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201. Hypersensitivity and bifurcations in dense cloud chemistry: zeta_He/zeta_H2 a new control parameter

Author

Wakelam, Valentine, Herbst, E., Selsis, Franck, Massacrier, Gérard, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Ohio State University [Columbus] (OSU), Department of Physics, Departments of Astronomy and Chemistry, Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Pomies, Marie-Paule, Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [PHYS.ASTR.CO] Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], [SDU.ASTR] Sciences of the Universe [physics]/Astrophysics [astro-ph]
Abstract

intervention; International audience; Theme : Modelling environments

Published
2007

203. Polycyclic aromatic hydrocarbons, carbon nanoparticles and the diffuse interstellar bands - Discussion

Author

Sarre, P., Crovisier, Kaiser, R. I., Chakrabarti, S., Richards, A. M. S., van Dishoeck, E. F., Herbst, E., Rowe, B. R., Semenov, D. A., Owen, T. C., Balucani, Nadia, Minard, R. D., Ehrenfreund, P., Kallenbach, R., Matthews, C., Smith, I. W. M., Sims, I. R., Mitchell, J. B. A., Wickham, A. J., de Bergh, C. M., Lintott, C. J., Dalgarno, A., Le Picard, S., Berteloite, C., Canosa, A., Black, J. H., Pino, T., Duley, W. W., Brechignac, P., Cox, N. L. J., Biennier, L., and Linnartz, H.

Subjects
astrochimica
Published
2006

204. Searching for sulphur polymers in young protostars with Herschel and ALMA

Author

Wakelam, Valentine, Caselli, P., Ceccarelli, C., Herbst, E., Mascetti, J., Castets, Alain, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1, INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Ohio State University [Columbus] (OSU), and Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB)

Subjects
[PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], [SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], ALMA, Low Mass Star Formation, Astrochemistry
Abstract

ISBN: 92-9092-855-7; International audience; Sulphur is a long-standing problem in the chemistry of the interstellar medium. This element is highly depleted on interstellar grains in dense sources but in an unobserved form. We have started to develop new clues regarding the form of the depleted sulphur using detailed modelling of the sulphur chemistry and comparisons with observations (Wakelam et al. 2004). This previous study underlined the possibility for sulphur to be depleted on grains in a polymeric form from S to S8 in complexity. Some of the lines of these species can be observed with ALMA and will require the high ALMA sensitivity and spatial resolution to be detected. In this contribution we discuss how possible ALMA observations could help to give constraints on the abundance of S-polymers. Finding these species would be an important step inthe understanding of the chemistry in both molecular clouds and protostars.

Published
2005

209. Upper limits to interstellar NH+and para-NH2−abundances

Author

Persson, C. M., primary, Hajigholi, M., additional, Hassel, G. E., additional, Olofsson, A. O. H., additional, Black, J. H., additional, Herbst, E., additional, Müller, H. S. P., additional, Cernicharo, J., additional, Wirström, E. S., additional, Olberg, M., additional, Hjalmarson, Å., additional, Lis, D. C., additional, Cuppen, H. M., additional, Gerin, M., additional, and Menten, K. M., additional

Published
2014
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212. Astrochemistry: Synthesis and modelling

Author

Smith, I.W.M., Cockell, C.S., Leach, S., Wakelam, V., Cuppen, H.M., Herbst, E., Smith, I.W.M., Cockell, C.S., Leach, S., Wakelam, V., Cuppen, H.M., and Herbst, E.

Abstract

Item does not contain fulltext

Published
2013

215. Chemistry of C-3 and carbon chain molecules in DR21(OH)

Author

Mookerjea, B., Hassel, G. E., Gerin, M., Giesen, T., Stutzki, J., Herbst, E., Black, J. H., Goldsmith, P. F., Menten, K. M., Krelowski, J., De Luca, M., Csengeri, T., Joblin, C., Kazmierczak, M., Schmidt, M., Goicoechea, J. R., Cernicharo, J., Mookerjea, B., Hassel, G. E., Gerin, M., Giesen, T., Stutzki, J., Herbst, E., Black, J. H., Goldsmith, P. F., Menten, K. M., Krelowski, J., De Luca, M., Csengeri, T., Joblin, C., Kazmierczak, M., Schmidt, M., Goicoechea, J. R., and Cernicharo, J.

Abstract

Context. C-3 is the smallest pure carbon chain detected in the dense environment of star-forming regions, although diatomic C-2 is detected in diffuse clouds. Measurement of the abundance of C-3 and the chemistry of its formation in dense star-forming regions has remained relatively unexplored. Aims. We aim to identify the primary C-3 formation routes in dense star-forming regions following a chemical network producing species like CCH and c-C3H2 in the star-forming cores associated with DR21(OH), a high-mass star-forming region. Methods. We observed velocity resolved spectra of four ro-vibrational far-infrared transitions of C-3 between the vibrational ground state and the low-energy nu(2) bending mode at frequencies between 1654-1897 GHz using HIFI on board Herschel, in DR21(OH). Several transitions of CCH and c-C3H2 were also observed with HIFI and the IRAM 30 m telescope. Rotational temperatures and column densities for all chemical species were estimated. A gas and grain warm-up model was used to obtain estimates of densities and temperatures of the envelope. The chemical network in the model was used to identify the primary C-3 forming reactions in DR21(OH). Results. We detected C-3 in absorption in four far-infrared transitions, P(4), P(10), Q(2), and Q(4). The continuum sources MM1 and MM2 in DR21(OH), though spatially unresolved, are sufficiently separated in velocity to be identified in the C-3 spectra. All C-3 transitions are detected from the embedded source MM2 and the surrounding envelope, whereas only Q(4) and P(4) are detected toward the hot core MM1. The abundance of C-3 in the envelope and MM2 is similar to 6 x 10(-10) and similar to 3 x 10(-9), respectively. For CCH and c-C3H2, we only detect emission from the envelope and MM1. The observed CCH, C-3 and c-C3H2 abundances are most consistent with a chemical model with n(H2) similar to 5 x 10(6) cm(-3), a post-warm-up dust temperature T-max = 30 K, and a time of similar to 0.7-3 Myr. Conclusions. Po

Published
2012

216. Herschel observations of Extra-Ordinary Sources: Methanol as a probe of physical conditions in Orion KL

Author

Wang, S., Bergin, E. A., Crockett, N. R., Goldsmith, P. F., Lis, D. C., Pearson, J. C., Schilke, P., Bell, T. A., Comito, C., Blake, G. A., Caux, E., Ceccarelli, C., Cernicharo, J., Daniel, F., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Gerin, M., Giesen, T. F., Goicoechea, J. R., Gupta, H., Herbst, E., Joblin, C., Johnstone, D., Langer, W. D., Latter, W. B., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Muller, H. S. P., Murphy, J. A., Neufeld, D. A., Ossenkopf, V., Perault, M., Phillips, T. G., Plume, R., Qin, S. -L., Schlemmer, S., Stutzki, J., Trappe, N., van der Tak, F. F. S., Vastel, C., Yorke, H. W., Yu, S., Zmuidzinas, J., Wang, S., Bergin, E. A., Crockett, N. R., Goldsmith, P. F., Lis, D. C., Pearson, J. C., Schilke, P., Bell, T. A., Comito, C., Blake, G. A., Caux, E., Ceccarelli, C., Cernicharo, J., Daniel, F., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Gerin, M., Giesen, T. F., Goicoechea, J. R., Gupta, H., Herbst, E., Joblin, C., Johnstone, D., Langer, W. D., Latter, W. B., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Muller, H. S. P., Murphy, J. A., Neufeld, D. A., Ossenkopf, V., Perault, M., Phillips, T. G., Plume, R., Qin, S. -L., Schlemmer, S., Stutzki, J., Trappe, N., van der Tak, F. F. S., Vastel, C., Yorke, H. W., Yu, S., and Zmuidzinas, J.

Abstract

We have examined methanol emission from Orion KL with of the {\em Herschel}/HIFI instrument, and detected two methanol bands centered at 524 GHz and 1061 GHz. The 524 GHz methanol band (observed in HIFI band 1a) is dominated by the isolated $\Delta$J$=$0, K$=-4\rightarrow$-3, v$_t$$=$0 Q branch, and includes 25 E-type and 2 A-type transitions. The 1061 GHz methanol band (observed in HIFI band 4b) is dominated by the $\Delta$J$=$0, K$=7\rightarrow$6, v$_t$$=$0 Q branch transitions which are mostly blended. We have used the isolated E-type v$_t$$=$0 methanol transitions to explore the physical conditions in the molecular gas. With HIFI's high velocity resolution, the methanol emission contributed by different spatial components along the line of sight toward Orion KL (hot core, low velocity flow, and compact ridge) can be distinguished and studied separately. The isolated transitions detected in these bands cover a broad energy range (upper state energy ranging from 80 K to 900 K), which provides a unique probe of the thermal structure in each spatial component. The observations further show that the compact ridge is externally heated. These observations demonstrate the power of methanol lines as probes of the physical conditions in warm regions in close proximity to young stars., Comment: 8 pages, 9 figures, accepted for publication in Astronomy & Astrophysics

Published
2011
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217. The Impact of Recent Advances in Laboratory Astrophysics on our Understanding of the Cosmos

Author

Savin, D. W., Brickhouse, N. S., Cowan, J. J., Drake, R. P., Federman, S. R., Ferland, G. J., Frank, A., Gudipati, M. S., Haxton, W. C., Herbst, E., Profumo, S., Salama, F., Ziurys, L. M., Zweibel, E. G., Savin, D. W., Brickhouse, N. S., Cowan, J. J., Drake, R. P., Federman, S. R., Ferland, G. J., Frank, A., Gudipati, M. S., Haxton, W. C., Herbst, E., Profumo, S., Salama, F., Ziurys, L. M., and Zweibel, E. G.

Abstract

An emerging theme in modern astrophysics is the connection between astronomical observations and the underlying physical phenomena that drive our cosmos. Both the mechanisms responsible for the observed astrophysical phenomena and the tools used to probe such phenomena - the radiation and particle spectra we observe - have their roots in atomic, molecular, condensed matter, plasma, nuclear and particle physics. Chemistry is implicitly included in both molecular and condensed matter physics. This connection is the theme of the present report, which provides a broad, though non-exhaustive, overview of progress in our understanding of the cosmos resulting from recent theoretical and experimental advances in what is commonly called laboratory astrophysics. This work, carried out by a diverse community of laboratory astrophysicists, is increasingly important as astrophysics transitions into an era of precise measurement and high fidelity modeling., Comment: 61 pages. 11 figures; to appear in Reports on Progress in Physics

Published
2011
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218. Herschel observations of EXtra-Ordinary Sources (HEXOS) : detecting spiral arm clouds by CH absorption lines

Author

Qin, S. -L, Schilke, P., Comito, C., Moeller, T., Rolffs, R., Mueller, H. S. P., Belloche, A., Menten, K. M., Lis, D. C., Phillips, T. G., Bergin, E. A., Bell, T. A., Crockett, N. R., Blake, G. A., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Daniel, F., Dubernet, M. -L, Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Herbst, E., Joblin, C., Johnstone, D., Langer, W. D., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Morris, P., Murphy, J. A., Neufeld, D. A., Ossenkopf, V., Pagani, L., Pearson, J. C., Perault, M., Plume, R., Salez, M., Schlemmer, S., Stutzki, J., Trappe, N., van der Tak, F. F. S., Vastel, C., Wang, S., Yorke, H. W., Yu, S., Zmuidzinas, J., Boogert, A., Guesten, R., Hartogh, P., Honingh, N., Karpov, A., Kooi, J., Krieg, J. -M, Schieder, R., Diez-Gonzalez, M. C., Bachiller, R., Martin-Pintado, J., Baechtold, W., Olberg, M., Nordh, Lennart H., Gill, J. L., Chattopadhyay, G., Qin, S. -L, Schilke, P., Comito, C., Moeller, T., Rolffs, R., Mueller, H. S. P., Belloche, A., Menten, K. M., Lis, D. C., Phillips, T. G., Bergin, E. A., Bell, T. A., Crockett, N. R., Blake, G. A., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Daniel, F., Dubernet, M. -L, Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Herbst, E., Joblin, C., Johnstone, D., Langer, W. D., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Morris, P., Murphy, J. A., Neufeld, D. A., Ossenkopf, V., Pagani, L., Pearson, J. C., Perault, M., Plume, R., Salez, M., Schlemmer, S., Stutzki, J., Trappe, N., van der Tak, F. F. S., Vastel, C., Wang, S., Yorke, H. W., Yu, S., Zmuidzinas, J., Boogert, A., Guesten, R., Hartogh, P., Honingh, N., Karpov, A., Kooi, J., Krieg, J. -M, Schieder, R., Diez-Gonzalez, M. C., Bachiller, R., Martin-Pintado, J., Baechtold, W., Olberg, M., Nordh, Lennart H., Gill, J. L., and Chattopadhyay, G.

Abstract

We have observed CH absorption lines (J = 3/2, N = 1 <- J = 1/2, N = 1) against the continuum source Sgr B2(M) using the Herschel/HIFI instrument. With the high spectral resolution and wide velocity coverage provided by HIFI, 31 CH absorption features with different radial velocities and line widths are detected and identified. The narrower line width and lower column density clouds show "spiral arm" cloud characteristics, while the absorption component with the broadest line width and highest column density corresponds to the gas from the Sgr B2 envelope. The observations show that each "spiral arm" harbors multiple velocity components, indicating that the clouds are not uniform and that they have internal structure. This line-of-sight through almost the entire Galaxy offers unique possibilities to study the basic chemistry of simple molecules in diffuse clouds, as a variety of different cloud classes are sampled simultaneously. We find that the linear relationship between CH and H-2 column densities found at lower AV by UV observations does not continue into the range of higher visual extinction. There, the curve flattens, which probably means that CH is depleted in the denser cores of these clouds., authorCount :70

Published
2010
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219. Reversal of infall in SgrB2(M) revealed by Herschel/HIFI observations of HCN lines at THz frequencies

Author

Rolffs, R., Schilke, P., Comito, C., Bergin, E. A., van der Tak, F. F. S., Lis, D. C., Qin, S. -L, Menten, K. M., Guesten, R., Bell, T. A., Blake, G. A., Caux, E., Ceccarelli, C., Cernicharo, J., Crockett, N. R., Daniel, F., Dubernet, M. -L, Emprechtinger, M., Encrenaz, P., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Herbst, E., Joblin, C., Johnstone, D., Langer, W. D., Latter, W. D., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Morris, P., Mueller, H. S. P., Murphy, J. A., Ossenkopf, V., Pearson, J. C., Perault, M., Phillips, T. G., Plume, R., Schlemmer, S., Stutzki, J., Trappe, N., Vastel, C., Wang, S., Yorke, H. W., Yu, S., Zmuidzinas, J., Diez-Gonzalez, M. C., Bachiller, R., Martin-Pintado, J., Baechtold, W., Olberg, M., Nordh, Lennart H., Gill, J. J., Chattopadhyay, G., Rolffs, R., Schilke, P., Comito, C., Bergin, E. A., van der Tak, F. F. S., Lis, D. C., Qin, S. -L, Menten, K. M., Guesten, R., Bell, T. A., Blake, G. A., Caux, E., Ceccarelli, C., Cernicharo, J., Crockett, N. R., Daniel, F., Dubernet, M. -L, Emprechtinger, M., Encrenaz, P., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Herbst, E., Joblin, C., Johnstone, D., Langer, W. D., Latter, W. D., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Morris, P., Mueller, H. S. P., Murphy, J. A., Ossenkopf, V., Pearson, J. C., Perault, M., Phillips, T. G., Plume, R., Schlemmer, S., Stutzki, J., Trappe, N., Vastel, C., Wang, S., Yorke, H. W., Yu, S., Zmuidzinas, J., Diez-Gonzalez, M. C., Bachiller, R., Martin-Pintado, J., Baechtold, W., Olberg, M., Nordh, Lennart H., Gill, J. J., and Chattopadhyay, G.

