# Astrophysical APL - Diamonds in the Sky

## Glenn Schneider, Paul Paluzzi and James Webb

### APL89 Conference Proceedings: APL as a Tool of Thought

#### ACM Press, New York, (APL Quote Quad), 19-4, pp. 308.

**ABSTRACT:** Computational astrophysics seeks to develop numerical
models which help elucidate the nature of astronomical systems.
Such
models must not only adequately describe the underlying physics which
give
rise to phenomena that have been observed, but must also be predictive
in asserting what future observations might unfold. Any model
which
is in conflict with physical observations, clearly, must be discarded
or
amended to reflect reality. As a computational modelling tool we
find APL useful for testing astrophysical hypotheses, and extending the
domain of our observationally based knowledge. Using APL to
build,
test, and expand astrophysical models frees the investigator from the
mechanical
drudgery of computer programming, thereby allowing the researcher to
concentrate
on understanding the physical universe.
As a quantitative example of how relatively complex astrophysical
phenomena
can be explored with ease using APL, we have developed a structure
model
for white dwarf stars. The model presented here considers such
effects
as Coulomb interactions between electrons and nucleons, inverse beta
decays,
and the effects of the general theory of relativity on the condition of
hydrostatic equilibrium. This structure model is valid for
zero-temperature
stars of varying chemical compositions, ionic partitions, and central
densities;
and is applicable over a wide range of partial and total degeneracy
regimes.

DOWNLOAD Conference Proceeding Paper: HERE

ACM Portal for Conference: Here

VIEGRAPHS from Presentation:

1. Functional Layering

2. Structure Equations

3. Equation of State

4. Equation of State (continued)

5. Structure Equtions in APL

6. Relativity Parameter

7. Numerical Integration

8. WHITEDWARF model

9. Structure: P/r

10. Structure: m/r

11. Mass vs. Radius

12. Stellar Rotation

13. Uniform Rotation

14. Figures of Equilibrium

15. Rotational Instability

16. Break Up Rotation