoretical programs that rank with the highest priority observational ones -- after all, we want to understand not just collect data.
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From page 275... ...
Theoretical astrophysics research is also supported by NSF and NASA through the employment of theorists at nationally prominent centers of astronomical research. The current staffing of theorists at a number of such centers is compared with the total (Ph.D.
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From page 276... ...
. The NASA support of theoretical astrophysics including staff theorists at astronomical research centers represents approximately 1.2 percent of the NASA budget for astrophysical science (about $230 million in fiscal year 1979)
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From page 277... ...
The support of theory by NSF at the National Astronomy Centers contrasts sharply with that in other sciences. For example, in high-energy physics the major DOE labs have theory groups that are substantial fractions of the total scientific staffs: 15/103 at Brookhaven; 16/146 at Fermilab; and 26/120 at the Stanford Linear Accelerator Center (SLAC)
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From page 278... ...
There is now a reservoir of well-trained and highly qualified theorists who are in a "holding pattern" of temporary postdoctoral research positions. While one or two years of postdoctoral study has been a desirable tradition for young theorists, the shortage of permanent positions has forced many theorists into their second or even third postdoctoral appointment.
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From page 279... ...
(2) We must create approximately 30 new permanent positions for theorists to meet the challenge posed by the impending explosion of astronomical data.
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From page 280... ...
NASA has made no comparable investment in the development of these basic theoretical understandings, which will suggest new directions in space astronomy or be the analytic tools for understanding the results of the observational programs to which the agency is already committed. As a minimum that is not only consistent with NASA's mission agency status but also seems required by that status is the investment by NASA in basic astrophysical theory at a level compatible with the amount of theory tnat in effect it consumes.
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From page 281... ...
Theory often suggests the way to more meaningful measurements, and theorists should be involved in mission planning and definition as well as data analysis and interpretation of results. RECOMMENDATION II.2: The National Astronomy Centers (e.~., National Radio Astronomy Observatory, National Astronomy and Ionosphere Center, Kitt Peak National
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From page 282... ...
Specifically, we advocate that the ratio of theorists to observers should be on the order of 1:5, roughly comparable with the ratio found in the larger university departments and high-energy physics laboratories. To be fully effective scientifically, the observational programs of the National Centers need the support of a strong theoretical research activity.
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From page 283... ...
As discussed earlier, the increasing role of computers in astrophysical theory predicted by the Greenstein report has now become a reality. However, access by theorists to computing power remains uneven and lags the development of the technology.
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From page 284... ...
Under the present arrangement, which divides astronomy artificially into the subdisciplines of "Stars and Stellar Evolution" and "Galactic and Extragalactic Astronomy," theory suffers. Good theory recognizes no arbitrary boundaries, and theoretical principles and techniques applicable in one area are valuable in the other; indeed, the research of many theorists can be placed equally in each category.
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From page 285... ...
Unfortunately, this fact has not been fully recognized by the funding agencies, because travel for theoretical research cannot be justified in such concrete and immediate terms as travel for observing. Support for the temporary relief from teaching duties should be available to capable theorists; this should be viewed as a routine device to initiate important projects and to increase scientific range and productivity.
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