Search

Your search keyword '"Daniel, Fabien"' showing total 32 results
Start Over Author "Daniel, Fabien"
32 results on '"Daniel, Fabien"'

1. Deuteration of ammonia in the starless core Ophiuchus/H-MM1

Author

Harju, Jorma, Daniel, Fabien, Sipilä, Olli, Caselli, Paola, Pineda, Jaime E., Friesen, Rachel K., Punanova, Anna, Güsten, Rolf, Wiesenfeld, Laurent, Myers, Philip C., Faure, Alexandre, Hily-Blant, Pierre, Rist, Claire, Rosolowsky, Erik, Schlemmer, Stephan, and Shirley, Yancy L.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

Ammonia and its deuterated isotopologues probe physical conditions in dense molecular cloud cores. With the aim of testing the current understanding of the spin-state chemistry of these molecules, we observed spectral lines of NH3, NH2D, NHD2, ND3, and N2D+ towards a dense, starless core in Ophiuchus with the APEX, GBT, and IRAM 30-m telescopes. The observations were interpreted using a gas-grain chemistry model combined with radiative transfer calculations. The chemistry model distinguishes between the different nuclear spin states of light hydrogen molecules, ammonia, and their deuterated forms. High deuterium fractionation ratios with NH2D/NH3=0.4, NHD2/NH2D=0.2, and ND3/NHD2=0.06 were found in the core. The observed ortho/para ratios of NH2D and NHD2 are close to the corresponding nuclear spin statistical weights. The chemistry model can approximately reproduce the observed abundances, but predicts uniformly too low ortho/para-NH2D, and too large ortho/para-NHD2 ratios. The longevity of N2H+ and NH3 in dense gas, which is prerequisite to their strong deuteration, can be attributed to the chemical inertia of N2 on grain surfaces. The discrepancies between the chemistry model and the observations are likely to be caused by the fact that the model assumes complete scrambling in principal gas-phase deuteration reactions of ammonia, which means that all the nuclei are mixed in reactive collisions. If, instead, these reactions occur through proton hop/hydrogen abstraction processes, statistical spin ratios are to be expected. The present results suggest that while the deuteration of ammonia changes with physical conditions and time, the nuclear spin ratios of ammonia isotopologues do not probe the evolutionary stage of a cloud., Comment: to appear in Astronomy & Astrophysics

Published
2016
Full Text
View/download PDF

2. Hyperfine excitation of N$_2$H$^+$ by H$_2$: Toward a revision of N$_2$H$^+$ abundance in cold molecular clouds

Author

Lique, François, Daniel, Fabien, Pagani, Laurent, and Feautrier, Nicole

Subjects
Astrophysics - Astrophysics of Galaxies, Physics - Chemical Physics
Abstract

The modelling of emission spectra of molecules seen in interstellar clouds requires the knowledge of collisional rate coefficients. Among the commonly observed species, N$_2$H$^+$ is of particular interest since it was shown to be a good probe of the physical conditions of cold molecular clouds. Thus, we have calculated hyperfine-structure resolved excitation rate coefficients of N$_2$H$^+$(X$^1\Sigma^+$) by H$_2(j=0)$, the most abundant collisional partner in the cold interstellar medium. The calculations are based on a new potential energy surface, obtained from highly correlated {\it ab initio} calculations. State-to-state rate coefficients between the first hyperfine levels were calculated, for temperatures ranging from 5 K to 70 K. By comparison with previously published N$_2$H$^+$-He rate coefficients, we found significant differences which cannot be reproduced by a simple scaling relationship. As a first application, we also performed radiative transfer calculations, for physical conditions typical of cold molecular clouds. We found that the simulated line intensities significantly increase when using the new H$_2$ rate coefficients, by comparison with the predictions based on the He rate coefficients. In particular, we revisited the modelling of the N$_2$H$^+$ emission in the LDN 183 core, using the new collisional data, and found that all three of the density, gas kinetic temperature and N$_2$H$^+$ abundance had to be revised.

