Publication:
The EChO science case

Loading...
Thumbnail Image
Full text at PDC
Publication Date
2015-12
Authors
Advisors (or tutors)
Editors
Journal Title
Journal ISSN
Volume Title
Publisher
Springer
Citations
Google Scholar
Research Projects
Organizational Units
Journal Issue
Abstract
The discovery of almost two thousand exoplanets has revealed an unexpectedly diverse planet population. We see gas giants in few-day orbits, whole multi-planet systems within the orbit of Mercury, and new populations of planets with masses between that of the Earth and Neptune—all unknown in the Solar System. Observations to date have shown that our Solar System is certainly not representative of the general population of planets in our Milky Way. The key science questions that urgently need addressing are therefore: What are exoplanets made of? Why are planets as they are? How do planetary systems work and what causes the exceptional diversity observed as compared to the Solar System? The EChO (Exoplanet Characterisation Observatory) space mission was conceived to take up the challenge to explain this diversity in terms of formation, evolution, internal structure and planet and atmospheric composition. This requires in-depth spectroscopic knowledge of the atmospheres of a large and well-defined planet sample for which precise physical, chemical and dynamical information can be obtained. In order to fulfil this ambitious scientific program, EChO was designed as a dedicated survey mission for transit and eclipse spectroscopy capable of observing a large, diverse and well-defined planet sample within its 4-year mission lifetime. The transit and eclipse spectroscopy method, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allows us to measure atmospheric signals from the planet at levels of at least 10^-4 relative to the star. This can only be achieved in conjunction with a carefully designed stable payload and satellite platform. It is also necessary to provide broad instantaneous wavelength coverage to detect as many molecular species as possible, to probe the thermal structure of the planetary atmospheres and to correct for the contaminating effects of the stellar photosphere. This requires wavelength coverage of at least 0.55 to 11 μm with a goal of covering from 0.4 to 16 μm. Only modest spectral resolving power is needed, with R ~ 300 for wavelengths less than 5 μm and R ~ 30 for wavelengths greater than this. The transit spectroscopy technique means that no spatial resolution is required. A telescope collecting area of about 1 m2 is sufficiently large to achieve the necessary spectro-photometric precision: for the Phase A study a 1.13 m2 telescope, diffraction limited at 3 μm has been adopted. Placing the satellite at L2 provides a cold and stable thermal environment as well as a large field of regard to allow efficient time-critical observation of targets randomly distributed over the sky. EChO has been conceived to achieve a single goal: exoplanet spectroscopy. The spectral coverage and signal-to-noise to be achieved by EChO, thanks to its high stability and dedicated design, would be a game changer by allowing atmospheric composition to be measured with unparalleled exactness: at least a factor 10 more precise and a factor 10 to 1000 more accurate than current observations. This would enable the detection of molecular abundances three orders of magnitude lower than currently possible and a fourfold increase from the handful of molecules detected to date. Combining these data with estimates of planetary bulk compositions from accurate measurements of their radii and masses would allow degeneracies associated with planetary interior modelling to be broken, giving unique insight into the interior structure and elemental abundances of these alien worlds. EChO would allow scientists to study exoplanets both as a population and as individuals. The mission can target super-Earths, Neptune-like, and Jupiter-like planets, in the very hot to temperate zones (planet temperatures of 300–3000 K) of F to M-type host stars. The EChO core science would be delivered by a three-tier survey. The EChO Chemical Census: This is a broad survey of a few-hundred exoplanets, which allows us to explore the spectroscopic and chemical diversity of the exoplanet population as a whole. The EChO Origin: This is a deep survey of a subsample of tens of exoplanets for which significantly higher signal to noise and spectral resolution spectra can be obtained to explain the origin of the exoplanet diversity (such as formation mechanisms, chemical processes, atmospheric escape). The EChO Rosetta Stones: This is an ultra-high accuracy survey targeting a subsample of select exoplanets. These will be the bright “benchmark” cases for which a large number of measurements would be taken to explore temporal variations, and to obtain two and three dimensional spatial information on the atmospheric conditions through eclipse-mapping techniques. If EChO were launched today, the exoplanets currently observed are sufficient to provide a large and diverse sample. The Chemical Census survey would consist of > 160 exoplanets with a range of planetary sizes, temperatures, orbital parameters and stellar host properties. Additionally, over the next 10 years, several new ground- and space-based transit photometric surveys and missions will come on-line (e.g. NGTS, CHEOPS, TESS, PLATO), which will specifically focus on finding bright, nearby systems. The current rapid rate of discovery would allow the target list to be further optimised in the years prior to EChO’s launch and enable the atmospheric characterisation of hundreds of planets.
