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Small-scale structure in the diffuse interstellar mediumThe initial results of a study to probe the small-scale structure in the diffuse interstellar medium (ISM) through IUE and optical observations of interstellar absorption lines toward both components of resolvable binary stars is reported. The binaries (Kappa CrA, 57 Aql, 59 And, HR 1609/10, 19 Lyn, and Theta Ser) observed with IUE have projected linear separations ranging from 5700 to 700 Au. Except for Kappa CrA, the strengths of the interstellar absorption lines toward both components of these binaries agree to within 10 percent. In the case of Kappa CrA, the optically thin interstellar Mg I and Mn II lines are about 50 percent stronger toward Kappa-2 CrA than Kappa-1 CrA. Higher resolution observations of interstellar Ca II show that this difference is concentrated in the main interstellar component at V(LSR) = 9 + or - 2 km/s. Interestingly, this velocity corresponds to an intervening cloud that may be associated with the prominent Loop I shell in the local ISM. Given the separation (23 arcsec) and distance (120 pc) of Kappa CrA, the line strength variations indicate that this cloud has structure on scales of 2800 AU or less.
Document ID
19910031864
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Meyer, David M.
(Northwestern University Evanston, IL, United States)
Date Acquired
August 15, 2013
Publication Date
November 20, 1990
Publication Information
Publication: Astrophysical Journal, Part 2 - Letters
Volume: 364
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
91A16487
Funding Number(s)
CONTRACT_GRANT: NAG5-1147
Distribution Limits
Public
Copyright
Other

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