Published
2014
Full Text
View/download PDF

3. Herschel/HIFI search for H2-17O and H2-18O in IRC+10216: constraints on models for the origin of water vapor

Author

Neufeld, David A., Tolls, Volker, Agúndez, Marcelino, González-Alfonso, Eduardo, Decin, Leen, Daniel, Fabien, Cernicharo, José, Melnick, Gary J., Schmidt, Miroslaw, and Szczerba, Ryszard

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We report the results of a sensitive search for the minor isotopologues of water, H2-17O and H2-18O, toward the carbon-rich AGB star IRC+10216 (a.k.a. CW Leonis) using the HIFI instrument on the Herschel Space Observatory. This search was motivated by the fact that any detection of isotopic enhancement in the H2-17O and H2-18O abundances would have strongly implicated CO photodissociation as the source of the atomic oxygen needed to produce water in a carbon-rich circumstellar envelope. Our observations place an upper limit of 1/470 on the H2-17O/H2-16O abundance ratio. Given the isotopic 17O/16O ratio of 1/840 inferred previously for the photosphere of IRC+10216, this result places an upper limit of a factor 1.8 on the extent of any isotope-selective enhancement of H2-17O in the circumstellar material, and provides an important constraint on any model that invokes CO photodissociation as the source of O for H2O production. In the context of the clumpy photodissociation model proposed previously for the origin of water in IRC+10216, our limit implies that 12C-16O (not 13C-16O or SiO) must be the dominant source of 16O for H2O production, and that the effects of self-shielding can only have reduced the 12C-16O photodissociation rate by at most a factor ~ 2., Comment: 14 pages, 4 figures, accepted for publication in ApJ Letters

Published
2013
Full Text
View/download PDF

4. On the frequency of N2H+ and N2D+

Author

Pagani, Laurent, Daniel, Fabien, and Dubernet, Marie-Lise

Subjects
Astrophysics
Abstract

Context : Dynamical studies of prestellar cores search for small velocity differences between different tracers. The highest radiation frequency precision is therefore required for each of these species. Aims : We want to adjust the frequency of the first three rotational transitions of N2H+ and N2D+ and extrapolate to the next three transitions. Methods : N2H+ and N2D+ are compared to NH3 the frequency of which is more accurately known and which has the advantage to be spatially coexistent with N2H+ and N2D+ in dark cloud cores. With lines among the narrowests, and N2H+ and NH3 emitting region among the largests, L183 is a good candidate to compare these species. Results : A correction of ~10 kHz for the N2H+ (J:1-0) transition has been found (~0.03 km/s) and similar corrections, from a few m/s up to ~0.05 km/s are reported for the other transitions (N2H+ J:3-2 and N2D+ J:1-0, J:2-1, and J:3-2) compared to previous astronomical determinations. Einstein spontaneous decay coefficients (Aul) are included.

Published
2008
Full Text
View/download PDF

5. Far-IR Excited OH Lines from Orion KL Outflows

Author

Goicoechea, Javier R., Cernicharo, Jose, Lerate, Mercedes R., Daniel, Fabien, Barlow, Michael J., Swinyard, Bruce M., Lim, Tanya L., Viti, Serena, and Yates, Jeremy

Subjects
Astrophysics
Abstract

As part of the first far-IR line survey towards Orion KL, we present the detection of seven new rotationally excited OH Lambda-doublets (at 48, 65, 71, 79, 98 and 115 um). Observations were performed with the Long Wavelength Spectrometer (LWS) Fabry-Perots on board the Infrared Space Observatory (ISO). In total, more than 20 resolved OH rotational lines, with upper energy levels up to 620 K, have been detected at an angular and velocity resolutions of 80$'' and 33 km s^-1 respectively. OH line profiles show a complex behavior evolving from pure absorption, P-Cygni type to pure emission. We also present a large scale 6' declination raster in the OH ^2\Pi_3/2 J=5/2^+-3/2^- and ^2\Pi_3/2 J=7/2^-5/2^+ lines (at 119.441 and 84.597 um) revealing the decrease of excitation outside the core of the cloud. From the observed profiles, mean intrinsic line widths and velocity offsets between emission and absorption line peaks we conclude that most of the excited OH arises from Orion outflow(s), i.e. the ``plateau'' component. We determine an averaged OH abundance relative to H_2 of X(OH)=(0.5-1.0)x10^-6, a kinetic temperature of 100 K and a density of n(H_2)=5x10^5 cm^-3. Even with these conditions, the OH excitation is heavily coupled with the strong dust continuum emission from the inner hot core regions and from the expanding flow itself., Comment: Pre-print version(5 pages, 3 figures). Accepted in ApJ letters, 2006 March 2

