[en] The very wide diversity of asteroid compositions in the main belt suggests significant material transport in the solar protoplanetary disk and hints at the presence of interstellar ices in hydrated bodies. However, only a few quantitative estimations of the contribution of interstellar ice in the inner solar system have been reported, leading to considerable uncertainty about the extent of radial inward mixing in the solar protoplanetary disk 4.56 Ga ago. We show that the pristine CM chondrite Paris contains primary Ca-carbonates whose O-isotopic compositions require an 8%–35% contribution from interstellar water. The presence of interstellar water in Paris is confirmed by its bulk D/H isotopic composition that shows significant D enrichment (D/H = (167 ± 0.2) × 10"−"6) relative to the mean D/H of CM chondrites ((145 ± 3) × 10"−"6) and the putative D/H of local CM water ((82 ± 1.5) × 10"−"6). These results imply that (i) efficient radial mixing of interstellar ices occurred from the outer zone of the solar protoplanetary disk inward and that (ii) chondrites accreted water ice grains from increasing heliocentric distances in the solar protoplanetary disk.

[en] A search for short-lived ¹⁰Be in 21 calcium-aluminum-rich inclusions (CAIs) from Isheyevo, a rare CB/CH chondrite, showed that only 5 CAIs had ¹⁰B/¹¹B ratios higher than chondritic correlating with the elemental ratio ⁹Be/¹¹B, suggestive of in situ decay of this key short-lived radionuclide. The initial (¹⁰Be/⁹Be)₀ ratios vary between ∼10^–3 and ∼10^–2 for CAI 411. The initial ratio of CAI 411 is one order of magnitude higher than the highest ratio found in CV3 CAIs, suggesting that the more likely origin of CAI 411 ¹⁰Be is early solar system irradiation. The low (²⁶Al/²⁷Al)₀ [≤ 8.9 × 10^–7] with which CAI 411 formed indicates that it was exposed to gradual flares with a proton fluence of a few 10¹⁹ protons cm^–2, during the earliest phases of the solar system, possibly the infrared class 0. The irradiation conditions for other CAIs are less well constrained, with calculated fluences ranging between a few 10¹⁹ and 10²⁰ protons cm^–2. The variable and extreme value of the initial ¹⁰Be/⁹Be ratios in carbonaceous chondrite CAIs is the reflection of the variable and extreme magnetic activity in young stars observed in the X-ray domain.

[en] The radioactive isotope ⁶⁰Fe (T _1/2 = 1.5 Myr) was present in the early solar system. It is unlikely that it was injected directly into the nascent solar system by a single, nearby supernova (SN). It is proposed instead that it was inherited during the molecular cloud (MC) stage from several SNe belonging to previous episodes of star formation. The expected abundance of ⁶⁰Fe in star-forming regions is estimated taking into account the stochasticity of the star-forming process, and it is showed that many MCs are expected to contain ⁶⁰Fe (and possibly ²⁶Al [T _1/2 = 0.74 Myr]) at a level compatible with that of the nascent solar system. Therefore, no special explanation is needed to account for our solar system's formation.

[en] Calcium-aluminum-rich inclusions (CAIs) from the metal-rich (CH/CB-like) carbonaceous chondrite Isheyevo are mineralogically pristine and show no evidence for postcrystallization alteration. Many of them are composed of very refractory minerals, such as hibonite (CaAl₁₂O₁₉), grossite (CaAl₄O₇), aluminum-rich pyroxene, and perovskite (CaTiO₃). Twenty-eight out of 35 studied CAIs from Isheyevo have oxygen isotopic compositions similar to those of CAIs from the CM and CR carbonaceous chondrites (Δ¹⁷O ∼ -20 per mille ). Five igneous CAIs are ¹⁶O-depleted to a level observed in Isheyevo chondrules (Δ¹⁷O ∼> -10 per mille ), suggesting remelting and isotope exchange in an ¹⁶O-poor gaseous reservoir. Two CAIs, WA9 and B1, show the highest enrichment in ¹⁶O (δ¹⁷O ∼ -68 per mille , δ¹⁸O ∼ -66 per mille , Δ¹⁷O ∼ -34 per mille ) ever observed among refractory inclusions. In the context of the self-shielding model for the evolution of oxygen isotopes in the solar accretion disk, these CAIs may have recorded the initial oxygen isotopic composition of the solar system, and hence of the Sun.