Abstract

Aims. To investigate the accretion and feedback processes in massive star formation, we analyze the shapes of emission lines from hot molecular cores, whose asymmetries trace infall and expansion motions. Methods. The high-mass star forming region SgrB2(M) was observed with Herschel/HIFI (HEXOS key project) in various lines of HCN and its isotopologues, complemented by APEX data. The observations are compared to spherically symmetric, centrally heated models with density power-law gradient and different velocity fields (infall or infall+expansion), using the radiative transfer code RATRAN. Results. The HCN line profiles are asymmetric, with the emission peak shifting from blue to red with increasing J and decreasing line opacity (HCN to (HCN)-C-13). This is most evident in the HCN 12-11 line at 1062 GHz. These line shapes are reproduced by a model whose velocity field changes from infall in the outer part to expansion in the inner part. Conclusions. The qualitative reproduction of the HCN lines suggests that infall dominates in the colder, outer regions, but expansion dominates in the warmer, inner regions. We are thus witnessing the onset of feedback in massive star formation, starting to reverse the infall and finally disrupting the whole molecular cloud. To obtain our result, the THz lines uniquely covered by HIFI were critically important., authorCount :57[

Published
2010
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220. Herschel spectral surveys of star- forming regions Overview of the 555-636 GHz range

Author

Ceccarelli, C., Bacmann, A., Boogert, A., Caux, E., Dominik, C., Lefloch, B., Lis, D., Schilke, P., van der Tak, F., Caselli, P., Cernicharo, J., Codella, C., Comito, C., Fuente, A., Baudry, A., Bell, T., Benedettini, M., Bergin, E. A., Blake, G. A., Bottinelli, S., Cabrit, S., Castets, A., Coutens, A., Crimier, N., Demyk, K., Encrenaz, P., Falgarone, E., Gerin, M., Goldsmith, P. F., Helmich, F., Hennebelle, P., Henning, T., Herbst, E., Hily-Blant, P., Jacq, T., Kahane, C., Kama, M., Klotz, A., Langer, W., Lord, S., Lorenzani, A., Maret, S., Melnick, G., Neufeld, D., Nisini, B., Pacheco, S., Pagani, L., Parise, B., Pearson, J., Phillips, T., Salez, M., Saraceno, P., Schuster, K., Tielens, X., van der Wiel, M. H. D., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wyrowski, F., Yorke, H., Liseau, R., Olberg, M., Szczerba, R., Benz, A. O., Melchior, M., Ceccarelli, C., Bacmann, A., Boogert, A., Caux, E., Dominik, C., Lefloch, B., Lis, D., Schilke, P., van der Tak, F., Caselli, P., Cernicharo, J., Codella, C., Comito, C., Fuente, A., Baudry, A., Bell, T., Benedettini, M., Bergin, E. A., Blake, G. A., Bottinelli, S., Cabrit, S., Castets, A., Coutens, A., Crimier, N., Demyk, K., Encrenaz, P., Falgarone, E., Gerin, M., Goldsmith, P. F., Helmich, F., Hennebelle, P., Henning, T., Herbst, E., Hily-Blant, P., Jacq, T., Kahane, C., Kama, M., Klotz, A., Langer, W., Lord, S., Lorenzani, A., Maret, S., Melnick, G., Neufeld, D., Nisini, B., Pacheco, S., Pagani, L., Parise, B., Pearson, J., Phillips, T., Salez, M., Saraceno, P., Schuster, K., Tielens, X., van der Wiel, M. H. D., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wyrowski, F., Yorke, H., Liseau, R., Olberg, M., Szczerba, R., Benz, A. O., and Melchior, M.

Abstract

High resolution line spectra of star-forming regions are mines of information: they provide unique clues to reconstruct the chemical, dynamical, and physical structure of the observed source. We present the first results from the Herschel key project " Chemical HErschel Surveys of Star forming regions", CHESS. We report and discuss observations towards five CHESS targets, one outflow shock spot and four protostars with luminosities bewteen 20 and 2 x 105 L similar to : L1157-B1, IRAS 16293-2422, OMC2-FIR4, AFGL 2591, and NGC 6334I. The observations were obtained with the heterodyne spectrometer HIFI on board Herschel, with a spectral resolution of 1 MHz. They cover the frequency range 555-636 GHz, a range largely unexplored before the launch of the Herschel satellite. A comparison of the five spectra highlights spectacular differences in the five sources, for example in the density of methanol lines, or the presence./absence of lines from S-bearing molecules or deuterated species. We discuss how these differences can be attributed to the different star-forming mass or evolutionary status., authorCount :66

Published
2010
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221. Reaction Networks For Interstellar Chemical Modelling: Improvements and Challenges

Author

Wakelam, V., Smith, I. W. M., Herbst, E., Troe, J., Geppert, W., Linnartz, H., Oberg, K., Roueff, E., Agundez, M., Pernot, P., Cuppen, H. M., Loison, J. C., Talbi, D., Wakelam, V., Smith, I. W. M., Herbst, E., Troe, J., Geppert, W., Linnartz, H., Oberg, K., Roueff, E., Agundez, M., Pernot, P., Cuppen, H. M., Loison, J. C., and Talbi, D.

Abstract

We survey the current situation regarding chemical modelling of the synthesis of molecules in the interstellar medium. The present state of knowledge concerning the rate coefficients and their uncertainties for the major gas-phase processes -- ion-neutral reactions, neutral-neutral reactions, radiative association, and dissociative recombination -- is reviewed. Emphasis is placed on those reactions that have been identified, by sensitivity analyses, as 'crucial' in determining the predicted abundances of the species observed in the interstellar medium. These sensitivity analyses have been carried out for gas-phase models of three representative, molecule-rich, astronomical sources: the cold dense molecular clouds TMC-1 and L134N, and the expanding circumstellar envelope IRC +10216. Our review has led to the proposal of new values and uncertainties for the rate coefficients of many of the key reactions. The impact of these new data on the predicted abundances in TMC-1 and L134N is reported. Interstellar dust particles also influence the observed abundances of molecules in the interstellar medium. Their role is included in gas-grain, as distinct from gas-phase only, models. We review the methods for incorporating both accretion onto, and reactions on, the surfaces of grains in such models, as well as describing some recent experimental efforts to simulate and examine relevant processes in the laboratory. These efforts include experiments on the surface-catalysed recombination of hydrogen atoms, on chemical processing on and in the ices that are known to exist on the surface of interstellar grains, and on desorption processes, which may enable species formed on grains to return to the gas-phase., Comment: Accepted for publication in Space Science Reviews

Published
2010
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222. The methanol lines and hot core of OMC2-FIR4, an intermediate-mass protostar, with Herschel-HIFI

Author

Kama, M., Dominik, C., Maret, S., van der Tak, F., Caux, E., Ceccarelli, C., Fuente, A., Crimier, N., Lord, S., Bacmann, A., Baudry, A., Bell, T., Benedettini, M., Bergin, E. A., Blake, G. A., Boogert, A., Bottinelli, S., Cabrit, S., Caselli, P., Castets, A., Cernicharo, J., Codella, C., Comito, C., Coutens, A., Demyk, K., Encrenaz, P., Falgarone, E., Gerin, M., Goldsmith, P. F., Helmich, F., Hennebelle, P., Henning, T., Herbst, E., Hily-Blant, P., Jacq, T., Kahane, C., Klotz, A., Langer, W., Lefloch, B., Lis, D., Lorenzani, A., Melnick, G., Nisini, B., Pacheco, S., Pagani, L., Parise, B., Pearson, J., Phillips, T., Salez, M., Saraceno, P., Schilke, P., Schuster, K., Tielens, A. G. G. M., van der Wiel, M. H. D., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wyrowski, F., Yorke, H., Cais, P., Güsten, R., Philipp, S., Klein, T., Kama, M., Dominik, C., Maret, S., van der Tak, F., Caux, E., Ceccarelli, C., Fuente, A., Crimier, N., Lord, S., Bacmann, A., Baudry, A., Bell, T., Benedettini, M., Bergin, E. A., Blake, G. A., Boogert, A., Bottinelli, S., Cabrit, S., Caselli, P., Castets, A., Cernicharo, J., Codella, C., Comito, C., Coutens, A., Demyk, K., Encrenaz, P., Falgarone, E., Gerin, M., Goldsmith, P. F., Helmich, F., Hennebelle, P., Henning, T., Herbst, E., Hily-Blant, P., Jacq, T., Kahane, C., Klotz, A., Langer, W., Lefloch, B., Lis, D., Lorenzani, A., Melnick, G., Nisini, B., Pacheco, S., Pagani, L., Parise, B., Pearson, J., Phillips, T., Salez, M., Saraceno, P., Schilke, P., Schuster, K., Tielens, A. G. G. M., van der Wiel, M. H. D., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wyrowski, F., Yorke, H., Cais, P., Güsten, R., Philipp, S., and Klein, T.

Abstract

In contrast with numerous studies on the physical and chemical structure of low- and high-mass protostars, much less is known about their intermediate-mass counterparts, a class of objects that could help to elucidate the mechanisms of star formation on both ends of the mass range. We present the first results from a rich HIFI spectral dataset on an intermediate-mass protostar, OMC2-FIR4, obtained in the CHESS (Chemical HErschel SurveyS of star forming regions) key programme. The more than 100 methanol lines detected between 554 and 961 GHz cover a range in upper level energy of 40 to 540 K. Our physical interpretation focusses on the hot core, but likely the cold envelope and shocked regions also play a role in reality, because an analysis of the line profiles suggests the presence of multiple emission components. An upper limit of 10^-6 is placed on the methanol abundance in the hot core, using a population diagram, large-scale source model and other considerations. This value is consistent with abundances previously seen in low-mass hot cores. Furthermore, the highest energy lines at the highest frequencies display asymmetric profiles, which may arise from infall around the hot core., Comment: 2 figures, accepted for publication in the A&A Herschel-HIFI special issue

Published
2010
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223. Herschel/HIFI observations of interstellar OH+ and H2O+ towards W49N: a probe of diffuse clouds with a small molecular fraction

Author

Neufeld, D. A., Goicoechea, J. R., Sonnentrucker, P., Black, J. H., Pearson, J., Yu, S., Phillips, T. G., Lis, D. C., De Luca, M., Herbst, E., Rimmer, P., Gerin, M., Bell, T. A., Boulanger, F., Cernicharo, J., Coutens, A., Dartois, E., Kazmierczak, M., Encrenaz, P., Falgarone, E., Geballe, T. R., Giesen, T., Godard, B., Goldsmith, P. F., Gry, C., Gupta, H., Hennebelle, P., Hily-Blant, P., Joblin, C., Kołos, R., Krełowski, J., Martın-Pintado, J., Menten, K. M., Monje, R., Mookerjea, B., Perault, M., Persson, C., Plume, R., Salez, M., Schlemmer, S., Schmidt, M., Stutzki, J., Teyssier, D., Vastel, C., Cros, A., Klein, K., Lorenzani, A., Philipp, S., Samoska, L. A., Shipman, R., Tielens, A. G. G. M., Szczerba, R., Zmuidzinas, J., Neufeld, D. A., Goicoechea, J. R., Sonnentrucker, P., Black, J. H., Pearson, J., Yu, S., Phillips, T. G., Lis, D. C., De Luca, M., Herbst, E., Rimmer, P., Gerin, M., Bell, T. A., Boulanger, F., Cernicharo, J., Coutens, A., Dartois, E., Kazmierczak, M., Encrenaz, P., Falgarone, E., Geballe, T. R., Giesen, T., Godard, B., Goldsmith, P. F., Gry, C., Gupta, H., Hennebelle, P., Hily-Blant, P., Joblin, C., Kołos, R., Krełowski, J., Martın-Pintado, J., Menten, K. M., Monje, R., Mookerjea, B., Perault, M., Persson, C., Plume, R., Salez, M., Schlemmer, S., Schmidt, M., Stutzki, J., Teyssier, D., Vastel, C., Cros, A., Klein, K., Lorenzani, A., Philipp, S., Samoska, L. A., Shipman, R., Tielens, A. G. G. M., Szczerba, R., and Zmuidzinas, J.

Abstract

We report the detection of absorption by interstellar hydroxyl cations and water cations, along the sight-line to the bright continuum source W49N. We have used Herschel's HIFI instrument, in dual beam switch mode, to observe the 972 GHz N = 1 - 0 transition of OH+ and the 1115 GHz 1(11) - 0(00) transition of ortho-H2O+. The resultant spectra show absorption by ortho-H2O+, and strong absorption by OH+, in foreground material at velocities in the range 0 to 70 km/s with respect to the local standard of rest. The inferred OH+/H2O+ abundance ratio ranges from ~ 3 to ~ 15, implying that the observed OH+ arises in clouds of small molecular fraction, in the 2 - 8% range. This conclusion is confirmed by the distribution of OH+ and H2O+ in Doppler velocity space, which is similar to that of atomic hydrogen, as observed by means of 21 cm absorption measurements, and dissimilar from that typical of other molecular tracers. The observed OH+/H abundance ratio of a few E-8 suggests a cosmic ray ionization rate for atomic hydrogen of (0.6 - 2.4) E-16 s-1, in good agreement with estimates inferred previously for diffuse clouds in the Galactic disk from observations of interstellar H3+ and other species., Comment: Accepted for publication in A&A Letters

Published
2010
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224. Herschel observations of EXtra-Ordinary Sources (HEXOS): Observations of H2O and its isotopologues towards Orion KL

Author

Melnick, G. J., Tolls, V., Neufeld, D. A., Bergin, E. A., Phillips, T. G., Wang, S., Crockett, N. R., Bell, T. A., Blake, G. A., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Comito, C., Daniel, F., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Herbst, E., Joblin, C., Johnstone, D., Langer, W. D., Latter, W. D., Lis, D. C., Lord, S. D., Maret, S., Martin, P. G., Menten, K. M., Morris, P., Muller, H. S. P., Murphy, J. A., Ossenkopf, V., Pagani, L., Pearson, J. C., Perault, M., Plume, R., Qin, S. -L., Salez, M., Schilke, P., Schlemmer, S., Stutzki, J., Trappe, N., van der Tak, F. F. S., Vastel, C., Yorke, H. W., Yu, S., Zmuidzinas, J., Melnick, G. J., Tolls, V., Neufeld, D. A., Bergin, E. A., Phillips, T. G., Wang, S., Crockett, N. R., Bell, T. A., Blake, G. A., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Comito, C., Daniel, F., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Herbst, E., Joblin, C., Johnstone, D., Langer, W. D., Latter, W. D., Lis, D. C., Lord, S. D., Maret, S., Martin, P. G., Menten, K. M., Morris, P., Muller, H. S. P., Murphy, J. A., Ossenkopf, V., Pagani, L., Pearson, J. C., Perault, M., Plume, R., Qin, S. -L., Salez, M., Schilke, P., Schlemmer, S., Stutzki, J., Trappe, N., van der Tak, F. F. S., Vastel, C., Yorke, H. W., Yu, S., and Zmuidzinas, J.