Published
2006
Full Text
View/download PDF

7. sj-pdf-1-hsr-10.1177_13558196211065704 ��� Supplemental material for An evaluation of five regional health information technology-based programmes to improve health and social care coordination: A quasi-experimental controlled before/after mixed design

Author

Salmi, Louis-Rachid, Roberts, Tamara, Renaud, Thomas, Buffeteau, Sophie, Cueille, Sandrine, Fourneyron, Emmanuelle, Gaillard, Aur��lie, Abraham, Maelys, Arditi, Nora, Castry, Mathieu, Daniel, Fabien, N'gom, N'deye Fatou, Gu��ry, Orlane, L'Horty, Yannick, Pincemail, St��phane, Purgues, Sonia, Thiessard, Franz, Ramel, Viviane, Langlois, Emmanuel, Saillour-Gl��nisson, Florence, Sib��, Matthieu, and Wittwer, J��r��me

Subjects
111708 Health and Community Services, 111799 Public Health and Health Services not elsewhere classified, FOS: Health sciences
Abstract

Supplemental material, sj-pdf-1-hsr-10.1177_13558196211065704 for An evaluation of five regional health information technology-based programmes to improve health and social care coordination: A quasi-experimental controlled before/after mixed design by Louis-Rachid Salmi, Tamara Roberts, Thomas Renaud, Sophie Buffeteau, Sandrine Cueille, Emmanuelle Fourneyron, Aur��lie Gaillard, Maelys Abraham, Nora Arditi, Mathieu Castry, Fabien Daniel, N'deye Fatou N'gom, Orlane Gu��ry, Yannick L'Horty, St��phane Pincemail, Sonia Purgues, Franz Thiessard, Viviane Ramel, Emmanuel Langlois, Florence Saillour-Gl��nisson, Matthieu Sib�� and J��r��me Wittwer in Journal of Health Services Research & Policy

Published
2022
Full Text
View/download PDF

8. An evaluation of five regional health information technology-based programmes to improve health and social care coordination: A quasi-experimental controlled before/after mixed design.

Author

Salmi, Louis-Rachid, Roberts, Tamara, Renaud, Thomas, Buffeteau, Sophie, Cueille, Sandrine, Fourneyron, Emmanuelle, Gaillard, Aurélie, Abraham, Maelys, Arditi, Nora, Castry, Mathieu, Daniel, Fabien, N'gom, N'deye Fatou, Guéry, Orlane, L'Horty, Yannick, Pincemail, Stéphane, Purgues, Sonia, Thiessard, Franz, Ramel, Viviane, Langlois, Emmanuel, and Saillour-Glénisson, Florence

Subjects
EVALUATION of human services programs, RESEARCH methodology, HEALTH status indicators, MEDICAL care, PATIENTS, INTERVIEWING, QUALITY assurance, MEDICAL informatics, CONTENT analysis, DATA analysis software, SOCIAL case work
Abstract

Objectives: Health information technology (HIT) can help coordinate health and social actors involved in patients' pathways. We assess five regional HIT-based programmes (' Territoires de Soins Numériques ' or TSN) introduced in France, covering the period 2012–2018. Methods: This was a quasi-experimental controlled before/after mixed design. We used data from the French National Health Insurance database, qualitative and quantitative surveys, and information extracted from project documents and databases. We assessed the impact of TSN using four main impact indicators: emergency room visits, unplanned hospitalizations, avoidable hospitalizations and rehospitalization within 30 days. We also collected qualitative and secondary quantitative data covering perceived needs, knowledge, use, satisfaction, adoption and understanding of projects, pathway experience, impact on professional practices and appropriateness of hospitalizations. Results: TSN implemented a heterogeneous mix of HIT. Implementation was slower than expected and was not well documented. Users perceived the HIT as having a positive but weak overall effect. There were no significant differences in trends for the main impact indicators, nor on the appropriateness of hospitalizations, but favourable trends on secondary polypharmacy indicators. Conclusions: If similar innovations take place in future, they should be based on a logical framework that defines causal, measurable links between services provided and expected impacts. [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

9. Robust hydrocarbon degradation and dynamics of bacterial communities during nutrient-enhanced oil spill bioremediation

Author

Roling, Wilfred F. M., Milner, Michael G., Jones, D. Matrin, Lee, Kenneth, Daniel, Fabien, Swannell, Richard J. P., and Head, Ian M.

