A giant impact as the likely origin of different twins in the Kepler-107 exoplanet system

Aldo S. Bonomo; Li Zeng; Mario Damasso; Zoë M. Leinhardt; Anders B. Justesen; Eric Lopez; Mikkel N. Lund; Luca Malavolta; Victor Silva Aguirre; Lars A. Buchhave; Enrico Corsaro; Thomas Denman; Mercedes Lopez-Morales; Sean M. Mills; Annelies Mortier; Ken Rice; Alessandro Sozzetti; Andrew Vanderburg; Laura Affer; Torben Arentoft; Mansour Benbakoura; François Bouchy; Jørgen Christensen-Dalsgaard; Andrew Collier Cameron; Rosario Cosentino; Courtney D. Dressing; Xavier Dumusque; Pedro Figueira; Aldo F.M. Fiorenzano; Rafael A. García; Rasmus Handberg; Avet Harutyunyan; John A. Johnson; Hans Kjeldsen; David W. Latham; Christophe Lovis; Mia S. Lundkvist; Savita Mathur; Michel Mayor; Giusi Micela; Emilio Molinari; Fatemeh Motalebi; Valerio Nascimbeni; Chantanelle Nava; Francesco Pepe; David F. Phillips; Giampaolo Piotto; Ennio Poretti; Dimitar Sasselov; Damien Ségransan; Stéphane Udry; Chris Watson

doi:10.1038/s41550-018-0684-9

A giant impact as the likely origin of different twins in the Kepler-107 exoplanet system

Aldo S. Bonomo^*, Li Zeng, Mario Damasso, Zoë M. Leinhardt, Anders B. Justesen, Eric Lopez, Mikkel N. Lund, Luca Malavolta, Victor Silva Aguirre, Lars A. Buchhave, Enrico Corsaro, Thomas Denman, Mercedes Lopez-Morales, Sean M. Mills, Annelies Mortier, Ken Rice, Alessandro Sozzetti, Andrew Vanderburg, Laura Affer, Torben ArentoftMansour Benbakoura, François Bouchy, Jørgen Christensen-Dalsgaard, Andrew Collier Cameron, Rosario Cosentino, Courtney D. Dressing, Xavier Dumusque, Pedro Figueira, Aldo F.M. Fiorenzano, Rafael A. García, Rasmus Handberg, Avet Harutyunyan, John A. Johnson, Hans Kjeldsen, David W. Latham, Christophe Lovis, Mia S. Lundkvist, Savita Mathur, Michel Mayor, Giusi Micela, Emilio Molinari, Fatemeh Motalebi, Valerio Nascimbeni, Chantanelle Nava, Francesco Pepe, David F. Phillips, Giampaolo Piotto, Ennio Poretti, Dimitar Sasselov, Damien Ségransan, Stéphane Udry, Chris Watson

^*Corresponding author for this work

Physics and Astronomy

Research output: Contribution to journal › Letter › peer-review

42 Citations (Scopus)

Abstract

Measures of exoplanet bulk densities indicate that small exoplanets with radius less than 3 Earth radii (R _⊕ ) range from low-density sub-Neptunes containing volatile elements ¹ to higher-density rocky planets with Earth-like ² or iron-rich ³ (Mercury-like) compositions. Such astonishing diversity in observed small exoplanet compositions may be the product of different initial conditions of the planet-formation process or different evolutionary paths that altered the planetary properties after formation ⁴ . Planet evolution may be especially affected by either photoevaporative mass loss induced by high stellar X-ray and extreme ultraviolet (XUV) flux ⁵ or giant impacts ⁶ . Although there is some evidence for the former ^7,8 , there are no unambiguous findings so far about the occurrence of giant impacts in an exoplanet system. Here, we characterize the two innermost planets of the compact and near-resonant system Kepler-107 (ref. ⁹ ). We show that they have nearly identical radii (about 1.5–1.6R _⊕ ), but the outer planet Kepler-107 c is more than twice as dense (about 12.6 g cm ^–3 ) as the innermost Kepler-107 b (about 5.3 g cm ⁻³ ). In consequence, Kepler-107 c must have a larger iron core fraction than Kepler-107 b. This imbalance cannot be explained by the stellar XUV irradiation, which would conversely make the more-irradiated and less-massive planet Kepler-107 b denser than Kepler-107 c. Instead, the dissimilar densities are consistent with a giant impact event on Kepler-107 c that would have stripped off part of its silicate mantle. This hypothesis is supported by theoretical predictions from collisional mantle stripping ¹⁰ , which match the mass and radius of Kepler-107 c.