Description
Artículo firmado por 355 autores. We would like to thank all the National Space Agencies who supported the EChO phase-A study. We also thank Nick Cowan for useful comments.
Unesco subjects
Keywords
Citation
Adams E.R., Seager, S., ApJ 673, 1160 (2008) Agol, E., et al., ApJ 721 1861 (2010) Agúndez, M., Venot, O., Iro, N., et al., A&A 548, A73 (2012) Agúndez, M., et al., A&A 564, A73, 21 (2014) Apai, D., et al., ApJ 768 121 (2013) Baraffe, I., Chabrier, G., Barman, T.S., Allard, F., & Hauschildt, P.H., A&A 337, 403 (1998). Baraffe, I., Chabrier, G., & Barman, T., A&A 482, 315 (2008) Barman, T. S., ApJ 661, L191 (2007). Barstow, J.K., et al., MNRAS, 430, 1188 (2013). Barstow, J.K., et al., MNRAS 434, 2616 (2013a) Barstow, J.K., et al.: Exoplanet atmospheres with EChO: spectral retrievals using EChOSim. Exp. Astron., (2014), DOI: 10.1007/s10686-014-9397-y. Baruteau, C., Meru, F., Paardekooper, S.-J., MNRAS, 416, 1971 (2011). Basri, G., Walkowicz L.M., Batalha N., et al., AJ, 141, 20 (2011). Batalha, N., et al ApJS 204, 24 (2013) Bean, J. L., Miller-Ricci Kempton, E., Homeier, D., Nature 468, 669 (2010). Beaulieu, J.-P., Carey S., Ribas, I. et al ApJ 677, 1343 (2008). Beaulieu, J.-P., Kipping, D.M., Batista, V., et al. MNRAS 409, 963 (2010). Beaulieu J.-P., Tinetti, G., Kipping, D.M., et al. ApJ 731, 16 (2011). Berta, Z. et al. ApJ 747 35 (2012) Birkby, J.L., et al. MNRAS 436, L35 (2013). Bodenheimer, P., et al., ApJ, 548, 466, (2001). Borucki, W.J. et al., Astrophysics & Space Science, 241, 1, 111 (1996). Borucki, W.J., et al., Science, 325, 709 (2009). Borucki, W.J., et al., ApJ 736, 19 (2011). Brogi, M., et al., Nature 486, 502 (2012). Brown, T.M., ApJ, 553, 1006 (2001). Buenzli, E., et al., ApJ 782, 77 (2014). Burrows, A., Hubeny, I., Budaj, J., Hubbard, W.B., ApJ 661, 502 (2007). Cassan, A., et al (2012) Nature 481, 167 (2012). Charbonneau, D., Brown T.M., Noyes R.W., Gilliland R.L., ApJ 568, 377 (2002). Charbonneau, D., Allen L.E., Megeath S.T. et al, ApJ 626, 529 (2005). Charbonneau, D., et al. ApJ 686,1341 (2008) Chatterjee, S., Ford, E., Matsumura, S., Rasio, F.A., , ApJ 686, 580 (2008). Cho, J. Y-K., Menou K., Hansen B. M. S., Seager S., ApJ 587, L117 (2003). Cho, J. Y.-K., Menou, K., Hansen, B. M. S., Seager, S., ApJ 675, 817 (2008). Clampin M in: Pathways toward habitable planets: ASP 430, 167 (2010). Coleman, G., Nelson, R.P., MNRAS 445, 479 (2014). Coradini, A., Rurrini, D., Federico, C., Magni, G., Space Sci. Rev.,163, 25 (2011). Cowan, N. B.. et al., 2012, ApJ 747, 82, 17 Crossfield, I.J.M., Hansen, B.M.S., Harrington, J., et al ApJ 723, 1436 (2010). Crouzet, N., McCullough, P.R., Burke, C., Long, D., ApJ 761, 7 (2012). Crouzet, N., et al.: Water vapor in the spectrum of the