Subjects
Hydrocarbons -- Physiological aspects, Biodegradation -- Physiological aspects, Microbial populations -- Genetic aspects, Microbial populations -- Physiological aspects, Biological sciences
Abstract

Research has been conducted on biodegradative microbial populations. The effect of nutrients ammendments on these populations has been investigated, and the results are reported.

Published
2002

11. Bacterial community dynamics and hydrocarbon degradation during a field-scale evaluation of bioremediation on a mudflat beach contaminated with buried oil

Author

Roling, Wilfred F. M., Fratepietro, Francesco, Milner, Michael G., Jones, D. Martin, Swannell, Richard P. J., Daniel, Fabien, and Head, Ian M.

Subjects
Bioremediation -- Research, Petroleum -- Research, Microbiology -- Research, Biological sciences
Abstract

A field-scale experiment with a complete randomized block design was performed to study the degradation of buried oil on a shoreline over a period of almost 1year.

Published
2004

12. Collisional dynamic study of the N2H+ and H2O molecules: implication on the characterization of star forming regions

Author

Daniel, Fabien, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Department of Molecular and Infrared Astrophysics (DAMIR), Université Pierre et Marie Curie - Paris VI, Marie-Lise dubernet, José Cernicharo(marie-lise.dubernet@obspm.fr), École normale supérieure - Paris (ENS-PSL), and Daniel, Fabien

Subjects
molécule, région de formation d'étoile, astrophysics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], radiative transfer, star forming region, taux de collision, N2H+, transfert de rayonnement, H2O, [SDU.ASTR] Sciences of the Universe [physics]/Astrophysics [astro-ph], collisional rate coefficient, astrophysique
Abstract