Abstract

We report the detection of more than 48 velocity-resolved ground rotational state transitions of H2(16)O, H2(18)O, and H2(17)O - most for the first time - in both emission and absorption toward Orion KL using Herschel/HIFI. We show that a simple fit, constrained to match the known emission and absorption components along the line of sight, is in excellent agreement with the spectral profiles of all the water lines. Using the measured H2(18)O line fluxes, which are less affected by line opacity than their H2(16)O counterparts, and an escape probability method, the column densities of H2(18)O associated with each emission component are derived. We infer total water abundances of 7.4E-5, 1.0E-5, and 1.6E-5 for the plateau, hot core, and extended warm gas, respectively. In the case of the plateau, this value is consistent with previous measures of the Orion-KL water abundance as well as those of other molecular outflows. In the case of the hot core and extended warm gas, these values are somewhat higher than water abundances derived for other quiescent clouds, suggesting that these regions are likely experiencing enhanced water-ice sublimation from (and reduced freeze-out onto) grain surfaces due to the warmer dust in these sources., Comment: 5 pages, 2 figures

Published
2010
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225. First detection of ND in the solar-mass protostar IRAS16293-2422

Author

Bacmann, A., Caux, E., Hily-Blant, P., Parise, B., Pagani, L., Bottinelli, S., Maret, S., Vastel, C., Ceccarelli, C., Cernicharo, J., Henning, T., Castets, A., Coutens, A., Bergin, E. A., Blake, G. A., Crimier, N., Demyk, K., Dominik, C., Gerin, M., Hennebelle, P., Kahane, C., Klotz, A., Melnick, G., Schilke, P., Wakelam, V., Walters, A., Baudry, A., Bell, T., Benedettini, M., Boogert, A., Cabrit, S., Caselli, P., Codella, C., Comito, C., Encrenaz, P., Falgarone, E., Fuente, A., Goldsmith, P. F., Helmich, F., Herbst, E., Jacq, T., Kama, M., Langer, W., Lefloch, B., Lis, D., Lord, S., Lorenzani, A., Neufeld, D., Nisini, B., Pacheco, S., Pearson, J., Phillips, T., Salez, M., Saraceno, P., Schuster, K., Tielens, A. G. G. M., van der Tak, F. F. S., van der Wiel, M. H. D., Viti, S., Wyrowski, F., Yorke, H., Faure, A., Benz, A., Coeur-Joly, O., Cros, A., Guesten, R., Ravera, L., Bacmann, A., Caux, E., Hily-Blant, P., Parise, B., Pagani, L., Bottinelli, S., Maret, S., Vastel, C., Ceccarelli, C., Cernicharo, J., Henning, T., Castets, A., Coutens, A., Bergin, E. A., Blake, G. A., Crimier, N., Demyk, K., Dominik, C., Gerin, M., Hennebelle, P., Kahane, C., Klotz, A., Melnick, G., Schilke, P., Wakelam, V., Walters, A., Baudry, A., Bell, T., Benedettini, M., Boogert, A., Cabrit, S., Caselli, P., Codella, C., Comito, C., Encrenaz, P., Falgarone, E., Fuente, A., Goldsmith, P. F., Helmich, F., Herbst, E., Jacq, T., Kama, M., Langer, W., Lefloch, B., Lis, D., Lord, S., Lorenzani, A., Neufeld, D., Nisini, B., Pacheco, S., Pearson, J., Phillips, T., Salez, M., Saraceno, P., Schuster, K., Tielens, A. G. G. M., van der Tak, F. F. S., van der Wiel, M. H. D., Viti, S., Wyrowski, F., Yorke, H., Faure, A., Benz, A., Coeur-Joly, O., Cros, A., Guesten, R., and Ravera, L.

Abstract

In the past decade, much progress has been made in characterising the processes leading to the enhanced deuterium fractionation observed in the ISM and in particular in the cold, dense parts of star forming regions such as protostellar envelopes. Very high molecular D/H ratios have been found for saturated molecules and ions. However, little is known about the deuterium fractionation in radicals, even though simple radicals often represent an intermediate stage in the formation of more complex, saturated molecules. The imidogen radical NH is such an intermediate species for the ammonia synthesis in the gas phase. Herschel/HIFI represents a unique opportunity to study the deuteration and formation mechanisms of such species, which are not observable from the ground. We searched here for the deuterated radical ND in order to determine the deuterium fractionation of imidogen and constrain the deuteration mechanism of this species. We observed the solar-mass Class 0 protostar IRAS16293-2422 with the heterodyne instrument HIFI as part of the Herschel key programme CHESS (Chemical HErschel Surveys of Star forming regions). The deuterated form of the imidogen radical ND was detected and securely identified with 2 hyperfine component groups of its fundamental transition in absorption against the continuum background emitted from the nascent protostar. The 3 groups of hyperfine components of its hydrogenated counterpart NH were also detected in absorption. We derive a very high deuterium fractionation with an [ND]/[NH] ratio of between 30 and 100%. The deuterium fractionation of imidogen is of the same order of magnitude as that in other molecules, which suggests that an efficient deuterium fractionation mechanism is at play. We discuss two possible formation pathways for ND, by means of either the reaction of N+ with HD, or deuteron/proton exchange with NH., Comment: Accepted; To appear in A&A Herschel/HIFI Special Issue

Published
2010
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226. Herschel observations of EXtra-Ordinary Sources: The Terahertz spectrum of Orion KL seen at high spectral resolution

Author

Crockett, N. R., Bergin, E. A., Wang, S., Lis, D. C., Bell, T. A., Blake, G. A., Boogert, A., Bumble, B., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Comito, C., Daniel, F., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Gusten, R., Hartogh, P., Helmich, F., Herbst, E., Honingh, N., Joblin, C., Johnstone, D., Karpov, A., Kawamura, J. H., Kooi, J., Krieg, J. -M., Langer, W. D., Latter, W. D., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Muller, H. S. P., Murphy, J. A., Neufeld, D. A., Ossenkopf, V., Pearson, J. C., Perault, M., Phillips, T. G., Plume, R., Qin, S. -L., Roelfsema, P., Schieder, R., Schilke, P., Schlemmer, S., Stutzki, J., van der Tak, F. F. S., Tielens, A., Trappe, N., Vastel, C., Yorke, H. W., Yu, S., Zmuidzinas, J., Crockett, N. R., Bergin, E. A., Wang, S., Lis, D. C., Bell, T. A., Blake, G. A., Boogert, A., Bumble, B., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Comito, C., Daniel, F., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Gusten, R., Hartogh, P., Helmich, F., Herbst, E., Honingh, N., Joblin, C., Johnstone, D., Karpov, A., Kawamura, J. H., Kooi, J., Krieg, J. -M., Langer, W. D., Latter, W. D., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Muller, H. S. P., Murphy, J. A., Neufeld, D. A., Ossenkopf, V., Pearson, J. C., Perault, M., Phillips, T. G., Plume, R., Qin, S. -L., Roelfsema, P., Schieder, R., Schilke, P., Schlemmer, S., Stutzki, J., van der Tak, F. F. S., Tielens, A., Trappe, N., Vastel, C., Yorke, H. W., Yu, S., and Zmuidzinas, J.

Abstract

We present the first high spectral resolution observations of Orion KL in the frequency ranges 1573.4 - 1702.8 GHz (band 6b) and 1788.4 - 1906.8 GHz (band 7b) obtained using the HIFI instrument on board the Herschel Space Observatory. We characterize the main emission lines found in the spectrum, which primarily arise from a range of components associated with Orion KL including the hot core, but also see widespread emission from components associated with molecular outflows traced by H2O, SO2, and OH. We find that the density of observed emission lines is significantly diminished in these bands compared to lower frequency Herschel/HIFI bands., Comment: Accepted for publication in the Herschel HIFI special issue of Astronomy and Astrophysics Letters, 5 pages, 3 figures

Published
2010
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227. The distribution of water in the high-mass star-forming region NGC 6334I

Author

Emprechtinger, M., Lis, D. C., Bell, T., Phillips, T. G., Schilke, P., Comito, C., Rolffs, R., van der Tak, F., Ceccarelli, C., Aarts, H., Bacmann, A., Baudry, A., Benedettini, M., Bergin, E. A., Blake, G., Boogert, A., Bottinelli, S., Cabrit, S., Caselli, P., Castets, A., Caux, E., Cernicharo, J., Codella, C., Coutens, A., Crimier, N., Demyk, K., Dominik, C., Encrenaz, P., Falgarone, E., Fuente, A., Gerin, M., Goldsmith, P., Helmich, F., Hennebelle, P., Henning, T., Herbst, E., Hily-Blant, P., Jacq, T., Kahane, C., Kama, M., Klotz, A., Kooi, J., Langer, W., Lefloch, B., Loose, A., Lord, S., Lorenzani, A., Maret, S., Melnick, G., Neufeld, D., Nisini, B., Ossenkopf, V., Pacheco, S., Pagani, L., Parise, B., Pearson, J., Risacher, C., Salez, M., Saraceno, P., Schuster, K., Stutzki, J., Tielens, X., van der Wiel, M., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wyrowski, F., Yorke, H., Emprechtinger, M., Lis, D. C., Bell, T., Phillips, T. G., Schilke, P., Comito, C., Rolffs, R., van der Tak, F., Ceccarelli, C., Aarts, H., Bacmann, A., Baudry, A., Benedettini, M., Bergin, E. A., Blake, G., Boogert, A., Bottinelli, S., Cabrit, S., Caselli, P., Castets, A., Caux, E., Cernicharo, J., Codella, C., Coutens, A., Crimier, N., Demyk, K., Dominik, C., Encrenaz, P., Falgarone, E., Fuente, A., Gerin, M., Goldsmith, P., Helmich, F., Hennebelle, P., Henning, T., Herbst, E., Hily-Blant, P., Jacq, T., Kahane, C., Kama, M., Klotz, A., Kooi, J., Langer, W., Lefloch, B., Loose, A., Lord, S., Lorenzani, A., Maret, S., Melnick, G., Neufeld, D., Nisini, B., Ossenkopf, V., Pacheco, S., Pagani, L., Parise, B., Pearson, J., Risacher, C., Salez, M., Saraceno, P., Schuster, K., Stutzki, J., Tielens, X., van der Wiel, M., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wyrowski, F., and Yorke, H.

Abstract

We present observations of twelve rotational transitions of H2O-16, H2O-18, and H2O-17 toward the massive star-forming region NGC 6334 I, carried out with Herschel/HIFI as part of the guaranteed time key program Chemical HErschel Surveys of Star forming regions (CHESS). We analyze these observations to obtain insights into physical processes in this region. We identify three main gas components (hot core, cold foreground, and outflow) in NGC 6334 I and derive the physical conditions in these components. The hot core, identified by the emission in highly excited lines, shows a high excitation temperature of 200 K, whereas water in the foreground component is predominantly in the ortho- and para- ground states. The abundance of water varies between 4 10^-5 (outflow) and 10^-8 (cold foreground gas). This variation is most likely due to the freeze-out of water molecules onto dust grains. The H2O-18/H2O-17 abundance ratio is 3.2, which is consistent with the O-18/O-17 ratio determined from CO isotopologues. The ortho/para ratio in water appears to be relatively low 1.6(1) in the cold, quiescent gas, but close to the equilibrium value of three in the warmer outflow material (2.5(0.8))., Comment: 7 pages, 3 figures, accepted by A&A

Published
2010
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228. Ortho-to-para ratio of interstellar heavy water

Author

Vastel, C., Ceccarelli, C., Caux, E., Coutens, A., Cernicharo, J., Bottinelli, S., Demyk, K., Faure, A., Wiesenfeld, L., Scribano, Y., Bacmann, A., Hily-Blant, P., Maret, S., Walters, A., Bergin, E. A., Blake, G. A., Castets, A., Crimier, N., Dominik, C., Encrenaz, P., Gérin, M., Hennebelle, P., Kahane, C., Klotz, A., Melnick, G., Pagani, L., Parise, B., Schilke, P., Wakelam, V., Baudry, A., Bell, T., Benedettini, M., Boogert, A., Cabrit, S., Caselli, P., Codella, C., Comito, C., Falgarone, E., Fuente, A., Goldsmith, P. F., Helmich, F., Henning, T., Herbst, E., Jacq, T., Kama, M., Langer, W., Lefloch, B., Lis, D., Lord, S., Lorenzani, A., Neufeld, D., Nisini, B., Pacheco, S., Pearson, J., Phillips, T., Salez, M., Saraceno, P., Schuster, K., Tielens, X., van der Tak, F., van der Wiel, M. H. D., Viti, S., Wyrowski, F., Yorke, H., Cais, P., Krieg, J. M., Olberg, M., Ravera, L., Vastel, C., Ceccarelli, C., Caux, E., Coutens, A., Cernicharo, J., Bottinelli, S., Demyk, K., Faure, A., Wiesenfeld, L., Scribano, Y., Bacmann, A., Hily-Blant, P., Maret, S., Walters, A., Bergin, E. A., Blake, G. A., Castets, A., Crimier, N., Dominik, C., Encrenaz, P., Gérin, M., Hennebelle, P., Kahane, C., Klotz, A., Melnick, G., Pagani, L., Parise, B., Schilke, P., Wakelam, V., Baudry, A., Bell, T., Benedettini, M., Boogert, A., Cabrit, S., Caselli, P., Codella, C., Comito, C., Falgarone, E., Fuente, A., Goldsmith, P. F., Helmich, F., Henning, T., Herbst, E., Jacq, T., Kama, M., Langer, W., Lefloch, B., Lis, D., Lord, S., Lorenzani, A., Neufeld, D., Nisini, B., Pacheco, S., Pearson, J., Phillips, T., Salez, M., Saraceno, P., Schuster, K., Tielens, X., van der Tak, F., van der Wiel, M. H. D., Viti, S., Wyrowski, F., Yorke, H., Cais, P., Krieg, J. M., Olberg, M., and Ravera, L.

