Exoplanet surveys around M dwarfs have detected a growing number of exoplanets with Earth-like insolation. It is expected that some of those planets are rocky planets with the potential for temperate climates favourable to surface liquid water. However, various models predict that terrestrial planets orbiting in the classical habitable zone around M dwarfs have no water or too much water, suggesting that habitable planets around M dwarfs might be rare. Here we present the results of an updated planetary population synthesis model, which includes the effects of water enrichment in the primordial atmosphere, caused by the oxidation of atmospheric hydrogen by rocky materials from incoming planetesimals and from the magma ocean. We find that this water production in the primordial atmosphere is found to significantly impact the occurrence of terrestrial rocky aqua planets, yielding ones with diverse water content. We estimate that 5–10% of the planets with a size of <1.3R⊕ orbiting early-to-mid M dwarfs have appropriate amounts of seawater for habitability. Such an occurrence rate would be high enough to detect potentially habitable planets by ongoing and near-future M-dwarf planet survey missions.
This is a preview of subscription content, access via your institution
Subscribe to Nature+
Get immediate online access to Nature and 55 other Nature journal
Subscribe to Journal
Get full journal access for 1 year
only $9.92 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
All data from the simulation are available via GitHub at https://github.com/TadahiroKimura/Kimura-Ikoma2022. Source data are provided with this paper.
The numerical code used in the current study is available from the corresponding authors on reasonable request.
Walker, J. C. G., Hays, P. B. & Kasting, J. F. A negative feedback mechanism for the long-term stabilization of the Earth’s surface temperature. J. Geophys. Res 86, 9776–9782 (1981).
Abbot, D. S., Cowan, N. B. & Ciesla, F. J. Indication of insensitivity of planetary weathering behavior and habitable zone to surface land fraction. Astrophys. J 756, 178 (2012).
Alibert, Y. On the radius of habitable planets. Astron. Astrophys 561, A41 (2014).
Nakayama, A., Kodama, T., Ikoma, M. & Abe, Y. Runaway climate cooling of ocean planets in the habitable zone: a consequence of seafloor weathering enhanced by melting of high-pressure ice. Mon. Notices Royal Astron. Soc 488, 1580–1596 (2019).
Genda, H. Origin of Earth’s oceans: an assessment of the total amount, history and supply of water. Geochem. J 50, 27–42 (2016).
Tian, F. & Ida, S. Water contents of Earth-mass planets around M dwarfs. Nat. Geosci. 8, 177–180 (2015).
Miguel, Y., Cridland, A., Ormel, C. W., Fortney J. J. & Ida, S. Diverse outcomes of planet formation and composition around low-mass stars and brown dwarfs. Mon. Notices Royal Astron. Soc. 491, 1998–2009 (2019).
Ikoma, M. & Genda, H. Constraints on the mass of a habitable planet with water of nebular origin. Astrophys 648, 696 (2006).
Kimura, T. & Ikoma, M. Formation of aqua planets with water of nebular origin: effects of water enrichment on the structure and mass of captured atmospheres of terrestrial planets. Mon. Notices Royal Astron. Soc 496, 3755–3766 (2020).
Ida, S., Lin, D. N. C. & Nagasawa, M. Toward a deterministic model of planetary formation. VII. Eccentricity distribution of gas giants. Astrophys. J. 775, 42 (2013).
Ida, S., Tanaka, H., Johansen, A., Kanagawa, K. D. & Tanigawa, T. Slowing down type II migration of gas giants to match observational data. Astrophys. J 864, 77 (2018).
Kopparapu, R. K. Habitable zones around main-sequence stars: dependence on planetary mass. Astrophys. J 787, L29 (2014).
Lodders, K., Palme, H. & Gail, H. P. Abundances of the elements in the solar system. Landolt Börnstein 4B, 712 (2009).
Booth, R. A., Clarke, C. J., Madhusudhan, N. & Ilee, J. D. Chemical enrichment of giant planets and discs due to pebble drift. Mon. Notices Royal Astron. Soc 469, 3994 (2017).
Lodders, K. Solar system abundances and condensation temperatures of the elements. Astrophys. J 591, 1220 (2003).
Brügger, N., Burn, R., Coleman, G. A. L., Alibert, Y. & Benz, W. Pebbles versus planetesimals. The outcomes of population synthesis models. Astron. Astrophys. 640, A21 (2020).
