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Article: The chemistry of disks around T Tauri and Herbig Ae/Be stars.

Agúndez, Marcelino / Roueff, Evelyne / Le Petit, Franck / Le Bourlot, Jacques

2018 Volume 616

Abstract: Context: Infrared and (sub-)mm observations of disks around T Tauri and Herbig Ae/Be stars point to a chemical differentiation between both types of disks, with a lower detection rate of molecules in disks around hotter stars.: Aims: To investigate ... ...

Abstract	Context: Infrared and (sub-)mm observations of disks around T Tauri and Herbig Ae/Be stars point to a chemical differentiation between both types of disks, with a lower detection rate of molecules in disks around hotter stars. Aims: To investigate the underlying causes of the chemical differentiation indicated by observations we perform a comparative study of the chemistry of T Tauri and Herbig Ae/Be disks. This is one of the first studies to compare chemistry in the outer regions of these two types of disks. Methods: We developed a model to compute the chemical composition of a generic protoplanetary disk, with particular attention to the photochemistry, and applied it to a T Tauri and a Herbig Ae/Be disk. We compiled cross sections and computed photodissociation and photoionization rates at each location in the disk by solving the FUV radiative transfer in a 1+1D approach using the Meudon PDR code and adopting observed stellar spectra. Results: The warmer disk temperatures and higher ultraviolet flux of Herbig stars compared to T Tauri stars induce some differences in the disk chemistry. In the hot inner regions, H Conclusions: The global chemical behavior of T Tauri and Herbig Ae/Be disks is quite similar. The main differences are driven by the warmer temperatures of the latter, which result in a larger reservoir or water and simple organics in the inner regions and a lower mass of ices in the outer disk.
Language	English
Publishing date	2018-09-05
Publishing country	Germany
Document type	Journal Article
ZDB-ID	1458466-9
ISSN	1432-0746 ; 0004-6361
ISSN (online)	1432-0746
ISSN	0004-6361
DOI	10.1051/0004-6361/201732518
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Article: Herschel

Champion, J / Berné, O / Vicente, S / Kamp, I / Le Petit, F / Gusdorf, A / Joblin, C / Goicoechea, J R

Astronomy and astrophysics

2017 Volume 604

Abstract: Context: Protoplanetary disks undergo substantial mass-loss by photoevaporation, a mechanism which is crucial to their dynamical evolution. However, the processes regulating the gas energetics have not been well constrained by observations so far.: ... ...

Abstract	Context: Protoplanetary disks undergo substantial mass-loss by photoevaporation, a mechanism which is crucial to their dynamical evolution. However, the processes regulating the gas energetics have not been well constrained by observations so far. Aims: We aim at studying the processes involved in disk photoevaporation when it is driven by far-UV photons (i.e. 6 < E < 13.6 eV). Methods: We present a unique Results: With this model, we successfully reproduce most of the observations and derive key physical parameters, i.e. densities at the disk surface of about 10 Conclusions: We have identified the energetic regime regulating FUV-photoevaporation in proplyds. This regime could be implemented into models of the dynamical evolution of protoplanetary disks.
Language	English
Publishing date	2017-08-08
Publishing country	Germany
Document type	Journal Article
ZDB-ID	1458466-9
ISSN	1432-0746 ; 0004-6361
ISSN (online)	1432-0746
ISSN	0004-6361
DOI	10.1051/0004-6361/201629404
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Article: Models of H3+ in warm, diffuse, molecular gas in the Galactic centre.

Le Petit, Franck / Roueff, Evelyne

Philosophical transactions. Series A, Mathematical, physical, and engineering sciences

2006 Volume 364, Issue 1848, Page(s) 3043–3047

Abstract: Oka et al. (Oka et al. 2005 Astrophys. J. 632, 882-893) have recently observed a large column density of H3+ in the Galactic centre. In one of the gaseous components, a column density of H3+ in its metastable level (3,3) of approximately 4 x 10(14) cm(-2) ...