extrasolar planet HD 189733b: 2. The eclipse, ApJ 795, 166 (2014). de Graauw, T., et al. A&A 321, L13 (2007). Danielski, C., et al. ApJ 785, 35 (2014). Danielski C., et al.: Gaussian Process for star and planet characterisation, submitted. De Kok, R.J., Stam, D.M. Icarus 221, 517 (2012). De Wit, J., Gillon, M., Demory, B.O., Seager, S., A&A 548, id.A128, 19 pp. (2012). Deming, D., Seager, D., Richardson L.J. et al. Nature 434, 740 (2005). Deming, D., et al. ApJ 774, 95, (2013). Demory, B. O., et al. 2013, ApJ 776, L25 (2013) De Wit, J., Gillion, M., Demory, B.O., Seager, S., A&A 548:128 (2012). Dressing, C. D., Charbonneau, D., ApJ 767, 20 (2013). Drossart, P., et al. Nature 340, 539 (1989). Dumusque, X., et al., ApJ 789, 154 (2014). Eccleston, P., et al. Exp. Astron., 11 (2014), DOI: 10.1007/s10686-014-9428-8. Elkins-Tanton, Astrophysics and Space Science, 332, 359 (2011). Encrenaz, T., et al. : Transit spectroscopy of exoplanets from space: how to optimize the wavelength coverage and spectral resolving power, Exp. Astron., (2014) DOI: 10.1007/s10686-014-9415-0. Encrenaz, T., Space Sci. Rev. 116, 99 (2004). Encrenaz et al., A&A 315 L397 (1996). Ehrenreich, D., et al, A&A in press, arXiv:1405.1056 (2014) Forget, F., Leconte, J., Phil. Trans. Royal Society 372, #20130084 (2014). Fraine, J., et al., Nature, 513, 526 (2014). Fressin, F., et al, ApJ 766, 81 (2013) Frith, J., MNRAS, 435, 2161 (2013). Fukui, A., et al., ApJ 770 95 (2013) García Piquer, A., et al.: Artificial intelligence for the EChO mission planning tool, Exp. Astron., (2014) DOI: 10.1007/s10686-014-9411-4. Glasse, A., et al., Mid-Infrared Instrument for James Webb Space Telescope IX: Predicted Sensitivity (2014). Goody, R.M., Yung, Y.L., Atmospheric radiation: theoretical basis. Oxford University Press, London (1989) Grasset, O., Schneider, J., & Sotin, C. ApJ 693, 722 (2009). Grillmair, C. J., Burrows, A., Charbonneau, D., et al., Nature 456, 767 (2008). Guillot, T., Ann. Rev. Earth Planet. Sci. 33, 493 (2005). Guillot, T., Santos, N.C., Pont, F., et al. 2006, A&A 453, L21 (2006). Guillot, T., Showman, A.P., A&A 385, 156 (2002). Guillot T., Stixrude L.: Characterizing planetary interiors with EChO, ECHO-TN-0001-OCA Hanel, R. et al., Journal of Geophysical Research 86. 8705 (1981) Hanel, R. A. et al., Icarus 53, 262 (1983) Harrington, J., Hansen, B. M., Luszcz, S. H., et al., Science 314, 623 (2006). Herrero, E. et al.: Correcting EChO data for stellar activity, by direct scaling of activity signals. Exp. Astron., (2014), DOI: 10.1007/s10686-014-9387-0. Hollis, M. D. J., et al., Computer Phys. Comms. 