Search

We revise the rates of reactions CH + S -> CS + H and C_2 + S -> CS + C, important CS formation routes in dark and diffuse warm gas. We performed ab initio calculations to characterize the main features of all the electronic states correlating to the open shell reactants. For CH+S we have calculated the full potential energy surfaces for the lowest doublet states and the reaction rate constant with a quasi-classical method. For C_2+S, the reaction can only take place through the three lower triplet states, which all present deep insertion wells. A detailed study of the long-range interactions for these triplet states allowed to apply a statistic adiabatic method to determine the rate constants. This study of the CH + S reaction shows that its rate is nearly independent on the temperature in a range of 10-500 K with an almost constant value of 5.5 10^{-11} cm^3/s at temperatures above 100~K. This is a factor \sim 2-3 lower than the value obtained with the capture model. The rate of the reaction C_2 + S depends on the temperature taking values close to 2.0 10^{-10} cm^3/s at low temperatures and increasing to 5. 10^{-10} cm^3/s for temperatures higher than 200~K. Our modeling provides a rate higher than the one currently used by factor of \sim 2. These reactions were selected for involving open-shell species with many degenerate electronic states, and the results obtained in the present detailed calculations provide values which differ a factor of \sim 2-3 from the simpler classical capture method. We have updated the sulphur network with these new rates and compare our results in the prototypical case of TMC1 (CP). We find a reasonable agreement between model predictions and observations with a sulphur depletion factor of 20 relative to the sulphur cosmic abundance, but it is not possible to fit all sulphur-bearing molecules better than a factor of 10 at the same chemical time., 13 pages, 10 figures

9 pags., 5 figs., H_2O submillimeter emission is a powerful diagnostic of the molecular interstellar medium in a variety of sources, including low- and high-mass star forming regions of the Milky Way, and from local to high redshift galaxies. However, the excitation mechanism of these lines in galaxies has been debated, preventing a basic consensus on the physical information that H_2O provides. Both radiative pumping due to H_2O absorption of far-infrared photons emitted by dust and collisional excitation in dense shocked gas have been proposed to explain the H_2O emission. Here we propose two basic diagnostics to distinguish between the two mechanisms: 1) in shock excited regions, the ortho-H_2O 3_{21}-2_{12} 75um and the para-H_2O 2_{20}-1_{11} 101um rotational lines are expected to be in emission while, if radiative pumping dominates, both far-infrared lines are expected to be in absorption; 2) based on statistical equilibrium of H_2O level populations, the radiative pumping scenario predicts that the apparent isotropic net rate of far-infrared absorption in the 3_{21}-2_{12} (75um) and 2_{20}-1_{11} (101um) lines should be higher than or equal to the apparent isotropic net rate of submillimeter emission in the 3_{21}-3_{12} (1163 GHz) and 2_20-2_{11} (1229 GHz) lines, respectively. Applying both criteria to all 16 galaxies and several galactic high-mass star-forming regions where the H_2O 75um and submillimeter lines have been observed with Herschel/PACS and SPIRE, we show that in most (extra)galactic sources the H_2O submillimeter line excitation is dominated by far-infrared pumping, with collisional excitation of the low-excitation levels in some of them. Based on this finding, we revisit the interpretation of the correlation between the luminosity of the H_2O 988 GHz line and the source luminosity in the combined galactic and extragalactic sample., EG-A is a Research Associate at the HarvardSmithsonian Center for Astrophysics, and thanks the Spanish MICINN for support under project PID2019-105552RB-C41. JRG thanks the Spanish MCINN for funding support under grant PID2019-106110GB-I00. JF and KPS gratefully acknowledge support through NASA grant NNH17ZD001N-ADAP. CY acknowledges support from ERC Advanced Grant 789410. MPS acknowledges support from the Comunidad de Madrid through the Atracción de Talento Investigador Grant 2018-T1/TIC-11035 and PID2019-105423GA-I00 (MCIU/AEI/FEDER,UE). PACS was developed by a consortium of institutes led by MPE (Germany) and including UVIE (Austria); KU Leuven, CSL, IMEC (Belgium); CEA, LAM (France); MPIA (Germany); INAFIFSI/OAA/OAP/OAT, LENS, SISSA (Italy); IAC (Spain). This development has been supported by the funding agencies BMVIT (Austria), ESA-PRODEX (Belgium), CEA/CNES (France), DLR (Germany), ASI/INAF (Italy), and CICYT/MCYT (Spain). SPIRE was developed by a consortium of institutes led by Cardiff University (UK) and including Univ. Lethbridge (Canada); NAOC (China); CEA, LAM (France); IFSI, Univ. Padua (Italy); IAC (Spain); Stockholm Observatory (Sweden); Imperial College London, RAL, UCL-MSSL, UKATC, Univ. Sussex (UK); and Caltech, JPL, NHSC, Univ.Colorado (USA). This development has been supported by national funding agencies: CSA (Canada); NAOC (China); CEA, CNES, CNRS (France); ASI (Italy); MCINN (Spain); SNSB (Sweden); STFC, UKSA (UK); and NASA (USA).

Far-ultraviolet photons from OB-type massive stars regulate the heating, ionization, and chemistry of much of the neutral interstellar gas in star-forming galaxies. The interaction of FUV radiation and interstellar matter takes place in environments broadly known as photodissociation regions (PDRs). PDR line diagnostics are the smoking gun of the radiative feedback from massive stars. Improving our understanding of stellar feedback in the ISM requires quantifying the energy budget, gas dynamics, and chemical composition of PDR environments. This goal demands astronomical instrumentation able to deliver multi-line spectroscopic images of the ISM (of the Milky Way and nearby galaxies). It also requires interdisciplinary collaborations to obtain the rate coefficients and cross sections of the many microphysical processes that occur in the ISM and that are included in models such as the Meudon PDR code., Comment: To appear in "The European Physical Journal Web of Conferences". Invited paper at "Multi-line Diagnostics of the Interstellar Medium", Nice 2022

Chapter 6. -- Colección: CSIC Scientific challenges : towards 2030

The far-infrared (FIR) regime is one of the wavelength ranges where no astronomical data with sub-arcsecond spatial resolution exist. None of the medium-term satellite projects like SPICA, Millimetron, or the Origins Space Telescope will resolve this malady. For many research areas, however, information at high spatial and spectral resolution in the FIR, taken from atomic fine-structure lines, from highly excited carbon monoxide (CO), light hydrides, and especially from water lines would open the door for transformative science. A main theme will be to trace the role of water in proto-planetary discs, to observationally advance our understanding of the planet formation process and, intimately related to that, the pathways to habitable planets and the emergence of life. Furthermore, key observations will zoom into the physics and chemistry of the star-formation process in our own Galaxy, as well as in external galaxies. The FIR provides unique tools to investigate in particular the energetics of heating, cooling, and shocks. The velocity-resolved data in these tracers will reveal the detailed dynamics engrained in these processes in a spatially resolved fashion, and will deliver the perfect synergy with ground-based molecular line data for the colder dense gas.

