[en] TRAPPIST-1 planets are invaluable for the study of comparative planetary science outside our Solar System and possibly habitability. First, we derive from N-body simulations possible planetary evolution scenarios, and show that each of the planets are likely to be in synchronous rotation. We then use a 3-D Global Climate Model to explore the possible climates of cool planets of the TRAPPIST-1 system. In particular, we look at the conditions required for cool planets to prevent possible volatile species to be lost by permanent condensation, irreversible burying or photochemical destruction. We also explore the resilience of the same volatiles (when in condensed phase) to a runaway greenhouse process. We find that background atmospheres made of N2, CO or O2 are resistant to atmospheric collapse. However, it should be difficult for TRAPPIST-1 planets to accumulate significant greenhouse gases like CO2, CH4, or NH3. CO2 can easily condense on the nightside, forming glaciers that would flow toward the substellar region. A complete CO2 ice cover is possible on TRAPPIST-1g and h only, although CO2 ice deposits could be gravitationally unstable and get buried beneath the water ice shell in geologically short timescales. Given TRAPPIST-1 planets large EUV irradiation (at least 1000x Titan's flux), CH4 and NH3 should be photodissociated rapidly and thus be hard to accumulate in the atmosphere. Photochemical hazes could then sedimentate and form a surface layer of tholins. Regarding habitability, we confirm that few bars of CO2 would suffice to warm the surface of TRAPPIST-1f and g above the melting point of water. We also show that TRAPPIST-1e is a remarkable candidate for surface habitability. If the planet is today synchronous and abundant in water, then it should always sustain surface liquid water at least in the substellar region, whatever the atmosphere considered.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Turbet, Martin
Bolmont, Emeline
Leconte, Jeremy
Forget, Francois
Selsis, Franck
Tobie, Gabriel
Caldas, Anthony
Naar, Joseph
Gillon, Michaël ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa)
Language :
English
Title :
Modelling climate diversity, tidal dynamics and the fate of volatiles on TRAPPIST-1 planets
Ribas, I., Bolmont, E., Selsis, F., et al. 2016, A&A, 596, A111
Richard, C., Gordon, I. E., Rothman, L. S., et al. 2012, J. Quant. Spec. Radiat. Transf., 113, 1276
Roder, H. M. 1978, J. Phys. Chem. Ref. Data, 7, 949
Rossow, W. B. 1978, Icarus, 36, 1
Rothman, L. S., Gordon, I. E., Babikov, Y., et al. 2013, J. Quant. Spec. Radiat. Transf., 130, 4
Schmitt, B., De Bergh, C., & Festou, M. 1997, Solar system ices (Kluwer Academic)
Shields, A. L., Meadows, V. S., Bitz, C. M., et al. 2013, Astrobiology, 13, 715
Sloan, E. 1998, Clathrate hydrates of natural gases, 2nd edn. (CRC Press)
Sotin, C., Tobie, G., Wahr, J., & McKinnon, W. B. 2009, in Tides and Tidal Heating on Europa, eds. R. T. Pappalardo, W. B. McKinnon, & K. K. Khurana, 85
Soto, A., Mischna, M., Schneider, T., Lee, C., & Richardson, M. 2015, Icarus, 250, 553
Span, R., & Wagner, W. 1996, J. Phys. Chem. Ref. Data, 25, 1509
Stern, S. A., Bagenal, F., Ennico, K., et al. 2015, Science, 350, aad1815
Stevenson, D. J. 1999, Nature, 400, 32
Tian, F., Kasting, J. F., & Zahnle, K. 2011, Earth Planet. Sci. Lett., 308, 417
Tobie, G., Lunine, J. I., & Sotin, C. 2006, Nature, 440, 61
Toon, O. B., McKay, C. P., Ackerman, T. P., & Santhanam, K. 1989, J. Geophys. Res., 94, 16287
Trowbridge, A. J., Melosh, H. J., Steckloff, J. K., & Freed, A. M. 2016, Nature, 534, 79
Turbet, M., & Tran, H. 2017, J. Geophys. Res.: Planets, 122, 2362
Turbet, M., Leconte, J., Selsis, F., et al. 2016, A&A, 596, A112
Turbet, M., Forget, F., Head, J. W., & Wordsworth, R. 2017a, Icarus, 288, 10
Turbet, M., Forget, F., Leconte, J., Charnay, B., & Tobie, G. 2017b, Earth Planet. Sci. Lett., 476, 11
Turcotte, D. L., & Schubert, G. 2001, Geodynamics, 2nd edn. (Cambridge Univ. Press)
Umurhan, O. M., Howard, A. D., Moore, J. M., et al. 2017, Icarus, 287, 301
Vinatier, S., Rannou, P., Anderson, C. M., et al. 2012, Icarus, 219, 5
von Paris, P., Grenfell, J. L., Hedelt, P., et al. 2013a, A&A, 549, A94
von Paris, P., Selsis, F., Kitzmann, D., & Rauer, H. 2013b, Astrobiology, 13, 899
Walker, J. C. G. 1985, Origins Life Evol. Biosphere, 16, 117
Wang, S., Wu, D.-H., Barclay, T., & Laughlin, G. P. 2017, ApJ, submitted [arXiv:1704. 04290]
Warren, S. G. 1984, Ann. Glaciol., 5, 177
Warren, S. G., & Wiscombe, W. J. 1980, J. Atmos. Sci., 37, 2734
Wheatley, P. J., Louden, T., Bourrier, V., Ehrenreich, D., & Gillon, M. 2017, MNRAS, 465, L74
Wieczorek, M. A., Correia, A. C. M., Le Feuvre, M., Laskar, J., & Rambaux, N. 2012, Nat. Geosci., 5, 18
Williams, J. G., Turyshev, S. G., & Boggs, D. H. 2014, Planet. Sci., 3, 2
Wolf, E. T. 2017, ApJ, 839, L1
Wolf, E. T., & Toon, O. B. 2010, Science, 328, 1266
Wolf, E. T., & Toon, O. B. 2013, Astrobiology, 13, 656
Wordsworth, R., Forget, F., & Eymet, V. 2010a, Icarus, 210, 992
Wordsworth, R., Forget, F., & Eymet, V. 2010b, Icarus, 210, 992
Wordsworth, R. D., Forget, F., Selsis, F., et al. 2010c, A&A, 522, A22
Wordsworth, R. D., Forget, F., Selsis, F., et al. 2011, ApJ, 733, L48
Wordsworth, R., Forget, F., Millour, E., et al. 2013, Icarus, 222, 1
Wordsworth, R. D., Kerber, L., Pierrehumbert, R. T., Forget, F., & Head, J. W. 2015, J. Geophys. Res.: (Planets), 120, 1201
Yang, J., Cowan, N. B., & Abbot, D. S. 2013, ApJ, 771, L45
Yoder, C. F., Konopliv, A. S., Yuan, D. N., Standish, E. M., & Folkner, W. M. 2003, Science, 300, 299
Yung, Y. L., Allen, M., & Pinto, J. P. 1984, ApJS, 55, 465
Ziethe, R., & Spohn, T. 2007, J. Geophys. Res.: (Solid Earth), 112, B09403