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Some Observational Limitations of Extinction Measurements in the Rocket Ultraviolet

Published online by Cambridge University Press:  08 February 2017

Jan Borgman
Jan Borgman*
Affiliation:
Kapteyn Observatory Roden, The Netherlands

Extract

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Even Before any Measurement of stellar fluxes in the ultraviolet had been obtained, predictions were being made on the basis of stellar atmosphere models. At the moment, it seems that such com-putations (for example, see ref. 1) are in reasonable agreement with actual observations from rockets (ref. 2) in the spectral region down to about 2000 Å. At shorter wavelengths it is necessary to take into account the appreciable blanketing by spectral lines which unavoidably is present in the transmission bands of any wide-band photometric system, even in the case of early B stars, as has been shown in reference 3.

It must be anticipated that the reduction of extinction measurements in the UV from spaceborne instruments will follow the same procedure that has been used so far: stars with the same intrinsic energy distribution but with different amounts of reddening material in the line of sight are compared, the difference in energy distribution being attributed to the wavelength dependence of interstellar extinction.

Type
Research Article
Information
International Astronomical Union Colloquium , Volume 7: Proper Motions , August 1965 , pp. 11 - 16
Copyright
Copyright © Kluwer Academic Publishers 1965

References

1. Underhill, A. B.: A Program for Computing Early-Type Model Atmospheres and Testing the Flux Integral. Pub. Dominion Astrophys. Obs., vol. 11, 1962, p. 433.Google Scholar
2. Strömgren, B.: Comparison of Observed and Theoretically Calculated Intensities in the Continuous Spectra of Main-Sequence B Stars. Rev. Mod. Phys., vol. 36, 1964, p. 532.10.1103/RevModPhys.36.532CrossRefGoogle Scholar
3. Mihalas, D. M.; and Morton, D. C.: A Model for a B1V Star with Line Blanketing. Astrophys. J., vol. 142, 1965, p. 253.10.1086/148281CrossRefGoogle Scholar
4. Boggess, A.; and Borgman, J.: Interstellar Extinction in the Middle Ultraviolet. Astrophys. J., vol. 140, 1964, p. 1636.10.1086/148079CrossRefGoogle Scholar
Hiltner, W. A.: Photoelectric, Polarization and Spectrographic Observations of O and B Stars. Astrophys. J. Suppl. Ser., vol. 2, 1956, p. 389.10.1086/190029CrossRefGoogle Scholar