211 p., Understanding the basic components of the Universe, its structure, and evolution is one of the noblest and most ambitious undertakings of humanity. The fundamental laws of nature are the basis of all technology. Finding and understanding them requires exploring both the elementary components of matter at the smallest scales and the observable Universe at the largest scales. Only through understanding the laws that dictated the first instances of the Universe will we be able to find the ultimate reason for its actual appearance and future fate. Challenges in physics are intimately associated with technological challenges for the design and building of telescopes, space missions or accelerators, reactor and underground experiments, as well as developments in mathematics. Their resolution requires a worldwide, transdisciplinary effort and the orchestrated involvement of researchers, engineers, and technicians. The challenges described here are fully aligned with the priorities identified in international and European strategies.

SPICA Science Conference from Exoplanets to Distant Galaxies: SPICA's New Window on the Cool Universe (June 18-21, 2013. Ito Hall, the University of Tokyo), Bunkyou-ku, Tokyo, Japan, SPICA will be a powerful facility to help us understand the formation and evolution of our solar system and exoplanetary systems in 2020's. The wavelength coverage (5-210 micrometers) is optimal for observations of key targets including exoplanets, protoplanetary and debris disks, and solar system small bodies. At this coverage SPICA will offer several dramatic advantages, including extremely high sensitivity and excellent image quality with a cooled (approximately 6 K) monolithic 3-m class mirror telescope, a variety of capabilities for spectroscopy and spectro-imaging, and an unprecedented high spectral resolution for mid-infrared spectroscopy free from telluric absorption and emission. We briefly summarize our discussions for possible science impacts on the above targets and research topics., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA1730027065, レポート番号: JAXA-SP-17-010E

The far-infrared (FIR) regime is one of the few wavelength ranges where no astronomical data with sub-arcsecond spatial resolution exist. Neither of the medium-term satellite projects like SPICA, Millimetron nor O.S.T. will resolve this malady. For many research areas, however, information at high spatial and spectral resolution in the FIR, taken from atomic fine-structure lines, from highly excited carbon monoxide (CO), light hydrids, and especially from water lines would open the door for transformative science. A main theme will be to trace the role of water in proto-planetary disks, to observationally advance our understanding of the planet formation process and, intimately related to that, the pathways to habitable planets and the emergence of life. Furthermore, key observations will zoom into the physics and chemistry of the star-formation process in our own Galaxy, as well as in external galaxies. The FIR provides unique tools to investigate in particular the energetics of heating, cooling and shocks. The velocity-resolved data in these tracers will reveal the detailed dynamics engrained in these processes in a spatially resolved fashion, and will deliver the perfect synergy with ground-based molecular line data for the colder dense gas., White Paper, submitted to ESA in August 2019 in response to the "Voyage 2050" process; 24 pages, 12 figures, 1 table; three references updated from preprint to journal status, one reference added in comparison to the version submitted to ESA

Understanding the basic components of the Universe, its structure and evolution isa complex of questions at the heart of humanity and has been one of its noblest andmost ambitious undertakings. It can be traced back to the first natural philosophers ofthe antique world, but it gathered enormous impact and speed with the emergence ofthe scientific method in modern times. This quest has a double impact on society. Onthe one hand, there are the profound mental, emotional, philosophical, and potentiallyeven political - if one thinks of the global environmental movement - changes that areprompted by our increasing understanding of our place in the Universe. On the other hand,fundamental mathematical and physical science is the basis of all of modern technology.

703. WE-Heraeus-Seminar, Physikzentrum Bad Honnef, Germany, 23 Oct - 25 Oct 2019, Far-UV photons (FUV, E < 13.6 eV) from massive stars regulate, or at least influence, the dynamics, heating, ionization, and chemistry of most of the neutral ISM (HI and H2 clouds). Investigating the interaction between FUV radiation and interstellar matter (molecules, atoms, and grains) thus plays a central role in Astrochemistry. Indeed, it contributes to a better understanding of a broad range of environments in which similar physical and chemical process operate (diffuse clouds, the interface between HII regions around massive stars and their parental dense cloud, planetary nebulae, starburst galaxies, etc.) all generically known as ¿photodissociation regions¿ (PDRs). The chemistry of PDRs depends on the propagation and attenuation of stellar FUV photons into the cloud. Different physical processes and chemical reactions control the molecular composition as a function of cloud depth. Traditionally considered to be too harsh environments to host a rich chemistry, modern-day observations using multi-wavelength techniques and broad-band spectrometers do show a distinctive (photo)chemistry. Specific ¿PDR molecules'' are the molecular ions CF+, CO+, HOC+, CH+, SH+, OH+ or H2Cl+ ions (some of them extremely reactive). Their formation routes often represent the first steps of interstellar chemistry. The list of molecules detected in prototypical PDRs such as the Horsehead Nebula or the Orion Bar steadily increases. It ranges from well-known radicals (e.g., C2H, CN, OH, HCO), heavier ions (such as l-C3H+) involved in the formation of small hydrocarbons (e.g., C3H2 and C3H), isotopologues and isotopomers (e.g., 13CCH, C13CH, DCN and HNC), to PAHs and complex organic molecules (COMs, e.g., CH3CN, HCOOH, CH2CO, etc.). Explaining the presence of COMs in PDRs is particularly challenging, and opens new avenues for grain surface and ice-mantle desorption studies. The emission from the above species not only reflects subtle excitation and chemical processes (photoreactions, state-to-state reactions with FUV-pumped vibrationally excited H2, fractionation reactions, photo-erosion of grains, etc.), also they trace the steep variations in the gas properties (physical and FUV-illumination conditions, ionization fraction, etc.) as a function cloud depth. In this contribution I will review our on-going modelling and observational efforts (with ALMA, Herschel and the IRAM 30m telescope) to characterize the chemistry of PDRs.