184, 2351 (2014). Howard, A., et al., ApJS 201, 15 (2012). Howard, A., Science 340, 572 (2013). Hyvarinen, A., IEEE Signal Processing Letters 6, 145 (1999) Ikoma M., Hori, Y., ApJ 753, 6 (2012) Jenkins, J. M. et al., ApJ 713, L87-L91 (2010). Knutson, H. A., Charbonneau, D., Allen, L.E. Nature 447, 183 (2007). Knutson, H. A. et al., ApJ 673, 526 (2008). Knutson, H. A. et al., ApJ 735, 23 (2011). Knutson, H. A. et al., Nature 505, 66 (2014). Kreidberg, L., et al. Nature 505, 69 (2014). Kreidberg, L., et al. ApJL 793, L27, (2014b). Koskinen, T. T.; Aylward, A.D.; Miller, S., Nature 450, 845 (2007). Lammer H.: Origin and Evolution of Planetary Atmospheres, Springer Briefs in Astronomy. ISBN 978-3- 642-32086-6. Springer (2013) Leconte, J., Forget, F., Lammer, H.: On the (anticipated) diversity of terrestrial planet atmospheres. Exp. Astron., (2014) DOI: 10.1007/s10686-014-9403-4. Lee, J.-M., Fletcher, L. N. and Irwin, P. MNRAS 420, 170 (2012). Léger, A., et al. Icarus 213, 1 (2011). Léger, A., Selsis, F., Sotin, C. et al. Icarus 169, 499 (2004). Lepine, S., et al., AJ 145, 102 (2013) Liang, M., Parkinson, C., Lee, A., Yung, Y., & Seager, S., ApJ 596, L247 (2003). Line, M.R., Yung, Y. ApJ 779, 6 (2013) Line, M. R., et al., ApJ 749,10 (2012) Line, M.R., Vasisht, G., Chen, P., et al., ApJ 738, 32 (2010) Linsky, J. L. et al., ApJ 717, 1291 (2010). Liou, K.N. International geophysics series, vol 84. Academic Press, San Diego. 583 pp. (2002). Lissauer, J.J., & Stevenson, D.J. 2007, in Protostars and Planets V, 591 Lovelock, J.E. Nature 207, 568 (1965). Madhusudhan, N., Seager, S., ApJ 707, 24 (2009). Madhusudhan, N., et al. Nature 469, 64 (2011). Maillard, J-P., Miller, S., 2011, in: Molecules in the Atmospheres of Extrasolar Planets. ASP Conference Series, Vol. 450. Edited by J.P. Beaulieu, S. Dieteres, and G. Tinetti. San Francisco: Astronomical Society of the Pacific, p.19 (2011). Majeau, C., Agol, E. and Cowan, N. B., ApJ 747, id L20 (2012). Mayor, M., Marmier, M., Lovis, C., et al., arXiv: 1109.2497 (2011) McCullough, P., et al., ApJ 791, 55 (2014). Micela, G., et al., The contribution of the major planet search surveys to EChO target selection, Exp. Astron. (2014) DOI:10.1007/s10686-014-9412-3. Micela, G.: Correcting for stellar activity, I. Exp. Astron.,(2014), DOI: 10.1007/s10686-014-9430-1. Morales, J.C., et al.: Brown dwarf characterization with EChO, Exp. Astron., (2015), DOI:10.1007/s10686-014-9434-x. Morales, J.C., et al.: Scheduling the EChO survey with known exoplanets, Exp. Astron., (2014), DOI: 10.1007/s10686-014-9409-y. Morello, G., et al., ApJ 786, 22 (2014). Morello, G., et al.: Revisiting Spitzer transit observations with Independent Component Analysis: new results for the GJ436 system, ApJ, in press (2015) arXiv:1501.05866. Moses, J., Visscher, C., Fortney, J., et al. ApJ 737, 15 (2011). Mousis, O., Lunine, J.L., Petit, J.M. et al., ApJ 