Original language	English
Pages (from-to)	416-423
Number of pages	8
Journal	Nature Astronomy
Volume	3
Issue number	5
DOIs	https://doi.org/10.1038/s41550-018-0684-9
Publication status	Published - 1 May 2019

Bibliographical note

Funding Information:
The authors wish to thank R. D. Haywood, R. Silvotti and D. Charbonneau for useful discussions. The HARPS-N project was funded by the Prodex Program of the Swiss Space Office (SSO), the Harvard-University Origin of Life Initiative (HUOLI), the Scottish Universities Physics Alliance (SUPA), the University of Geneva, the Smithsonian Astrophysical Observatory (SAO), the Italian National Astrophysical Institute (INAF), University of St. Andrews, Queen’s University Belfast and University of Edinburgh. The present work is based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di AstroFisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. This paper exploited data collected by the Kepler mission; funding for the Kepler mission is provided by the NASA (National Aeronautics and Space Administration) Science Mission directorate. The research leading to these results received funding from the European Union Seventh Framework Programme (FP7/2007–2013) under grant agreement number 313014 (ETAEARTH). L.Z. acknowledges support from the Simons Foundation (SCOL (award no. 337090)). M.D. acknowledges financial support from Progetto Premiale 2015 FRONTIERA funding scheme of the Italian Ministry of Education, University, and Research. Funding for the Stellar Astrophysics Centre is provided by The Danish National Research Foundation (grant agreement no. DNRF106). V.S.A. acknowledges support from VILLUM FONDEN (research grant 10118). E.C. is funded by the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement no. 664931. T.D. is supported by a STFC PhD studentship. R.A.G. acknowledges support from CNES. This work has been carried out in the frame of the National Centre for Competence in Research PlanetS supported by the Swiss National Science Foundation (SNSF). C.L., F.B., F.P. and S.U. acknowledge the financial support of the SNSF. M.S.L. is supported by The Independent Research Fund Denmark’s Sapere Aude program (grant agreement no. DFF–5051–00130). S.M. acknowledges support from the Ramon y Cajal fellowship number RYC-2015–17697.

Publisher Copyright:
© 2019, The Author(s), under exclusive licence to Springer Nature Limited.

ASJC Scopus subject areas

Astronomy and Astrophysics

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10.1038/s41550-018-0684-9

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Bonomo, A. S., Zeng, L., Damasso, M., Leinhardt, Z. M., Justesen, A. B., Lopez, E., Lund, M. N., Malavolta, L., Silva Aguirre, V., Buchhave, L. A., Corsaro, E., Denman, T., Lopez-Morales, M., Mills, S. M., Mortier, A., Rice, K., Sozzetti, A., Vanderburg, A., Affer, L., ... Watson, C. (2019). A giant impact as the likely origin of different twins in the Kepler-107 exoplanet system. Nature Astronomy, 3(5), 416-423. https://doi.org/10.1038/s41550-018-0684-9

@article{2db141214a814525ab83e6be2f9cd8bf,

title = "A giant impact as the likely origin of different twins in the Kepler-107 exoplanet system",