Mission to the Universe: from Earth to Planets, Stars & Galaxies, Stuttgart, 16 to 20 September 2019. -- https://conference.dsi.uni-stuttgart.de/event/2/, We present a 400 square arcmin map of the velocity-resolved C+ emission toward 30 Doradus super stellar cluster in the LMC. The C+ emission observed with the UPGREAT receiver delineates shell structures around large-scale bubbles filled with hot, X-ray emitting gas ultimately produced by the strong stellar feedback from tens of massive stars in the region. We present a preliminary analysis of the gas velocity field and compare it with the orientation and strength of the magnetic field inferred from polarization observations at 154 microns and obtained with SOFIA/HAWC+.

Conferencia invitada. -- A symposium in honour of John H. Black, Gothenburg, June 24 - 28, 2019, Reactive ions are transient species for which the timescale of reactive collisions (leading to a chemical reaction) with H2, H, or e¿ is comparable to, or shorter than, that of inelastic collisions (Black et al. 1998). The formation of reactive ions such as CH+ and SH+ depends on the availability of C+ and S+ (i.e., of UV pho- tons, thus high ionization fractions xe = n(e¿ ) / nH ) and on the presence of excited H2 (either UV-pumped or hot and thermally excited). This allows overcoming the high endothermicity (and sometimes barrier) of their formation (Sternberg & Dalgargo 1995; Agu ¿ndez et al. 2010). The reaction C+ + H2(v) ¿ CH+ + H (1), for example, is endothermic by ¿E/k ¿ 4300 K if v=0, but exothermic and fast for v¿1 (Hierl et al. 1997). The reaction S+ + H2(v) ¿ SH+ + H (endothermic by ¿E/k¿9860 K when v=0) becomes exothermic when v¿2 (Zanchet et al. 2019). CH+ was one of the first molecules detected in the 1930s. Due to the high endothermicity of reaction (1), explaining the presence of CH+ absorption lines in diffuse clouds has been a long standing problem in astrochemistry (e.g. Godard, Falgarone et al. 2012). Herschel and now ALMA, have allowed us to image the emission from CH+ and SH+ rotational lines toward interstellar and circumstellar sources irradiated by strong stellar UV fields (see Gerin et al. 2016 for a review). In dense gas, nH ¿¿ 105 cm¿3, the lifetime of CH+ is so short, a few hours, that the molecule may form and be de- stroyed without experiencing non-reactive collisions with other species. Contrary to most interstellar molecules, this implies that CH+ does not have time to thermalize, by elastic collisions, its translational motions to a ve- locity distribution at Tk. Hence, CH+ rotational lines are expected to show broad line shapes related to the energy excess upon formation (thousands of K) and not to the actual Tk nor to an enhanced gas turbulence. Hence, CH+ can be excited by radiation many times during its its mean-free-time for non-reactive collisions, so that it remains kinetically hot (large velocity dispersion) and rotationally warm (high Trot) while it emits. Reac- tive ions can thus ¿retain some memory of the energetics of the formation process¿. This ¿formation pumping¿ was anticipated by John Black in his eloquent Faraday Discussion¿s paper (1998) and explicitly modelled af- ter Herschel¿s detections (Nagy et al. 2013; Godard & Cernicharo 2013). Today, CH+ (J = 1¿0) emission has mapped at parsec scales along Orion star-forming region (Goicoechea et al. 2019) and SH+ emission has been spatially resolved at the edge of the Orion Bar PDR with ALMA at ¿¿ 10¿2 pc resolution (Goicoechea et al. 2017). Research on reactive ions is active and offers a common ground to study fundamental processes by as- tronomers and chemists (both in the lab and by ab initio quantum calculations).

The Promise of SPICA, Crete, Greece, 20-23 May 2019, Massive stars dominate the injection of radiative and mechanical energy into the ISM through ionizing radiation, stellar winds, supernova explosions, and merger encounters. This energy input shakes the environment, heats the gas, disrupts star-forming molecular clouds, and creates the cloud and intercloud phases of the ISM. Massive stars are born inside dense giant molecular cloud (GMC) cores. Protostars of different masses develop inside these star-forming cores. Their protostellar outflows shock the ambient cloud, heating and compressing the molecular gas around them. Young stellar objects can be detected by the bright far-IR/submm luminosity of their obscured dusty cocoons. Their properties and energetics can be constrained by studying the far-IR high-J CO and H2O line emission, the unambiguous signature of warm shocked gas. On the spatial scales of an entire GMC, however, most of the gas and dust thermal emission do not arise from individual protostars but from the extended cloud component ([Cii]158¿m and [Oi]63¿m being the brightest lines from the neutral ISM). Once a new massive-star cluster is formed, the energy and momentum injected by photoionization, radiation pressure, and stellar winds ionize and erode the natal molecular cloud, creating Hii regions and blowing expanding bubbles. This stellar feedback can thus determine the gas physical conditions on large scales, drive the evolution of the natal cloud itself, and regulate the formation of new stars. Finding observational tracers of these radiative and mechanical feedback processes is crucial not only for Milky Way studies, but also in the general framework of star formation across cosmic time. There, it is not easy - at high-z yet almost impossible - to disentangle where the emission comes from: nuclear outflows, galactic winds, embedded star-forming sites, quiescent molecular clouds, turbulent halos, etc. While the low-energy lines that can be detected from ground-based radio telescopes like ALMA typically trace cold and quiescent gas, the warm gas affected by feedback processes (i.e., heated by strong stellar UV fields, enhanced X-ray dozes, cosmic-ray particles, or affected by shocks and turbulence dissipation) naturally emits at far-IR wavelengths; through a plethora of atomic fine-structure lines (from the neutral and ionized phases of the ISM) and rotationally-exited molecular lines (from CO, H2O, CH+, HD, and other hydrides) that cannot be detected from the ground. These far-IR lines (often the most luminous lines emitted by the ISM of galaxies) prove to be unique diagnostics of the different types of energy and momentum input deposited into the ISM, that is, of the different feedback mechanisms. SPICA¿s exquisite sensitivity for broad-band far-IR multi-line detection will revolutionize our understanding of the stellar feedback processes that operate in the ISM of galaxies and how this connects/regulates their star-forming history. SPICA¿s multi-tracer capabilities will allow us to measure the physical conditions and chemical content of template star-forming regions in the local Universe and, for the first time, to obtain the same kind of quantitative description of the ISM of primitive star-forming galaxies, thus shedding light on their origin and evolution.