Abstract

Despite the low elemental deuterium abundance in the Galaxy, enhanced molecular D/H ratios have been found in the environments of low-mass star forming regions, and in particular the Class 0 protostar IRAS 16293-2422. The CHESS (Chemical HErschel Surveys of Star forming regions) Key Program aims at studying the molecular complexity of the interstellar medium. The high sensitivity and spectral resolution of the HIFI instrument provide a unique opportunity to observe the fundamental 1,1,1 - 0,0,0 transition of the ortho-D2O molecule, inaccessible from the ground, and to determine the ortho-to-para D2O ratio. We have detected the fundamental transition of the ortho-D2O molecule at 607.35 GHz towards IRAS 16293-2422. The line is seen in absorption with a line opacity of 0.62 +/- 0.11 (1 sigma). From the previous ground-based observations of the fundamental 1,1,0 - 1,0,1 transition of para-D2O seen in absorption at 316.80 GHz we estimate a line opacity of 0.26 +/- 0.05 (1 sigma). We show that the observed absorption is caused by the cold gas in the envelope of the protostar. Using these new observations, we estimate for the first time the ortho to para D2O ratio to be lower than 2.6 at a 3 sigma level of uncertainty, to be compared with the thermal equilibrium value of 2:1., Comment: 5 pages, 5 figures, accepted the A&A HIFI Special Issue as a letter

Published
2010
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229. Herschel observations of extra-ordinary sources: Detection of Hydrogen Fluoride in absorption towards Orion~KL

Author

Phillips, T. G., Bergin, E. A., Lis, D. C., Neufeld, D. A., Bell, T. A., Wang, S., Crockett, N. R., Emprechtinger, M., Blake, G. A., Caux, E., Ceccarelli, C., Cernicharo, J., Comito, C., Daniel, F., Dubernet, M. -L., Encrenaz, P., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Herbst, E., Joblin, C., Johnstone, D., Langer, W. D., Latter, W. D., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Muller, H. S. P., Murphy, J. A., Ossenkopf, V., Pearson, J. C., Perault, M., Plume, R., Qin, S. -L., Schilke, P., Schlemmer, S., Stutzki, J., Trappe, N., van der Tak, F. F. S., Vastel, C., Yorke, H. W., Yu, S., Zmuidzinas, J., Boogert, A., Gusten, R., Hartogh, P., Honingh, N., Karpov, A., Kooi, J., Krieg, J. -M., Schieder, R., Phillips, T. G., Bergin, E. A., Lis, D. C., Neufeld, D. A., Bell, T. A., Wang, S., Crockett, N. R., Emprechtinger, M., Blake, G. A., Caux, E., Ceccarelli, C., Cernicharo, J., Comito, C., Daniel, F., Dubernet, M. -L., Encrenaz, P., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Herbst, E., Joblin, C., Johnstone, D., Langer, W. D., Latter, W. D., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Muller, H. S. P., Murphy, J. A., Ossenkopf, V., Pearson, J. C., Perault, M., Plume, R., Qin, S. -L., Schilke, P., Schlemmer, S., Stutzki, J., Trappe, N., van der Tak, F. F. S., Vastel, C., Yorke, H. W., Yu, S., Zmuidzinas, J., Boogert, A., Gusten, R., Hartogh, P., Honingh, N., Karpov, A., Kooi, J., Krieg, J. -M., and Schieder, R.

Abstract

We report a detection of the fundamental rotational transition of hydrogen fluoride in absorption towards Orion KL using Herschel/HIFI. After the removal of contaminating features associated with common molecules ("weeds"), the HF spectrum shows a P-Cygni profile, with weak redshifted emission and strong blue-shifted absorption, associated with the low-velocity molecular outflow. We derive an estimate of 2.9 x 10^13 cm^-2 for the HF column density responsible for the broad absorption component. Using our best estimate of the H2 column density within the low-velocity molecular outflow, we obtain a lower limit of ~1.6 x 10^-10 for the HF abundance relative to hydrogen nuclei, corresponding to 0.6% of the solar abundance of fluorine. This value is close to that inferred from previous ISO observations of HF J=2--1 absorption towards Sgr B2, but is in sharp contrast to the lower limit of 6 x 10^-9 derived by Neufeld et al. (2010) for cold, foreground clouds on the line of sight towards G10.6-0.4., Comment: 5 pages, 3 figures, paper to be published in the Herschel special issue of A&A letters

Published
2010
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230. Detection of hydrogen fluoride absorption in diffuse molecular clouds with Herschel/HIFI: a ubiquitous tracer of molecular gas

Author

Sonnentrucker, P., Neufeld, D. A., Phillips, T. G., Gerin, M., Lis, D. C., De Luca, M., Goicoechea, J. R., Black, J. H., Bell, T. A., Boulanger, F., Cernicharo, J., Coutens, A., Dartois, E., Kazmierczak, M., Encrenaz, P., Falgarone, E., Geballe, T. R., Giesen, T., Godard, B., Goldsmith, P. F., Gry, C., Gupta, H., Hennebelle, P., Herbst, E., Hily-Blant, P., Joblin, C., Kolos, R., Krelowski, J., Martın-Pintado, J., Menten, K. M., Monje, R., Mookerjea, B., Pearson, J., Perault, M., Persson, C. M., Plume, R., Salez, M., Schlemmer, S., Schmidt, M., Stutzki, J., Teyssier, D., Vastel, C., Yu, S., Caux, E., Gusten, R., Hatch, W. A., Klein, T., Mehdi, I., Morris, P., Ward, J. S., Sonnentrucker, P., Neufeld, D. A., Phillips, T. G., Gerin, M., Lis, D. C., De Luca, M., Goicoechea, J. R., Black, J. H., Bell, T. A., Boulanger, F., Cernicharo, J., Coutens, A., Dartois, E., Kazmierczak, M., Encrenaz, P., Falgarone, E., Geballe, T. R., Giesen, T., Godard, B., Goldsmith, P. F., Gry, C., Gupta, H., Hennebelle, P., Herbst, E., Hily-Blant, P., Joblin, C., Kolos, R., Krelowski, J., Martın-Pintado, J., Menten, K. M., Monje, R., Mookerjea, B., Pearson, J., Perault, M., Persson, C. M., Plume, R., Salez, M., Schlemmer, S., Schmidt, M., Stutzki, J., Teyssier, D., Vastel, C., Yu, S., Caux, E., Gusten, R., Hatch, W. A., Klein, T., Mehdi, I., Morris, P., and Ward, J. S.

Abstract

We discuss the detection of absorption by interstellar hydrogen fluoride (HF) along the sight line to the submillimeter continuum sources W49N and W51. We have used Herschel's HIFI instrument in dual beam switch mode to observe the 1232.4762 GHz J = 1 - 0 HF transition in the upper sideband of the band 5a receiver. We detected foreground absorption by HF toward both sources over a wide range of velocities. Optically thin absorption components were detected on both sight lines, allowing us to measure - as opposed to obtain a lower limit on - the column density of HF for the first time. As in previous observations of HF toward the source G10.6-0.4, the derived HF column density is typically comparable to that of water vapor, even though the elemental abundance of oxygen is greater than that of fluorine by four orders of magnitude. We used the rather uncertain N(CH)-N(H2) relationship derived previously toward diffuse molecular clouds to infer the molecular hydrogen column density in the clouds exhibiting HF absorption. Within the uncertainties, we find that the abundance of HF with respect to H2 is consistent with the theoretical prediction that HF is the main reservoir of gas-phase fluorine for these clouds. Thus, hydrogen fluoride has the potential to become an excellent tracer of molecular hydrogen, and provides a sensitive probe of clouds of small H2 column density. Indeed, the observations of hydrogen fluoride reported here reveal the presence of a low column density diffuse molecular cloud along the W51 sight line, at an LSR velocity of ~ 24kms-1, that had not been identified in molecular absorption line studies prior to the launch of Herschel., Comment: 4 pages, 3 figures, A&A Letter special issue, accepted on 07/13/2010

Published
2010
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231. Herschel observations of EXtra-Ordinary Sources: the present and future of spectral surveys with Herschel/HIFI

Author

Bergin, E. A., Phillips, T. G., Comito, C., Crockett, N. R., Lis, D. C., Schilke, P., Wang, S., Bell, T. A., Blake, G. A., Bumble, B., Caux, E., Cabrit, S., Ceccarelli, C., Cernicharo, J., Daniel, F., de Graauw, Th., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Hartogh, P., Helmich, F. P., Herbst, E., Joblin, C., Johnstone, D., Kawamura, J. H., Langer, W. D., Latter, W. B., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Muller, H. S. P., Murphy, J. A., Neufeld, D. A., Ossenkopf, V., Pagani, L., Pearson, J. C., Perault, M., Plume, R., Roelfsema, P., Qin, S. -L., Salez, M., Schlemmer, S., Stutzki, J., Tielens, A. G. G. M., Trappe, N., van der Tak, F. F. S., Vastel, C., Yorke, H. W., Yu, S., Zmuidzinas, J., Bergin, E. A., Phillips, T. G., Comito, C., Crockett, N. R., Lis, D. C., Schilke, P., Wang, S., Bell, T. A., Blake, G. A., Bumble, B., Caux, E., Cabrit, S., Ceccarelli, C., Cernicharo, J., Daniel, F., de Graauw, Th., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Hartogh, P., Helmich, F. P., Herbst, E., Joblin, C., Johnstone, D., Kawamura, J. H., Langer, W. D., Latter, W. B., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Muller, H. S. P., Murphy, J. A., Neufeld, D. A., Ossenkopf, V., Pagani, L., Pearson, J. C., Perault, M., Plume, R., Roelfsema, P., Qin, S. -L., Salez, M., Schlemmer, S., Stutzki, J., Tielens, A. G. G. M., Trappe, N., van der Tak, F. F. S., Vastel, C., Yorke, H. W., Yu, S., and Zmuidzinas, J.

Abstract

We present initial results from the Herschel GT key program: Herschel observations of EXtra-Ordinary Sources (HEXOS) and outline the promise and potential of spectral surveys with Herschel/HIFI. The HIFI instrument offers unprecedented sensitivity, as well as continuous spectral coverage across the gaps imposed by the atmosphere, opening up a largely unexplored wavelength regime to high-resolution spectroscopy. We show the spectrum of Orion KL between 480 and 560 GHz and from 1.06 to 1.115 THz. From these data, we confirm that HIFI separately measures the dust continuum and spectrally resolves emission lines in Orion KL. Based on this capability we demonstrate that the line contribution to the broad-band continuum in this molecule-rich source is ~20-40% below 1 THz and declines to a few percent at higher frequencies. We also tentatively identify multiple transitions of HD18O in the spectra. The first detection of this rare isotopologue in the interstellar medium suggests that HDO emission is optically thick in the Orion hot core with HDO/H2O ~ 0.02. We discuss the implications of this detection for the water D/H ratio in hot cores., Comment: 6 pages, 5 figures, accepted and to be published in Herschel HIFI special issue of A&A Letters

Published
2010
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232. Nitrogen hydrides in interstellar gas: Herschel/HIFI observations towards G10.6-0.4 (W31C)

Author

Persson, C. M., Black, J. H., Cernicharo, J., Goicoechea, J. R., Hassel, G. E., Herbst, E., Gerin, M., De Luca, M., Bell, T. A., Coutens, A., Falgarone, E., Goldsmith, P. F., Gupta, H., Kazmierczak, M., Lis, D. C., Mookerjea, B., Neufeld, D. A., Pearson, J., Phillips, T. G., Sonnentrucker, P., Stutzki, J., Vastel, C., Yu, S., Boulanger, F., Dartois, E., Encrenaz, P., Geballe, T. R., Giesen, T., Godard, B., Gry, C., Hennebelle, P., Hily-Blant, P., Joblin, C., Kolos, R., Krelowski, J., Martin-Pintado, J., Menten, K., Monje, R., Perault, M., Plume, R., Salez, M., Schlemmer, S., Schmidt, M., Teyssier, D., Peron, I., Cais, P., Gaufre, P., Cros, A., Ravera, L., Morris, P., Lord, S., Planesas, P., Persson, C. M., Black, J. H., Cernicharo, J., Goicoechea, J. R., Hassel, G. E., Herbst, E., Gerin, M., De Luca, M., Bell, T. A., Coutens, A., Falgarone, E., Goldsmith, P. F., Gupta, H., Kazmierczak, M., Lis, D. C., Mookerjea, B., Neufeld, D. A., Pearson, J., Phillips, T. G., Sonnentrucker, P., Stutzki, J., Vastel, C., Yu, S., Boulanger, F., Dartois, E., Encrenaz, P., Geballe, T. R., Giesen, T., Godard, B., Gry, C., Hennebelle, P., Hily-Blant, P., Joblin, C., Kolos, R., Krelowski, J., Martin-Pintado, J., Menten, K., Monje, R., Perault, M., Plume, R., Salez, M., Schlemmer, S., Schmidt, M., Teyssier, D., Peron, I., Cais, P., Gaufre, P., Cros, A., Ravera, L., Morris, P., Lord, S., and Planesas, P.

Abstract

The HIFI instrument on board the Herschel Space Observatory has been used to observe interstellar nitrogen hydrides along the sight-line towards G10.6-0.4 in order to improve our understanding of the interstellar chemistry of nitrogen. We report observations of absorption in NH N=1-0, J=2-1 and ortho-NH2 1_1,1-0_0,0. We also observed ortho-NH3 1_0-0_0, and 2_0-1_0, para-NH3 2_1-1_1, and searched unsuccessfully for NH+. All detections show emission and absorption associated directly with the hot-core source itself as well as absorption by foreground material over a wide range of velocities. All spectra show similar, non-saturated, absorption features, which we attribute to diffuse molecular gas. Total column densities over the velocity range 11-54 km/s are estimated. The similar profiles suggest fairly uniform abundances relative to hydrogen, approximately 6*10^-9, 3*10^-9, and 3*10^-9 for NH, NH2, and NH3, respectively. These abundances are discussed with reference to models of gas-phase and surface chemistry., Comment: 5 pages, 3 figures, 2 online pages with 2 figures. Accepted for publication in A&A July 6 (Herschel/HIFI special issue)

Published
2010
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233. Herschel observations of deuterated water towards Sgr B2(M)

Author

Comito, Claudia, Schilke, Peter, Rolffs, Rainer, Lis, D. C., Belloche, A., Bergin, E. A., Phillips, T. G., Bell, T. A., Crockett, N. R., Wang, S., Blake, G. A., Caux, E., Ceccarelli, C., Cernicharo, J., Daniel, F., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Herbst, E., Joblin, C., Johnstone, D., Langer, W. D., Latter, W. D., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Mueller, H. S. P., Murphy, J. A., Neufeld, D. A., Ossenkopf, V., Pearson, J. C., Perault, M., Plume, R., Qin, S. -L., Schlemmer, S., Stutzki, J., Trappe, N., van der Tak, F. F. S., Vastel, C., Yorke, H. W., Yu, S., Olberg, M., Szczerba, R., Larsson, B., Liseau, R., Lin, R. H., Samoska, L. A., Schlecht, E., Comito, Claudia, Schilke, Peter, Rolffs, Rainer, Lis, D. C., Belloche, A., Bergin, E. A., Phillips, T. G., Bell, T. A., Crockett, N. R., Wang, S., Blake, G. A., Caux, E., Ceccarelli, C., Cernicharo, J., Daniel, F., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Herbst, E., Joblin, C., Johnstone, D., Langer, W. D., Latter, W. D., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Mueller, H. S. P., Murphy, J. A., Neufeld, D. A., Ossenkopf, V., Pearson, J. C., Perault, M., Plume, R., Qin, S. -L., Schlemmer, S., Stutzki, J., Trappe, N., van der Tak, F. F. S., Vastel, C., Yorke, H. W., Yu, S., Olberg, M., Szczerba, R., Larsson, B., Liseau, R., Lin, R. H., Samoska, L. A., and Schlecht, E.

