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Ample evidence exists regarding supernovae being a major contributor to interstellar dust. In this work, the deepest far-infrared observations of the Crab Nebula are used to revisit the estimation of the dust mass present in this supernova remnant. Images in filters between 70 and 500 μ m taken by the PACS and SPIRE instruments on-board of the Herschel Space Observatory are used. With a novel and automated approach we constructed the spectral energy distribution of the Crab nebula to recover the dust mass. This approach makes use of several image processing techniques (thresholding, morphological processes, contouring, etc..) to objectively separate the nebula from its surrounding background. After subtracting the non-thermal synchrotron component from the integrated fluxes, the spectral energy distribution is found to be best fitted using a single modified blackbody of temperature T = 42.06 ± 1.14 K and a dust mass of Md = 0.056 ± 0.037 M⊙. Our aim in this paper is to highlight the importance of the photometric methods and spectral energy distribution construction on the accuracy of inference for astrophysical parameters.

We present evidence for the impact of a supernova blast‐wave on a molecular cloud located inside the Local Bubble, in the area of interaction with the Sco‐Cen OB association.The evidence comes from the analysis of the line of sight toward the nearby (170 pc) star HD102065, located behind the tail of a cometary‐shaped, infrared cirrus‐cloud which we believe is only 70 pc away from the Sun. The analysis includes numerous transitions of atoms, ions and molecules, in absorption and in emission, in the UV, the optical and the sub‐millimeter.Several peculiar characteristics of the cloud like the spatial structure of its cold phase, the high negative velocities, the high abundance of atoms in excited states and the highly ionized species associated with the highest velocities, as well as the unusually high abundance of small dust particles, are interpreted as the result of the interaction with a supernova shock wave.This line of sight provides an ideal laboratory to study turbulent flows and mixing layers in the ISM.We present evidence for the impact of a supernova blast‐wave on a molecular cloud located inside the Local Bubble, in the area of interaction with the Sco‐Cen OB association.The evidence comes from the analysis of the line of sight toward the nearby (170 pc) star HD102065, located behind the tail of a cometary‐shaped, infrared cirrus‐cloud which we believe is only 70 pc away from the Sun. The analysis includes numerous transitions of atoms, ions and molecules, in absorption and in emission, in the UV, the optical and the sub‐millimeter.Several peculiar characteristics of the cloud like the spatial structure of its cold phase, the high negative velocities, the high abundance of atoms in excited states and the highly ionized species associated with the highest velocities, as well as the unusually high abundance of small dust particles, are interpreted as the result of the interaction with a supernova shock wave.This line of sight provides an ideal laboratory to study turbulent flows and mixing layers in the...

Aims. We model a diffuse molecular cloud present along the line of sight to the star HD 102065. We compare our modeling with observations to test our understanding of physical conditions and chemistry in diffuse molecular clouds. Methods. We analyze an extensive set of spectroscopic observations which characterize the diffuse molecular cloud observed toward HD 102065. Absorption observations provide the extinction curve, H2, C I, CO, CH, and CH+ column densities and excitation. These data are complemented by observations of CII, CO and dust emission. Physical conditions are determined using the Meudon PDR model of UV illuminated gas. Results. We find that all observational results, except column densities of CH, CH+ and H2 in its excited (J > 2) levels, are consistent with a cloud model implying a Galactic radiation field (G~0.4 in Draine's unit), a density of 80 cm-3 and a temperature (60-80 K) set by the equilibrium between heating and cooling processes. To account for excited (J >2) H2 levels column densities, an additional component of warm (~ 250K) and dense (nH>10^4 cm-3) gas within 0.03 pc of the star would be required. This solution reproduces the observations only if the ortho-to-para H2 ratio at formation is 1. In view of the extreme physical conditions and the unsupported requirement on the ortho-to-para ratio, we conclude that H2 excitation is most likely to be accounted for by the presence of warm molecular gas within the diffuse cloud heated by the local dissipation of turbulent kinetic energy. This warm H2 is required to account for the CH+ column density. It could also contribute to the CH abundance and explain the inhomogeneity of the CO abundance indicated by the comparison of absorption and emission spectra., 10 pages, 17 figures. Accepted for publication in Astronomy and Astrophysics. Typos corrected

We present the revised ``Meudon'' model of Photon Dominated Region (PDR code), presently available on the web under the Gnu Public Licence at: http://aristote.obspm.fr/MIS. General organisation of the code is described down to a level that should allow most observers to use it as an interpretation tool with minimal help from our part. Two grids of models, one for low excitation diffuse clouds and one for dense highly illuminated clouds, are discussed, and some new results on PDR modelisation highlighted., accepted in ApJ supp

We use far-UV absorption spectra obtained with FUSE towards three late B stars to study the formation and excitation of H2 in the diffuse ISM. The data interpretation relies on a model of the chemical and thermal balance in photon-illuminated gas. The data constrain well the nR product between gas density and H2 formation rate on dust grains: nR = 1 to 2.2 e-15 s-1. For each line of sight the mean effective H2 density n, assumed uniform, is obtained by the best fit of the model to the observed N(J=1)/N(J=0) ratio, since the radiation field is known. Combining n with the nR values, we find similar H2 formation rates for the three stars of about R = 4 e-17 cm3/s. Because the target stars do not interact with the absorbing matter we can show that the H2 excitation in the J>2 levels cannot be accounted for by the UV pumping of the cold H2 but implies collisional excitation in regions where the gas is much warmer. The existence of warm H2 is corroborated by the fact that the star with the largest column density of CH+ has the largest amount of warm H2., 7 pages, 4 figures, to be published in Astronomy & Astrophysics