Abstract	Oka et al. (Oka et al. 2005 Astrophys. J. 632, 882-893) have recently observed a large column density of H3+ in the Galactic centre. In one of the gaseous components, a column density of H3+ in its metastable level (3,3) of approximately 4 x 10(14) cm(-2) is measured. From the excitation of H3+, they deduce a density below 50 cm(-3) and a temperature approximately 270 K. In this paper, we report results for this region from a new version of our PDR code which includes the H3+ excitation. Models show it is unlikely that the mean temperature of the gas could be above 100 K. We also show that there is a possibility to produce hot H3+ in C-shocks.
Language	English
Publishing date	2006-11-15
Publishing country	England
Document type	Journal Article
ZDB-ID	208381-4
ISSN	1471-2962 ; 1364-503X ; 0080-4614 ; 0264-3820 ; 0264-3952
ISSN (online)	1471-2962
ISSN	1364-503X ; 0080-4614 ; 0264-3820 ; 0264-3952
DOI	10.1098/rsta.2006.1873
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Article: [Cii] emission from L1630 in the Orion B molecular cloud.

Pabst, C H M / Goicoechea, J R / Teyssier, D / Berné, O / Ochsendorf, B B / Wolfire, M G / Higgins, R D / Riquelme, D / Risacher, C / Pety, J / Le Petit, F / Roueff, E / Bron, E / Tielens, A G G M

Astronomy and astrophysics

2017 Volume 606

Abstract: Context: L1630 in the Orion B molecular cloud, which includes the iconic Horsehead Nebula, illuminated by the star system : Aims: Observations toward L1630 allow us to study the interplay between stellar radiation and a molecular cloud under ... ...

Abstract	Context: L1630 in the Orion B molecular cloud, which includes the iconic Horsehead Nebula, illuminated by the star system Aims: Observations toward L1630 allow us to study the interplay between stellar radiation and a molecular cloud under relatively benign conditions, that is, intermediate densities and an intermediate UV radiation field. Contrary to the well-studied Orion Molecular Cloud 1 (OMC1), which hosts much harsher conditions, L1630 has little star formation. Our goal is to relate the [Cii] fine-structure line emission to the physical conditions predominant in L1630 and compare it to studies of OMC1. Methods: The [Cii] 158 Results: Of the [Cii] emission from the mapped area 95%, 13 Conclusions: In L1630 only a small fraction of the gas mass is traced by [Cii]. Most of the [Cii] emission in the mapped area stems from PDR surfaces. The layered edge-on structure of the molecular cloud and limitations in spatial resolution put constraints on our ability to relate different tracers to each other and to the physical conditions. From our study, we conclude that the relation between [Cii] emission and physical conditions is likely to be more complicated than often assumed. The theoretical heating efficiency is higher than the one we calculate from the observed [Cii] emission in the L1630 molecular cloud.
Language	English
Publishing date	2017-10-03
Publishing country	Germany
Document type	Journal Article
ZDB-ID	1458466-9
ISSN	1432-0746 ; 0004-6361
ISSN (online)	1432-0746
ISSN	0004-6361
DOI	10.1051/0004-6361/201730881
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Article: Structure of photodissociation fronts in star-forming regions revealed by observations of high-J CO emission lines with Herschel.

Joblin, C / Bron, E / Pinto, C / Pilleri, P / Le Petit, F / Gerin, M / Le Bourlot, J / Fuente, A / Berne, O / Goicoechea, J R / Habart, E / Köhler, M / Teyssier, D / Nagy, Z / Montillaud, J / Vastel, C / Cernicharo, J / Röllig, M / Ossenkopf-Okada, V /

Bergin, E A

Astronomy and astrophysics

2018 Volume 615

Abstract: Context: In bright photodissociation regions (PDRs) associated to massive star formation, the presence of dense "clumps" that are immersed in a less dense interclump medium is often proposed to explain the difficulty of models to account for the ... ...

Abstract	Context: In bright photodissociation regions (PDRs) associated to massive star formation, the presence of dense "clumps" that are immersed in a less dense interclump medium is often proposed to explain the difficulty of models to account for the observed gas emission in high-excitation lines. Aims: We aim at presenting a comprehensive view of the modeling of the CO rotational ladder in PDRs, including the high-J lines that trace warm molecular gas at PDR interfaces. Methods: We observed the Results: A grid of models was run to explore the parameter space of only two parameters: thermal gas pressure and a global scaling factor that corrects for approximations in the assumed geometry. We conclude that the emission in the high-J CO lines, which were observed up to J Conclusions: Compiling data from the literature, we found that the gas thermal pressure increases with the intensity of the UV radiation field given by
Language	English
Publishing date	2018-07-27
Publishing country	Germany
Document type	Journal Article
ZDB-ID	1458466-9
ISSN	1432-0746 ; 0004-6361
ISSN (online)	1432-0746
ISSN	0004-6361
DOI	10.1051/0004-6361/201832611
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Article: Oxygen fractionation in dense molecular clouds.