Abstract

Observations of HDO are an important complement for studies of water, because they give strong constraints on the formation processes -- grain surfaces versus energetic process in the gas phase, e.g. in shocks. The HIFI observations of multiple transitions of HDO in Sgr~B2(M) presented here allow the determination of the HDO abundance throughout the envelope, which has not been possible before with ground-based observations only. The abundance structure has been modeled with the spherical Monte Carlo radiative transfer code RATRAN, which also takes radiative pumping by continuum emission from dust into account. The modeling reveals that the abundance of HDO rises steeply with temperature from a low abundance ($2.5\times 10^{-11}$) in the outer envelope at temperatures below 100~K through a medium abundance ($1.5\times 10^{-9}$) in the inner envelope/outer core, at temperatures between 100 and 200~K, and finally a high abundance ($3.5\times 10^{-9}$) at temperatures above 200~K in the hot core., Comment: A&A HIFI special issue, accepted

Published
2010
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234. Herschel/HIFI discovery of interstellar chloronium (H$_2$Cl$^+$)

Author

Lis, D. C., Pearson, J. C., Neufeld, D. A., Schilke, P., Müller, H. S. P., Gupta, H., Bell, T. A., Comito, C., Phillips, T. G., Bergin, E. A., Ceccarelli, C., Goldsmith, P. F., Blake, G. A., Bacmann, A., Baudry, A., Benedettini, M., Benz, A., Black, J., Boogert, A., Bottinelli, S., Cabrit, S., Caselli, P., Castets, A., Caux, E., Cernicharo, J., Codella, C., Coutens, A., Crimier, N., Crockett, N. R., Daniel, F., Demyk, K., Dominic, C., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Fuente, A., Gerin, M., Giesen, T. F., Goicoechea, J. R., Helmich, F., Hennebelle, P., Henning, Th., Herbst, E., Hily-Blant, P., Hjalmarson, Å., Hollenbach, D., Jack, T., Joblin, C., Johnstone, D., Kahane, C., Kama, M., Kaufman, M., Klotz, A., Langer, W. D., Larsson, B., Bourlot, J. Le, Lefloch, B., Petit, F. Le, Li, D., Liseau, R., Lord, S. D., Lorenzani, A., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Murphy, J. A., Nagy, Z., Nisini, B., Ossenkopf, V., Pacheco, S., Pagani, L., Parise, B., Pérault, M., Plume, R., Qin, S. -L., Roueff, E., Salez, M., Sandqvist, A., Saraceno, P., Schlemmer, S., Schuster, K., Snell, R., Stutzki, J., Tielens, A., Trappe, N., van der Tak, F. F. S., van der Wiel, M. H. D., van Dishoeck, E., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wang, S., Wyrowski, F., Yorke, H. W., Yu, S., Zmuidzinas, J., Delorme, Y., Desbat, J. -P., Güsten, R., Krieg, J. -M., Delforge, B., Lis, D. C., Pearson, J. C., Neufeld, D. A., Schilke, P., Müller, H. S. P., Gupta, H., Bell, T. A., Comito, C., Phillips, T. G., Bergin, E. A., Ceccarelli, C., Goldsmith, P. F., Blake, G. A., Bacmann, A., Baudry, A., Benedettini, M., Benz, A., Black, J., Boogert, A., Bottinelli, S., Cabrit, S., Caselli, P., Castets, A., Caux, E., Cernicharo, J., Codella, C., Coutens, A., Crimier, N., Crockett, N. R., Daniel, F., Demyk, K., Dominic, C., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Fuente, A., Gerin, M., Giesen, T. F., Goicoechea, J. R., Helmich, F., Hennebelle, P., Henning, Th., Herbst, E., Hily-Blant, P., Hjalmarson, Å., Hollenbach, D., Jack, T., Joblin, C., Johnstone, D., Kahane, C., Kama, M., Kaufman, M., Klotz, A., Langer, W. D., Larsson, B., Bourlot, J. Le, Lefloch, B., Petit, F. Le, Li, D., Liseau, R., Lord, S. D., Lorenzani, A., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Murphy, J. A., Nagy, Z., Nisini, B., Ossenkopf, V., Pacheco, S., Pagani, L., Parise, B., Pérault, M., Plume, R., Qin, S. -L., Roueff, E., Salez, M., Sandqvist, A., Saraceno, P., Schlemmer, S., Schuster, K., Snell, R., Stutzki, J., Tielens, A., Trappe, N., van der Tak, F. F. S., van der Wiel, M. H. D., van Dishoeck, E., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wang, S., Wyrowski, F., Yorke, H. W., Yu, S., Zmuidzinas, J., Delorme, Y., Desbat, J. -P., Güsten, R., Krieg, J. -M., and Delforge, B.

Abstract

We report the first detection of chloronium, H$_2$Cl$^+$, in the interstellar medium, using the HIFI instrument aboard the \emph{Herschel} Space Observatory. The $2_{12}-1_{01}$ lines of ortho-H$_2^{35}$Cl$^+$ and ortho-H$_2^{37}$Cl$^+$ are detected in absorption towards NGC~6334I, and the $1_{11}-0_{00}$ transition of para-H$_2^{35}$Cl$^+$ is detected in absorption towards NGC~6334I and Sgr~B2(S). The H$_2$Cl$^+$ column densities are compared to those of the chemically-related species HCl. The derived HCl/H$_2$Cl$^+$ column density ratios, $\sim$1--10, are within the range predicted by models of diffuse and dense Photon Dominated Regions (PDRs). However, the observed H$_2$Cl$^+$ column densities, in excess of $10^{13}$~cm$^{-2}$, are significantly higher than the model predictions. Our observations demonstrate the outstanding spectroscopic capabilities of HIFI for detecting new interstellar molecules and providing key constraints for astrochemical models., Comment: Accepted for publication in A&A, HIFI Special Issue; 4 pages, 2 figures, 1 table

Published
2010
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235. Herschel observations of ortho- and para-oxidaniumyl (H2O+) in spiral arm clouds toward Sgr B2(M)

Author

Schilke, P., Comito, C., Mueller, H. S. P., Bergin, E. A., Herbst, E., Lis, D. C., Neufeld, D. A., Phillips, T. G., Bell, T. A., Blake, G. A., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Crockett, N. R., Daniel, F., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., ~Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Joblin, C., Johnstone, D., Langer, W. D., Latter, W. B., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Murphy, J. A., Ossenkopf, V., Pagani, L., Pearson, J. C., Perault, M., Plume, R., Qin, S. -L., Salez, M., Schlemmer, S., Stutzki, J., Trappe, N., van der Tak, F. F. S., Vastel, C., Wang, S., Yorke, H. W., Yu, S., Erickson, N., Maiwald, F. W., Kooi, J., Karpov, A., Zmuidzinas, J., Boogert, A., Schieder, R., Zaal, P., Schilke, P., Comito, C., Mueller, H. S. P., Bergin, E. A., Herbst, E., Lis, D. C., Neufeld, D. A., Phillips, T. G., Bell, T. A., Blake, G. A., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Crockett, N. R., Daniel, F., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., ~Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Joblin, C., Johnstone, D., Langer, W. D., Latter, W. B., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Murphy, J. A., Ossenkopf, V., Pagani, L., Pearson, J. C., Perault, M., Plume, R., Qin, S. -L., Salez, M., Schlemmer, S., Stutzki, J., Trappe, N., van der Tak, F. F. S., Vastel, C., Wang, S., Yorke, H. W., Yu, S., Erickson, N., Maiwald, F. W., Kooi, J., Karpov, A., Zmuidzinas, J., Boogert, A., Schieder, R., and Zaal, P.

Abstract

H2O+ has been observed in its ortho- and para- states toward the massive star forming core Sgr B2(M), located close to the Galactic center. The observations show absorption in all spiral arm clouds between the Sun and Sgr B2. The average o/p ratio of H2O+ in most velocity intervals is 4.8, which corresponds to a nuclear spin temperature of 21 K. The relationship of this spin temperature to the formation temperature and current physical temperature of the gas hosting H2O+ is discussed, but no firm conclusion is reached. In the velocity interval 0 to 60 km/s, an ortho/para ratio of below unity is found, but if this is due to an artifact of contamination by other species or real is not clear., Comment: A&A, HIFI special issue, accepted

Published
2010
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236. Herschel/HIFI measurements of the ortho/para ratio in water towards Sagittarius B2(M) and W31C

Author

Lis, D. C., Phillips, T. G., Goldsmith, P. F., Neufeld, D. A., Herbst, E., Comito, C., Schilke, P., Müller, H. S. P., Bergin, E. A., Gerin, M., Bell, T. A., Emprechtinger, M., Black, J. H., Blake, G. A., Boulanger, F., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Coutens, A., Crockett, N. R., Daniel, F., Dartois, E., De Luca, M., Dubernet, M. -L., Encrenaz, P., Falgarone, E., Geballe, T. R., Godard, B., Giesen, T. F., Goicoechea, J. R., Gry, C., Gupta, H., Hennebelle, P., Hily-Blant, P., Kołos, R., Krełowski, J., Joblin, C., Johnstone, D., Kaźmierczak, M., Lord, S. D., Maret, S., Martin, P. G., Martín-Pintado, J., Melnick, G. J., Menten, K. M., Monje, R., Mookerjea, B., Morris, P., Murphy, J. A., Ossenkopf, V., Pagani, L., Pearson, J. C., Pérault, M., Persson, C., Plume, R., Qin, S. -L., Salez, M., Schlemmer, S., Schmidt, M., Sonnentrucker, P., Stutzki, J., Teyssier, D., Trappe, N., van der Tak, F. F. S., Vastel, C., Wang, S., Yorke, H. W., Yu, S., Zmuidzinas, J., Boogert, A., Erickson, N., Karpov, A., Kooi, J., Maiwald, F. W., Schieder, R., Zaal, P., Lis, D. C., Phillips, T. G., Goldsmith, P. F., Neufeld, D. A., Herbst, E., Comito, C., Schilke, P., Müller, H. S. P., Bergin, E. A., Gerin, M., Bell, T. A., Emprechtinger, M., Black, J. H., Blake, G. A., Boulanger, F., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Coutens, A., Crockett, N. R., Daniel, F., Dartois, E., De Luca, M., Dubernet, M. -L., Encrenaz, P., Falgarone, E., Geballe, T. R., Godard, B., Giesen, T. F., Goicoechea, J. R., Gry, C., Gupta, H., Hennebelle, P., Hily-Blant, P., Kołos, R., Krełowski, J., Joblin, C., Johnstone, D., Kaźmierczak, M., Lord, S. D., Maret, S., Martin, P. G., Martín-Pintado, J., Melnick, G. J., Menten, K. M., Monje, R., Mookerjea, B., Morris, P., Murphy, J. A., Ossenkopf, V., Pagani, L., Pearson, J. C., Pérault, M., Persson, C., Plume, R., Qin, S. -L., Salez, M., Schlemmer, S., Schmidt, M., Sonnentrucker, P., Stutzki, J., Teyssier, D., Trappe, N., van der Tak, F. F. S., Vastel, C., Wang, S., Yorke, H. W., Yu, S., Zmuidzinas, J., Boogert, A., Erickson, N., Karpov, A., Kooi, J., Maiwald, F. W., Schieder, R., and Zaal, P.

Abstract

We present Herschel/HIFI observations of the fundamental rotational transitions of ortho- and para-H$_2^{16}$O and H$_2^{18}$O in absorption towards Sagittarius~B2(M) and W31C. The ortho/para ratio in water in the foreground clouds on the line of sight towards these bright continuum sources is generally consistent with the statistical high-temperature ratio of 3, within the observational uncertainties. However, somewhat unexpectedly, we derive a low ortho/para ratio of $2.35 \pm 0.35$, corresponding to a spin temperature of $\sim$27~K, towards Sagittarius~B2(M) at velocities of the expanding molecular ring. Water molecules in this region appear to have formed with, or relaxed to, an ortho/para ratio close to the value corresponding to the local temperature of the gas and dust., Comment: Accepted for publication in A&A, HIFI Special Issue; 5 pages, 3 figures

Published
2010
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237. Herschel/HIFI observations of spectrally resolved methylidyne signatures toward the high-mass star-forming core NGC6334I

Author

van der Wiel, M. H. D., van der Tak, F. F. S., Lis, D. C., Bell, T., Bergin, E. A., Comito, C., Emprechtinger, M., Schilke, P., Caux, E., Ceccarelli, C., Baudry, A., Goldsmith, P. F., Herbst, E., Langer, W., Lord, S., Neufeld, D., Pearson, J., Philips, T., Rolffs, R., Yorke, H., Bacmann, A., Benedettini, M., Blake, G. A., Boogert, A., Bottinelli, S., Cabrit, S., Caselli, P., Castets, A., Cernicharo, J., Codella, C., Coutens, A., Crimier, N., Demyk, K., Dominik, C., Encrenaz, P., Falgarone, E., Fuente, A., Gerin, M., Helmich, F., Hennebelle, P., Henning, T., Hily-Blant, P., Jacq, T., Kahane, C., Kama, M., Klotz, A., Lefloch, B., Lorenzani, A., Maret, S., Melnick, G., Nisini, B., Pacheco, S., Pagani, L., Parise, B., Salez, M., Saraceno, P., Schuster, K., Tielens, A. G. G. M., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wyrowski, F., Edwards, K., Zmuidzinas, J., Morris, P., Samoska, L. A., Teyssier, D., van der Wiel, M. H. D., van der Tak, F. F. S., Lis, D. C., Bell, T., Bergin, E. A., Comito, C., Emprechtinger, M., Schilke, P., Caux, E., Ceccarelli, C., Baudry, A., Goldsmith, P. F., Herbst, E., Langer, W., Lord, S., Neufeld, D., Pearson, J., Philips, T., Rolffs, R., Yorke, H., Bacmann, A., Benedettini, M., Blake, G. A., Boogert, A., Bottinelli, S., Cabrit, S., Caselli, P., Castets, A., Cernicharo, J., Codella, C., Coutens, A., Crimier, N., Demyk, K., Dominik, C., Encrenaz, P., Falgarone, E., Fuente, A., Gerin, M., Helmich, F., Hennebelle, P., Henning, T., Hily-Blant, P., Jacq, T., Kahane, C., Kama, M., Klotz, A., Lefloch, B., Lorenzani, A., Maret, S., Melnick, G., Nisini, B., Pacheco, S., Pagani, L., Parise, B., Salez, M., Saraceno, P., Schuster, K., Tielens, A. G. G. M., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wyrowski, F., Edwards, K., Zmuidzinas, J., Morris, P., Samoska, L. A., and Teyssier, D.