Gardner, J. P. The James Webb space telescope. Space Sci. Rev. 123, 485–606 (2006).
Tinetti, G. A chemical survey of exoplanets with ARIEL. Exp. Astron. 46, 135–209 (2018).
Abe, Y., Abe-Ouchi, A., Sleep, N. H. & Zahnle, K. J. Habitable zone limits for dry planets. Astrobiology 11, 443–460 (2011).
Kaltenegger, L., Sasselov, D. & Rugheimer, S. Water-planets in the habitable zone: atmospheric chemistry, observable features, and the case of Kepler-62e and -62f. Astrophys. J 775, L47 (2013).
Moore, K. & Cowan, N. B. Keeping M-earths habitable in the face of atmospheric loss by sequestering water in the mantle. Mon. Notices Royal Astron. Soc 496, 3786–3795 (2020).
Kodama, T., Genda, H., O’ishi, R., Abe-Ouchi, A. & Abe, Y. Inner edge of habitable zones for Earth-sized planets with various surface water distributions. J. Geophys. Res. Planets 124, 2306–2324 (2019).
Cowan, N. B. & Abbot, D. S. Water cycling between ocean and mantle: super-earths need not be waterworlds. Astrophys. J. 781, 27 (2014).
Joshi, M. M., Haberle, R. M. & Reynolds, R. T. Simulations of the atmospheres of synchronously rotating terrestrial planets orbiting M dwarfs: conditions for atmospheric collapse and the implications for habitability. Icarus 129, 450–465 (1997).
Wordsworth, R. D. Gliese 581d is the first discovered terrestrial-mass exoplanet in the habitable zone. Astrophys. J. Lett. 733, L48 (2011).
Kunimoto, M., Winn, J., Ricker, G. R. & Vanderspek, R. K. Predicting the exoplanet yield of the TESS Prime and extended missions through years 1–7. Astrophys. J. 163, 290 (2022).
Rauer, H. The PLATO 2.0 mission. Exp. Astron. 38, 249–330 (2014).
Baraffe, I., Chabrier, G., Allard, F. & Hauschildt, P. H. Evolutionary models for solar metallicity low-mass stars: mass-magnitude relationships and color-magnitude diagrams. Astron. Astrophys. 337, 403 (1998).
Emsenhuber, A. The New Generation Planetary Population Synthesis (NGPPS). I. Bern global model of planet formation and evolution, model tests, and emerging planetary systems. Astron. Astrophys. 656, A69 (2021).
Veras, D. & Armitage, P. J. Outward migration of extrasolar planets to large orbital radii. Mon. Notices Royal Astron. Soc. 347, 624 (2004).
Andrews, S. M., Wilner, D. J., Hughes, A. M., Qi, C. & Dullemond, C. P. Protoplanetary disk structures in Ophiuchus. II. Extension to fainter sources. Astrophys. J. 723, 1241 (2010).
Lynden-Bell, D. & Pringle, J. E. The evolution of viscous discs and the origin of the nebular variables. Mon. Notices Royal Astron. Soc. 168, 603–637 (1974).
Hartmann, L., Calvet, N., Gullbring, E. & D’Alessio, P. Accretion and the evolution of T Tauri disks. Astrophys. J. 495, 385 (1998).
Shakura, N. I. & Sunyaev, R. A. Black holes in binary systems. Observational appearance. Astron. Astrophys. 24, 337–355 (1973).
Matsuyama, I., Johnstone, D. & Hartmann, L. Viscous diffusion and photoevaporation of stellar disks. Astrophys. J. 582, 893 (2003).
Liffman, K. The gravitational radius of an irradiated disk. Publ. Astron. Soc. Aust. 20, 337–339 (2003).
Begelman, M. C., McKee, C. F. & Shields, G. A. Compton heated winds and coronae above accretion disks. I. Dynamics. Astrophys. J. 271, 70–88 (1983).
Adams, F. C., Hollenbach, D., Laughlin, G. & Gorti, U. Photoevaporation of circumstellar disks due to external far-ultraviolet radiation in stellar aggregates. Astrophys. J. 611, 360 (2004).
Font, A. S., McCarthy, I. G., Johnstone, D. & Ballantyne, D. R. Photoevaporation of circumstellar disks around young stars. Astrophys. J. 607, 890 (2004).
Hollenbach, D., Johnstone, D., Lizano, S. & Shu, F. Photoevaporation of disks around massive stars and application to ultracompact H ii regions. Astrophys. J. 428, 654–669 (1994).