Loison, Jean-Christophe / Wakelam, Valentine / Gratier, Pierre / Hickson, Kevin M / Bacmann, Aurore / Agùndez, Marcelino / Marcelino, Nuria / Cernicharo, José / Guzman, Viviana / Gerin, Maryvonne / Goicoechea, Javier R / Roueff, Evelyne / Le Petit, Franck / Pety, Jérome / Fuente, Asunción / Riviere-Marichalar, Pablo

Monthly notices of the Royal Astronomical Society

2019 Volume 485, Issue 4, Page(s) 5777–5789

Abstract: We have developed the first gas-grain chemical model for oxygen fractionation (also including sulphur fractionation) in dense molecular clouds, demonstrating that gas-phase chemistry generates variable oxygen fractionation levels, with a particularly ... ...

Abstract	We have developed the first gas-grain chemical model for oxygen fractionation (also including sulphur fractionation) in dense molecular clouds, demonstrating that gas-phase chemistry generates variable oxygen fractionation levels, with a particularly strong effect for NO, SO, O
Language	English
Publishing date	2019-02-27
Publishing country	England
Document type	Journal Article
ZDB-ID	207232-4
ISSN	0035-8711
ISSN	0035-8711
DOI	10.1093/mnras/stz560
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Article: Chemical complexity in the horsehead photodissociation region.

Guzmán, Viviana V / Pety, Jérôme / Gratier, Pierre / Goicoechea, Javier R / Gerin, Maryvonne / Roueff, Evelyne / Le Petit, Franck / Le Bourlot, Jacques

Faraday discussions

2014 Volume 168, Page(s) 103–127

Abstract: The interstellar medium is known to be chemically complex. Organic molecules with up to 11 atoms have been detected in the interstellar medium, and are believed to be formed on the ices around dust grains. The ices can be released into the gas-phase ... ...

Abstract	The interstellar medium is known to be chemically complex. Organic molecules with up to 11 atoms have been detected in the interstellar medium, and are believed to be formed on the ices around dust grains. The ices can be released into the gas-phase either through thermal desorption, when a newly formed star heats the medium around it and completely evaporates the ices; or through non-thermal desorption mechanisms, such as photodesorption, when a single far-UV photon releases only a few molecules from the ices. The first mechanism dominates in hot cores, hot corinos and strongly UV-illuminated PDRs, while the second dominates in colder regions, such as low UV-field PDRs. This is the case of the Horsehead were dust temperatures are approximately eual to 20-30 K, and therefore offers a clean environment to investigate the role of photodesorption. We have carried out an unbiased spectral line survey at 3, 2 and 1mm with the IRAM-30m telescope in the Horsehead nebula, with an unprecedented combination of bandwidth, high spectral resolution and sensitivity. Two positions were observed: the warm PDR and a cold condensation shielded from the UV field (dense core), located just behind the PDR edge. We summarize our recently published results from this survey and present the first detection of the complex organic molecules HCOOH, CH2CO, CH3CHO and CH3CCH in a PDR. These species together with CH3CN present enhanced abundances in the PDR compared to the dense core. This suggests that photodesorption is an efficient mechanism to release complex molecules into the gas-phase in far-UV illuminated regions.
Language	English
Publishing date	2014-09-05
Publishing country	England
Document type	Journal Article
ISSN	1359-6640
ISSN	1359-6640
DOI	10.1039/c3fd00114h
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Article: Hydride spectroscopy of the diffuse interstellar medium: new clues on the gas fraction in molecular form and cosmic ray ionization rate in relation to H3+.