Conferencia invitada, España 10 de Octubre de 2019

XT2019, Palais des Papes, Avignon,, France, 2-6 September 2019. -- Celebrating the first 40 years of Alexander Tielens’ contribution to Science, Far-UV photons (FUV, E < 13.6 eV) from hot massive stars regulate, or at least influence, the heating, ionization, and chemistry in many regions of the ISM. The Orion Bar, the prototypical strongly irradiated PDR, is illuminated by a FUV flux of few 104 times the mean interstellar radiation field. Because of its proximity and nearly edge-on orientation, the Bar provides an excellent template to investigate the chemical content, structure, and dynamics of an irradiated molecular cloud edge. In the last years, we have used ALMA to image a small field of the Orion Bar, where the transition from atomic to molecular gas takes place. These observations provide an unprecedented sharp view of this critical transition layer (< 1'' angular resolution or < 414 AU). The resulting images show the small-scale structure in gas density and temperature, as well as the steep chemical abundance gradients. The images suggest photo-evaporative gas flows and instabilities at the edge of the molecular cloud. These observations have triggered the development of new hydrodynamic PDR models that try to explain some of the most unexpected observational results, for example the apparent small separation between the H/H2 and C+/CO dissociation fronts and the high gas thermal pressures inferred in the molecular PDR. In this talk I will stress the dynamical and non-equilibrium nature of the interaction between UV radiation from young massive stars with their parental cloud. These questions are at the core of our understanding of stellar feedback, a collection of complicated processes that take place at many galactic scales and drive the evolution of the ISM.

The rate constants for the formation, destruction, and collisional excitation of SH$^+$ are calculated from quantum mechanical approaches using two new SH$_2^+$ potential energy surfaces (PESs) of $^4A''$ and $^2A''$ electronic symmetry. The PESs were developed to describe all adiabatic states correlating to the SH$^+$ ($^3\Sigma^-$) + H($^2S$) channel. The formation of SH$^+$ through the S$^+$ + H$_2$ reaction is endothermic by $\approx$ 9860 K, and requires at least two vibrational quanta on the H$_2$ molecule to yield significant reactivity. Quasi-classical calculations of the total formation rate constant for H$_2$($v=2$) are in very good agreement with the quantum results above 100K. Further quasi-classical calculations are then performed for $v=3$, 4, and 5 to cover all vibrationally excited H$_2$ levels significantly populated in dense photodissociation regions (PDR). The new calculated formation and destruction rate constants are two to six times larger than the previous ones and have been introduced in the Meudon PDR code to simulate the physical and illuminating conditions in the Orion bar prototypical PDR. New astrochemical models based on the new molecular data produce four times larger SH$^+$ column densities, in agreement with those inferred from recent ALMA observations of the Orion bar., Comment: 8 pages, 7 figures

The radiative and mechanical interaction of stars with their environment drives the evolution of the ISM and of galaxies as a whole. The far-IR emission (lambda ~30 to 350 microns) from atoms and molecules dominates the cooling of the warm gas in the neutral ISM, the material that ultimately forms stars. Far-IR lines are thus the most sensitive probes of stellar feedback processes, and allow us to quantify the deposition and cycling of energy in the ISM. While ALMA (in the (sub)mm) and JWST (in the IR) provide astonishing sub-arcsecond resolution images of point sources and their immediate environment, they cannot access the main interstellar gas coolants, nor are they designed to image entire star-forming regions (SFRs). Herschel far-IR photometric images of the interstellar dust thermal emission revealed the ubiquitous large-scale filamentary structure of SFRs, their mass content, and the location of thousands of prestellar cores and protostars. These images, however, provide a static view of the ISM: not only they dont constrain the cloud dynamics, moreover they cannot reveal the chemical composition and energy transfer within the cloud, thus giving little insight into the regulation process of star formation by stellar feedback. In this white paper we emphasize the need of a space telescope with wide-field spectral-imaging capabilities in the critical far-IR domain., Comment: White Paper submitted to the Astro 2020 Decadal Survey on Astronomy and Astrophysics (National Academies of Science, Engineering, and Medicine)

Recent Herschel and ALMA observations of Photodissociation Regions (PDRs) have revealed the presence of a high thermal pressure (P ~ 10^7-10^8 K cm-3) thin compressed layer at the PDR surface where warm molecular tracer emission (e.g. CH+, SH+, high-J CO, H2,...) originate. These high pressures (unbalanced by the surrounding environment) and a correlation between pressure and incident FUV field (G0) seem to indicate a dynamical origin with the radiation field playing an important role in driving the dynamics. We investigate whether photoevaporation of the illuminated edge of a molecular cloud could explain these high pressures and pressure-UV field correlation. We developed a 1D hydrodynamical PDR code coupling hydrodynamics, EUV and FUV radiative transfer and time-dependent thermo-chemical evolution. We applied it to a 1D plane-parallel photoevaporation scenario where a UV-illuminated molecular cloud can freely evaporate in a surrounding low-pressure medium. We find that photoevaporation can produce high thermal pressures and the observed P-G0 correlation, almost independently from the initial gas density. In addition, we find that constant-pressure PDR models are a better approximation to the structure of photoevaporating PDRs than constant-density PDR models, although moderate pressure gradients are present. Strong density gradients from the molecular to the neutral atomic region are found, which naturally explain the large density contrasts (1-2 orders of magnitude) derived from observations of different tracers. The photoevaporating PDR is preceded by a low velocity shock (a few km/s) propagating into the molecular cloud. Photoevaporating PDR models offer a promising explanation to the recent observational evidence of dynamical effects in PDRs., Submitted to A&A, comments are welcome. 16 pages, 18 figures

