Context. Our general understanding of multiple star and planet formation is primarily based on observations of young multiple systems in low density regions like Tau-Aur and Oph. Since many, if not most, of the stars are born in clusters, observational constraints from young binaries in those environments are fundamental for understanding both the formation of multiple systems and planets in multiple systems throughout the Galaxy. Aims. We build upon the largest survey for young binaries in the Orion Nebula Cluster (ONC), which is based on Hubble Space Telescope observations to derive both stellar and circumstellar properties of newborn binary systems in this cluster environment. Methods. We present adaptive optics spatially-resolved JHKL′-band photometry and K-band R ~ 5000 spectra for a sample of eight ONC binary systems from this database. We characterize the stellar properties of binary components and obtain a census of protoplanetary disks through K - L′ color excess. For a combined sample of ONC binaries including 7 additional systems with NIR spectroscopy from the literature, we derive mass ratio and relative age distributions. We compare the stellar and circumstellar properties of binaries in ONC with those in Tau-Aur and Oph from samples of binaries with stellar properties derived for each component from spectra and/or visual photometry and with a disk census obtained through K - L color excess. Results. The mass ratio distribution of ONC binaries is found to be indistinguishable from that of Tau-Aur and, to some extent, to that of Oph in the separation range 85-560 AU and for primary mass in the range 0.15 to 0.8 M ⊙. A trend toward a lower mass ratio with larger separation is suggested in ONC binaries, which is not seen in Tau-Aur binaries. The components of ONC binaries are found to be significantly more coeval than the overall ONC population and as coeval as components of binaries in Tau-Aur and Oph. There is a hint of a larger fraction of mixed pairs, i.e. systems with a disk around only one component, in wide ONC binaries in comparison to wide binaries in Tau-Aur and Oph within the same primary mass range that could be caused by hierarchical triples. The mass ratio distributions of mixed and unmixed pairs in the overall population of T Tauri binaries are shown to be different. Some of these trends require confirmation with observations of a larger sample of binary systems. © ESO, 2013.

Recent Atacama Large Millimeter/submillimeter Array observations present mounting evidence for the presence of exocometary gas released within Kuiper Belt analogs around nearby main-sequence stars. This represents a unique opportunity to study their ice reservoir at the younger ages when volatile delivery to planets is most likely to occur. We here present the detection of CO J = 2-1 emission colocated with dust emission from the cometary belt in the 440 Myr old Fomalhaut system. Through spectrospatial filtering, we achieve a 5.4σ detection and determine that the ring's sky-projected rotation axis matches that of the star. The CO mass derived ((0.65-42) × 10-7 M⊕) is the lowest of any circumstellar disk detected to date and must be of exocometary origin. Using a steady-state model, we estimate the CO+CO2 mass fraction of exocomets around Fomalhaut to be between 4.6% and 76%, consistent with solar system comets and the two other belts known to host exocometary gas. This is the first indication of a similarity in cometary compositions across planetary systems that may be linked to their formation scenario and is consistent with direct interstellar medium inheritance. In addition, we find tentative evidence that (49 ± 27)% of the detected flux originates from a region near the eccentric belt's pericenter. If confirmed, the latter may be explained through a recent impact event or CO pericenter glow due to exocometary release within a steady-state collisional cascade. In the latter scenario, we show how the azimuthal dependence of the CO release rate leads to asymmetries in gas observations of eccentric exocometary belts.

The next generation of 4π arrays for high-precision γ-ray spectroscopy AGATA will consist of γ-ray tracking detectors. They represent high-fold segmented Ge detectors and a front-end electronics, based on digital signal processing techniques, which allows to extract energy, timing and spatial information on the interactions of a γ-ray in the Ge detector by pulse shape analysis of its signals. Utilizing the information on the positions of the interaction points and the energies released at each point the tracks of the γ-rays in a Ge shell can be reconstructed in three dimensions on the basis of the Compton-scattering formula.

The Euroball-IV γ-detector array, equipped with the ancillary charged particle detector array DIAMANT was used to study the residues of the fusion reaction 64Ni ⇒ 128Ba at Ebeam = 255 and 261 MeV, in an attempt to reach the highest anguar momentum and verify the existence of predicted hyperdeformed rotational bands. No discrete hyperdeformed bands were identified, but nevertheless a breakthrough was obtained a systematic search for rotational ridge structure with very large moments of inertia J (2) ≥ 100 ℏ2 MeV(-1), in agreement with theoretical predictions for hyperdeformed shapes. Evidence for hyperdeformiation was obtained by charged particle + γ-ray gating, selectiong triple correlated ridge structures in the continuum of each of the nuclei, 118Te, 124Xe and 124,125Cs. In 7 additional nuclei, rotational ridges were also identified with J(2) = 71-77ℏ2Mev(-1), which most probably correspond to surperdeformed shape. The angular distributions of the emitted charged particles show an excess in forward direction over expectations from pure compound evaporation, which may indicate that in-complete fusion plays an important role in the population of very elongated shapes.

Directly detecting thermal emission from young extrasolar planets allows measurement of their atmospheric compositions and luminosities, which are influenced by their formation mechanisms. Using the Gemini Planet Imager, we discovered a planet orbiting the ~20-million-year-old star 51 Eridani at a projected separation of 13 astronomical units. Near-infrared observations show a spectrum with strong methane and water-vapor absorption. Modeling of the spectra and photometry yields a luminosity (normalized by the luminosity of the Sun) of 1.6 to 4.0 × 10(-6) and an effective temperature of 600 to 750 kelvin. For this age and luminosity, "hot-start" formation models indicate a mass twice that of Jupiter. This planet also has a sufficiently low luminosity to be consistent with the "cold-start" core-accretion process that may have formed Jupiter.