Gerin, M / Levrier, F / Falgarone, E / Godard, B / Hennebelle, P / Le Petit, F / De Luca, M / Neufeld, D / Sonnentrucker, P / Goldsmith, P / Flagey, N / Lis, D C / Persson, C M / Black, J H / Goicoechea, J R / Menten, K M

Philosophical transactions. Series A, Mathematical, physical, and engineering sciences

2012 Volume 370, Issue 1978, Page(s) 5174–5185

Abstract: The Herschel-guaranteed time key programme PRobing InterStellar Molecules with Absorption line Studies (PRISMAS)(1) is providing a survey of the interstellar hydrides containing the elements C, O, N, F and Cl. As the building blocks of interstellar ... ...

Abstract	The Herschel-guaranteed time key programme PRobing InterStellar Molecules with Absorption line Studies (PRISMAS)(1) is providing a survey of the interstellar hydrides containing the elements C, O, N, F and Cl. As the building blocks of interstellar molecules, hydrides provide key information on their formation pathways. They can also be used as tracers of important physical and chemical properties of the interstellar gas that are difficult to measure otherwise. This paper presents an analysis of two sight-lines investigated by the PRISMAS project, towards the star-forming regions W49N and W51. By combining the information extracted from the detected spectral lines, we present an analysis of the physical properties of the diffuse interstellar gas, including the electron abundance, the fraction of gas in molecular form, and constraints on the cosmic ray ionization rate and the gas density.
Language	English
Publishing date	2012-11-13
Publishing country	England
Document type	Journal Article
ZDB-ID	208381-4
ISSN	1471-2962 ; 1364-503X ; 0080-4614 ; 0264-3820 ; 0264-3952
ISSN (online)	1471-2962
ISSN	1364-503X ; 0080-4614 ; 0264-3820 ; 0264-3952
DOI	10.1098/rsta.2012.0023
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Article ; Online: Determination of the ortho to para ratio of H2Cl+ and H2O+ from submillimeter observations.

Gerin, Maryvonne / de Luca, Massimo / Lis, Dariusz C / Kramer, Carsten / Navarro, Santiago / Neufeld, David / Indriolo, Nick / Godard, Benjamin / Le Petit, Franck / Peng, Ruisheng / Phillips, Thomas G / Roueff, Evelyne

The journal of physical chemistry. A

2013 Volume 117, Issue 39, Page(s) 10018–10026

Abstract: The opening of the submillimeter sky with the Herschel Space Observatory has led to the detection of new interstellar molecular ions, H2O(+), H2Cl(+), and HCl(+), which are important intermediates in the synthesis of water vapor and hydrogen chloride. In ...

Abstract	The opening of the submillimeter sky with the Herschel Space Observatory has led to the detection of new interstellar molecular ions, H2O(+), H2Cl(+), and HCl(+), which are important intermediates in the synthesis of water vapor and hydrogen chloride. In this paper, we report new observations of H2O(+) and H2Cl(+) performed with both Herschel and ground-based telescopes, to determine the abundances of their ortho and para forms separately and derive the ortho-to-para ratio. At the achieved signal-to-noise ratio, the observations are consistent with an ortho-to-para ratios of 3 for both H2O(+) and H2Cl(+), in all velocity components detected along the lines-of-sight to the massive star-forming regions W31C and W49N. We discuss the mechanisms that contribute to establishing the observed ortho-to-para ratio and point to the need for a better understanding of chemical reactions, which are important for establishing the H2O(+) and H2Cl(+) ortho-to-para ratios.
Language	English
Publishing date	2013-10-03
Publishing country	United States
Document type	Journal Article
ISSN	1520-5215
ISSN (online)	1520-5215
DOI	10.1021/jp4004533
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Article ; Online: A far-ultraviolet-driven photoevaporation flow observed in a protoplanetary disk.