The Orion Bar is the archetypal edge-on molecular cloud surface illuminated by strong ultraviolet radiation from nearby massive stars. Owing to the close distance to Orion (about 1,350 light-year), the effects of stellar feedback on the parental cloud can be studied in detail. Visible-light observations of the Bar(1) show that the transition between the hot ionised gas and the warm neutral atomic gas (the ionisation front) is spatially well separated from the transition from atomic to molecular gas (the dissociation front): about 15 arcseconds or 6,200 astronomical units (one astronomical unit is the Earth-Sun distance). Static equilibrium models(2,3) used to interpret previous far-infrared and radio observations of the neutral gas in the Bar(4,5,6) (typically at 10-20 arcsecond resolution) predict an inhomogeneous cloud structure consisting of dense clumps embedded in a lower density extended gas component. Here we report one-arcsecond-resolution millimetre-wave images that allow us to resolve the molecular cloud surface. In contrast to stationary model predictions(7,8,9), there is no appreciable offset between the peak of the H2 vibrational emission (delineating the H/H2 transition) and the edge of the observed CO and HCO+ emission. This implies that the H/H2 and C+/C/CO transition zones are very close. These observations reveal a fragmented ridge of high-density substructures, photoablative gas flows and instabilities at the molecular cloud surface. The results suggest that the cloud edge has been compressed by a high-pressure wave that currently moves into the molecular cloud. The images demonstrate that dynamical and nonequilibrium effects are important for the cloud evolution., Comment: Manuscript accepted for publication in Nature. This is the author's submitted version (preprint). Definitive version of the manuscript was published online by Nature on 10 August 2016

Oral presentation given at the European Week of Astronomy and Space Science (EWASS 2016) held in Athens (Greece) on July 4-8th, 2016. S8 - Interstellar dust and gas coupling., We have investigated the presence of complex organic molecules (COMs) in dense photo-dissociation regions (PDRs). These environments have been traditionally considered too harsh to maintain a complex chemistry and thus significant abundances of polyatomic organic species (excluding PAHs). We have used the IRAM-30m millimetre-wave telescope and carried out two line surveys, complemented with maps, of the Orion Bar and Horsehead edges. These nearly edge-on PDRs provide excellent templates to study the molecular content and spatial stratification in strongly and mildly UV-irradiated material (G0>104 for the Bar, G0~102 for the Horsehead). In these PDRs, the UV-driven chemistry can be investigated for different gas and dust temperatures (Tgas~150K and Tdust~75K for the Bar, and Tgas~60K and Tdust~30K for the Horsehead). Warm grains at the edge of the Orion Bar should be mostly ice mantle-free grains. The dust temperature in the Horsehead PDR, however, is significantly lower than the sublimation temperature of abundant interstellar ices (water, methanol, etc.). The study of these two prototypical PDRs provide a unique opportunity to discuss the role of pure warm gas-phase reactions and ice-mantle photo-processing in the formation of COMs. Our observations show the detection of hundreds of lines from COMs in both PDRs. Surprisingly, the abundance of several COMs is enhanced in the UV-illuminated material. The presence of COMs in the interstellar medium is thus more widespread that initially expected. COM formation reflects the complicate interplay between gas and grain surface chemistry. However, the specific formation pathways are not fully clear yet. More theoretical work and laboratory experiments, constraining formation routes and reaction rates at different temperatures, as well as photo-desorption yields and chemical desorption rates are clearly needed.

We present the first 7.5'x11.5' velocity-resolved map of the [CII]158um line toward the Orion molecular cloud-1 (OMC-1) taken with the Herschel/HIFI instrument. In combination with far-infrared (FIR) photometric images and velocity-resolved maps of the H41alpha hydrogen recombination and CO J=2-1 lines, this data set provides an unprecedented view of the intricate small-scale kinematics of the ionized/PDR/molecular gas interfaces and of the radiative feedback from massive stars. The main contribution to the [CII] luminosity (~85%) is from the extended, FUV-illuminated face of the cloud G_0>500, n_H>5x10^3 cm^-3) and from dense PDRs (G_0~10^4, n_H~10^5 cm^-3) at the interface between OMC-1 and the HII region surrounding the Trapezium cluster. Around 15% of the [CII] emission arises from a different gas component without CO counterpart. The [CII] excitation, PDR gas turbulence, line opacity (from [13CII]) and role of the geometry of the illuminating stars with respect to the cloud are investigated. We construct maps of the [CII]/FIR and FIR/M_Gas ratios and show that [CII]/FIR decreases from the extended cloud component (10^-2-10^-3) to the more opaque star-forming cores (10^-3-10^-4). The lowest values are reminiscent of the "[CII] deficit" seen in local ultra-luminous IR galaxies hosting vigorous star formation. Spatial correlation analysis shows that the decreasing [CII]/FIR ratio correlates better with the column density of dust through the molecular cloud than with FIR/M_Gas. We conclude that the [CII] emitting column relative to the total dust column along each line of sight is responsible for the observed [CII]/FIR variations through the cloud., 21 pages, 17 figures. Accepted for publication in the Astrophysical Journal (2015 August 12). Figures 2, 6 and 7 are bitmapped to lower resolution. This is version 2 after minor editorial changes. Notes added after proofs included

We report additional detections of the chloronium molecular ion, H$_2$Cl$^+$, toward four bright submillimeter continuum sources: G29.96, W49N, W51, and W3(OH). With the use of the HIFI instrument on the Herschel Space Observatory, we observed the $2_{12}-1_{01}$ transition of ortho-H$_2^{35}$Cl$^+$ at 781.627 GHz in absorption toward all four sources. Much of the detected absorption arises in diffuse foreground clouds that are unassociated with the background continuum sources and in which our best estimates of the $N({\rm H_2Cl^+})/N({\rm H})$ ratio lie in the range $(0.9 - 4.8) \times 10^{-9}$. These chloronium abundances relative to atomic hydrogen can exceed the predictions of current astrochemical models by up to a factor of 5. Toward W49N, we have also detected the $2_{12}-1_{01}$ transition of ortho-H$_2^{37}$Cl$^+$ at 780.053 GHz and the $1_{11}-0_{00}$ transition of para-H$_2^{35}$Cl$^+$ at 485.418 GHz. These observations imply $\rm H_2^{35}Cl^+/H_2^{37}Cl^+$ column density ratios that are consistent with the solar system $^{35}$Cl/$^{37}$Cl isotopic ratio of 3.1, and chloronium ortho-to-para ratios consistent with 3, the ratio of spin statistical weights., 31 pages, including 7 figures. Accepted for publication in the ApJ