Abstract

In contrast to extensively studied dense star-forming cores, little is known about diffuse gas surrounding star-forming regions. We study molecular gas in the high-mass star-forming region NGC6334I, which contains diffuse, quiescent components that are inconspicuous in widely used molecular tracers such as CO. We present Herschel/HIFI observations of CH toward NGC6334I observed as part of the CHESS key program. HIFI resolves the hyperfine components of its J=3/2-1/2 transition, observed in both emission and absorption. The CH emission appears close to the systemic velocity of NGC6334I, while its measured linewidth of 3 km/s is smaller than previously observed in dense gas tracers such as NH3 and SiO. The CH abundance in the hot core is 7 10^-11, two to three orders of magnitude lower than in diffuse clouds. While other studies find distinct outflows in, e.g., CO and H2O toward NGC6334I, we do not detect outflow signatures in CH. To explain the absorption signatures, at least two absorbing components are needed at -3.0 and +6.5 km/s with N(CH)=7 10^13 and 3 10^13 cm^-2. Two additional absorbing clouds are found at +8.0 and 0.0 km/s, both with N(CH)=2 10^13 cm^-2. Turbulent linewidths for the four absorption components vary between 1.5 and 5.0 km/s in FWHM. We constrain physical properties of our CH clouds by matching our CH absorbers with other absorption signatures. In the hot core, molecules such as H2O and CO trace gas that is heated and dynamically influenced by outflow activity, whereas CH traces more quiescent material. The four CH absorbers have column densities and turbulent properties consistent with diffuse clouds: two are located near NGC6334, and two are unrelated foreground clouds. Local density and dynamical effects influence the chemical composition of physical components of NGC6334, causing some components to be seen in CH but not in other tracers, and vice versa., Comment: Accepted by A&A Letters; 5 pages, 1 figure; v2: minor textual and typographical changes

Published
2010
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238. CHESS, Chemical Herschel surveys of star forming regions:Peering into the protostellar shock L1157-B1

Author

Lefloch, B., Cabrit, S., Codella, C., Melnick, G., Cernicharo, J., Caux, E., Benedettini, M., Boogert, A., Caselli, P., Ceccarelli, C., Gueth, F., Hily-Blant, P., Lorenzani, A., Neufeld, D., Nisini, B., Pacheco, S., Pagani, L., Pardo, J. R., Parise, B., Salez, M., Schuster, K., Viti, S., Bacmann, A., Baudry, A., Bell, T., Bergin, E. A., Blake, G., Bottinelli, S., Castets, A., Comito, C., Coutens, A., Crimier, N., Dominik, C., Demyk, K., Encrenaz, P., Falgarone, E., Fuente, A., Gerin, M., Goldsmith, P., Helmich, F., Hennebelle, P., Henning, T., Herbst, E., Jacq, T., Kahane, C., Kama, M., Klotz, A., Langer, W., Lis, D., Lord, S., Maret, S., Pearson, J., Phillips, T., Saraceno, P., Schilke, P., Tielens, A. G. G. M., van der Tak, F., van der Wiel, M., Vastel, C., Wakelam, V., Walters, A., Wyrowski, F., Yorke, H., Bachiller, R., Borys, C., De Lange, G., Delorme, Y., Kramer, C., Larsson, B., Lai, R., Maiwald, F. W., Martin-Pintado, J., Mehdi, I., Ossenkopf, V., Siegel, P., Stutzki, J., Wunsch, J. H., Lefloch, B., Cabrit, S., Codella, C., Melnick, G., Cernicharo, J., Caux, E., Benedettini, M., Boogert, A., Caselli, P., Ceccarelli, C., Gueth, F., Hily-Blant, P., Lorenzani, A., Neufeld, D., Nisini, B., Pacheco, S., Pagani, L., Pardo, J. R., Parise, B., Salez, M., Schuster, K., Viti, S., Bacmann, A., Baudry, A., Bell, T., Bergin, E. A., Blake, G., Bottinelli, S., Castets, A., Comito, C., Coutens, A., Crimier, N., Dominik, C., Demyk, K., Encrenaz, P., Falgarone, E., Fuente, A., Gerin, M., Goldsmith, P., Helmich, F., Hennebelle, P., Henning, T., Herbst, E., Jacq, T., Kahane, C., Kama, M., Klotz, A., Langer, W., Lis, D., Lord, S., Maret, S., Pearson, J., Phillips, T., Saraceno, P., Schilke, P., Tielens, A. G. G. M., van der Tak, F., van der Wiel, M., Vastel, C., Wakelam, V., Walters, A., Wyrowski, F., Yorke, H., Bachiller, R., Borys, C., De Lange, G., Delorme, Y., Kramer, C., Larsson, B., Lai, R., Maiwald, F. W., Martin-Pintado, J., Mehdi, I., Ossenkopf, V., Siegel, P., Stutzki, J., and Wunsch, J. H.

Abstract

The outflow driven by the low-mass class 0 protostar L1157 is the prototype of the so-called chemically active outflows. The bright bowshock B1 in the southern outflow lobe is a privileged testbed of magneto-hydrodynamical (MHD) shock models, for which dynamical and chemical processes are strongly interdependent. We present the first results of the unbiased spectral survey of the L1157-B1 bowshock, obtained in the framework of the key program "Chemical Herschel Surveys of Star Forming Regions" (CHESS). The main aim is to trace the warm and chemically enriched gas and to infer the excitation conditions in the shock region. The CO 5-4 and H2O lines have been detected at high-spectral resolution in the unbiased spectral survey of the HIFI-Band 1b spectral window (555-636 GHz), presented by Codella et al. in this volume. Complementary ground-based observations in the submm window help establish the origin of the emission detected in the main-beam of HIFI, and the physical conditions in the shock.}{Both lines exhibit broad wings, which extend to velocities much higher than reported up to now. We find that the molecular emission arises from two regions with distinct physical conditions: an extended, warm (100K), dense (3e5 cm-3) component at low-velocity, which dominates the water line flux in Band~1; a secondary component in a small region of B1 (a few arcsec) associated with high-velocity, hot (> 400 K) gas of moderate density ((1.0-3.0)e4 cm-3), which appears to dominate the flux of the water line at 179mu observed with PACS. The water abundance is enhanced by two orders of magnitude between the low- and the high-velocity component, from 8e-7 up to 8e-5. The properties of the high-velocity component agree well with the predictions of steady-state C-shock models., Comment: Accepted for Publication in Astronomy and Astrophysics (Herschel Special Issue)

Published
2010
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239. Detection of interstellar oxidaniumyl: abundant H2O+ towards the star-forming regions DR21, Sgr B2, and NGC6334

Author

Ossenkopf, V., Müller, H. S. P., Lis, D. C., Schilke, P., Bell, T. A., Bruderer, S., Bergin, E., Ceccarelli, C., Comito, C., Stutzki, J., Bacman, A., Baudry, A., Benz, A. O., Benedettini, M., Berne, O., Blake, G., Boogert, A., Bottinelli, S., Boulanger, F., Cabrit, S., Caselli, P., Caux, E., Cernicharo, J., Codella, C., Coutens, A., Crimier, N., Crockett, N. R., Daniel, F., Demyk, K., Dieleman, P., Dominik, C., Dubernet, M. L., Emprechtinger, M., Encrenaz, P., Falgarone, E., France, K., Fuente, A., Gerin, M., Giesen, T. F., di Giorgio, A. M., Goicoechea, J. R., Goldsmith, P. F., Güsten, R., Harris, A., Helmich, F., Herbst, E., Hily-Blant, P., Jacobs, K., Jacq, T., Joblin, Ch., Johnstone, D., Kahane, C., Kama, M., Klein, T., Klotz, A., Kramer, C., Langer, W., Lefloch, B., Leinz, C., Lorenzani, A., Lord, S. D., Maret, S., Martin, P. G., Martin-Pintado, J., McCoey, C., Melchior, M., Melnick, G. J., Menten, K. M., Mookerjea, B., Morris, P., Murphy, J. A., Neufeld, D. A., Nisini, B., Pacheco, S., Pagani, L., Parise, B., Pearson, J. C., Pérault, M., Phillips, T. G., Plume, R., Quin, S. -L., Rizzo, R., Röllig, M., Salez, M., Saraceno, P., Schlemmer, S., Simon, R., Schuster, K., van der Tak, F. F. S., Tielens, A. G. G. M., Teyssier, D., Trappe, N., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wang, S., Whyborn, N., van der Wiel, M., Yorke, H. W., Yu, S., Zmuidzinas, J., Ossenkopf, V., Müller, H. S. P., Lis, D. C., Schilke, P., Bell, T. A., Bruderer, S., Bergin, E., Ceccarelli, C., Comito, C., Stutzki, J., Bacman, A., Baudry, A., Benz, A. O., Benedettini, M., Berne, O., Blake, G., Boogert, A., Bottinelli, S., Boulanger, F., Cabrit, S., Caselli, P., Caux, E., Cernicharo, J., Codella, C., Coutens, A., Crimier, N., Crockett, N. R., Daniel, F., Demyk, K., Dieleman, P., Dominik, C., Dubernet, M. L., Emprechtinger, M., Encrenaz, P., Falgarone, E., France, K., Fuente, A., Gerin, M., Giesen, T. F., di Giorgio, A. M., Goicoechea, J. R., Goldsmith, P. F., Güsten, R., Harris, A., Helmich, F., Herbst, E., Hily-Blant, P., Jacobs, K., Jacq, T., Joblin, Ch., Johnstone, D., Kahane, C., Kama, M., Klein, T., Klotz, A., Kramer, C., Langer, W., Lefloch, B., Leinz, C., Lorenzani, A., Lord, S. D., Maret, S., Martin, P. G., Martin-Pintado, J., McCoey, C., Melchior, M., Melnick, G. J., Menten, K. M., Mookerjea, B., Morris, P., Murphy, J. A., Neufeld, D. A., Nisini, B., Pacheco, S., Pagani, L., Parise, B., Pearson, J. C., Pérault, M., Phillips, T. G., Plume, R., Quin, S. -L., Rizzo, R., Röllig, M., Salez, M., Saraceno, P., Schlemmer, S., Simon, R., Schuster, K., van der Tak, F. F. S., Tielens, A. G. G. M., Teyssier, D., Trappe, N., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wang, S., Whyborn, N., van der Wiel, M., Yorke, H. W., Yu, S., and Zmuidzinas, J.

Abstract

We identify a prominent absorption feature at 1115 GHz, detected in first HIFI spectra towards high-mass star-forming regions, and interpret its astrophysical origin. The characteristic hyperfine pattern of the H2O+ ground-state rotational transition, and the lack of other known low-energy transitions in this frequency range, identifies the feature as H2O+ absorption against the dust continuum background and allows us to derive the velocity profile of the absorbing gas. By comparing this velocity profile with velocity profiles of other tracers in the DR21 star-forming region, we constrain the frequency of the transition and the conditions for its formation. In DR21, the velocity distribution of H2O+ matches that of the [CII] line at 158\mu\m and of OH cm-wave absorption, both stemming from the hot and dense clump surfaces facing the HII-region and dynamically affected by the blister outflow. Diffuse foreground gas dominates the absorption towards Sgr B2. The integrated intensity of the absorption line allows us to derive lower limits to the H2O+ column density of 7.2e12 cm^-2 in NGC 6334, 2.3e13 cm^-2 in DR21, and 1.1e15 cm^-2 in Sgr B2., Comment: Accepted for publication in A&A

Published
2010
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240. Strong absorption by interstellar hydrogen fluoride: Herschel/HIFI observations of the sight-line to G10.6-0.4 (W31C)

Author

Neufeld, D. A., Sonnentrucker, P., Phillips, T. G., Lis, D. C., De Luca, M., Goicoechea, J. R., Black, J. H., Gerin, M., Bell, T., Boulanger, F., Cernicharo, J., Coutens, A., Dartois, E., Kazmierczak, M., Encrenaz, P., Falgarone, E., Geballe, T. R., Giesen, T., Godard, B., Goldsmith, P. F., Gry, C., Gupta, H., Hennebelle, P., Herbst, E., Hily-Blant, P., Joblin, C., Kolos, R., Krelowski, J., Martin-Pintado, J., Menten, K. M., Monje, R., Mookerjea, B., Pearson, J., Perault, M., Persson, C., Plume, R., Salez, M., Schlemmer, S., Schmidt, M., Stutzki, J., Teyssier, D., Vastel, C., Yu, S., Cais, P., Caux, E., Liseau, R., Morris, P., Planesas, P., Neufeld, D. A., Sonnentrucker, P., Phillips, T. G., Lis, D. C., De Luca, M., Goicoechea, J. R., Black, J. H., Gerin, M., Bell, T., Boulanger, F., Cernicharo, J., Coutens, A., Dartois, E., Kazmierczak, M., Encrenaz, P., Falgarone, E., Geballe, T. R., Giesen, T., Godard, B., Goldsmith, P. F., Gry, C., Gupta, H., Hennebelle, P., Herbst, E., Hily-Blant, P., Joblin, C., Kolos, R., Krelowski, J., Martin-Pintado, J., Menten, K. M., Monje, R., Mookerjea, B., Pearson, J., Perault, M., Persson, C., Plume, R., Salez, M., Schlemmer, S., Schmidt, M., Stutzki, J., Teyssier, D., Vastel, C., Yu, S., Cais, P., Caux, E., Liseau, R., Morris, P., and Planesas, P.

Abstract

We report the detection of strong absorption by interstellar hydrogen fluoride along the sight-line to the submillimeter continuum source G10.6-0.4 (W31C). We have used Herschel's HIFI instrument, in dual beam switch mode, to observe the 1232.4763 GHz J=1-0 HF transition in the upper sideband of the Band 5a receiver. The resultant spectrum shows weak HF emission from G10.6-0.4 at LSR velocities in the range -10 to -3 km/s, accompanied by strong absorption by foreground material at LSR velocities in the range 15 to 50 km/s. The spectrum is similar to that of the 1113.3430 GHz 1(11)-0(00) transition of para-water, although at some frequencies the HF (hydrogen fluoride) optical depth clearly exceeds that of para-H2O. The optically-thick HF absorption that we have observed places a conservative lower limit of 1.6E+14 cm-2 on the HF column density along the sight-line to G10.6-0.4. Our lower limit on the HF abundance, 6E-9 relative to hydrogen nuclei, implies that hydrogen fluoride accounts for between ~ 30 and 100% of the fluorine nuclei in the gas phase along this sight-line. This observation corroborates theoretical predictions that - because the unique thermochemistry of fluorine permits the exothermic reaction of F atoms with molecular hydrogen - HF will be the dominant reservoir of interstellar fluorine under a wide range of conditions., Comment: Accepted for publication in Astronomy and Astrophysics (Herschel special issue). This revised version corrects a typographic error in the HTML abstract, in which the lower limit on the HF abundance (should be 6E-9) was previously misstated. The abstract in the PDF version is correct and the latter has not been modified

Published
2010
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241. Sensitivity analyses of dense cloud chemical models

Author

Wakelam, V., Herbst, E., Bourlot, J. Le, Hersant, F., Selsis, F., Guilloteau, S., Wakelam, V., Herbst, E., Bourlot, J. Le, Hersant, F., Selsis, F., and Guilloteau, S.