727, 77 (2011). Oberg, K.I., Murray-Clay, R., Bergin, E.A., ApJ 743, 16 (2011). Parmentier, V., Showman, A., de Wit, J., Unveiling the atmospheres of giant exoplanets, Exp. Astron., (2014), DOI: 10.1007/s10686-014-9395-0. Pascale, E., et al.: EChOSim: The Exoplanet Characterisation Observatory software simulator. Exp. Astron., arXiv:1406.3984 (2014). Pearl, J. C. et al., Icarus 84,12 (1990). Pinfield D., M-dwarf catalogues, ECHO-TN-0001-UH Pearl, J. C., Conrath, B. J., JGR 96, Issue S01 (1991). Puig, L., et al.: The phase 0/A study of the ESA M3 mission candidate EChO, Exp. Astron., (2014), DOI: 10.1007/s10686-014-9419-9. Rauscher, E., Menou, K., Cho, J.Y.-K., Seager, S., & Hansen, B.M.S. ApJ 662, L115 (2007). Rauscher, E., Menou, K., Cho, J.Y.-K., Seager, S., & Hansen, B.M.S. ApJ 681, 1646 (2008). Redfield et al., ApJ 673 L87 (2008). Rein H., http://www.openexoplanetcatalogue.com (2015). Rothman, L.S., et al: The HITRAN 2012 molecular spectroscopic database. J. Quant. Spectrosc. Rad. Transf. 130, 4 (2013). Rouan, D., et al. ApJ 741, L30 (2011). Rowe, J., et al., ApJ 689,1345 (2008). Rye, R., Holland, H.D. Am J Sci 298, 621 (1998). Scandariato, G., et al.: EChO spectra and stellar activity II. The case of dM stars. Exp. Astron. (2014), DOI:10.1007/s10686-014-9390-5. Schneider, J., http://exoplanet.eu Seager, S., Sasselov, D.D., ApJ 537, 916 (2000). Seager, S., et al. ApJ 669, 1279 (2007). Selsis, F., Wordsworth, R.D., Forget, F. A&A 532, A1 (2011). Sharp, C. M., Burrows, A. ApJS, 168, 140 (2007). Showman, A. et al. ApJ 762, 24 (2013). Sing, D. K., et al. MNRAS 416, 1443 (2011). Snellen, I., et al., A&A 487, 357 (2008). Snellen, I., et al., Nature 459, 543 (2009). Snellen, I., et al., Nature 465, 1049 (2010). Snels, M., et al., Journal of Quantitative Spectroscopy and Radiative Transfer 133, 464 (2014). Sotin, C., Grasset, O., Mocquet, A. Icarus 191, 337 (2007). Sozzetti, A., et al. The Gaia Survey Contribution to EChO Target Selection & Characterization. Exp. Astron. (2014), DOI: 10.1007/s10686-014-9416-z. Stixrude, L., Karki, B., Science 310, 297 (2005). Stark, C.C. The transit light curve of an exozodiacal cloud. AJ 142, 123 (2011). Stefani, S. et al. Journal of Quantitative Spectroscopy and Radiative Transfer 117, 21 (2013). Stevenson, K. B., et al. Nature 464, 1161 (2010). Stevenson, K. B., et al. ApJ (2014). Swain, M. R. et al., Nature 463, 637 (2010). Swain, M. R. et al., ApJ 704, 1616 (2009). Swain, M. R., Vasisht, G., Tinetti, G., Nature 452, 329 (2008). Swain, M. R., et al. ApJ 690, L114 (2009). Tennyson, J., Yurchenko, S.N. MNRAS 425, 21 (2012). Tennyson, J., Yurchenko, S.N.: The Status of Spectroscopic Data for the EChO Mission. Exp. Astron., (2014), DOI: 10.1007/s10686-014-9385-2. Tessenyi, M., Ollivier, M., Tinetti, G., et al. ApJ 746, 45 (2012). Tessenyi, M., et al., Icarus 226, 1654 (2013). Tinetti, G., et al. Exp Astron. 