Oral presentation given at the 30 years of Photodissociation Regions: a symposium to honor David Hollenbach's lifetime in science, held in Asilomar (US) on June 28th - July 3rd, 2015., The chemistry of PDRs is driven by the penetration of FUV photons. Depending on the FUV radiation strength and gas density, different physical processes and chemical reactions control the molecular composition as a function of cloud depth. Traditionally considered as harsh environments to host a rich chemistry, modern-day observations using multi-wavelength techniques and broad-band spectrometers do show a distinctive ¿PDR molecular content¿. Specific ¿PDR molecules¿ are the CF+, CO+, HOC+, CH+, SH+, OH+ or H2Cl+ ions. Their formation represents the first steps of the PDR chemistry. The list of molecules detected in prototypical PDRs such as the Horsehead or the Orion Bar steadily increases. It ranges from well-known radicals (e.g. C2H, CN, OH, HCO), heavy ions such as l-C3H+ involved in the forma- tion of small hydrocarbons (e.g., C3H2 and C3H), isotopologues and isotopomers (e.g., 13CCH, C13CH, DCN and HNC), to PAHs and even complex organic molecules (COMs such as CH3CN, CH3NC, HCOOH, CH2CO, etc.). Explaining the presence of COMs in PDRs is particularly chal- lenging, and opens new avenues for grain surface and ice-mantle photodesorption studies. The emission from all the above species not only reflects subtle chemical and excitation processes (photoreactions, reactions with vibrationally excited H2, state-to-state formation, frac- tionation reactions, photo-erosion of grains, etc.), also they trace the steep gradients in the PDR gas properties (physical conditions, molecular fraction, ionization fraction, etc.) as a function of cloud depth. Their emission not only dominates the spectra of galactic PDRs and star-forming regions near massive stars. They are also becoming powerful diagnostic tools to understand the emission from sources as different as the nuclei of distant galaxies, planetary nebulae, protostellar shocks irradiated by FUV fields, or the illuminated surfaces of protoplanetary disks. In this contribution I will review the on-going observational and modeling efforts made to characterize the chemistry of PDRs. I will also show the first ALMA images of the Orion Bar.

Context. The Helix nebula (NGC 7293) is our closest planetary nebulae. Therefore, it is an ideal template for photochemical studies at small spatial scales in planetary nebulae. Aims. We aim to study the spatial distribution of the atomic and the molecular gas, and the structure of the photodissociation region along the western rims of the Helix nebula as seen in the submillimeter range with Herschel. Methods. We used five SPIRE FTS pointing observations to make atomic and molecular spectral maps. We analyzed the molecular gas by modeling the CO rotational lines using a non-local thermodynamic equilibrium (non-LTE) radiative transfer model. Results. For the first time, we have detected extended OH+ emission in a planetary nebula. The spectra towards the Helix nebula also show CO emission lines (from J = 4 to 8), [N ii] at 1461 GHz from ionized gas, and [C i] (3P2- 3P1), which together with the OH+ lines trace extended CO photodissociation regions along the rims. The estimated OH + column density is ~ 1012 - 1013 cm -2. The CH+ (1-0) line was not detected at the sensitivity of our observations. Non-LTE models of the CO excitation were used to constrain the average gas density (n(H2) ~ (1 - 5) × 105 cm-3) and the gas temperature (Tk ~ 20-40 K). Conclusions. The SPIRE spectral-maps suggest that CO arises from dense and shielded clumps in the western rims of the Helix nebula, whereas OH+ and [C i] lines trace the diffuse gas and the UV and X-ray illuminated clump surfaces where molecules reform after CO photodissociation. The [N ii] line traces a more diffuse ionized gas component in the interclump medium., We thank ASTROMADRID for funding support through the grant S2009ESP-1496, the consolider programme ASTROMOL: CSD2009-00038, and the Spanish MINECO (grants AYA2009-07304 and AYA2012-32032). F.K. is supported by the FWF project P23586 and the ffg ASAP project HIL. P.v.H. and P.R. acknowledge support from the Belgian Science Policy Office (Belspo) through the ESA PRODEX program. This development has been supported by national funding agencies: CSA (Canada); NAOC (China); CEA, CNES, CNRS (France); ASI (Italy); MCINN (Spain); SNSB (Sweden); STFC, UKSA (UK); and NASA (USA).

The rate constants required to model the OH+ observations in different regions of the interstellar medium have been determined using state of the art quantum methods. First, state-to-state rate constants for the H-2(V = 0, J = 0, 1) + O+ ((4) S) -> H + OH+ (X-3 Sigma(-),v ', N) reaction have been obtained using a quantum wave packet method. The calculations have been compared with time-independent results to assess the accuracy of reaction probabilities at collision energies of about 1 meV. The good agreement between the simulations and the existing experimental cross sections in the 0.01-1 eV energy range shows the quality of the results. The calculated state-to-state rate constants have been fitted to an analytical form. Second, the Einstein coefficients of OH+ have been obtained for all astronomically significant rovibrational bands involving the X-3 Sigma and/or A(3) Pi electronic states. For this purpose, the potential energy curves and electric dipole transition moments for seven electronic states of OH+ are calculated with ab initio methods at the highest level, including spin orbit terms, and the rovibrational levels have been calculated including the empirical spin rotation and spin spin terms. Third, the state-to-state rate constants for inelastic collisions between He and 014 (X-3 Sigma,2) have been calculated using a time-independent close coupling method on a new potential energy surface. All these rates have been implemented in detailed chemical and radiative transfer models. Applications of these models to various astronomical sources show that inelastic collisions dominate the excitation of the rotational levels of OH. In the models considered, the excitation resulting from the chemical formation of OH+ increases the line fluxes by about 10% or less depending on the density of the gas.

Paper conference presented at International Symposium The Universe Explored by Herschel that took place in Noordwijk (Netherlands) during 15-18th October 2013., The Galactic centre (GC), in particular the interstellar material in the immediate vicinity (

著者人数：16名, タイトルの誤記: Studies of exoplanets and solar systems with SPICA, Accepted: 2009-11-06, 資料番号: SA1002575000

International audience; We present a summary of our previous investigations of the physical and chemical structure of the Horsehead nebula, and discuss how these studies led to advances on the understanding of the impact of FUV radiation on the structure of dense interstellar clouds. Specific molecular tracers can be used to isolate different environments, that are more sensitive to changes in the FUV radiation or density than the classical tracers of molecular gas : the CO isotopologues or the dust (sub)millimeter continuum emission. They include the HCO or CCH radicals for the FUV illuminated interfaces, or the molecular ions H$^{13}$CO$^+$, DCO$^+$ and other deuterated species (DNC, DCN) for the cold dense core. We discuss future prospects in the context of Herschel and ALMA.

