Giovanna Tinetti, Pierre Drossart, Paul Eccleston, Paul Hartogh, Astrid Heske, Jérémy Leconte, Giusi Micela, Marc Ollivier, Göran Pilbratt, Ludovic Puig, Diego Turrini, Bart Vandenbussche, Paulina Wolkenberg, Jean-Philippe Beaulieu, Lars A. Buchave, Martin Ferus, Matt Griffin, Manuel Guedel, Kay Justtanont, Pierre-Olivier Lagage, Pedro Machado, Giuseppe Malaguti, Michiel Min, Hans Ulrik Nørgaard-Nielsen, Mirek Rataj, Tom Ray, Ignasi Ribas, Mark Swain, Robert Szabo, Stephanie Werner, Joanna Barstow, Matt Burleigh, James Cho, Vincent Coudé du Foresto, Athena Coustenis, Leen Decin, Therese Encrenaz, Marina Galand, Michael Gillon, Ravit Helled, Juan Carlos Morales, Antonio García Muñoz, Andrea Moneti, Isabella Pagano, Enzo Pascale, Giuseppe Piccioni, David Pinfield, Subhajit Sarkar, Franck Selsis, Jonathan Tennyson, Amaury Triaud, Olivia Venot, Ingo Waldmann, David Waltham, Gillian Wright, Jerome Amiaux, Jean-Louis Auguères, Michel Berthé, Naidu Bezawada, Georgia Bishop, Neil Bowles, Deirdre Coffey, Josep Colomé, Martin Crook, Pierre-Elie Crouzet, Vania Da Peppo, Isabel Escudero Sanz, Mauro Focardi, Martin Frericks, Tom Hunt, Ralf Kohley, Kevin Middleton, Gianluca Morgante, Roland Ottensamer, Emanuele Pace, Chris Pearson, Richard Stamper, Kate Symonds, Miriam Rengel, Etienne Renotte, Peter Ade, Laura Affer, Christophe Alard, Nicole Allard, Francesca Altieri, Yves André, Claudio Arena, Ioannis Argyriou, Alan Aylward, Cristian Baccani, Gaspar Bakos, Marek Banaszkiewicz, Mike Barlow, Virginie Batista, Giancarlo Bellucci, Serena Benatti, Pernelle Bernardi, Bruno Bézard, Maria Blecka, Emeline Bolmont, Bertrand Bonfond, Rosaria Bonito, Aldo S. Bonomo, John Robert Brucato, Allan Sacha Brun, Ian Bryson, Waldemar Bujwan, Sarah Casewell, Bejamin Charnay, Cesare Cecchi Pestellini, Guo Chen, Angela Ciaravella, Riccardo Claudi, Rodolphe Clédassou, Mario Damasso, Mario Damiano, Camilla Danielski, Pieter Deroo, Anna Maria Di Giorgio, Carsten Dominik, Vanessa Doublier, Simon Doyle, René Doyon, Benjamin Drummond, Bastien Duong, Stephen Eales, Billy Edwards, Maria Farina, Ettore Flaccomio, Leigh Fletcher, François Forget, Steve Fossey, Markus Fränz, Yuka Fujii, Álvaro García-Piquer, Walter Gear, Hervé Geoffray, Jean Claude Gérard, Lluis Gesa, H. Gomez, Rafał Graczyk, Caitlin Griffith, Denis Grodent, Mario Giuseppe Guarcello, Jacques Gustin, Keiko Hamano, Peter Hargrave, Yann Hello, Kevin Heng, Enrique Herrero, Allan Hornstrup, Benoit Hubert, Shigeru Ida, Masahiro Ikoma, Nicolas Iro, Patrick Irwin, Christopher Jarchow, Jean Jaubert, Hugh Jones, Queyrel Julien, Shingo Kameda, Franz Kerschbaum, Pierre Kervella, Tommi Koskinen, Matthijs Krijger, Norbert Krupp, Marina Lafarga, Federico Landini, Emanuel Lellouch, Giuseppe Leto, A. Luntzer, Theresa Rank-Lüftinger, Antonio Maggio, Jesus Maldonado, Jean-Pierre Maillard, Urs Mall, Jean-Baptiste Marquette, Stephane Mathis, Pierre Maxted, Taro Matsuo, Alexander Medvedev, Yamila Miguel, Vincent Minier, Giuseppe Morello, Alessandro Mura, Norio Narita, Valerio Nascimbeni, N. Nguyen Tong, Vladimiro Noce, Fabrizio Oliva, Enric Palle, Paul Palmer, Maurizio Pancrazzi, Andreas Papageorgiou, Vivien Parmentier, Manuel Perger, Antonino Petralia, Stefano Pezzuto, Ray Pierrehumbert, Ignazio Pillitteri, Giampaolo Piotto, Giampaolo Pisano, Loredana Prisinzano, Aikaterini Radioti, Jean-Michel Réess, Ladislav Rezac, Marco Rocchetto, Albert Rosich, Nicoletta Sanna, Alexandre Santerne, Giorgio Savini, Gaetano Scandariato, Bruno Sicardy, Carles Sierra, Giuseppe Sindoni, Konrad Skup, Ignas Snellen, Mateusz Sobiecki, Lauriane Soret, Alessandro Sozzetti, A. Stiepen, Antoine Strugarek, Jake Taylor, William Taylor, Luca Terenzi, Marcell Tessenyi, Angelos Tsiaras, C. Tucker, Diana Valencia, Gautam Vasisht, Allona Vazan, Francesc Vilardell, Sabrine Vinatier, Serena Viti, Rens Waters, Piotr Wawer, Anna Wawrzaszek, Anthony Whitworth, Yuk L. Yung, Sergey N. Yurchenko, María Rosa Zapatero Osorio, Robert Zellem, Tiziano Zingales & Frans Zwart. A chemical survey of exoplanets with ARIEL. Experimental Astronomy 46, 1, 135-209, DOI: 10.1007/s10686-018-9598-x
