Spatially resolved images of reactive ions in the Orion Bar

• We report high angular resolution (4.9" X 3.0") images of reactive ions SH+, HOC+, and SO+ toward the Orion Bar photodissociation region (PDR). We used ALMA-ACA to map several rotational lines at 0.8 mm, complemented with multi-line observations obtained with the IRAM 30m telescope. The SH+ and HOC+ emission is restricted to a narrow layer of 2" - to 10" -width (approximate to 800 to 4000AU depending on the assumed PDR geometry) that follows the vibrationally excited H-2(*) emission. Both ions efficiently form very close to the H/H-2 transition zone, at a depth of AV less than or similar to 1 mag into the neutral cloud, where abundant C+, S+, and H-2(*) coexist. SO+ peaks slightly deeper into the cloud. The observed ions have low rotational temperatures (T-rot approximate to 10-30K

Ämnesord

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

Nyckelord

(ISM:) photon-dominated region (PDR)

line: identification

ISM: clouds

astrochemistry

Publikations- och innehållstyp

art (ämneskategori)

ref (ämneskategori)