C. Kahane

Centre National de la Recherche Scientifique

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C. Ceccarelli

Centre National de la Recherche Scientifique

Adam Walters

Université Toulouse III - Paul Sabatier

Mihkel Kama

Tartu Observatory

C. Vastel

Centre National de la Recherche Scientifique

B. Leflóch

Institut de Planétologie et d'Astrophysique de Grenoble

C. Codella

Arcetri Astrophysical Observatory

R. A. Motiyenko

Laboratoire de Physique des Lasers, Atomes et Molécules

Jean‐Claude Guillemin

Centre National de la Recherche Scientifique

P. Caselli

Max Planck Institute for Extraterrestrial Physics

E. Caux

Université de Toulouse

Cooperative Institutions

Centre National de la Recherche Scientifique

Institut de Planétologie et d'Astrophysique de Grenoble

Max Planck Society

Université Grenoble Alpes

Sorbonne Université

California Institute of Technology

Max Planck Institute for Radio Astronomy

Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères

Observatoire de Paris

Université Paris Cité

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Observations millimétriques de molécules circumstellaires : de la recherche de nouvelles espèces, à la mesure d'abondances isotopiques

HAL (Le Centre pour la Communication Scientifique Directe) (1989)

C. Kahane

La premiere partie de ce travail concerne la recherche de nouvelles molecules interstellaires et circumstellaires. Apres une description des divers hamiltoniens utilises pour le calcul des frequences des spectres moleculaires dans le domaine des ondes millimetriques,elle expose la recherche et la detection de nouvelles molecules, a l'aide d'observations realisees avec le radiotelescope de 30m de l 'IRAM, ainsi que la couverture spectrale, effectuee a 2mm et 3mm, de l'emission de l'enveloppe circumstellaire IRC+ 10216. La deuxieme partie de ce travail est consacree a la determination de rapports d'abondances isotopiques dans des enveloppes circumstellaires de Geantes Rouges, a partir d'observations millimetriques de raies moleculaires. Les rapports isotopiques du carbone, de l'azote, du soufre et du silicium sont mesures dans l'enveloppe d'une etoile carbonee, IRC+10216; ceux du carbone, dans quatre enveloppes d'etoiles de type J (Y CVn, RY Dra, T Lyr, et WZ Cas); ceux de l'oxygene, dans deux etoiles carbonees (CIT6 et IRC+10216), deux pre-nebuleuses planetaires (CRL618 et CRL2688) et une nebuleuse planetaire (NGC7027). Les rapports isotopiques ainsi mesures sont compares aux valeurs deduites d'observations infrarouge, ainsi qu'aux predictions des modeles theoriques des processus de nucleosynthese et de melange dans les etoiles de type Geantes Rouges.

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VizieR Online Data Catalog: Formamide detection with ASAI-IRAM (Lopez-Sepulcre+, 2015)

VizieR Online Data Catalog (2017)

A. López-Sepulcre A. Jaber Al-Edhari E. Mendoza B. Leflóch C. Ceccarelli

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Water ice deuteration: a tracer of the chemical history of protostars

Astronomy and Astrophysics (2012)

V. Taquet Phillip Peters C. Kahane C. Ceccarelli A. López-Sepulcre

Context. Millimetric observations have measured high degrees of molecular deuteration in several species seen around low-mass protostars. The Herschel Space Telescope, launched in 2009, is now providing new measures of the deuterium fractionation of water, the main constituent of interstellar ices. Aims. We aim at theoretically studying the formation and the deuteration of water, which is believed to be formed on interstellar grain surfaces in molecular clouds. Methods. We used our gas-grain astrochemical model GRAINOBLE, which considers the multilayer formation of interstellar ices. We varied several input parameters to study their impact on water deuteration. We included the treatment of ortho- and para-states of key species, including H2, which affects the deuterium fractionation of all molecules. The model also includes relevant laboratory and theoretical works on the water formation and deuteration on grain surfaces. In particular, we computed the transmission probabilities of surface reactions using the Eckart model, and we considered ice photodissociation following molecular dynamics simulations. Results. The use of a multilayer approach allowed us to study the influence of various parameters on the abundance and the deuteration of water. Deuteration of water is found to be very sensitive to the ortho-to-para ratio of H2 and to the total density, but it also depends on the gas/grain temperatures and the visual extinction of the cloud. Since the deuteration is very sensitive to the physical conditions, the comparison with sub-millimetric observation towards the low-mass protostar IRAS 16293 allows us to suggest that water ice is formed together with CO2 in molecular clouds with limited density, whilst formaldehyde and methanol are mainly formed in a later phase, where the condensation becomes denser and colder.