34, 311 (2012). Tinetti, G., Encrenaz E., Coustenis A., Astron Astrophys Rev. 21, 63 (2013). Tinetti, G., M.C. Liang, et al. ApJ, 654, L99 (2007a). Tinetti, G., et al. Nature 448 169 (2007b). Tinetti, G., Deroo, P., Swain, M., et al. ApJ 712, L139 (2010). Todorov, K. O. et al., ApJ 796, 100 (2014). Tsiganis, K., Gomes, R., Morbidelli, A., Levison, H. F., Nature 435, 459 (2005). Turrini, D., Nelson, R., Barbieri, M.: The role of planetary formation and evolution in shaping the composition of exoplanetary atmospheres, Exp. Astron., (2014), DOI: 10.1007/s10686-014-9401-6 arXiv:1401.5119. Turrini, D., Coradini, A., Magni, ApJ 750, 8 (2012). Turrini, D., Magni, G., Coradini, A., MNRAS 413, 2439 (2011) Valencia, D., O’Connel, R. J., Sasselov, D., Icarus 181, 545 (2006). Valencia, D., Sasselov, D.D., O'Connell, R.J., ApJ 665, 1413 (2007). Valencia, D., Guillot T., Parmentier V., Freeman R., ApJ 775, 10 (2013). Varley, R. et al. Generation of a target list of observable exoplanets for EChO, Exp. Astron. (2015), DOI:10.1007/s10686-014-9436-8. Venot, O., Hébrard, E., Agundez, M., et al., A&A 546, A43 (2012). Venot, O., et al., A&A 562, A51, 11 (2013). Venot, O., Fray, N., Bénilan, Y., et al. A&A 551, A131 (2013a). Venot, O., et al.: Chemical modelling of exoplanet atmospheres, Exp. Astron., (2014) DOI: 10.1007/s10686-014-9406-1. Vidal-Madjiar, A. et al., Nature, 422, 143 (2003). Waldmann, I.P., ApJ 747, 12 (2012). Waldmann, I.P., Tinetti, G., Drossart, P., Swain, M.R., et al., ApJ 744, 35 (2012). Waldmann, I.P., et al., ApJ 766, 9 (2013). Waldmann, I.P., ApJ 780,10 (2014). Waldmann, I.P., Pascale, E.: Data analysis pipeline for EChO end-to-end simulations, Exp. Astron., DOI: 10.1007/s10686-014-9408-z, arXiv:1402.4408 (2014). Waldmann, I.P., et al.: Tau-REx I: A next generation retrieval code for exoplanetary atmospheres, ApJ in press, arXiv:1409.2312 (2014). Wang, F., Yan, P., Suzuki, K., Shen, D. (Eds.): Machine Learning in Medical Imaging. Springer Lecture Notes in Computer Science (2010). Weidenschilling, S. J., Marzari, F., Nature 384, 619 (1996). Wordsworth, R.D., Forget, F., Selsis, F., et al., A&A 522, A22 (2010). Yelle, R.V., Icarus 170, 167 (2004). Yung, Y. L., DeMore, W. B.: Photochemistry of planetary atmospheres, New York: Oxford University Press (1999). Yurchenko, S.N., Barber, R.J., Tennyson, J., MNRAS 413, 1828 (2011). Yurchenko, S.N., Tennyson, J., Bailey, J., Hollis, M.D.J., Tinetti, G., Proc. Nat. Acad. Sci. 111, 9379 (2014). Zahnle, K., Marley, M., Freedman, R., Lodders, K., Fortney, J. ApJ 701, L20 (2009). Zhu, Z. et al., ApJL 758, L42 (2012).
Collections