[en] The zodiacal cloud is a thick circumsolar disk of small debris particles produced by asteroid collisions and comets. Their relative contribution and how particles of different sizes dynamically evolve to produce the observed phenomena of light scattering, thermal emission, and meteoroid impacts are unknown. Until now, zodiacal cloud models have been phenomenological in nature, composed of ad hoc components with properties not understood from basic physical processes. Here, we present a zodiacal cloud model based on the orbital properties and lifetimes of comets and asteroids, and on the dynamical evolution of dust after ejection. The model is quantitatively constrained by Infrared Astronomical Satellite (IRAS) observations of thermal emission, but also qualitatively consistent with other zodiacal cloud observations, with meteor observations, with spacecraft impact experiments, and with properties of recovered micrometeorites (MMs). We find that particles produced by Jupiter-family comets (JFCs) are scattered by Jupiter before they are able to orbitally decouple from the planet and drift down to 1 AU. Therefore, the inclination distribution of JFC particles is broader than that of their source comets and leads to good fits to the broad latitudinal distribution of fluxes observed by IRAS. We find that 85%-95% of the observed mid-infrared emission is produced by particles from JFCs and <10% by dust from long-period comets. The JFC particles that contribute to the observed cross section area of the zodiacal cloud are typically D ∼ 100 μm in diameter. Asteroidal dust is found to be present at <10%. We suggest that spontaneous disruptions of JFCs, rather than the usual cometary activity driven by sublimating volatiles, is the main mechanism that liberates cometary particles into the zodiacal cloud. The ejected mm to cm-sized particles, which may constitute the basic grain size in comets, are disrupted on ∼<10,000 yr to produce the 10-1000 μm grains that dominate the thermal emission and mass influx. Breakup products with D > 100 μm undergo a further collisional cascade with smaller fragments being progressively more affected by Poynting-Robertson (PR) drag. Upon reaching D < 100 μm, the particles typically drift down to <1 AU without suffering further disruptions. The resulting Earth-impact speed and direction of JFC particles is a strong function of particle size. While 300 μm to 1 mm sporadic meteoroids are still on eccentric JFC-like orbits and impact from antihelion/helion directions, which is consistent with the aperture radar observations, the 10-300 μm particles have their orbits circularized by PR drag, impact at low speeds, and are not detected by radar. Our results imply that JFC particles represent ∼85% of the total mass influx at Earth. Since their atmospheric entry speeds are typically low (∼14.5 km s^-1 mean for D = 100-200 μm with ∼12 km s^-1 being the most common case), many JFC grains should survive frictional heating and land on Earth's surface. This explains why most MMs collected in antarctic ice have primitive carbonaceous composition. The present mass of the inner zodiacal cloud at <5 AU is estimated to be 1-2 x 10¹⁹ g, mainly in D = 100-200 μm particles. The inner zodiacal cloud should have been >10⁴ times brighter during the Late Heavy Bombardment (LHB) epoch ∼3.8 Gyr ago, when the outer planets scattered numerous comets into the inner solar system. The bright debris disks with a large 24 μm excess observed around mature stars may be an indication of massive cometary populations existing in those systems. We estimate that at least ∼10²², ∼2 x 10²¹, and ∼2 x 10²⁰ g of primitive dark dust material could have been accreted during LHB by the Earth, Mars, and Moon, respectively.

[en] New infrared absorption measurements of oxygen isotope ratios in CO gas from individual young stellar objects confirm that the solar system is anomalously high in its [¹⁸O]/[¹⁷O] ratio compared with extrasolar oxygen in the Galaxy. We show that this difference in oxygen isotope ratios is best explained by ∼1% enrichment of the protosolar molecular cloud by ejecta from Type II supernovae from a cluster having of order a few hundred stars that predated the Sun by at least 10-20 Myr. The likely source of exogenous oxygen was the explosion of one or more B stars during a process of propagating star formation.

[en] This document publishes the oral contributions and the 66 posters presented during a colloquium on physics and chemistry of interstellar medium. The following themes have been addressed: New views on the interstellar medium with Herschel, Planck and Alma, Cycle of interstellar dusts, Physics and Dynamics of the interstellar medium, Molecular complexifying and the link towards pre-biotic chemistry. More precisely, the oral contributions addressed the following topics: Interstellar medium with Herschel and Planck; The anomalous microwave emission: a new window on the physics of small grains; Sub-millimetre spectroscopy of complex molecules and of radicals for ALMA and Herschel missions; Analysing observations of molecules in the ISM: theoretical and experimental studies of energy transfer; Unravelling the labyrinth of star formation with Herschel; Star formation regions with Herschel and Alma: astro-chemistry in the Netherlands; Physical structure of gas and dust in photo-dissociation regions observed with Herschel; Photo-desorption of analogues of interstellar ices; Formation of structures in the interstellar medium: theoretical and numerical aspects; Towards a 3D mapping of the galactic ISM by inversion of absorption individual measurements; Low velocity shocks as signatures of turbulent dissipation in diffuse irradiated gas; Early phases of solar system formation: 3D physical and chemical modelling of the collapse of pre-stellar dense core; Cosmic-ray propagation in molecular clouds; Protostellar shocks in the time of Herschel; A new PDR model of the physics and chemistry of the interstellar gas; Molecular spectroscopy in the ALMA era and laboratory Astrophysics in Spain; Which molecules to be searched for in the interstellar medium; Physics and chemistry of UV illuminated neutral gas: the Horsehead case; Nitrogen fractionation in dark clouds; Molecular spectral surveys from millimetre range to far infrared; Mechanisms and synthesis at the surface of cold grains; Ice deuteration: models and observations to interpret the protostar history; Molecular complexity induced by thermal reactions in analogues of interstellar ices; VUV spectroscopy and photochemistry of interstellar and putative pre-biotic molecules; Internal rotation in astrophysical and pre-biotic molecules; Detection and rate of branching of chemical reaction products in gas phase at very low temperatures: new experimental developments; Investigation of ion chemistry and polymerization processes on interstellar grain and meteorite stimulants; Formation of the Sun in a dense collected shell: evidence from meteorites; Dust: from the Milky Way to nearby galaxies; Dust emission in dense areas: separating effects of radiation properties from grain properties; Effect of cosmic rays on hydrocarbon dusts; Stability of isolated and aggregated polycyclic aromatic hydrocarbons probed by collision with slow ions; Recent advances in the simulation of the absorption and emission spectroscopy; Infrared emission of aromatic molecules measured with the FIREFLY spectrometer; From PAHs to carbon clusters in photo-dissociation regions; VO-theory and theoretical services for the interstellar medium