abstract = " Measures of exoplanet bulk densities indicate that small exoplanets with radius less than 3 Earth radii (R ⊕ ) range from low-density sub-Neptunes containing volatile elements 1 to higher-density rocky planets with Earth-like 2 or iron-rich 3 (Mercury-like) compositions. Such astonishing diversity in observed small exoplanet compositions may be the product of different initial conditions of the planet-formation process or different evolutionary paths that altered the planetary properties after formation 4 . Planet evolution may be especially affected by either photoevaporative mass loss induced by high stellar X-ray and extreme ultraviolet (XUV) flux 5 or giant impacts 6 . Although there is some evidence for the former 7,8 , there are no unambiguous findings so far about the occurrence of giant impacts in an exoplanet system. Here, we characterize the two innermost planets of the compact and near-resonant system Kepler-107 (ref. 9 ). We show that they have nearly identical radii (about 1.5–1.6R ⊕ ), but the outer planet Kepler-107 c is more than twice as dense (about 12.6 g cm –3 ) as the innermost Kepler-107 b (about 5.3 g cm −3 ). In consequence, Kepler-107 c must have a larger iron core fraction than Kepler-107 b. This imbalance cannot be explained by the stellar XUV irradiation, which would conversely make the more-irradiated and less-massive planet Kepler-107 b denser than Kepler-107 c. Instead, the dissimilar densities are consistent with a giant impact event on Kepler-107 c that would have stripped off part of its silicate mantle. This hypothesis is supported by theoretical predictions from collisional mantle stripping 10 , which match the mass and radius of Kepler-107 c.",

author = "Bonomo, {Aldo S.} and Li Zeng and Mario Damasso and Leinhardt, {Zo{\"e} M.} and Justesen, {Anders B.} and Eric Lopez and Lund, {Mikkel N.} and Luca Malavolta and {Silva Aguirre}, Victor and Buchhave, {Lars A.} and Enrico Corsaro and Thomas Denman and Mercedes Lopez-Morales and Mills, {Sean M.} and Annelies Mortier and Ken Rice and Alessandro Sozzetti and Andrew Vanderburg and Laura Affer and Torben Arentoft and Mansour Benbakoura and Fran{\c c}ois Bouchy and J{\o}rgen Christensen-Dalsgaard and {Collier Cameron}, Andrew and Rosario Cosentino and Dressing, {Courtney D.} and Xavier Dumusque and Pedro Figueira and Fiorenzano, {Aldo F.M.} and Garc{\'i}a, {Rafael A.} and Rasmus Handberg and Avet Harutyunyan and Johnson, {John A.} and Hans Kjeldsen and Latham, {David W.} and Christophe Lovis and Lundkvist, {Mia S.} and Savita Mathur and Michel Mayor and Giusi Micela and Emilio Molinari and Fatemeh Motalebi and Valerio Nascimbeni and Chantanelle Nava and Francesco Pepe and Phillips, {David F.} and Giampaolo Piotto and Ennio Poretti and Dimitar Sasselov and Damien S{\'e}gransan and St{\'e}phane Udry and Chris Watson",

note = "Funding Information: The authors wish to thank R. D. Haywood, R. Silvotti and D. Charbonneau for useful discussions. The HARPS-N project was funded by the Prodex Program of the Swiss Space Office (SSO), the Harvard-University Origin of Life Initiative (HUOLI), the Scottish Universities Physics Alliance (SUPA), the University of Geneva, the Smithsonian Astrophysical Observatory (SAO), the Italian National Astrophysical Institute (INAF), University of St. Andrews, Queen{\textquoteright}s University Belfast and University of Edinburgh. The present work is based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundaci{\'o}n Galileo Galilei of the INAF (Istituto Nazionale di AstroFisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrof{\'i}sica de Canarias. This paper exploited data collected by the Kepler mission; funding for the Kepler mission is provided by the NASA (National Aeronautics and Space Administration) Science Mission directorate. The research leading to these results received funding from the European Union Seventh Framework Programme (FP7/2007–2013) under grant agreement number 313014 (ETAEARTH). L.Z. acknowledges support from the Simons Foundation (SCOL (award no. 337090)). M.D. acknowledges financial support from Progetto Premiale 2015 FRONTIERA funding scheme of the Italian Ministry of Education, University, and Research. Funding for the Stellar Astrophysics Centre is provided by The Danish National Research Foundation (grant agreement no. DNRF106). V.S.A. acknowledges support from VILLUM FONDEN (research grant 10118). E.C. is funded by the European Union{\textquoteright}s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement no. 664931. T.D. is supported by a STFC PhD studentship. R.A.G. acknowledges support from CNES. This work has been carried out in the frame of the National Centre for Competence in Research PlanetS supported by the Swiss National Science Foundation (SNSF). C.L., F.B., F.P. and S.U. acknowledge the financial support of the SNSF. M.S.L. is supported by The Independent Research Fund Denmark{\textquoteright}s Sapere Aude program (grant agreement no. DFF–5051–00130). S.M. acknowledges support from the Ramon y Cajal fellowship number RYC-2015–17697. Publisher Copyright: {\textcopyright} 2019, The Author(s), under exclusive licence to Springer Nature Limited.",