Understanding the processes that lead to the formation of stars from the dense phase of the interstellar medium is possible through the observation of molecules. They allow us to constrain, through modeling of their emission, the physical, dynamical and chemical conditions present in the clouds during various stages of the collapse. For most molecules, environments surveyed in this type of study correspond to conditions such that the populating of molecular energy levels is out of thermodynamical equilibrium. The analysis of the radiation thus requires data from microscopic physics whose accuracy strongly influences the description of the regions modeled. The work performed during this thesis is inscribed in this context: firstly, it focused on the determination of rate constants for the collision of the N2H+ and H2O molecules and secondly, on the interpretation of spectra that were obtained for these molecules in regions of star formation. The first of these molecules, N2H+, is an excellent tracer of the densest regions of cold dark clouds and the second one, H2O, is the third most abundant molecular specie in massive or low mass star forming regions and constitute the main objective of the Herschel satellite. For the N2H+ molecule, collisional rate coefficients that consider the hyperfine structure have been obtained for hyperfine levels associated with the first 7 rotational energy levels and in the temperature range T=5-50 K . To do so, the collisional dynamics has been studied with a time independent quantum approach where the hyperfine structure was introduced through a recoupling method. These data were then used to interpret the emission observed in a sample of pre-protostellar clouds. In particular, different approaches were used in order to solve the coupled sets of radiative transfer and statistical equilibrium equations. This enabled to emphasize on the respective influences of collisional rate coefficients, radiative trapping and of the structure of the cloud (density and temperature variations) on the emerging hyperfine line ratio associated with the j=1-0 rotational line. For H2O, the objective of this work was firstly, to update the rate constants of the collisional system H2O-H_2 based on a potential energy surface (PES) recently calculated and whose accuracy is superior to that which has previously been used. This allowed a study that established the sensitivity of rate constants to different SEP parameters. Then, we determined collisional line broadening parameters using for this the impact approximation theory. The interest of this latter study was twofold: first, these data are needed to study planetary atmospheres and secondly, through a comparison between theoretical results and experimental data, we obtain an estimate of the quality of the PES from which the data are derived. Finally, in parallel of this work it was made an analysis of the emission from H2O observed in the Kleimann-Low nebula in Orion. Using data obtained with the ISO satellite, it was then possible to constrain the physical conditions prevailing in the source and the spatial distribution of the water abundance., La compréhension des processus amenant à la formation d'étoiles depuis la phase dense du milieu interstellaire est possible via l'observation des molécules. Celles--ci nous permettent de contraindre, par l'intermédiaire d'une modélisation de leur émission, les conditions physiques, dynamiques et chimiques présentes dans les nuages au cours des différents stades de l'effondrement. Les milieux sondés lors de ce type d'étude correspondent, pour la plupart des molécules, à des conditions pour lesquelles le peuplement des niveaux d'énergie s'effectue hors équilibre thermodynamique. L'analyse du rayonnement nécessite alors des données de physique microscopique dont la précision influence fortement la description des régions modélisées. C'est dans ce contexte que s'inscrit le travail effectué durant cette thèse: celui-ci a porté, d'une part, sur la détermination de constantes de vitesses de collision pour les molécules N2H+ et H2O et d'autre part, sur l'interprétation de spectres observés pour ces molécules dans des régions de formation d'étoiles. La première de ces molécules, N2H+, constitue un excellent traceur des régions denses des nuages froids et la seconde, H2O, est la troisième espèce moléculaire la plus abondante dans les régions de formation d'étoiles massives ou de faibles masses et constituera le principal objectif du satellite Herschel. Pour la molécule N2H+, des constantes de vitesse de collision concernant la structure hyperfine ont été obtenues pour les niveaux hyperfins associés aux 7 premiers niveaux rotationnels et pour la gamme de température T=5-50 K. Pour cela, la dynamique collisionnelle a été etudiée avec une approche quantique indépendante du temps où la structure hyperfine est introduite via une méthode de recouplage. Ces données ont ensuite été utilisées afin d'interpréter l'émission observée dans un échantillon de nuages pré-protostellaires. En particulier, différentes approches ont été envisagées afin de traiter la résolution des équations d'équilibre statistique ce qui a permis de dégager les influences respectives qu'ont les taux de collision, le couplage radiatif et la structure en densité et température de la source sur les rapports d'intensité des transitions hyperfines associées à la transition j=1-0. Concernant H2O, l'objectif de ce travail est d'une part, de réactualiser les constantes de vitesse de collision du système H2O-H2, en se basant sur une surface d'énergie potentielle (SEP) récemment calculée et dont la précision est supérieure à celle qui a précédemment été utilisée. Ceci a tout d'abord permis une comparaison visant à établir la sensibilité des constantes de vitesse de collision à différents paramètres de la SEP. Ensuite, nous nous sommes intéressés à la détermination des paramètres d'élargissement de raies par collisions, en se basant sur l'approximation d'impact. L'intérêt de cette dernière étude est double: d'une part, ces données sont nécessaires à l'étude des atmosphères planétaires et d'autre part, par l'intermédiaire d'une confrontation entre résultats théoriques et données expérimentales, celle--ci nous donne une estimation de la qualité de la SEP et des données qui en sont issues. Finalement, en parallèle à ce travail, il a été effectué une analyse de l'émission de H2O observée dans la nébuleuse de Kleimann-Low dans Orion. A partir de données obtenues avec le satellite ISO, il a alors été possible de contraindre les conditions physiques de la source ainsi que la répartition spatiale de l'abondance de l'eau.

Published
2007

13. Rotational excitation of 45 levels of ortho/para-H2O by excited ortho/para-H2 from 5K to 1500K: state-to-state, effective and thermalized rate coefficients

Author

Daniel, Fabien, Dubernet, Marie-Lise, Grosjean, Alain, Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), and Debray, Bernard

Subjects
[SDU] Sciences of the Universe [physics], [SDU]Sciences of the Universe [physics], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2011

14. Collision Rate Coefficients

Author

Dubernet, Marie-Lise, Roueff, Evelyne, Daniel, Fabien, Grosjean, Alain, Stoecklin, T., Francois, Francoise, Laboratoire de Physique Moleculaire pour l'Atmosphere et l'Astrophysique (LPMAA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), and Université de Franche-Comté (UFC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)

Subjects
[PHYS.ASTR.EP] Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2010

16. N2H+ and N2D+ in interstellar molecular clouds. II- Observations

Author

Daniel, Fabien, Cernicharo, José, Roueff, E., Gerin, M., and Dubernet, M. L.