Clarke, C. J., Gendrin, A. & Sotomayor, M. The dispersal of circumstellar discs: the role of the ultraviolet switch. Mon. Notices Royal Astron. Soc 328, 485–491 (2001).
Nakamoto, T. & Nakagawa, Y. Formation, early evolution, and gravitational stability of protoplanetary disks. Astrophys. J. 421, 640–650 (1994).
Hueso, R. & Guillot, T. Evolution of protoplanetary disks: constraints from DM Tauri and GM Aurigae. Astrophys. J. 442, 703–725 (2005).
Bell, K. R. & Lin, D. N. C. Using FU Orionis outbursts to constrain self-regulated protostellar disk models. Astrophys. J. 427, 987 (1994).
Suzuki, T. K., Ogihara, M., Morbidelli, A. R., Crida, A. & Guillot, T. Evolution of protoplanetary discs with magnetically driven disc winds. Astron. Astrophys. 596, A74 (2016).
Kusaka, T., Nakano, T. & Hayashi, C. Growth of solid particles in the primordial solar nebula. Prog. Theor. Phys. 44, 1580–1595 (1970).
Adams, F. C., Lada, C. J. & Shu, F. H. The disks of T Tauri stars with flat infrared spectra. Astrophys. J. 326, 865–883 (1988).
Ruden, S. P. & Pollack, J. B. The dynamical evolution of the protosolar nebula. Astrophys. J. 375, 740–760 (1991).
Chiang, E. I. & Goldreich, P. Spectral energy distributions of T Tauri stars with passive circumstellar disks. Astrophys. J. 490, 368 (1997).
Birnstiel, T., Klahr, H. & Ercolano, B. A simple model for the evolution of the dust population in protoplanetary disks. Astron. Astrophys. 539, A148 (2012).
Birnstiel, T. & Andrews, S. M. On the outer edges of protoplanetary dust disks. Astrophys. J. 780, 153 (2014).
Ansdell, M. ALMA survey of Lupus protoplanetary disks. II. Gas disk radii. Astrophys. J. 859, 21 (2018).
Kokubo, E. & Ida, S. Formation of protoplanet systems and diversity of planetary systems. Astrophys. J. 581, 666 (2002).
Inaba, S., Tanaka, H., Nakazawa, K., Wetherill, G. W. & Kokubo, E. High-accuracy statistical simulation of planetary accretion: II. Comparison with N-body simulation. Icarus 149, 235–250 (2001).
Greenzweig, Y. & Lissauer, J. J. Accretion rates of protoplanets. Icarus 87, 40–77 (1990).
Greenzweig, Y. & Lissauer, J. J. Accretion rates of protoplanets II. Gaussian distributions of planetesimal velocities. Icarus 100, 440–463 (1992).
Inaba, S. & Ikoma, M. Enhanced collisional growth of a protoplanet that has an atmosphere. Astron. Astrophys. 410, 711–723 (2003).
Ida, S. & Lin, D. N. C. Toward a deterministic model of planetary formation. I. A desert in the mass and semimajor axis distributions of extrasolar planets. Astrophys. J. 604, 388 (2004).
Ikoma, M., Nakazawa, K. & Emori, H. Formation of giant planets: dependences on core accretion rate and grain opacity. Astrophys. J. 537, 1013 (2000).
Ikoma, M. & Hori, Y. In situ accretion of hydrogen-rich atmospheres on short-period super-Earths: implications for the Kepler-11 planets. Astrophys. J. 753, 66 (2012).
Guillot, T., Chabrier, G., Gautier, D. & Morel, P. Effect of radiative transport on the evolution of Jupiter and Saturn. Astrophys. J. 450, 463 (1995).
Papaloizou, J. C. B. & Nelson, R. P. Models of accreting gas giant protoplanets in protostellar disks. Astron. Astrophys. 433, 247–265 (2005).
Mordasini, C., Alibert, Y., Klahr, H. & Henning, T. Characterization of exoplanets from their formation. I. Models of combined planet formation and evolution. Astron. Astrophys. 547, A111 (2012).
Fortier, A., Alibert, Y., Carron, F., Benz, W. & Dittkrist, K. M. Planet formation models: the interplay with the planetesimal disc. Astron. Astrophys. 549, A44 (2013).
Piso, A.-M. A. & Youdin, A. N. On the minimum core mass for giant planet formation at wide separations. Astrophys. J. 786, 21 (2014).
