The nearby Supernova 1987A was accompanied by a burst of neutrino emission, which indicates that a compact object (a neutron star or black hole) was formed in the explosion. There has been no direct observation of this compact object. In this work, we observe the supernova remnant with JWST spectroscopy, finding narrow infrared emission lines of argon and sulfur.
View Article and Find Full Text PDFWASP-107b is a warm (approximately 740 K) transiting planet with a Neptune-like mass of roughly 30.5 M and Jupiter-like radius of about 0.94 R (refs.
View Article and Find Full Text PDFBrown dwarfs serve as ideal laboratories for studying the atmospheres of giant exoplanets on wide orbits, as the governing physical and chemical processes within them are nearly identical. Understanding the formation of gas-giant planets is challenging, often involving the endeavour to link atmospheric abundance ratios, such as the carbon-to-oxygen (C/O) ratio, to formation scenarios. However, the complexity of planet formation requires further tracers, as the unambiguous interpretation of the measured C/O ratio is fraught with complexity.
View Article and Find Full Text PDFThe formation of stars and planets is accompanied not only by the build-up of matter, namely accretion, but also by its expulsion in the form of highly supersonic jets that can stretch for several parsecs. As accretion and jet activity are correlated and because young stars acquire most of their mass rapidly early on, the most powerful jets are associated with the youngest protostars. This period, however, coincides with the time when the protostar and its surroundings are hidden behind many magnitudes of visual extinction.
View Article and Find Full Text PDFTerrestrial and sub-Neptune planets are expected to form in the inner (less than 10 AU) regions of protoplanetary disks. Water plays a key role in their formation, although it is yet unclear whether water molecules are formed in situ or transported from the outer disk. So far Spitzer Space Telescope observations have only provided water luminosity upper limits for dust-depleted inner disks, similar to PDS 70, the first system with direct confirmation of protoplanet presence.
View Article and Find Full Text PDFThe understanding of planet formation has changed recently, embracing the new idea of pebble accretion. This means that the influx of pebbles from the outer regions of planet-forming disks to their inner zones could determine the composition of planets and their atmospheres. The solid and molecular components delivered to the planet-forming region can be best characterized by mid-infrared spectroscopy.
View Article and Find Full Text PDFEarly results from the James Webb Space Telescope-Mid-InfraRed Instrument (JWST-MIRI) guaranteed time programs on protostars (JOYS) and disks (MINDS) are presented. Thanks to the increased sensitivity, spectral and spatial resolution of the MIRI spectrometer, the chemical inventory of the planet-forming zones in disks can be investigated with unprecedented detail across stellar mass range and age. Here, data are presented for five disks, four around low-mass stars and one around a very young high-mass star.
View Article and Find Full Text PDFWater is a fundamental molecule in the star and planet formation process, essential for catalysing the growth of solid material and the formation of planetesimals within disks. However, the water snowline and the HDO:HO ratio within proto-planetary disks have not been well characterized because water only sublimates at roughly 160 K (ref. ), meaning that most water is frozen out onto dust grains and that the water snowline radii are less than 10 AU (astronomical units).
View Article and Find Full Text PDFExoplanet science is one of the most thriving fields of modern astrophysics. A major goal is the atmospheric characterization of dozens of small, terrestrial exoplanets in order to search for signatures in their atmospheres that indicate biological activity, assess their ability to provide conditions for life as we know it, and investigate their expected atmospheric diversity. None of the currently adopted projects or missions, from ground or in space, can address these goals.
View Article and Find Full Text PDFThe design, implementation, and performance of a customized carbon atom beam source for the purpose of investigating solid-state reaction routes in interstellar ices in molecular clouds are discussed. The source is integrated into an existing ultrahigh vacuum setup, SURFace REaction SImulation DEvice (SURFRESIDE), which extends this double atom (H/D, O, and N) beamline apparatus with a third atom (C) beamline to a unique system that is fully suited to explore complex organic molecule solid-state formation under representative interstellar cloud conditions. The parameter space for this system is discussed, which includes the flux of the carbon atoms hitting the ice sample, their temperature, and the potential impact of temperature on ice reactions.
View Article and Find Full Text PDFThe physics of star formation and the deposition of mass, momentum and energy into the interstellar medium by massive stars ('feedback') are the main uncertainties in modern cosmological simulations of galaxy formation and evolution. These processes determine the properties of galaxies but are poorly understood on the scale of individual giant molecular clouds (less than 100 parsecs), which are resolved in modern galaxy formation simulations. The key question is why the timescale for depleting molecular gas through star formation in galaxies (about 2 billion years) exceeds the cloud dynamical timescale by two orders of magnitude.
View Article and Find Full Text PDFThe composition of the neutral gas comas of most comets is dominated by H2O, CO and CO2, typically comprising as much as 95 per cent of the total gas density. In addition, cometary comas have been found to contain a rich array of other molecules, including sulfuric compounds and complex hydrocarbons. Molecular oxygen (O2), however, despite its detection on other icy bodies such as the moons of Jupiter and Saturn, has remained undetected in cometary comas.
View Article and Find Full Text PDFPhotodesorption of CO ice is suggested to be the main process that maintains a measurable amount of gaseous CO in cold interstellar clouds. A classical molecular dynamics simulation is used to gain insight into the underlying mechanism. Site-site pair potentials were developed on the basis of ab initio calculations for the ground and excited nonrigid CO dimer.
View Article and Find Full Text PDFA brief introduction and overview of the astrochemistry of dust, ice and gas and their interplay is presented. The importance of basic chemical physics studies of critical reactions is illustrated through a number of recent examples. Such studies have also triggered new insight into chemistry, illustrating how astronomy and chemistry can enhance each other.
View Article and Find Full Text PDFThe dynamics of the reaction H + OH → O ((3)P) + H2 have been studied in a series of quasi-classical trajectory (QCT) calculations and transition state theory (TST) methods using high quality (3)A' and (3)A″ potential energy surfaces (PESs). Accurate OH (υ, j) state resolved cross sections and rate constants on both potential energy surfaces are presented and fitted for OH at (υ = 0, j = 0-16) and (υ = 1, j = 0-6). The cross sections were calculated for different collisional energies (Ec), ranging from the threshold energy at each specific rovibrational state up to 1.
View Article and Find Full Text PDFPlanets form in the disks around young stars. Their formation efficiency and composition are intimately linked to the protoplanetary disk locations of "snow lines" of abundant volatiles. We present chemical imaging of the carbon monoxide (CO) snow line in the disk around TW Hya, an analog of the solar nebula, using high spatial and spectral resolution Atacama Large Millimeter/Submillimeter Array observations of diazenylium (N2H(+)), a reactive ion present in large abundance only where CO is frozen out.
View Article and Find Full Text PDFThe cosmic abundance of hydrides depends critically on high-energy UV, X-ray, and particle irradiation. Here we study hydrides in star-forming regions where irradiation by the young stellar object can be substantial, and density and temperature can be much enhanced over interstellar values. Lines of OH, CH, NH, and SH and their ions OH(+), CH(+), NH(+), SH(+), H2O(+), and H3O(+) were observed in star-forming regions by the HIFI spectrometer onboard the Herschel Space Observatory.
View Article and Find Full Text PDF