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On the λ4430 Absorbers in, “Normal” and in Perturbed Clouds

Published online by Cambridge University Press:  08 February 2017

Kurt Dressler*
Affiliation:
Princeton University, Princeton, New Jersey

Extract

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Regions Perturbed By Early-Type Stars are characterized by the occurrence of high Ca II velocities and an increase in the abundance ratio Ca II/Na I (ref. 1), by a decrease in the λ4430 absorption to color excess (ref. 2), and possibly by a deficiency of small relative to large grains (large values of the ratio of total extinction to color excess, A/E). According to reference 3, the grain temperatures in the same regions are expected to be higher, and therefore may lead to selective evaporation of the smallest grains. Since these observations may be connected by way of λ4430 absorption originating in very small grains, it is of interest to compare the value of nf (number of absorbers times flvalue) of the λ4430 absorbers with the number of molecules nmol in the grains responsible for extinction in the visible.

Type
Research Article
Copyright
Copyright © Kluwer Academic Publishers 1965

References

1. Routly, P.; and Spitzer, L. Jr.: A Comparison of Components in Interstellar Sodium and Calcium. Astrophys. J., vol. 115, 1952, p. 227.CrossRefGoogle Scholar
2. Stoeckly, R.; and Dressler, K.: On the Interstellar λ4430 Line. Astrophys. J., vol. 139, 1964, pp. 240247.10.1086/147750CrossRefGoogle Scholar
3. Greenherg, J. M.; and Lichtenstew, P. R.: Absorption Lines Produced in Interstellar Grains. Astron. J., vol. 68, 1963, p. 279.10.1086/109093CrossRefGoogle Scholar