year = "2019",

month = may,

day = "1",

doi = "10.1038/s41550-018-0684-9",

language = "English",

volume = "3",

pages = "416--423",

journal = "Nature Astronomy",

issn = "2397-3366",

publisher = "Nature Publishing Group",

number = "5",

}

Bonomo, AS, Zeng, L, Damasso, M, Leinhardt, ZM, Justesen, AB, Lopez, E, Lund, MN, Malavolta, L, Silva Aguirre, V, Buchhave, LA, Corsaro, E, Denman, T, Lopez-Morales, M, Mills, SM, Mortier, A, Rice, K, Sozzetti, A, Vanderburg, A, Affer, L, Arentoft, T, Benbakoura, M, Bouchy, F, Christensen-Dalsgaard, J, Collier Cameron, A, Cosentino, R, Dressing, CD, Dumusque, X, Figueira, P, Fiorenzano, AFM, García, RA, Handberg, R, Harutyunyan, A, Johnson, JA, Kjeldsen, H, Latham, DW, Lovis, C, Lundkvist, MS, Mathur, S, Mayor, M, Micela, G, Molinari, E, Motalebi, F, Nascimbeni, V, Nava, C, Pepe, F, Phillips, DF, Piotto, G, Poretti, E, Sasselov, D, Ségransan, D, Udry, S & Watson, C 2019, 'A giant impact as the likely origin of different twins in the Kepler-107 exoplanet system', Nature Astronomy, vol. 3, no. 5, pp. 416-423. https://doi.org/10.1038/s41550-018-0684-9

TY - JOUR

T1 - A giant impact as the likely origin of different twins in the Kepler-107 exoplanet system

AU - Bonomo, Aldo S.

AU - Zeng, Li

AU - Damasso, Mario

AU - Leinhardt, Zoë M.

AU - Justesen, Anders B.

AU - Lopez, Eric

AU - Lund, Mikkel N.

AU - Malavolta, Luca

AU - Silva Aguirre, Victor

AU - Buchhave, Lars A.

AU - Corsaro, Enrico

AU - Denman, Thomas

AU - Lopez-Morales, Mercedes

AU - Mills, Sean M.

AU - Mortier, Annelies

AU - Rice, Ken

AU - Sozzetti, Alessandro

AU - Vanderburg, Andrew

AU - Affer, Laura

AU - Arentoft, Torben

AU - Benbakoura, Mansour

AU - Bouchy, François

AU - Christensen-Dalsgaard, Jørgen

AU - Collier Cameron, Andrew

AU - Cosentino, Rosario

AU - Dressing, Courtney D.

AU - Dumusque, Xavier

AU - Figueira, Pedro

AU - Fiorenzano, Aldo F.M.

AU - García, Rafael A.

AU - Handberg, Rasmus

AU - Harutyunyan, Avet

AU - Johnson, John A.

AU - Kjeldsen, Hans

AU - Latham, David W.

AU - Lovis, Christophe

AU - Lundkvist, Mia S.

AU - Mathur, Savita

AU - Mayor, Michel

AU - Micela, Giusi

AU - Molinari, Emilio

AU - Motalebi, Fatemeh

AU - Nascimbeni, Valerio

AU - Nava, Chantanelle

AU - Pepe, Francesco

AU - Phillips, David F.