Abstract

Because of new telescopes that will dramatically improve our knowledge of the interstellar medium, chemical models will have to be used to simulate the chemistry of many regions with diverse properties. To make these models more robust, it is important to understand their sensitivity to a variety of parameters. In this article, we report a study of the sensitivity of a chemical model of a cold dense core, with homogeneous and time-independent physical conditions, to variations in the following parameters: initial chemical inventory, gas temperature and density, cosmic-ray ionization rate, chemical reaction rate coefficients, and elemental abundances. From the results of the parameter variations, we can quantify the sensitivity of the model to each parameter as a function of time. Our results can be used in principle with observations to constrain some parameters for different cold clouds. We also attempted to use the Monte Carlo approach with all parameters varied collectively. Within the parameter ranges studied, the most critical parameters turn out to be the reaction rate coefficients at times up to 4e5 yr and elemental abundances at later times. At typical times of best agreement with observation, models are sensitive to both of these parameters. The models are less sensitive to other parameters such as the gas density and temperature. The improvement of models will require that the uncertainties in rate coefficients of important reactions be reduced. As the chemistry becomes better understood and more robust, it should be possible to use model sensitivities concerning other parameters, such as the elemental abundances and the cosmic ray ionization rate, to yield detailed information on cloud properties and history. Nevertheless, at the current stage, we cannot determine the best values of all the parameters simultaneously based on purely observational constraints., Comment: Accepted for publication in Astronomy & Astrophysics

Published
2010
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242. Beyond the pseudo-time-dependent approach: chemical models of dense core precursors

Author

Hassel, G. E., Herbst, E., Bergin, E. A., Hassel, G. E., Herbst, E., and Bergin, E. A.

Abstract

Context: Chemical models of dense cloud cores often utilize the so-called pseudo-time-dependent approximation, in which the physical conditions are held fixed and uniform as the chemistry occurs. In this approximation, the initial abundances chosen, which are totally atomic in nature except for molecular hydrogen, are artificial. A more detailed approach to the chemistry of dense cold cores should include the physical evolution during their early stages of formation. Aims: Our major goal is to investigate the initial synthesis of molecular ices and gas-phase molecules as cold molecular gas begins to form behind a shock in the diffuse interstellar medium. The abundances calculated as the conditions evolve can then be utilized as reasonable initial conditions for a theory of the chemistry of dense cores. Methods: Hydrodynamic shock-wave simulations of the early stages of cold core formation are used to determine the time-dependent physical conditions for a gas-grain chemical network. We follow the cold post-shock molecular evolution of ices and gas-phase molecules for a range of visual extinction up to AV ~ 3, which increases with time. At higher extinction, self-gravity becomes important. Results: As the newly condensed gas enters its cool post-shock phase, a large amount of CO is produced in the gas. As the CO forms, water ice is produced on grains, while accretion of CO produces CO ice. The production of CO2 ice from CO occurs via several surface mechanisms, while the production of CH4 ice is slowed by gas-phase conversion of C into CO., Comment: 9 pages, 3 figures, 2 tables

Published
2010
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243. CH+(1-0) and (CH+)-C-13(1-0) absorption lines in the direction of massive star-forming regions

Author

Falgarone, E., Godard, B., Cernicharo, J., De Luca, M., Gerin, M., Phillips, T. G., Black, J. H., Lis, D. C., Bell, T. A., Boulanger, F., Coutens, A., Dartois, E., Encrenaz, P., Giesen, T., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Gry, C., Hennebelle, P., Herbst, E., Hily-Blant, P., Joblin, C., Kazmierczak, M., Kolos, R., Krelowski, J., Martin-Pintado, J., Monje, R., Mookerjea, B., Neufeld, D. A., Perault, M., Pearson, J. C., Persson, C., Plume, R., Salez, M., Schmidt, M., Sonnentrucker, P., Stutzki, J., Teyssier, D., Vastel, C., Yu, S., Menten, K., Geballe, T. R., Schlemmer, S., Shipman, R., Tielens, A. G. G. M., Philipp, S., Cros, A., Zmuidzinas, J., Samoska, L. A., Klein, K., Lorenzani, A., Szczerba, R., Peron, I., Cais, P., Gaufre, P., Ravera, L., Morris, P., Lord, S., Planesas, P., Falgarone, E., Godard, B., Cernicharo, J., De Luca, M., Gerin, M., Phillips, T. G., Black, J. H., Lis, D. C., Bell, T. A., Boulanger, F., Coutens, A., Dartois, E., Encrenaz, P., Giesen, T., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Gry, C., Hennebelle, P., Herbst, E., Hily-Blant, P., Joblin, C., Kazmierczak, M., Kolos, R., Krelowski, J., Martin-Pintado, J., Monje, R., Mookerjea, B., Neufeld, D. A., Perault, M., Pearson, J. C., Persson, C., Plume, R., Salez, M., Schmidt, M., Sonnentrucker, P., Stutzki, J., Teyssier, D., Vastel, C., Yu, S., Menten, K., Geballe, T. R., Schlemmer, S., Shipman, R., Tielens, A. G. G. M., Philipp, S., Cros, A., Zmuidzinas, J., Samoska, L. A., Klein, K., Lorenzani, A., Szczerba, R., Peron, I., Cais, P., Gaufre, P., Ravera, L., Morris, P., Lord, S., and Planesas, P.

Abstract

We report the detection of the ground-state rotational transition of the methylidyne cation CH+ and its isotopologue (CH+)-C-13 toward the remote massive star-forming regions W33A, W49N, and W51 with the HIFI instrument onboard the Herschel satellite. Both lines are seen only in absorption against the dust continuum emission of the star-forming regions. The CH+ absorption is saturated over almost the entire velocity ranges sampled by the lines-of-sight that include gas associated with the star-forming regions (SFR) and Galactic foreground material. The CH+ column densities are inferred from the optically thin components. A lower limit of the isotopic ratio [(CH+)-C-12]/[(CH+)-C-13]> 35.5 is derived from the absorptions of foreground material toward W49N. The column density ratio, N(CH+)/N(HCO+), is found to vary by at least a factor 10, between 4 and > 40, in the Galactic foreground material. Line-of-sight 12CH+ average abundances relative to total hydrogen are estimated. Their average value, N(CH+)/NH > 2.6 x 10(-8), is higher than that observed in the solar neighborhood and confirms the high abundances of CH+ in the Galactic interstellar medium. We compare this result to the predictions of turbulent dissipation regions (TDR) models and find that these high abundances can be reproduced for the inner Galaxy conditions. It is remarkable that the range of predicted N(CH+)/ N(HCO+) ratios, from 1 to similar to 50, is comparable to that observed.

Published
2010

244. Excitation and abundance of C-3 in star forming cores Herschel/HIFI observations of the sight-lines to W31C and W49N

Author

Mookerjea, B., Giesen, T., Stutzki, J., Cernicharo, J., Goicoechea, J. R., De Luca, M., Bell, T. A., Gupta, H., Gerin, M., Persson, C. M., Sonnentrucker, P., Makai, Z., Black, J., Boulanger, F., Coutens, A., Dartois, E., Encrenaz, P., Falgarone, E., Geballe, T., Godard, B., Goldsmith, P. F., Gry, C., Hennebelle, P., Herbst, E., Hily-Blant, P., Joblin, C., Kazmierczak, M., Kolos, R., Krelowski, J., Lis, D. C., Martin-Pintado, J., Menten, K. M., Monje, R., Pearson, J. C., Perault, M., Phillips, T. G., Plume, R., Salez, M., Schlemmer, S., Schmidt, M., Teyssier, D., Vastel, C., Yu, S., Dieleman, P., Guesten, R., Honingh, C. E., Morris, P., Roelfsema, P., Schieder, R., Tielens, A. G. G. M., Zmuidzinas, J., Mookerjea, B., Giesen, T., Stutzki, J., Cernicharo, J., Goicoechea, J. R., De Luca, M., Bell, T. A., Gupta, H., Gerin, M., Persson, C. M., Sonnentrucker, P., Makai, Z., Black, J., Boulanger, F., Coutens, A., Dartois, E., Encrenaz, P., Falgarone, E., Geballe, T., Godard, B., Goldsmith, P. F., Gry, C., Hennebelle, P., Herbst, E., Hily-Blant, P., Joblin, C., Kazmierczak, M., Kolos, R., Krelowski, J., Lis, D. C., Martin-Pintado, J., Menten, K. M., Monje, R., Pearson, J. C., Perault, M., Phillips, T. G., Plume, R., Salez, M., Schlemmer, S., Schmidt, M., Teyssier, D., Vastel, C., Yu, S., Dieleman, P., Guesten, R., Honingh, C. E., Morris, P., Roelfsema, P., Schieder, R., Tielens, A. G. G. M., and Zmuidzinas, J.

Abstract

We present spectrally resolved observations of triatomic carbon (C-3) in several ro-vibrational transitions between the vibrational ground state and the low-energy nu(2) bending mode at frequencies between 1654-1897 GHz along the sight-lines to the submillimeter continuum sources W31C and W49N, using Herschel's HIFI instrument. We detect C-3 in absorption arising from the warm envelope surrounding the hot core, as indicated by the velocity peak position and shape of the line profile. The sensitivity does not allow to detect C-3 absorption due to diffuse foreground clouds. From the column densities of the rotational levels in the vibrational ground state probed by the absorption we derive a rotation temperature (T-rot) of similar to 50-70 K, which is a good measure of the kinetic temperature of the absorbing gas, as radiative transitions within the vibrational ground state are forbidden. It is also in good agreement with the dust temperatures for W31C and W49N. Applying the partition function correction based on the derived T-rot, we get column densities N(C-3) similar to 7-9 x 10(14) cm(-2) and abundance x(C-3) similar to 10(-8) with respect to H-2. For W31C, using a radiative transfer model including far-infrared pumping by the dust continuum and a temperature gradient within the source along the line of sight we find that a model with x(C-3) = 10(-8), T-kin = 30-50 K, N(C-3) = 1.5 x 10(15) cm(-2) fits the observations reasonably well and provides parameters in very good agreement with the simple excitation analysis.

Published
2010

245. The methanol lines and hot core of OMC2-FIR4, an intermediate-mass protostar, with Herschel/HIFI

Author

Kama, M., Dominik, C., Maret, S., van der Tak, F., Caux, E., Ceccarelli, C., Fuente, A., Crimier, N., Lord, S., Bacmann, A., Baudry, A., Bell, T., Benedettini, M., Bergin, E. A., Blake, G. A., Boogert, A., Bottinelli, S., Cabrit, S., Caselli, P., Castets, A., Cernicharo, J., Codella, C., Comito, C., Coutens, A., Demyk, K., Encrenaz, P., Falgarone, E., Gerin, M., Goldsmith, P. F., Helmich, F., Hennebelle, P., Henning, T., Herbst, E., Hily-Blant, P., Jacq, T., Kahane, C., Klotz, A., Langer, W., Lefloch, B., Lis, D., Lorenzani, A., Melnick, G., Nisini, B., Pacheco, S., Pagani, L., Parise, B., Pearson, J., Phillips, T., Salez, M., Saraceno, P., Schilke, P., Schuster, K., Tielens, X., van der Wiel, M. H. D., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wyrowski, F., Yorke, H., Cais, P., Guesten, R., Philipp, S., Klein, T., Kama, M., Dominik, C., Maret, S., van der Tak, F., Caux, E., Ceccarelli, C., Fuente, A., Crimier, N., Lord, S., Bacmann, A., Baudry, A., Bell, T., Benedettini, M., Bergin, E. A., Blake, G. A., Boogert, A., Bottinelli, S., Cabrit, S., Caselli, P., Castets, A., Cernicharo, J., Codella, C., Comito, C., Coutens, A., Demyk, K., Encrenaz, P., Falgarone, E., Gerin, M., Goldsmith, P. F., Helmich, F., Hennebelle, P., Henning, T., Herbst, E., Hily-Blant, P., Jacq, T., Kahane, C., Klotz, A., Langer, W., Lefloch, B., Lis, D., Lorenzani, A., Melnick, G., Nisini, B., Pacheco, S., Pagani, L., Parise, B., Pearson, J., Phillips, T., Salez, M., Saraceno, P., Schilke, P., Schuster, K., Tielens, X., van der Wiel, M. H. D., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wyrowski, F., Yorke, H., Cais, P., Guesten, R., Philipp, S., and Klein, T.

Abstract

In contrast with numerous studies on the physical and chemical structure of low-and high-mass protostars, much less is known about their intermediate-mass counterparts, a class of objects that could help to elucidate the mechanisms of star formation on both ends of the mass range. We present the first results from a rich HIFI spectral dataset on an intermediate-mass protostar, OMC2-FIR4, obtained in the CHESS (Chemical HErschel Survey of Star forming regions) key programme. The more than 100 methanol lines detected between 554 and 961 GHz cover a range in upper level energy of 40 to 540 K. Our physical interpretation focusses on the hot core, but likely the cold envelope and shocked regions also play a role in reality, because an analysis of the line profiles suggests the presence of multiple emission components. An upper limit of 10 (6) is placed on the methanol abundance in the hot core, using a population diagram, large-scale source model and other considerations. This value is consistent with abundances previously seen in low-mass hot cores. Furthermore, the highest energy lines at the highest frequencies display asymmetric profiles, which may arise from infall around the hot core.

Published
2010

246. Herschel observations of EXtra-Ordinary Sources (HEXOS): The present and future of spectral surveys with Herschel/ HIFI

Author

Bergin, E. A., Phillips, T. G., Comito, C., Crockett, N. R., Lis, D. C., Schilke, P., Wang, S., Bell, T. A., Blake, G. A., Bumble, B., Caux, E., Cabrit, S., Ceccarelli, C., Cernicharo, J., Daniel, F., de Graauw, Th., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Hartogh, P., Helmich, F. P., Herbst, E., Joblin, C., Johnstone, D., Kawamura, J. H., Langer, W. D., Latter, W. B., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Mueller, H. S. P., Murphy, J. A., Neufeld, D. A., Ossenkopf, V., Pagani, L., Pearson, J. C., Perault, M., Plume, R., Roelfsema, P., Qin, S. -L., Salez, M., Schlemmer, S., Stutzki, J., Tielens, A. G. G. M., Trappe, N., van der Tak, F. F. S., Vastel, C., Yorke, H. W., Yu, S., Zmuidzinas, J., Bergin, E. A., Phillips, T. G., Comito, C., Crockett, N. R., Lis, D. C., Schilke, P., Wang, S., Bell, T. A., Blake, G. A., Bumble, B., Caux, E., Cabrit, S., Ceccarelli, C., Cernicharo, J., Daniel, F., de Graauw, Th., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Hartogh, P., Helmich, F. P., Herbst, E., Joblin, C., Johnstone, D., Kawamura, J. H., Langer, W. D., Latter, W. B., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Mueller, H. S. P., Murphy, J. A., Neufeld, D. A., Ossenkopf, V., Pagani, L., Pearson, J. C., Perault, M., Plume, R., Roelfsema, P., Qin, S. -L., Salez, M., Schlemmer, S., Stutzki, J., Tielens, A. G. G. M., Trappe, N., van der Tak, F. F. S., Vastel, C., Yorke, H. W., Yu, S., and Zmuidzinas, J.

