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Ratio of extinction to reddening for interstellar matter using galaxies. I. A limit on the neutral extinction from photometry of the 3C 129 group

Journal Article · · Publ. Astron. Soc. Pac., v. 87, no. 520, pp. 853-857
DOI:https://doi.org/10.1086/129859· OSTI ID:4007705
The ratio of total extinction to reddening of interstellar matter has been determined by a new method applied to galaxies in the highly obscured 3C 129 and 3C 129.1 group (l = 160⁰, b = 0⁰). The difference between the observed magnitude of the first-ranked group member and the magnitude calculated from the redshift-apparent magnitude (Hubble) diagram (at the known redshift of the group) is the total extinction Av to within the sigma(Mv) that applies to the first-ranked cluster member. Comparison of the observed color with the known intrinsic color of giant E galaxies gives E(B--V), and therefore R. Photometry of the 3C 129 group gives R identical with Av/E(B--V) = 3.72 +- 0.32(sigma). Correction for the finite bandwidth of the BV system gives R (O star base) = 3.35 +- 0.29 (sigma). Comparison with R determined from the color- difference method gives a limit for the fraction of neutral-to-selective extinction of f = A/sub v/ (neutral)/A/sub v/ (selective) = 0.10 +- 0.15(sigma) which is a null result (f = 0) to within the statistics. Hence, no neutral extinction has been detected at the 1 sigma level of the experiment. Use of the method on many additional groups of galaxies is expected to substantially reduce the error of this limit. (auth)
Research Organization:
Originating Research Org. not identified
Sponsoring Organization:
USDOE
NSA Number:
NSA-33-027065
OSTI ID:
4007705
Journal Information:
Publ. Astron. Soc. Pac., v. 87, no. 520, pp. 853-857, Journal Name: Publ. Astron. Soc. Pac., v. 87, no. 520, pp. 853-857; ISSN PASPA
Country of Publication:
United States
Language:
English