We summarize the main highlights from ISO observations towards Sgr B2 and Orion KL in the far-IR domain (~43 to 197 um). Both Star-Forming Regions are among the best sources to construct a template for more distant and unresolved regions (e.g., extragalactic). We stress some peculiarities in the interpretation (excitation and radiative transfer) of far-IR spectral lines and dust continuum emission., Comment: ''Far-Infrared and Submillimeter Emission of the Interstellar Medium: Models meet extragalactic and Galactic Observations''. Proceedings of the FIR Workshop 2007. Eds. C. Kramer, R. Simon et al

Accepted in ApJ letters, 2006 March 2, 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.

We have observed with the 30-m IRAM telescope, the CSO telescope and the ISOsatellite (Infrared Space Observatory) the rotational lines of CO at millimeter, submillimeter and far infrared wavelengths in the direction of C-rich stellar objects at different stages of evolution : CRL 2688 (a very young Proto-Planetary Nebula), CRL 618 (a Proto-Planetary Nebula), and NGC 7027 (a young Planetary Nebula). Several changes in the longwave emission of CO and other molecules are discussed here in relation with the degree of evolution of the objects. In the early stages, represented by CRL 2688, the longwave emission is dominated by CO lines. In the intermediate stage, CRL 618, very fast outflows are present which, together with the strong UV field from the central star, dissociate CO. The released atomic oxygen is seen via its atomic lines, and allows the formation of new O-bearing species, such as water and OH. The abundance of HNC is enhanced with respect to HCN as a result of the chemical processes occurring in the photo-dissociation region (PDR). At this stage, CO lines and [OI] lines are the dominant coolants, while the cooling effect of [CII] is rising. At the Planetary Nebula stage, NGC 7027, large parts of the old CO AGB material have been reprocessed. The spectrum is then dominated by atomic and ionic lines. New species such as CH+ appear. Water has probably been reprocessed in OH.

We present Infrared Space Observatory (ISO) observations of 16OH and 18OH toward Sgr B2 with a spectral resolution of 35 km/s. The OH J=5/2-3/2 and J=3/2-1/2 rotational lines of the 2Pi1/2 ladder are seen in emission while the cross-ladder transitions (from the 2Pi3/2 J=3/2 to the J=1/2, 3/2 and 5/2 levels of the 2Pi1/2ladder), and the 2Pi3/2 J=5/2-3/2 and J=7/2-5/2 lines are detected in absorption. The 18OH 2Pi3/2 J=5/2-3/2 Lambda-doublet at 120 mu is also observed in absorption. All OH Lambda-doublets are resolved (except the 98 mu) and show, in addition to the strong absorption at the velocity of Sgr B2, several velocity components associated to the gas surrounding Sgr B2 and to the foreground clouds along the line of sight. No asymmetries in the line intensities of each doublet have been observed. We have modeled the observations using a non-local radiative transfer code and found that the OH absorption/emission must arise in a shell around Sgr B2 not resolved by the ISO/LWS beam. The gas density is moderate, with upper limits of 10^4 cm^{-3} and 300 K in temperature. The OH abundance is high,(2-5)10^{-6}. We argue that a widespread photon dominated region explains the enhancement of OH abundance.

4 pags., 2 figs., We report the first far-infrared detection of the hydronium ion (H3O+) toward the Sagittarius B2 molecular cloud, near the Galactic center. Using the Infrared Space Observatory Long-Wavelength Spectrometer, we have detected three lines arising from the v2 ground-state inversion mode (0+→0-) at 55.3 cm-1. All transitions are observed in absorption against the optically thick infrared continuum emission of the dust. Two different absorption regions can be distinguished, the H3O+ associated with the Sgr B2 extended envelope and that of foreground gas along the line of sight. The derived abundances for both components are rather similar, ≲1 × 10-9, and may explain the high water abundance found in the low-density gas toward Sgr B2 as its dissociative recombination leads to the formation of important molecules OH and H2O. Contribution of the ℚ(1, 1) line of para-H3O+ to the 212-101line of H2 18O is also analyzed. This allows a better determination of water abundance from far-infrared observations. The corrected H2O abundances are ≤10-6 for the diffuse clouds along the line of sight and a few times 10-6 for the gas associated with the Sgr B2 envelope, in good agreement with water vapor observations from the Submillimeter Wave Astronomy Satellite., We thank the Spanish DGES and PNIE for funding support under grants PB96-0883 and ESP98-1351-E

We report on the detection of nine lines of the v2 bending mode of triatomic carbon, C3, in the direction of Sagittarius B2. The R(4) and R(2) lines of C3 have been also detected in the carbon-rich star IRC +10216. The abundances of C3 in the direction of Sgr B2 and IRC +10216 are ≃3 × 10-8 and ≃10-6, respectively. In Sgr B2 we have also detected the 23-12 line of NH with an abundance of a few times 10-9. Polyatomic molecules will have a weak contribution from their pure rotational spectrum to the emission/absorption in the far-infrared. We suggest, however, that they could be, through their low-lying vibrational bending modes, the dominant carriers of emission/absorption in the spectrum of bright far-infrared sources., J. C. and J. R. G. thank Spanish DGES and PNIE for funding support under grants PB96-0883 and ESP98-1351-E.

8 pags., 7 figs., 4 tabs., The rate constants for the formation, destruction, and collisional excitation of SH are calculated from quantum mechanical approaches using two new SH potential energy surfaces (PESs) of A″ and A″ electronic symmetry. The PESs were developed to describe all adiabatic states correlating to the SH(ς) + H(S) channel. The formation of SH through the S + H reaction is endothermic by ≈9860 K, and requires at least two vibrational quanta on the H molecule to yield significant reactivity. Quasi-classical calculations of the total formation rate constant for H(v? =? 2) are in very good agreement with the quantum results above 100 K. Further quasi-classical calculations are then performed for v? =? 3, 4, and 5 to cover all vibrationally excited H levels significantly populated in dense photodissociation regions (PDR). The new calculated formation and destruction rate constants are two to six times larger than the previous ones and have been introduced in the Meudon PDR code to simulate the physical and illuminating conditions in the Orion bar prototypical PDR. New astrochemical models based on the new molecular data produce four times larger SH column densities, in agreement with those inferred from recent ALMA observations of the Orion bar., The research leading to these results has received funding from MICIU under grants No. FIS2017-83473-C2 and AYA2017- 85111-P. FL acknowledges financial support from the Institut Universitaire de France. NB acknowledges the computing facilities by TUBITAK-TRUBA.