Abstract

We present initial results from the Herschel GT key program: Herschel observations of EXtra-Ordinary Sources (HEXOS) and outline the promise and potential of spectral surveys with Herschel/HIFI. The HIFI instrument offers unprecedented sensitivity, as well as continuous spectral coverage across the gaps imposed by the atmosphere, opening up a largely unexplored wavelength regime to high-resolution spectroscopy. We show the spectrum of Orion KL between 480 and 560 GHz and from 1.06 to 1.115 THz. From these data, we confirm that HIFI separately measures the dust continuum and spectrally resolves emission lines in Orion KL. Based on this capability we demonstrate that the line contribution to the broad-band continuum in this molecule-rich source is similar to 20-40% below 1 THz and declines to a few percent at higher frequencies. We also tentatively identify multiple transitions of (HDO)-O-18 in the spectra. The first detection of this rare isotopologue in the interstellar medium suggests that HDO emission is optically thick in the Orion hot core with HDO/H2O similar to 0.02. We discuss the implications of this detection for the water D/H ratio in hot cores.

Published
2010

247. Herschel/HIFI observations of spectrally resolved methylidyne signatures toward the high-mass star-forming core NGC 6334I

Author

van der Wiel, M. H. D., van der Tak, F. F. S., Lis, D. C., Bell, T., Bergin, E. A., Comito, C., Emprechtinger, M., Schilke, P., Caux, E., Ceccarelli, C., Baudry, A., Goldsmith, P. F., Herbst, E., Langer, W., Lord, S., Neufeld, D., Pearson, J., Phillips, T., Rolffs, R., Yorke, H., Bacmann, A., Benedettini, M., Blake, G. A., Boogert, A., Bottinelli, S., Cabrit, S., Caselli, P., Castets, A., Cernicharo, J., Codella, C., Coutens, A., Crimier, N., Demyk, K., Dominik, C., Encrenaz, P., Falgarone, E., Fuente, A., Gerin, M., Helmich, F., Hennebelle, P., Henning, T., Hily-Blant, P., Jacq, T., Kahane, C., Kama, M., Klotz, A., Lefloch, B., Lorenzani, A., Maret, S., Melnick, G., Nisini, B., Pacheco, S., Pagani, L., Parise, B., Salez, M., Saraceno, P., Schuster, K., Tielens, A. G. G. M., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wyrowski, F., Edwards, K., Zmuidzinas, J., Morris, P., Samoska, L. A., Teyssier, D., van der Wiel, M. H. D., van der Tak, F. F. S., Lis, D. C., Bell, T., Bergin, E. A., Comito, C., Emprechtinger, M., Schilke, P., Caux, E., Ceccarelli, C., Baudry, A., Goldsmith, P. F., Herbst, E., Langer, W., Lord, S., Neufeld, D., Pearson, J., Phillips, T., Rolffs, R., Yorke, H., Bacmann, A., Benedettini, M., Blake, G. A., Boogert, A., Bottinelli, S., Cabrit, S., Caselli, P., Castets, A., Cernicharo, J., Codella, C., Coutens, A., Crimier, N., Demyk, K., Dominik, C., Encrenaz, P., Falgarone, E., Fuente, A., Gerin, M., Helmich, F., Hennebelle, P., Henning, T., Hily-Blant, P., Jacq, T., Kahane, C., Kama, M., Klotz, A., Lefloch, B., Lorenzani, A., Maret, S., Melnick, G., Nisini, B., Pacheco, S., Pagani, L., Parise, B., Salez, M., Saraceno, P., Schuster, K., Tielens, A. G. G. M., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wyrowski, F., Edwards, K., Zmuidzinas, J., Morris, P., Samoska, L. A., and Teyssier, D.

Abstract

Context. In contrast to the more extensively studied dense star-forming cores, little is known about diffuse gas surrounding star-forming regions. Aims. We study the molecular gas in the Galactic high-mass star-forming region NGC 6334I, which contains diffuse, quiescent components that are inconspicuous in widely used molecular tracers such as CO. Methods. We present Herschel/HIFI observations of methylidyne (CH) toward NGC 6334I observed as part of the Chemical HErschel Survey of Star forming regions (CHESS) key program. HIFI resolves each of the six hyperfine components of the lowest rotational transition (J = 3/2-1/2) of CH, observed in both emission and absorption. Results. The CH emission features appear close to the systemic velocity of NGC 6334I, while its measured FWHM linewidth of 3 km s(-1) is smaller than previously observed in dense gas tracers such as NH3 and SiO. The CH abundance in the hot core is similar to 7 x 10(-11), two to three orders of magnitude lower than in diffuse clouds. While other studies find distinct outflows in, e. g., CO and H2O toward NGC 6334I, we do not detect any outflow signatures in CH. At least two redshifted components of cold absorbing material must be present at -3.0 and +6.5 km s(-1) to explain the absorption signatures. We derive a CH column density (N-CH) of 7 x 10(13) and 3 x 10(13) cm(-2) for these two absorbing clouds. We find evidence of two additional absorbing clouds at +8.0 and 0.0 km s(-1), both with N-CH approximate to 2 x 10(13) cm(-2). Turbulent linewidths for the four absorption components vary between 1.5 and 5.0 km s(-1) in FWHM. We constrain the physical properties and locations of the clouds by matching our CH absorbers with the absorption signatures seen in other molecular tracers. Conclusions. In the hot core, molecules such as H2O and CO trace gas that is heated and dynamically influenced by outflow activity, whereas the CH molecule traces more quiescent material. The four CH absorbing clouds have colu

Published
2010

248. Herschel observations of deuterated water towards Sgr B2(M)

Author

Comito, C., Schilke, P., Rolffs, R., Lis, D. C., Belloche, A., Bergin, E. A., Phillips, T. G., Bell, T. A., Crockett, N. R., Wang, S., Blake, G. A., Caux, E., Ceccarelli, C., Cernicharo, J., Daniel, F., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Herbst, E., Joblin, C., Johnstone, D., Langer, W. D., Latter, W. D., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Mueller, H. S. P., Murphy, J. A., Neufeld, D. A., Ossenkopf, V., Pearson, J. C., Perault, M., Plume, R., Qin, S. -L., Schlemmer, S., Stutzki, J., Trappe, N., van der Tak, F. F. S., Vastel, C., Yorke, H. W., Yu, S., Olberg, M., Szczerba, R., Larsson, B., Liseau, R., Lin, R. H., Samoska, L. A., Schlecht, E., Comito, C., Schilke, P., Rolffs, R., Lis, D. C., Belloche, A., Bergin, E. A., Phillips, T. G., Bell, T. A., Crockett, N. R., Wang, S., Blake, G. A., Caux, E., Ceccarelli, C., Cernicharo, J., Daniel, F., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Herbst, E., Joblin, C., Johnstone, D., Langer, W. D., Latter, W. D., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Mueller, H. S. P., Murphy, J. A., Neufeld, D. A., Ossenkopf, V., Pearson, J. C., Perault, M., Plume, R., Qin, S. -L., Schlemmer, S., Stutzki, J., Trappe, N., van der Tak, F. F. S., Vastel, C., Yorke, H. W., Yu, S., Olberg, M., Szczerba, R., Larsson, B., Liseau, R., Lin, R. H., Samoska, L. A., and Schlecht, E.

Abstract

Observations of HDO are an important complement for studies of water, because they give strong constraints on the formation processes - grain surfaces versus energetic process in the gas phase, e. g. in shocks. The HIFI observations of multiple transitions of HDO in Sgr B2(M) presented here allow the determination of the HDO abundance throughout the envelope, which has not been possible before with ground-based observations only. The abundance structure has been modeled with the spherical Monte Carlo radiative transfer code RATRAN, which also takes radiative pumping by continuum emission from dust into account. The modeling reveals that the abundance of HDO rises steeply with temperature from a low abundance (2.5 x 10(-11)) in the outer envelope at temperatures below 100 K through a medium abundance (1.5 x 10(-9)) in the inner envelope/outer core at temperatures between 100 and 200 K, and finally a high abundance (3.5 x 10(-9)) at temperatures above 200 K in the hot core.

Published
2010

249. Herschel observations of EXtra-Ordinary Sources (HEXOS): The Terahertz spectrum of Orion KL seen at high spectral resolution

Author

Crockett, N. R., Bergin, E. A., Wang, S., Lis, D. C., Bell, T. A., Blake, G. A., Boogert, A., Bumble, B., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Daniel, F., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Guesten, R., Hartogh, P., Helmich, F., Herbst, E., Honingh, N., Joblin, C., Johnstone, D., Karpov, A., Kawamura, J. H., Kooi, J., Krieg, J. -M., Langer, W. D., Latter, W. D., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Mueller, H. S. P., Murphy, J. A., Neufeld, D. A., Ossenkopf, V., Pearson, J. C., Perault, M., Phillips, T. G., Plume, R., Qin, S. -L., Roelfsema, P., Schieder, R., Schilke, P., Schlemmer, S., Stutzki, J., van der Tak, F. F. S., Tielens, A., Trappe, N., Vastel, C., Yorke, H. W., Yu, S., Zmuidzinas, J., Crockett, N. R., Bergin, E. A., Wang, S., Lis, D. C., Bell, T. A., Blake, G. A., Boogert, A., Bumble, B., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Daniel, F., Dubernet, M. -L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T. F., Goicoechea, J. R., Goldsmith, P. F., Gupta, H., Guesten, R., Hartogh, P., Helmich, F., Herbst, E., Honingh, N., Joblin, C., Johnstone, D., Karpov, A., Kawamura, J. H., Kooi, J., Krieg, J. -M., Langer, W. D., Latter, W. D., Lord, S. D., Maret, S., Martin, P. G., Melnick, G. J., Menten, K. M., Morris, P., Mueller, H. S. P., Murphy, J. A., Neufeld, D. A., Ossenkopf, V., Pearson, J. C., Perault, M., Phillips, T. G., Plume, R., Qin, S. -L., Roelfsema, P., Schieder, R., Schilke, P., Schlemmer, S., Stutzki, J., van der Tak, F. F. S., Tielens, A., Trappe, N., Vastel, C., Yorke, H. W., Yu, S., and Zmuidzinas, J.

Abstract

We present the first high spectral resolution observations of Orion KL in the frequency ranges 1573.4-1702.8 GHz (band 6b) and 1788.4-1906.8 GHz (band 7b) obtained using the HIFI instrument on board the Herschel Space Observatory. We characterize the main emission lines found in the spectrum, which primarily arise from a range of components associated with Orion KL including the hot core, but also see widespread emission from components associated with molecular outflows traced by H2O, SO2, and OH. We find that the density of observed emission lines is significantly diminished in these bands compared to lower frequency Herschel/HIFI bands.

Published
2010

250. The distribution of water in the high-mass star-forming region NGC 6334 I

Author

Emprechtinger, M., Lis, D. C., Bell, T., Phillips, T. G., Schilke, P., Comito, C., Rolffs, R., van der Tak, F., Ceccarelli, C., Aarts, H., Bacmann, A., Baudry, A., Benedettini, M., Bergin, E. A., Blake, G., Boogert, A., Bottinelli, S., Cabrit, S., Caselli, P., Castets, A., Caux, E., Cernicharo, J., Codella, C., Coutens, A., Crimier, N., Demyk, K., Dominik, C., Encrenaz, P., Falgarone, E., Fuente, A., Gerin, M., Goldsmith, P., Helmich, F., Hennebelle, P., Henning, T., Herbst, E., Hily-Blant, P., Jacq, T., Kahane, C., Kama, M., Klotz, A., Kooi, J., Langer, W., Lefloch, B., Loose, A., Lord, S., Lorenzani, A., Maret, S., Melnick, G., Neufeld, D., Nisini, B., Ossenkopf, V., Pacheco, S., Pagani, L., Parise, B., Pearson, J., Risacher, C., Salez, M., Saraceno, P., Schuster, K., Stutzki, J., Tielens, X., van der Wiel, M., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wyrowski, F., Yorke, H., Emprechtinger, M., Lis, D. C., Bell, T., Phillips, T. G., Schilke, P., Comito, C., Rolffs, R., van der Tak, F., Ceccarelli, C., Aarts, H., Bacmann, A., Baudry, A., Benedettini, M., Bergin, E. A., Blake, G., Boogert, A., Bottinelli, S., Cabrit, S., Caselli, P., Castets, A., Caux, E., Cernicharo, J., Codella, C., Coutens, A., Crimier, N., Demyk, K., Dominik, C., Encrenaz, P., Falgarone, E., Fuente, A., Gerin, M., Goldsmith, P., Helmich, F., Hennebelle, P., Henning, T., Herbst, E., Hily-Blant, P., Jacq, T., Kahane, C., Kama, M., Klotz, A., Kooi, J., Langer, W., Lefloch, B., Loose, A., Lord, S., Lorenzani, A., Maret, S., Melnick, G., Neufeld, D., Nisini, B., Ossenkopf, V., Pacheco, S., Pagani, L., Parise, B., Pearson, J., Risacher, C., Salez, M., Saraceno, P., Schuster, K., Stutzki, J., Tielens, X., van der Wiel, M., Vastel, C., Viti, S., Wakelam, V., Walters, A., Wyrowski, F., and Yorke, H.

Abstract

Aims. We present observations of twelve rotational transitions of (H2O)-O-16, (H2O)-O-18, and (H2O)-O-17 toward the massive star-forming region NGC 6334 I, carried out with Herschel/HIFI as part of the guaranteed time key program Chemical HErschel Surveys of Star forming regions (CHESS). We analyze these observations to obtain insights into physical processes in this region. Methods. We identify three main gas components (hot core, cold foreground, and outflow) in NGC 6334 I and derive the physical conditions in these components. Results. The hot core, identified by the emission in highly excited lines, shows a high excitation temperature of similar to 200 K, whereas water in the foreground component is predominantly in the ortho-and para-ground states. The abundance of water varies between 4 x 10(-5) (outflow) and 10(-8) (cold foreground gas). This variation is most likely due to the freeze-out of water molecules onto dust grains. The (H2O)-O-18/(H2O)-O-17 abundance ratio is 3.2, which is consistent with the O-18/O-17 ratio determined from CO isotopologues. The ortho/para ratio in water appears to be relatively low (1.6 +/- 1) in the cold, quiescent gas, but close to the equilibrium value of three in the warmer outflow material (2.5 +/- 0.8).

Published
2010

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