Subjects
clouds: molecules: abundances [ISM], Astrophysics (astro-ph), individual (TMC1, L183) [ISM], Radiative transfer, FOS: Physical sciences, ISM: individual (TMC1, L183), Line: formation: profiles, Astrophysics, ISM: clouds: molecules: abundances, Molecular processes, formation: profiles [Line]
Abstract

Accepted for publication in The Astrophysical Journal (ApJ)., We present observations of the J=1-0, 2-1, and 3-2 rotational transitions of N2H+ and N2D+ towards a sample of prototypical dark clouds. The data have been interpreted using non-local radiative transfer models., The authors acknowledge funding support under grants PNAYA2000-1784, ESP2001-4516, PNAYA2002-10113-E, ESP2002-01627, PNAYA2003-02785, PNAYA2004-0579 and the Madrid DGU PRICIT Program S-0505/ESP-0237 (ASTROCAM).

Published
2007

17. Etude de la dynamique colisionelle des molécules N2H+ et H2O: implication sur la caractérisation des régions de formation d´étoile

Author

Daniel, Fabien, Cernicharo Quintanilla, José, Dubernet-Tuckey, Marie Lise, Universidad Autónoma de Madrid, and Université Pierre et Marie Curie (Francia)

Subjects
Astrofísica, Estrellas - Formación
Abstract

Tesis doctoral inédita cotutelada por la Université Pierre et Marie Curie y la Universidad Autónoma de Madrid. Fecha de lectura: 23-2-2007

Published
2007

18. Influence of a new potential energy surface on the rotational (de)excitation of H2O by H2 at low temperature

Author

Dubernet, Marie-Lise, Daniel, Fabien, Grosjean, Alain, Faure, A., Valiron, Pierre, Wernli, Michael, Rist, Claire, Noga, J., Tennyson, J., Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'astrophysique de l'observatoire de Besançon (UMR 6091) (LAOB), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), 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), Department of Physics and Astronomy [UCL London], University College of London [London] (UCL), École normale supérieure - Paris (ENS-PSL), and Debray, Bernard

Subjects
[PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], [PHYS.ASTR.CO] Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]
Published
2006

19. Ro-Vibrational Collisional Excitation Database: BASECOL

Author

Dubernet, Marie-Lise, Grosjean, Alain, Flower, David, Roueff, Evelyne, Daniel, Fabien, Moreau, Nicolas, Debray, Bernard, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'astrophysique de l'observatoire de Besançon (LAOB), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Paris, PSL Research University (PSL), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Laboratoire d'astrophysique de l'observatoire de Besançon (UMR 6091) (LAOB), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Université Paris sciences et lettres (PSL), Debray, Bernard, École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics], ComputingMilieux_MISCELLANEOUS, [PHYS] Physics [physics]
Abstract

International audience

Published
2006

20. Ro-Vibrational Collisional Excitation Database: BASECOL - http://www.obspm.fr/basecol

Author

Dubernet, Marie-Lise, Grosjean, Alain, Flower, David, Roueff, Evelyne, Daniel, Fabien, Moreau, Nicolas, Debray, Bernard, Observatoire de Paris, Université Paris sciences et lettres (PSL), Laboratoire d'astrophysique de l'observatoire de Besançon (UMR 6091) (LAOB), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Department of Physics [Durham University], Durham University, T. Kato, H. Funaba, C. Suzuki, T. Minami, Debray, Bernard, and T. Kato, H. Funaba, C. Suzuki, T. Minami

Subjects
molecules rotation vibration, [PHYS.PHYS.PHYS-ATM-PH]Physics [physics]/Physics [physics]/Atomic and Molecular Clusters [physics.atm-clus], [PHYS.PHYS.PHYS-ATM-PH] Physics [physics]/Physics [physics]/Atomic and Molecular Clusters [physics.atm-clus], excitation, [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], database, collision
Abstract

International audience; The BASECOL database is presented. The 2004 Version contains bibliographical and numerical data on collisional ro-vibrational excitation of molecules by H, He and H 2 . It provides collisional rotational and ro-vibrational excitation rate coefficients for molecules of astrophysical interest, the molecular energy levels and a complete description of the chain of errors. It gives information on current calculations and is designed as a reference database to be used by both astrophysicists and physicists.

