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 molecules

interstellar matter


Ronald J. Allen

Space Telescope Science Institute (STScI)

M. I. Rodriguez

CSIC - Instituto de Astrofísica 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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