Protostar

Interstellar ice

Water ice

Low Mass

10.1051/0004-6361/201220084

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Citations (65)

SOLIS

Astronomy and Astrophysics (2022)

A. de A. Schutzer P. R. Rivera-Ortíz B. Leflóch A. Gusdorf Cécile Favre

Protostellar jets are an important agent of star formation feedback, tightly connected with the mass-accretion process. The history of jet formation and mass-ejection provides constraints on the mass accretion history and the nature of the driving source. We want to characterize the time-variability of the mass-ejection phenomena at work in the Class 0 protostellar phase, in order to better understand the dynamics of the outflowing gas and bring more constraints on the origin of the jet chemical composition and the mass-accretion history. We have observed the emission of the CO 2-1 and SO N_J=5_4-4_3 rotational transitions with NOEMA, towards the intermediate-mass Class 0 protostellar system Cep E. The CO high-velocity jet emission reveals a central component associated with high-velocity molecular knots, also detected in SO, surrounded by a collimated layer of entrained gas. The gas layer appears to accelerate along the main axis over a length scale delta_0 ~700 au, while its diameter gradually increases up to several 1000au at 2000au from the protostar. The jet is fragmented into 18 knots of mass ~10^-3 Msun, unevenly distributed between the northern and southern lobes, with velocity variations up to 15 km/s close to the protostar, well below the jet terminal velocities. The knot interval distribution is approximately bimodal with a scale of ~50-80yr close to the protostar and ~150-200yr at larger distances >12". The mass-loss rates derived from knot masses are overall steady, with values of 2.7x10^-5 Msun/yr (8.9x10^-6 Msun/yr) in the northern (southern) lobe. The interaction of the ambient protostellar material with high-velocity knots drives the formation of a molecular layer around the jet, which accounts for the higher mass-loss rate in the north. The jet dynamics are well accounted for by a simple precession model with a period of 2000yr and a mass-ejection period of 55yr.

Protostar

Submillimeter Array

10.1051/0004-6361/202142931

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La recherche publique en France en 2019 : Diagnostic et propositions du Comité national

HAL (Le Centre pour la Communication Scientifique Directe) (2019)

Dorothée Berthomieu Olivier Coutard Dimitri Peaucelle Philippe Büttgen Julie Gavard

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Extension of the millimeter- and submillimeter-wave spectral databases of deuterated methyl cyanides (CH₂DCN and CHD₂CN)

Astronomy and Astrophysics (2013)

L. Nguyen Adam Walters L. Margulès R. A. Motiyenko Jean‐Claude Guillemin

Context. The study of deuterated abundant molecules is recognized as important in understanding molecular complexity in star-forming regions.

Star (game theory)

Extremely high frequency

10.1051/0004-6361/201220088

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Citations (17)

VizieR Online Data Catalog: Submm spectrum of deuterated glycolaldehydes (Bouchez+, 2012)

yCat (2012)

Antonin H. Bouchez L. Margulès R. A. Motiyenko Jean‐Claude Guillemin Adam Walters

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Mono-deuterated dimethyl ether: laboratory spectrum up to 1 THz

Astronomy and Astrophysics (2013)

C. Richard L. Margulès E. Caux C. Kahane C. Ceccarelli

Context. Dimethyl ether is one of the most abundant complex organic molecules (COMs) in star-forming regions. Like other COMs, its formation process is not yet clearly established, but the relative abundances of its deuterated isotopomers may provide crucial hints in studying its chemistry and tracing the source history. The mono-deuterated species (CHDOCH) is still a relatively light molecule compared to other COMs. Its spectrum is the most intense in the THz domain in the 100–150 K temperature regime, tracing the inner parts of the low-mass star-forming region. Therefore, it is necessary to measure and assign its transitions in this range in order to be able to compute accurate predictions required by astronomical observations, in particular with the telescope operating in the submm range, such as ALMA.

Isotopomers

Dimethyl ether

Tracing

Star (game theory)

10.1051/0004-6361/201220826

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Citations (29)

peters-JPCA-115-8983-2011-info

Phillip Peters Denis Duflot Alexandre Faure C. Kahane C. Ceccarelli

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First Measurement of the¹⁴N/¹⁵N Ratio in the Analog of the Sun Progenitor OMC-2 FIR4

The Astrophysical Journal (2018)

C. Kahane A. Jaber Al-Edhari C. Ceccarelli A. López-Sepulcre F. Fontani

Abstract We present a complete census of the 14 N/ 15 N isotopic ratio in the most abundant N-bearing molecules toward the cold envelope of the protocluster OMC-2 FIR4, the best known Sun progenitor. To this scope, we analyzed the unbiased spectral survey obtained with the IRAM 30 m telescope at 3, 2, and 1 mm. We detected several lines of CN, HCN, HNC, HC 3 N, N 2 H + , and their respective 13 C and 15 N isotopologues. The lines’ relative fluxes are compatible with LTE conditions, and moderate line opacities have been corrected via a population diagram method or theoretical relative intensity ratios of the hyperfine structures. The five species lead to very similar 14 N/ 15 N isotopic ratios, without any systematic difference between amine- and nitrile-bearing species as previously found in other protostellar sources. The weighted average of the 14 N/ 15 N isotopic ratio is 270 ± 30. This 14 N/ 15 N value is remarkably consistent with the [250–350] range measured for the local galactic ratio but significantly differs from the ratio measured in comets (around 140). High-angular resolution observations are needed to examine whether this discrepancy is maintained at smaller scales. In addition, using the CN, HCN, and HC 3 N lines, we derived a 12 C/ 13 C isotopic ratio of 50 ± 5.

Isotopologue

Line (geometry)

Mass ratio

10.3847/1538-4357/aa9e88

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Citations (31)