Faint extended OH emission from the local interstellar medium in the direction l ≈ 108°, b ≈ 5°
Artikel i vetenskaplig tidskrift, 2012

We have mapped faint 1667 OH line emission (TA ≈ 20-40 mK in our ≈30' beam) along many lines of sight in the Galaxy covering an area of ≈4° × 4° in the general direction of l ≈ 108°, b ≈ 5°. The OH emission is widespread, similar in extent to the local H I (r lsim 2 kpc) both in space and in velocity. The OH profile amplitudes show a good general correlation with those of H I in spectral channels of ≈1 km s–1; this relation is described by TA (OH) ≈1.50 × 10–4 TB (H I) for values of TB (H I) lsim 60-70 K. Beyond this the H I line appears to "saturate," and few values are recorded above ≈90 K. However, the OH brightness continues to rise, by a further factor ≈3. The OH velocity profiles show multiple features with widths typically 2-3 km s–1, but less than 10% of these features are associated with CO(1-0) emission in existing surveys of the area smoothed to comparable resolution.

interstellar matter

interstellar molecules


Ronald J. Allen

Space Telescope Science Institute (STScI)

M. I. Rodriguez

Instituto de Astrofisica de Andalucía (IAA)

John H Black

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

Roy Booth

Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium

Astronomical Journal

0004-6256 (ISSN) 1538-3881 (eISSN)

Vol. 143 4 Article 97, pp. 1-8 97


Astronomi, astrofysik och kosmologi


Grundläggande vetenskaper


Onsala rymdobservatorium



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