Explanipedia

Excitation of Molecules and Atoms for Astrophysics (EMAA): A spectroscopic and collisional database Open

Alexandre Faure, A. Bacmann, Raymond G. Jacquot · 2025

Context . In astrophysical environments, the energy levels of molecules, atoms, and ions are rarely populated at local thermodynamic equilibrium (LTE), that is the level populations reflect the competition between radiative and collisional…

Cosmic-ray induced sputtering of interstellar formaldehyde ices Open

Mathilde Faure, A. Bacmann, Alexandre Faure, E. Quirico, P. Boduch , et al. · 2024

Context. In the cold and dense regions of the interstellar medium (ISM), for example in prestellar cores, gas-phase chemical abundances undergo a steep decrease due to the freeze-out of molecules onto the dust grain surfaces. While the dep…

NIKA2 observations of dust grain evolution from star-forming filament to T-Tauri disk: Preliminary results from NIKA2 observations of the Taurus B211/B213 filament Open

Q. Nguyễn Lương, R. Adam, P. A. R. Ade, H. Ajeddig, P. André , et al. · 2024

To understand the evolution of dust properties in molecular clouds in the course of the star formation process, we constrain the changes in the dust emissivity index from star-forming filaments to prestellar and protostellar cores to T Tau…

NIKA2 observations of dust grain evolution from star-forming filament to T-Tauri disk: Preliminary results from NIKA2 observations of the Taurus B211/B213 filament Open

Q. Nguyễn Lương, R. Adam, P. A. R. Ade, H. Ajeddig, P. André , et al. · 2023

To understand the evolution of dust properties in molecular clouds in the course of the star formation process, we constrain the changes in the dust emissivity index from star-forming filaments to prestellar and protostellar cores to T Tau…

Galactic Star Formation with NIKA2 (GASTON): Evidence of mass accretion onto dense clumps Open

A. J. Rigby, R. Adam, P. A. R. Ade, H. Ajeddig, Michael Anderson , et al. · 2022

High-mass stars (m * ≳ 8 M ⊙ ) play a crucial role in the evolution of galaxies, and so it is imperative that we understand how they are formed. We have used the New IRAM KIDs Array 2 (NIKA2) camera on the Institut de Radio Astronomie Mill…

Galactic star formation with NIKA2 (GASTON): Filament convergence and its link to star formation Open

N. Peretto, R. Adam, P. A. R. Ade, H. Ajeddig, P. André , et al. · 2022

In the past decade filaments have been recognised as a major structural element of the interstellar medium, the densest of these filaments hosting the formation of most stars. In some star-forming molecular clouds converging networks of fi…

Galactic star formation with NIKA2 (GASTON): Filament convergence and its link to star formation Open

R. Adam, H. Ajeddig, E. Artis, A. Bacmann, Anita Beelen , et al. · 2021

In the past decade filaments have been recognised as a major structural element of the interstellar medium, the densest of these filaments hosting the formation of most stars. In some star-forming molecular clouds converging networks of fi…

GASTON: Galactic Star Formation with NIKA2 – evidence for the mass growth of star-forming clumps Open

A. J. Rigby, N. Peretto, R. Adam, P. A. R. Ade, Michael Anderson , et al. · 2021

Determining the mechanism by which high-mass stars are formed is essential for our understanding of the energy budget and chemical evolution of galaxies. By using the New IRAM KIDs Array 2 (NIKA2) camera on the Institut de Radio Astronomie…

Probing episodic accretion with chemistry: CALYPSO observations of the very-low-luminosity Class 0 protostar IRAM 04191+1522 Open

S. Anderl, S. Maret, S. Cabrit, A. Maury, А. Беллоче , et al. · 2020

Context. The process of mass accretion in the earliest phases of star formation is still not fully understood: does the accretion rate smoothly decline with the age of the protostar or are there short, intermittent accretion bursts? The la…

Deuterium fractionation of nitrogen hydrides: detections of NHD and ND2 Open

A. Bacmann, Alexandre Faure, P. Hily-Blant, Kaori Kobayashi, Hiroyuki Ozeki , et al. · 2020

Although ammonia is an abundant molecule commonly observed towards the dense interstellar medium, it has not yet been established whether its main formation route is from gas-phase ion–molecule reactions or grain-surface hydrogen additions…

Questioning the spatial origin of complex organic molecules in young protostars with the CALYPSO survey Open

А. Беллоче, A. Maury, S. Maret, S. Anderl, A. Bacmann , et al. · 2020

Context. Complex organic molecules (COMs) have been detected in a few Class 0 protostars but their origin is not well understood. While the usual picture of a hot corino explains their presence as resulting from the heating of the inner en…

Non-thermal desorption of complex organic molecules Open

E. Dartois, M. Chabot, A. Bacmann, P. Boduch, Alicja Domaracka , et al. · 2020

Aims. Methanol ice is embedded in interstellar ice mantles present in dense molecular clouds. We aim to measure the sputtering efficiencies starting from different ice mantles of varying compositions experimentally, in order to evaluate th…

Non-thermal desorption of complex organic molecules: Cosmic-ray sputtering of CH3OH embedded in CO2 ice Open

E. Dartois, M. Chabot, A. Bacmann, P. Boduch, Alicja Domaracka , et al. · 2020

Methanol ice is embedded in interstellar ice mantles present in dense molecular clouds. We aim to measure the sputtering efficiencies starting from different ice mantles of varying compositions experimentally, in order to evaluate their po…

