Context. Solid interstellar CO2 is an abundant component of ice dust mantles. Its ubiquity towards quiescent molecular clouds, as well as protostellar envelopes, has recently been confirmed by the IRS (InfraRed Spectrograph) aboard the Spitzer Space Telescope. Although it has been shown that CO2 cannot be efficiently formed in the gas phase, the CO2 surface formation pathway is still unclear. T...

The 4.62μm absorption band, observed along the line-of-sight towards various young stellar objects, is generally used as a qualitative indicator for energetic processing of interstellar ice mantles. This interpretation is based on the excellent fit with OCN−, which is readily formed by ultraviolet (UV) or ion-irradiation of ices containing H2O, CO and NH3. However, the assignment requires both ...

We present experimental results obtained from photoionization and photodissociation processes of abundant interstellar CH3-X type organic molecules like methanol (CH3OH), methylamine (CH3NH2) and acetonitrile (CH3CN) as alternative route for the production of H+3 in interstellar and star forming environments. The measurements were taken at the Brazilian Synchrotron Light Laboratory (LNLS), empl...

Observations suggest that star formation occurs in only one or two crossing times for a range of scales spanning a factor of ∼ 1000. These observations include (1) measurements of embedded cluster ages in comparison with the cloud core dynamical times, (2) measurements of the age difference versus separation for clusters in the Large Magellanic Clouds in comparison with the crossing time versus...

Optical absorption line observations of interstellar CH+ andCHare presented towards the southernOBassociations CMa OB1,NGC 2439,Vela OB1,NGC 4755, andCen OB1.A total of 5–11 stars per associationwere observed, with visual extinctions ranging fromAV = 0.5–4.5 mag. The derived CH+ and CH velocities agree within the measurement errors. Towards a particular association, the CH+ column densityN (CH+...

We present a power spectrum analysis of the Herschel-SPIRE observations of the Polaris flare, a high Galactic latitude cirrus cloud midway between the diffuse and molecular phases. The SPIRE images of the Polaris flare reveal for the first time the structure of the diffuse interstellar medium down to 0.01 parsec over a 10 square degrees region. These exceptional observations highlight the highl...

1. INTRODUCTION H 3 + is of fundamental importance to interstellar chemistry both because it is a hydrogenic species (and >90% of all nuclei in the universe are hydrogen nuclei; see Figure 1) and because it serves as the universal protonator, initiating a chain of ion-neutral reactions that is responsible for the formation of most interstellar molecules. The chemistry of H 3 + in dense (molecul...