Faint extended OH emission from the local interstellar medium in the direction l ≈ 108°, b ≈ 5°
Journal article, 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

Author

Ronald J. Allen

Space Telescope Science Institute (STScI)

M. I. Rodriguez

Institute of Astrophysics of Andalusia (IAA)

John H Black

Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics

Roy Booth

Chalmers, Earth and Space Sciences, Onsala Space Observatory

Astronomical Journal

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

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

Subject Categories

Astronomy, Astrophysics and Cosmology

Roots

Basic sciences

Infrastructure

Onsala Space Observatory

DOI

10.1088/0004-6256/143/4/97

More information

Latest update

4/1/2021 1