Chemistry under EUV Irradiation of H$_2$-CO-N$_2$ Gas Mixtures: Implications for Photochemistry in the Outer CSE of Evolved Stars Open

Jérémy Bourgalais, David V. Bekaert, A. Bacmann, Bernard Marty, Nathalie Carrasco · 2020

{CircumStellar Envelopes (CSEs) of stars are complex chemical objects for which theoretical models encounter difficulties in elaborating a comprehensive overview of the occurring chemical processes. Along with photodissociation, ion-neutra…

Chemistry under EUV Irradiation of H$_2$-CO-N$_2$ Gas Mixtures:\n Implications for Photochemistry in the Outer CSE of Evolved Stars Open

Jérémy Bourgalais, David V. Bekaert, A. Bacmann, Bernard Marty, Nathalie Carrasco · 2020

{CircumStellar Envelopes (CSEs) of stars are complex chemical objects for\nwhich theoretical models encounter difficulties in elaborating a comprehensive\noverview of the occurring chemical processes. Along with photodissociation,\nion-neu…

The excitation of NH2 in the interstellar medium Open

Nezha Bouhafs, A. Bacmann, Alexandre Faure, François Lique · 2019

Accurate estimation of the abundance of the NH2 radical in the interstellar medium requires accurate radiative and collisional rate coefficients. The calculation of hyperfine-resolved rate coefficients for the collisional (de-)excitation o…

Oxygen fractionation in dense molecular clouds Open

Jean‐Christophe Loison, Valentine Wakelam, P. Gratier, Kevin M. Hickson, A. Bacmann , et al. · 2019

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 p…

Characterizing young protostellar disks with the CALYPSO IRAM-PdBI survey: large Class 0 disks are rare Open

A. Maury, Ph. André, L. Testi, S. Maret, А. Беллоче , et al. · 2018

Context. Understanding the formation mechanisms of protoplanetary disks and multiple systems and also their pristine properties are key questions for modern astrophysics. The properties of the youngest disks, embedded in rotating infalling…

French SKA White Book - The French Community towards the Square Kilometre Array Open

F. Acero, Y. Akrami, M. Allen, R. Ammanouil, E. Armengaud , et al. · 2018

The "Square Kilometre Array" (SKA) is a large international radio telescope project characterised, as suggested by its name, by a total collecting area of approximately one square kilometre, and consisting of several interferometric arrays…

Probing changes of dust properties along a chain of solar-type prestellar and protostellar cores in Taurus with NIKA Open

A. Bracco, P. Palmeirim, Ph. André, R. Adam, P. A. R. Ade , et al. · 2017

The characterization of dust properties in the interstellar medium is key for understanding the physics and chemistry of star formation. Mass estimates are crucial to determine gravitational collapse conditions for the birth of new stellar…

Rotational excitation of the interstellar NH2 radical by H2 Open

Nezha Bouhafs, François Lique, Alexandre Faure, A. Bacmann, Jun Li , et al. · 2017

We present quantum close-coupling calculations for the rotational excitation of the interstellar amidogen radical NH2 due to collisions with H2 molecules. The calculations are based on a recent, high-accuracy full-dimensional NH4 potential…

Prestellar core modeling in the presence of a\n filament Open

Jürgen M. Steinacker, A. Bacmann, Th. Henning, Stefan Heigl · 2016

\n Context. Lacking a paradigm for the onset of star formation, it is\n important to derive basic physical properties of prestellar cores and filaments like\n density and temperature structures.\n Aims. We aim to disentangle the spatial va…

Probing the CO and methanol snow lines in young protostars Open

S. Anderl, S. Maret, S. Cabrit, А. Беллоче, A. Maury , et al. · 2016

Context. "Snow lines", marking regions where abundant volatiles freeze out\nonto the surface of dust grains, play an important role for planet growth and\nbulk composition in protoplanetary disks. They can already be observed in the\nenvel…

Detection of protonated formaldehyde in the prestellar core L1689B Open

A. Bacmann, Enrique Alonso García, Alexandre Faure · 2016

Complex organic molecules (COMs) are detected in many regions of the interstellar medium, including prestellar cores. However, their formation mechanisms in cold (~10 K) cores remain to this date poorly understood. The formyl radical HCO i…

Stratified NH and ND emission in the prestellar core 16293E in L1689N Open

A. Bacmann, F. Daniel, P. Caselli, C. Ceccarelli, D. C. Lis , et al. · 2016

\n Context. High degrees of deuterium fractionation are commonly found in cold prestellar cores and in the envelopes around young protostars. As it brings strong constraints to chemical models, deuterium chemistry is often used to infer co…

Collisional excitation of doubly and triply deuterated ammonia ND2H and ND3by H2 Open

F. Daniel, Claire Rist, Alexandre Faure, E. Roueff, Maryvonne Gérin , et al. · 2016

The availability of collisional rate coefficients is a prerequisite for an accurate interpretation of astrophysical observations, since the observed media often harbour densities where molecules are populated under non-local thermodynamic …

The origin of gas-phase HCO and CH3O radicals in prestellar cores Open

A. Bacmann, Alexandre Faure · 2016

The recent unexpected detection of terrestrial complex organic molecules in the cold (~ 10 K) gas has cast doubts on the commonly accepted formation mechanisms of these species. Standard gas-phase mechanisms are inefficient and tend to und…

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