Venturini, J., Alibert, Y. & Benz, W. Planet formation with envelope enrichment: new insights on planetary diversity. Astron. Astrophys. 596, A90 (2016).
Lee, E. J., Chiang, E. & Ormel, C. W. Make super-Earths, not Jupiters: accreting nebular gas onto solid cores at 0.1 au and beyond. Astrophys. J. 797, 95 (2014).
Hubickyj, O., Bodenheimer, P. & Lissauer, J. J. Accretion of the gaseous envelope of Jupiter around a 5–10 Earth-mass core. Icarus 179, 415–431 (2005).
Tanigawa, T. & Ikoma, M. A systematic study of the final masses of gas giant planets. Astrophys. J. 667, 557 (2007).
Tajima, N. & Nakagawa, Y. Evolution and dynamical stability of the proto-giant-planet envelope. Icarus 126, 282–292 (1997).
Tanigawa, T. & Tanaka, H. Final masses of giant planets. II. Jupiter formation in a gas-depleted disk. Astrophys. J. 823, 48 (2016).
Tanaka, H., Murase, K. & Tanigawa, T. Final masses of giant planets. III. Effect of photoevaporation and a new planetary migration model. Astrophys. J. 891, 143 (2020).
Kanagawa, K. D., Tanaka, H., Muto, T., Tanigawa, T. & Takeuchi, T. Formation of a disc gap induced by a planet: effect of the deviation from Keplerian disc rotation. Mon. Notices Royal Astron. Soc 448, 994–1006 (2015).
Simon, J. B., Bai, X.-N., Stone, J. M., Armitage, P. J. & Beckwith, K. Turbulence in the outer regions of protoplanetary disks. I. Weak accretion with no vertical magnetic flux. Astrophys. J. 764, 66 (2013).
Armitage, P. J., Simon, J. B. & Martin, R. G. Two timescale dispersal of magnetized protoplanetary disks. Astrophys. J. 778, L14 (2013).
Hasegawa, Y., Okuzumi, S., Flock, M. & Turner, N. J. Magnetically induced disk winds and transport in the HL Tau disk. Astrophys. J. 845, 31 (2017).
Zeng, L. Growth model interpretation of planet size distribution. Proc. Natl Acad. Sci. USA 116, 9723–9728 (2019).
Fortney, J. J., Marley, M. S. & Barnes, J. W. Planetary radii across five orders of magnitude in mass and stellar insolation: application to transits. Astrophys. J. 659, 1661 (2007).
Kurosaki, K. & Ikoma, M. Acceleration of cooling of ice giants by condensation in early atmospheres. Astrophys. J. 153, 260 (2017).
Saumon, D., Chabrier, G. & van Horn, H. M. An equation of state for low-mass stars and giant planets. Astrophys. J. Suppl. Ser. 99, 713–741 (1995).
Lyon, S. P. & Johnson, J. D. Sesame: The Los Alamos National Laboratory Equation of State Database. Report No. LA-UR-92-3407 (Los Alamos National Laboratory, 1992).
Matsui, T. & Abe, Y. Impact-induced atmospheres and oceans on Earth and Venus. Nature 322, 526–528 (1986).
Lopez, E. D. & Fortney, J. J. Understanding the mass–radius relation for sub-Neptunes: radius as a proxy for composition. Astrophys. J 792, 1 (2014).
Kubyshkina, D. Grid of upper atmosphere models for 1–40M⊕ planets: application to CoRoT-7 b and HD 219134 b,c. Astron. Astrophys. 619, A151 (2018).
Kubyshkina, D. Overcoming the limitations of the energy-limited approximation for planet atmospheric escape. Astrophys. J. 866, L18 (2018).
Johnstone, C. P., Bartel, M. & Güdel, M. The active lives of stars: a complete description of the rotation and XUV evolution of F, G, K, and M dwarfs. Astron. Astrophys. 649, A96 (2021).
Jiménez, M. A. & Masset, F. S. Improved torque formula for low- and intermediate-mass planetary migration. Mon. Notices Royal Astron. Soc. 471, 4917–4929 (2017).
Casoli, J. & Masset, F. S. On the horseshoe drag of a low-mass planet. I. Migration in isothermal disks. Astrophys. J. 703, 845 (2009).