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física Teórica. Fecha de lectura: 15-09-2017, Esta tesis tiene embargado el acceso al texto completo hasta el 15-03-2019

22 pags., 8 figs., 1 tab., Massive stars disrupt their natal molecular cloud material through radiative and mechanical feedback processes. These processes have profound effects on the evolution of interstellar matter in our Galaxy and throughout the universe, from the era of vigorous star formation at redshifts of 1-3 to the present day. The dominant feedback processes can be probed by observations of the Photo-Dissociation Regions (PDRs) where the far-ultraviolet photons of massive stars create warm regions of gas and dust in the neutral atomic and molecular gas. PDR emission provides a unique tool to study in detail the physical and chemical processes that are relevant for most of the mass in inter-and circumstellar media including diffuse clouds, proto-planetary disks, and molecular cloud surfaces, globules, planetary nebulae, and star-forming regions. PDR emission dominates the infrared (IR) spectra of star-forming galaxies. Most of the Galactic and extragalactic observations obtained with the James Webb Space Telescope (JWST) will therefore arise in PDR emission. In this paper we present an Early Release Science program using the MIRI, NIRSpec, and NIRCam instruments dedicated to the observations of an emblematic and nearby PDR: the Orion Bar. These early JWST observations will provide template data sets designed to identify key PDR characteristics in JWST observations. These data will serve to benchmark PDR models and extend them into the JWST era. We also present the Science-Enabling products that we will provide to the community. These template data sets and Science-Enabling products will guide the preparation of future proposals on star-forming regions in our Galaxy and beyond and will facilitate data analysis and interpretation of forthcoming JWST observations., Support for JWST-ERS program ID 1288 was provided through grants from the STScI under NASA contract NAS5-03127 to STScI (K.G., D.V.D.P., M.R.), Univ. of Maryland (M.W., M.P.), Univ. of Michigan (E.B., F.A.), and Univ. of Toledo (T.S.-Y.L.). O.B. and E.H. are supported by the Programme National “Physique et Chimie du Milieu Interstellaire” (PCMI) of CNRS/INSU with INC/INP co-funded by CEA and CNES, and through APR grants 6315 and 6410 provided by CNES. E. P. and J.C. acknowledge support from the National Science and Engineering Council of Canada (NSERC) Discovery Grant program (RGPIN-2020-06434 and RGPIN-2021-04197 respectively). E.P. acknowledges support from a Western Strategic Support Accelerator Grant (ROLA ID 0000050636). J.R.G. and S.C. thank the Spanish MCINN for funding support under grant PID2019-106110GB-I00. Work by M.R. and Y.O. is carried out within the Collaborative Research Centre 956, subproject C1, funded by the Deutsche Forschungsgemeinschaft (DFG)—project ID 184018867. T.O. acknowledges support from JSPS Bilateral Program, grant No. 120219939. M.P. and M.W. acknowledge support from NASA Astrophysics Data Analysis Program award #80NSSC19K0573. C.B. is grateful for an appointment at NASA Ames Research Center through the San José State University Research Foundation (NNX17AJ88A) and acknowledges support from the Internal Scientist Funding Model (ISFM) Directed Work Package at NASA Ames titled: “Laboratory Astrophysics—The NASA Ames PAH IR Spectroscopic Database.”

39 pags., 78 figs., 2 tabs. 6 apps., Understanding the initial properties of star-forming material and how they affect the star formation process is key. From an observational point of view, the feedback from young high-mass stars on future star formation properties is still poorly constrained. In the framework of the IRAM 30m ORION-B large program, we obtained observations of the translucent and moderately dense gas, which we used to analyze the kinematics over a field of 5 deg^2 around the filamentary structures. We used the ROHSA algorithm to decompose and de-noise the C18O(1-0) and 13CO(1-0) signals by taking the spatial coherence of the emission into account. We produced gas column density and mean velocity maps to estimate the relative orientation of their spatial gradients. We identified three cloud velocity layers at different systemic velocities and extracted the filaments in each velocity layer. The filaments are preferentially located in regions of low centroid velocity gradients. By comparing the relative orientation between the column density and velocity gradients of each layer from the ORION-B observations and synthetic observations from 3D kinematic toy models, we distinguish two types of behavior in the dynamics around filaments: (i) radial flows perpendicular to the filament axis that can be either inflows (increasing the filament mass) or outflows and (ii) longitudinal flows along the filament axis. The former case is seen in the Orion B data, while the latter is not identified. We have also identified asymmetrical flow patterns, usually associated with filaments located at the edge of an HII region. This is the first observational study to highlight feedback from HII regions on filament formation and, thus, on star formation in the Orion B cloud. This simple statistical method can be used for any molecular cloud to obtain coherent information on the kinematics., This work was supported in part by the French Agence Nationale de la Recherche through the DAOISM grant ANR21-CE31-0010 and by the Programme National “Physique et Chimie du Milieu Interstellaire” (PCMI) of CNRS/INSU with INC/INP, co-funded by CEA and CNES. We thank “le centre Jules Jensen” from Observatoire de Paris for its hospitality during the workshops devoted to this project. This research has made use of data from the Herschel Gould Belt Survey (HGBS) project (http: //gouldbelt-herschel.cea.fr). The HGBS is a Herschel Key Programme jointly carried out by SPIRE Specialist Astronomy Group 3 (SAG 3), scientists of several institutes in the PACS Consortium (CEA Saclay, INAF-IFSI Rome and INAF-Arcetri, KU Leuven, MPIA Heidelberg), and scientists of the Herschel Science Center (HSC). J.R.G. and M.G.S.M. thank the Spanish MCIYU for funding support under grant PID2019-106110GB-I00. J.O. acknowledges funding from the Swedish Research Council, grant No. 2017-03864.