The interstellar medium of galaxies is the reservoir out of which stars are born and into
which stars inject newly created elements as they age. The physical properties of the …

▪ Abstract All neutral atomic hydrogen gas and a large fraction of the molecular gas in the
Milky Way Galaxy and external galaxies lie in PDRs, and PDRs are the origin of most of the …

Recombination lines at radio wavelengths have been-and still are-a pow erful tool for
modern astronomy. For more than thirty years they have allowed astronomers to probe the …

The large-scale distribution of the CI (3 P 1–3 P 0, 492 GHz) emission line from Orion A and
B giant molecular clouds has been imaged with the Mount Fuji submillimeter-wave …

Context. L1630 in the Orion B molecular cloud, which includes the iconic Horsehead
Nebula, illuminated by the star system σ Ori, is an example of a photodissociation region …

The chemical structure of neutral clouds in low-metallicity environments is examined, with
particular emphasis on the H to H 2 and C+ to CO transitions. We observed near-IR H 2 (1 …

We present 15–20 μm spectral maps toward the reflection nebula NGC 2023 obtained with
the Infrared Spectrograph in short-wavelength, high-resolution mode on board the Spitzer …

Context. We analyze the NGC 2024 Hii region and molecular cloud interface using [12 Cii]
and [13 Cii] observations. Aims. We attempt to gain insight into the physical structure of the …

We present ISOCAM observations (5-18 μm) of the southern part of Orion B, including the
reflection nebula NGC 2023 and the Horsehead nebula illuminated by the B star HD 37903 …

Abstract Model calculations for the photon-dominated region S 140 are presented. The
overall geometry and an inhomogeneous density distribution are incorporated and the …