Masset, F. S. & Casoli, J. On the horseshoe drag of a low-mass planet. II. Migration in adiabatic disks. Astrophys. J. 703, 857 (2009).
Masset, F. S. & Casoli, J. Saturated torque formula for planetary migration in viscous disks with thermal diffusion: recipe for protoplanet population synthesis. Astrophys. J. 723, 1393 (2010).
Masset, F. S. Coorbital thermal torques on low-mass protoplanets. Mon. Notices Royal Astron. Soc. 472, 4204–4219 (2017).
Kanagawa, K. D., Tanaka, H. & Szuszkiewicz, E. Radial migration of gap-opening planets in protoplanetary disks. I. The case of a single planet. Astrophys. J. 861, 140 (2018).
Murray, C. D. and Dermott, S. F. Solar System Dynamics (Cambridge Univ. Press, 1999).
Ida, S. & Lin, D. N. C. Toward a deterministic model of planetary formation. VI. Dynamical interaction and coagulation of multiple rocky embryos and super-Earth systems around solar-type stars. Astrophys. J. 719, 810 (2010).
Goldreich, P. & Tremaine, S. The dynamics of planetary rings. Annu. Rev. Astron. Astrophys. 20, 249–283 (1982).
Hasegawa, M. & Nakazawa, K. Distant encounter between Keplerian particles. Astron. Astrophys. 227, 619–627 (1990).
Ogihara, M., Duncan, M. J. & Ida, S. Eccentricity trap: trapping of resonantly interacting planets near the disk inner edge. Astrophys. J. 721, 1184 (2010).
Tanaka, H. & Ward, W. R. Three-dimensional interaction between a planet and an isothermal gaseous disk. II. Eccentricity waves and bending waves. Astrophys. J. 602, 388 (2004).
Shiraishi, M. & Ida, S. Infall of planetesimals onto growing giant planets: onset of runaway gas accretion and metallicity of their gas envelopes. Astrophys. J. 684, 1416 (2008).
Artymowicz, P. Disk-satellite interaction via density waves and the eccentricity evolution of bodies embedded in disks. Astrophys. J. 419, 166 (1993).
Iwasaki, K., Emori, H., Nakazawa, K. & Tanaka, H. Orbital stability of a protoplanet system under a drag force proportional to the random velocity. Publ. Astron. Soc. Jpn. 54, 471–479 (2002).
Zhou, J.-L., Lin, D. N. C. & Sun, Y.-S. Post-oligarchic evolution of protoplanetary embryos and the stability of planetary systems. Astrophys. J. 666, 423 (2007).
Emsenhuber, A. The New Generation Planetary Population Synthesis (NGPPS). II. Planetary population of solar-like stars and overview of statistical results. Astron. Astrophys. 656, A70 (2021).
Tychoniec, Ł. The VLA Nascent Disk and Multiplicity Survey of Perseus Protostars (VANDAM). IV. Free–free emission from protostars: links to infrared properties, outflow tracers, and protostellar disk masses. Astrophys. J. 238, 19 (2018).
Andrews, S. M., Rosenfeld, K. A., Kraus, A. L. & Wilner, D. J. The mass dependence between protoplanetary disks and their stellar hosts. Astrophys. J. 771, 129 (2013).
Santos, N. C. Spectroscopic metallicities for planet-host stars: extending the samples. Astron. Astrophys. 437, 1127–1133 (2005).
Venuti, L. CSI 2264: investigating rotation and its connection with disk accretion in the young open cluster NGC 2264. Astron. Astrophys. 599, A23 (2017).
Burn, R. The New Generation Planetary Population Synthesis (NGPPS). IV. Planetary systems around low-mass stars. Astron. Astrophys. 656, A72 (2021).
Mamajek, E. E. Initial conditions of planet formation: lifetimes of primordial disks. AIP Conf. Proc. 1158, 3 (2009).
This work is supported by JSPS KAKENHI (nos. JP18H05439, JP21H01141 and JP22J11725). T.K. is a JSPS Research Fellow, and also supported by the International Graduate Program for Excellence in Earth-Space Science (IGPEES).
The authors declare no competing interests.
Peer review information
Nature Astronomy thanks Nicolas Cowan and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Kimura, T., Ikoma, M. Predicted diversity in water content of terrestrial exoplanets orbiting M dwarfs. Nat Astron 6, 1296–1307 (2022). https://doi.org/10.1038/s41550-022-01781-1
This article is cited by
Nature Astronomy (2022)