Related papers: Rotationally Warm Molecular Hydrogen in the Orion …

We present JWST/MIRI spectra from the Medium-Resolution Spectrometer of IZw18, a nearby dwarf galaxy with a metallicity of $\sim 3$% Solar. Here, we investigate warm molecular hydrogen, H2, observed in spectra extracted in $\sim 120$ pc…

We present far-IR (57-196 mu) spectra of 21 protostars in the Orion molecular clouds, obtained with the Photodetector Array Camera and Spectrometer (PACS) onboard the Herschel Space observatory, as part of the Herschel Orion Protostar…

Molecular hydrogen is the most abundant molecule in the Universe. It is thought that a large portion of H2 forms by association of hydrogen atoms to polycyclic aromatic hydrocarbons (PAHs). We model the influence of PAHs on total H2…

The formation of hydrides by gas-phase reactions between H2 and a heavy element atom is a very selective process. Reactions with ground-state neutral carbon, oxygen, nitrogen, and sulfur atoms are very endoergic and have high energy…

We present a comparative study of the near-infrared (NIR) H$_2$ line emission from five regions near hot young stars: Sharpless 140, NGC 2023, IC 63, the Horsehead Nebula, and the Orion Bar. This emission originates in photodissociation or…

We have mapped the warm molecular gas traced by the H_2 S(0) - H_2 S(5) pure rotational mid-infrared emission lines over a radial strip across the nucleus and disk of M51 (NGC 5194) using the Infrared Spectrograph (IRS) on the Spitzer Space…

We report a detection in the interstellar medium of an infrared transition within the electronic ground state of the deuterated hydrogen molecule, HD. Through a deep integration with the Short-Wavelength-Spectrometer on ISO, the pure…

A new molecular hydrogen cloud has been identified at z = 3.025 in the absorption-line spectrum of the quasar 0347-3819 observed with the UVES spectrograph at the VLT/Kueyen telescope. At the same redshift numerous metal lines and the DI…

Recent Herschel and ALMA observations of Photodissociation Regions (PDRs) have revealed the presence of a high thermal pressure (P ~ 10^7-10^8 K cm-3) thin compressed layer at the PDR surface where warm molecular tracer emission (e.g. CH+,…

I review recent studies of the emission-line regions in Orion and M17. Both have similar geometries, a bubble of hot shocked gas surrounding the central star cluster, with H^+, H^0, and H_2 regions, often referred to as H II regions, PDRs,…

Context. Multitransition CO observations of galaxy centers have revealed that significant fractions of the dense circumnuclear gas have high kinetic temperatures, which are hard to explain by pure photon excitation, but may be caused by…

We study the spatial distribution and chemistry of small hydrocarbons in the Orion Bar PDR. We used the IRAM-30m telescope to carry out a millimetre line survey towards the Orion Bar edge, complemented with ~2'x2' maps of the C2H and c-C3H2…

We use the IRS on Spitzer to observe the southern part of the reflection nebula NGC 2023, including the Southern Ridge, which is a photodissociation region par excellence excited by HD 37903. Five pure-rotational H2 emission lines are…

We have observed the S(0), S(1), S(2), S(3), S(4) and S(5) rotational lines of molecular hydrogen (H2) towards the peak of the photodissociation region (PDR) associated with the reflection nebula NGC 7023. The observed H2 line ratios show…

Observations of OH$^+$ are used to infer the interstellar cosmic ray ionization rate in diffuse atomic clouds, thereby constraining the propagation of cosmic rays through and the shielding by interstellar clouds, as well as the low energy…

We have measured the gas temperature in the IC 63 photodissociation region (PDR) using the S(1) and S(5) pure rotation lines of molecular hydrogen with SOFIA/EXES. We divide the PDR into three regions for analysis based on the illumination…

Vibration-rotation lines of H$_{2}$ from highly excited levels approaching the dissociation limit have been detected at a number of locations in the shocked gas of the Orion Molecular Cloud (OMC-1), including in a Herbig-Haro object near…

We report observations of three rotational transitions of molecular oxygen (O2) in emission from the H2 Peak 1 position of vibrationally excited molecular hydrogen in Orion. We observed the 487 GHz, 774 GHz, and 1121 GHz lines using HIFI on…

We present the detection and analysis of molecular hydrogen emission toward ten interstellar regions in the Large Magellanic Cloud. We examined low-resolution infrared spectral maps of twelve regions obtained with the Spitzer infrared…

Due to its proximity to the Earth and its nearly edge-on geometry, the Orion Bar provides an excellent testbed for detailed models of the structure of HII regions and the surrounding photon-dominated regions. In the present study, a…