Identification of carbon dioxide in an exoplanet atmosphere

Carbon dioxide (CO2) is a key chemical species that is found in a wide range of planetary atmospheres. In the context of exoplanets, CO2 is an indicator of the metal enrichment (that is, elements heavier than helium, also called ‘metallicity’), and thus the formation processes of the primary atmospheres of hot gas giants. It is also one of the most promising species to detect in the secondary atmospheres of terrestrial exoplanets. Previous photometric measurements of transiting planets with the Spitzer Space Telescope have given hints of the presence of CO2, but have not yielded definitive detections owing to the lack of unambiguous spectroscopic identification. Here we present the detection of CO2 in the atmosphere of the gas giant exoplanet WASP-39b from transmission spectroscopy observations obtained with JWST as part of the Early Release Science programme. The data used in this study span 3.0–5.5 micrometres in wavelength and show a prominent CO2 absorption feature at 4.3 micrometres (26-sigma significance). The overall spectrum is well matched by one-dimensional, ten-times solar metallicity models that assume radiative–convective–thermochemical equilibrium and have moderate cloud opacity. These models predict that the atmosphere should have water, carbon monoxide and hydrogen sulfide in addition to CO2, but little methane. Furthermore, we also tentatively detect a small absorption feature near 4.0 micrometres that is not reproduced by these models

Closing gaps to our origins EUVO: the ultraviolet-visible window into the Universe

This article reproduces the contents of the White Paper entitled by the same name submitted to the call issued by the European Space Agency soliciting ideas from the scientific community for the science themes that should be covered during the Voyage 2050 planning cycle. This contribution focus in the investigation of the emergence of life and the role that astronomy has to play in it. Three fundamental areas of activity are identified: [1] measuring the chemical enrichment of the Universe, [2] investigating planet formation and searching for exoplanets with signatures of life and, [3] determining the abundance of amino acids and the chemical routes to amino acid and protein growth in astronomical bodies. This proposal deals with the first two. The building blocks of life in the Universe began as primordial gas processed in stars and mixed at galactic scales. The mechanisms responsible for this development are not well-understood and have changed over the intervening 13 billion years. To follow the evolution of matter over cosmic time, it is necessary to study the strongest (resonance) transitions of the most abundant species in the Universe. Most of them are in the ultraviolet (UV; 950 Å - 3000 Å) spectral range that is unobservable from the ground; the “missing” metals problem cannot be addressed without this access. Habitable planets grow in protostellar discs under ultraviolet irradiation, a by-product of the accretion process that drives the physical and chemical evolution of discs and young planetary systems. The electronic transitions of the most abundant molecules are pumped by this UV field that is the main oxidizing agent in the disc chemistry and provides unique diagnostics of the planet-forming environment that cannot be accessed from the ground. Knowledge of the variability of the UV radiation field is required for the astrochemical modelling of protoplanetary discs, to understand the formation of planetary atmospheres and the photochemistry of the precursors of life. Earth’s atmosphere is in constant interaction with the interplanetary medium and the solar UV radiation field. The exosphere of the Earth extends up to 35 planetary radii providing an amazing wealth of information on our planet’s winds and the atmospheric compounds. To access to it in other planetary systems, observation of the UV resonance transitions is required. The investigation for the emergence of life calls for the development of large astronomical facilities, including instrumentation in optical and UV wavelengths. In this contribution, the need to develop a large observatory in the optical and in the UV is revealed, in order to complete the scientific goals to investigate the origin of life, inaccessible through other frequencies in the electromagnetic spectrum

Finding the UV-Visible Path Forward: Proceedings of the Community Workshop to Plan the Future of UV/Visible Space Astrophysics

We present the science cases and technological discussions that came from the workshop entitled "Finding the UV-Visible Path Forward" held at NASA GSFC June 25-26, 2015. The material presented outlines the compelling science that can be enabled by a next generation space-based observatory dedicated for UV-visible science, the technologies that are available to include in that observatory design, and the range of possible alternative launch approaches that could also enable some of the science. The recommendations to the Cosmic Origins Program Analysis Group from the workshop attendees on possible future development directions are outlined