Published
2004

22. THE ALMA SPECTRUM OF IRC+10216

Author

Cernicharo, Jose, primary, Goicoechea, Javier, additional, Guélin, Michel, additional, Joblin, Christine, additional, Marcelino, Nuria, additional, Castro-Carrizo, Arancha, additional, Daniel, Fabien, additional, and Agúndez, Marcelino, additional

Published
2014
Full Text
View/download PDF

23. Warm water vapour in the sooty outflow from a luminous carbon star

Author

Decin, L., Agúndez, Marcelino, Barlow, Michael J., Daniel, Fabien, Cernicharo, José, Lombaert, J. R., Beck, E. de, Royer, P., Vandenbussche, B., Wesson, R., Polehampton, Edward, Blommaert, J. A. D. L., Meester, W. de, Exter, K., Feuchtgruber, H., Gear, W. K., Gómez, H.L., Groenewegen, M.A.T., Guélin, M., Hargrave, P. C., Huygen, R., Imhof, P., Ivison, R. J., Jean, C., Kahane, C., Kerschbaum, F., Leeks, S. J., Lim, T., Matsuura, M., Olofsson, G., Posch, T., Regibo, S., Savini, Giovanni, Sibthorpe, B., Swinyard, B. M., Yates, J. A., Waelkens, C., Decin, L., Agúndez, Marcelino, Barlow, Michael J., Daniel, Fabien, Cernicharo, José, Lombaert, J. R., Beck, E. de, Royer, P., Vandenbussche, B., Wesson, R., Polehampton, Edward, Blommaert, J. A. D. L., Meester, W. de, Exter, K., Feuchtgruber, H., Gear, W. K., Gómez, H.L., Groenewegen, M.A.T., Guélin, M., Hargrave, P. C., Huygen, R., Imhof, P., Ivison, R. J., Jean, C., Kahane, C., Kerschbaum, F., Leeks, S. J., Lim, T., Matsuura, M., Olofsson, G., Posch, T., Regibo, S., Savini, Giovanni, Sibthorpe, B., Swinyard, B. M., Yates, J. A., and Waelkens, C.

Abstract

The detection1 of circumstellar water vapour around the ageing carbon star IRC +10216 challenged the current understanding of chemistry in old stars, because water was predicted2 to be almost absent in carbon-rich stars. Several explanations for the water were postulated, including the vaporization of icy bodies (comets or dwarf planets) in orbit around the star1, grain surface reactions3, and photochemistry in the outer circumstellar envelope4. With a single water line detected so far from this one carbon-rich evolved star, it is difficult to discriminate between the different mechanisms proposed. Here we report the detection of dozens of water vapour lines in the far-infrared and sub-millimetre spectrum of IRC +10216 using the Herschel satellite5. This includes some high-excitation lines with energies corresponding to ~1,000 K, which can be explained only if water is present in the warm inner sooty region of the envelope. A plausible explanation for the warm water appears to be the penetration of ultraviolet photons deep into a clumpy circumstellar envelope. This mechanism also triggers the formation of other molecules, such as ammonia, whose observed abundances6 are much higher than hitherto predicted7.

Published
2010

25. The Excitation of N2H+ in Interstellar Molecular Clouds. I. Models

Author

Cernicharo, José, Daniel, Fabien, Dubernet, M. L., Cernicharo, José, Daniel, Fabien, and Dubernet, M. L.

Abstract

We present large velocity gradient (LVG) and nonlocal radiative transfer calculations involving the rotational and hyperfine structure of the spectrum of N2H+, with collisional rate coefficients recently derived by us. The goal of this study is to check the validity of the assumptions made to treat the hyperfine structure and to study the physical mechanisms leading to the observed hyperfine anomalies. We find that the usual hypothesis of identical excitation temperatures for all hyperfine components of the –0 transition is not correct within the range of densities existing in cold dense cores, i.e., a few < a few 106 cm−3. This is due to different radiative trapping effects in the hyperfine components. Moreover, within this range of densities and considering the typical abundance of N2H+, the total opacity of rotational lines has to be derived taking into account the hyperfine structure. The error made when only considering the rotational energy structure can be as large as 100%. Using nonlocal models, we find that, due to saturation, hyperfine anomalies appear as soon as the total opacity of the –0 transition becomes larger than 20. Radiative scattering in less dense regions enhances these anomalies and particularly induces a differential increase of the excitation temperatures of the hyperfine components. This process is more effective for the transitions with the highest opacities for which emerging intensities are also reduced by self‐absorption effects. These effects are not as critical as in HCO+ or HCN, but should be taken into account when interpreting the spatial extent of the N2H+ emission in dark clouds.