Thousands of exoplanets have now been discovered with a huge range of masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface of their host star. However, the essential nature of these exoplanets remains largely mysterious: there is no known, discernible pattern linking the presence, size, or orbital parameters of a planet to the nature of its parent star. We have little idea whether the chemistry of a planet is linked to its formation environment, or whether the type of host star drives the physics and chemistry of the planet’s birth, and evolution. ARIEL was conceived to observe a large number (1000) of transiting planets for statistical understanding, including gas giants, Neptunes, super-Earths and Earth-size planets around a range of host star types using transit spectroscopy in the 1.25-7.8m spectral range and multiple narrow-band photometry in the optical. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres which should show minimal condensation and sequestration of high-Z materials compared to their colder Solar System siblings. Said warm and hot atmospheres are expected to be more representative of the planetary bulk composition. Observations of these warm/hot exoplanets, and in particular of their elemental composition (especially C, O, N, S, Si), will allow the understanding of the early stages of planetary and atmospheric formation during the nebular phase and the following few million years. ARIEL will thus provide a representative picture of the chemical nature of the exoplanets and relate this directly to the type and chemical environment of the host star. ARIEL is designed as a dedicated survey mission for combined-light spectroscopy, capable of observing a large and well-defined planet sample within its 4-year mission lifetime. Transit, eclipse and phase-curve spectroscopy methods, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allow us to measure atmospheric signals from the planet at levels of 10-100 part per million (ppm) relative to the star and, given the bright nature of targets, also allows more sophisticated techniques, such as eclipse mapping, to give a deeper insight into the nature of the atmosphere. These types of observations require a stable payload and satellite platform with broad, instantaneous wavelength coverage to detect many molecular species, probe the thermal structure, identify clouds and monitor the stellar activity. The wavelength range proposed covers all the expected major atmospheric gases from e.g. H2O, CO2, CH4 NH3, HCN, H2S through to the more exotic metallic compounds, such as TiO, VO, and condensed species. Simulations of ARIEL performance in conducting exoplanet surveys have been performed – using conservative estimates of mission performance and a full model of all significant noise sources in the measurement – using a list of potential ARIEL targets that incorporates the latest available exoplanet statistics. The conclusion at the end of the Phase A study, is that ARIEL – in line with the stated mission objectives – will be able to observe about 1000 exoplanets depending on the details of the adopted survey strategy, thus confirming the feasibility of the main science objectives.