Berné, Olivier / Habart, Emilie / Peeters, Els / Schroetter, Ilane / Canin, Amélie / Sidhu, Ameek / Chown, Ryan / Bron, Emeric / Haworth, Thomas J / Klaassen, Pamela / Trahin, Boris / Van De Putte, Dries / Alarcón, Felipe / Zannese, Marion / Abergel, Alain / Bergin, Edwin A / Bernard-Salas, Jeronimo / Boersma, Christiaan / Cami, Jan /

Cuadrado, Sara / Dartois, Emmanuel / Dicken, Daniel / Elyajouri, Meriem / Fuente, Asunción / Goicoechea, Javier R / Gordon, Karl D / Issa, Lina / Joblin, Christine / Kannavou, Olga / Khan, Baria / Lacinbala, Ozan / Languignon, David / Le Gal, Romane / Maragkoudakis, Alexandros / Meshaka, Raphael / Okada, Yoko / Onaka, Takashi / Pasquini, Sofia / Pound, Marc W / Robberto, Massimo / Röllig, Markus / Schefter, Bethany / Schirmer, Thiébaut / Simmer, Thomas / Tabone, Benoit / Tielens, Alexander G G M / Vicente, Sílvia / Wolfire, Mark G / Aleman, Isabel / Allamandola, Louis / Auchettl, Rebecca / Baratta, Giuseppe Antonio / Baruteau, Clément / Bejaoui, Salma / Bera, Partha P / Black, John H / Boulanger, Francois / Bouwman, Jordy / Brandl, Bernhard / Brechignac, Philippe / Brünken, Sandra / Buragohain, Mridusmita / Burkhardt, Andrew / Candian, Alessandra / Cazaux, Stéphanie / Cernicharo, Jose / Chabot, Marin / Chakraborty, Shubhadip / Champion, Jason / Colgan, Sean W J / Cooke, Ilsa R / Coutens, Audrey / Cox, Nick L J / Demyk, Karine / Meyer, Jennifer Donovan / Engrand, Cécile / Foschino, Sacha / García-Lario, Pedro / Gavilan, Lisseth / Gerin, Maryvonne / Godard, Marie / Gottlieb, Carl A / Guillard, Pierre / Gusdorf, Antoine / Hartigan, Patrick / He, Jinhua / Herbst, Eric / Hornekaer, Liv / Jäger, Cornelia / Janot-Pacheco, Eduardo / Kaufman, Michael / Kemper, Francisca / Kendrew, Sarah / Kirsanova, Maria S / Knight, Collin / Kwok, Sun / Labiano, Álvaro / Lai, Thomas S-Y / Lee, Timothy J / Lefloch, Bertrand / Le Petit, Franck / Li, Aigen / Linz, Hendrik / Mackie, Cameron J / Madden, Suzanne C / Mascetti, Joëlle / McGuire, Brett A / Merino, Pablo / Micelotta, Elisabetta R / Morse, Jon A / Mulas, Giacomo / Neelamkodan, Naslim / Ohsawa, Ryou / Paladini, Roberta / Palumbo, Maria Elisabetta / Pathak, Amit / Pendleton, Yvonne J / Petrignani, Annemieke / Pino, Thomas / Puga, Elena / Rangwala, Naseem / Rapacioli, Mathias / Ricca, Alessandra / Roman-Duval, Julia / Roueff, Evelyne / Rouillé, Gaël / Salama, Farid / Sales, Dinalva A / Sandstrom, Karin / Sarre, Peter / Sciamma-O'Brien, Ella / Sellgren, Kris / Shannon, Matthew J / Simonnin, Adrien / Shenoy, Sachindev S / Teyssier, David / Thomas, Richard D / Togi, Aditya / Verstraete, Laurent / Witt, Adolf N / Wootten, Alwyn / Ysard, Nathalie / Zettergren, Henning / Zhang, Yong / Zhang, Ziwei E / Zhen, Junfeng

Science (New York, N.Y.)

2024 Volume 383, Issue 6686, Page(s) 988–992

Abstract: Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photodissociation regions (PDRs) on the surfaces of ... ...

Abstract	Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photodissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, which affects planet formation within the disks. We report James Webb Space Telescope and Atacama Large Millimeter Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula. Emission lines are detected from the PDR; modeling their kinematics and excitation allowed us to constrain the physical conditions within the gas. We quantified the mass-loss rate induced by the FUV irradiation and found that it is sufficient to remove gas from the disk in less than a million years. This is rapid enough to affect giant planet formation in the disk.
Language	English
Publishing date	2024-02-29
Publishing country	United States
Document type	Journal Article
ZDB-ID	128410-1
ISSN	1095-9203 ; 0036-8075
ISSN (online)	1095-9203
ISSN	0036-8075
DOI	10.1126/science.adh2861
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