Published
2006

26. Hyperfine excitation of N2H+ by H2: towards a revision of N2H+ abundance in cold molecular clouds.

Author

Lique, François, Daniel, Fabien, Pagani, Laurent, and Feautrier, Nicole

Subjects
*MOLECULAR clouds, *INTERSTELLAR molecules, *GALAXIES, *STELLAR mass, *DENSITY of stars, *ASTRONOMICAL surveys, *ASTRONOMICAL observations
Abstract

The modelling of emission spectra of molecules seen in interstellar clouds requires the knowledge of collisional rate coefficients. Among the commonly observed species, N2H+ is of particular interest since it was shown to be a good probe of the physical conditions of cold molecular clouds. Thus, we have calculated hyperfine-structure-resolved excitation rate coefficients of N2H+(X1Σ +) by H2(j = 0), the most abundant collisional partner in the cold interstellar medium. The calculations are based on a new potential energy surface, obtained from highly correlated ab initio calculations. State-to-state rate coefficients between the first hyperfine levels were calculated, for temperatures ranging from 5 to 70 K. By comparison with previously published N2H+-He rate coefficients, we found significant differences which cannot be reproduced by a simple scaling relationship. As a first application, we also performed radiative transfer calculations, for physical conditions typical of cold molecular clouds. We found that the simulated line intensities significantly increase when using the new H2 rate coefficients, by comparison with the predictions based on the He rate coefficients. In particular, we revisited the modelling of the N2H+ emission in the LDN 183 core, using the new collisional data, and found that all three of the density, gas kinetic temperature and N2H+ abundance had to be revised. [ABSTRACT FROM AUTHOR]

Published
2015
Full Text
View/download PDF

27. The Water Vapor Abundance in Orion KL Outflows

Author

Cernicharo, José, primary, Goicoechea, Javier R., additional, Daniel, Fabien, additional, Lerate, Mercedes R., additional, Barlow, Michael J., additional, Swinyard, Bruce M., additional, van Dishoeck, Ewine F., additional, Lim, Tanya L., additional, Viti, Serena, additional, and Yates, Jeremy, additional

Published
2006
Full Text
View/download PDF

28. Far-Infrared Excited Hydroxyl Lines from Orion KL Outflows

Author

Goicoechea, Javier R., primary, Cernicharo, José, additional, Lerate, Mercedes R., additional, Daniel, Fabien, additional, Barlow, Michael J., additional, Swinyard, Bruce M., additional, Lim, Tanya L., additional, Viti, Serena, additional, and Yates, Jeremy, additional

Published
2006
Full Text
View/download PDF

32. [Feasibility and practical value of statistical matching of a general practice database and a health insurance database applied to diabetes and hypertension].

Author

Perlbarg J, Allonier C, Boisnault P, Daniel F, Le Fur P, Szidon P, and Bourgueil Y

Subjects
Adult, Feasibility Studies, Female, Humans, Male, Databases, Factual, Diabetes Mellitus, General Practice statistics & numerical data, Hypertension, Insurance, Health
Abstract

Objectives: Public Health actors in France are striving to improve the use of national databases for public health and research. The main objective of this project was to develop a research tool in ambulatory care by matching medical data and reimbursement data., Methods: Data sources were the health insurance database (SNIIRAM) and the General Practice Observatory (OMG) database. The SNIIRAM is a national medical and administrative database comprising data used in healthcare reimbursement. The OMG is a medical database on ambulatory care recording presenting complaints called "Results of Consultation" (RC). Based on data for patients who consulted one of the 30 general practitioners selected in 2008, we performed a probabilistic matching of the two databases., Results: The linkage procedure allowed matching of 89,211 consultations or doctor visits and 29,088 patients. Comparison of long-term diseases (ALD) and RC showed that 94% of patients with diabetes as ALD had at least one RC coded as diabetes during the year, but only 65% of patients with one RC coded as diabetes were reported as ALD for this disease. Matching of the databases identified 12% of diabetic patients without antidiabetic treatment and without ALD for this affection; these patients were therefore not identifiable in the SNIIRAM database., Conclusion: This study describes an innovative database matching methodology. It also illustrates the contribution of this model of matched data in terms of targeting populations at risk. Other approaches to analysis of comorbidities, medical practices and care pathways could be proposed.

Published
2014

Catalog

Books, media, physical & digital resources
See catalog results