AU - Piotto, Giampaolo

AU - Poretti, Ennio

AU - Sasselov, Dimitar

AU - Ségransan, Damien

AU - Udry, Stéphane

AU - Watson, Chris

N1 - Funding Information: The authors wish to thank R. D. Haywood, R. Silvotti and D. Charbonneau for useful discussions. The HARPS-N project was funded by the Prodex Program of the Swiss Space Office (SSO), the Harvard-University Origin of Life Initiative (HUOLI), the Scottish Universities Physics Alliance (SUPA), the University of Geneva, the Smithsonian Astrophysical Observatory (SAO), the Italian National Astrophysical Institute (INAF), University of St. Andrews, Queen’s University Belfast and University of Edinburgh. The present work is based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di AstroFisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. This paper exploited data collected by the Kepler mission; funding for the Kepler mission is provided by the NASA (National Aeronautics and Space Administration) Science Mission directorate. The research leading to these results received funding from the European Union Seventh Framework Programme (FP7/2007–2013) under grant agreement number 313014 (ETAEARTH). L.Z. acknowledges support from the Simons Foundation (SCOL (award no. 337090)). M.D. acknowledges financial support from Progetto Premiale 2015 FRONTIERA funding scheme of the Italian Ministry of Education, University, and Research. Funding for the Stellar Astrophysics Centre is provided by The Danish National Research Foundation (grant agreement no. DNRF106). V.S.A. acknowledges support from VILLUM FONDEN (research grant 10118). E.C. is funded by the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement no. 664931. T.D. is supported by a STFC PhD studentship. R.A.G. acknowledges support from CNES. This work has been carried out in the frame of the National Centre for Competence in Research PlanetS supported by the Swiss National Science Foundation (SNSF). C.L., F.B., F.P. and S.U. acknowledge the financial support of the SNSF. M.S.L. is supported by The Independent Research Fund Denmark’s Sapere Aude program (grant agreement no. DFF–5051–00130). S.M. acknowledges support from the Ramon y Cajal fellowship number RYC-2015–17697. Publisher Copyright: © 2019, The Author(s), under exclusive licence to Springer Nature Limited.

PY - 2019/5/1

Y1 - 2019/5/1

N2 - Measures of exoplanet bulk densities indicate that small exoplanets with radius less than 3 Earth radii (R ⊕ ) range from low-density sub-Neptunes containing volatile elements 1 to higher-density rocky planets with Earth-like 2 or iron-rich 3 (Mercury-like) compositions. Such astonishing diversity in observed small exoplanet compositions may be the product of different initial conditions of the planet-formation process or different evolutionary paths that altered the planetary properties after formation 4 . Planet evolution may be especially affected by either photoevaporative mass loss induced by high stellar X-ray and extreme ultraviolet (XUV) flux 5 or giant impacts 6 . Although there is some evidence for the former 7,8 , there are no unambiguous findings so far about the occurrence of giant impacts in an exoplanet system. Here, we characterize the two innermost planets of the compact and near-resonant system Kepler-107 (ref. 9 ). We show that they have nearly identical radii (about 1.5–1.6R ⊕ ), but the outer planet Kepler-107 c is more than twice as dense (about 12.6 g cm –3 ) as the innermost Kepler-107 b (about 5.3 g cm −3 ). In consequence, Kepler-107 c must have a larger iron core fraction than Kepler-107 b. This imbalance cannot be explained by the stellar XUV irradiation, which would conversely make the more-irradiated and less-massive planet Kepler-107 b denser than Kepler-107 c. Instead, the dissimilar densities are consistent with a giant impact event on Kepler-107 c that would have stripped off part of its silicate mantle. This hypothesis is supported by theoretical predictions from collisional mantle stripping 10 , which match the mass and radius of Kepler-107 c.

AB - Measures of exoplanet bulk densities indicate that small exoplanets with radius less than 3 Earth radii (R ⊕ ) range from low-density sub-Neptunes containing volatile elements 1 to higher-density rocky planets with Earth-like 2 or iron-rich 3 (Mercury-like) compositions. Such astonishing diversity in observed small exoplanet compositions may be the product of different initial conditions of the planet-formation process or different evolutionary paths that altered the planetary properties after formation 4 . Planet evolution may be especially affected by either photoevaporative mass loss induced by high stellar X-ray and extreme ultraviolet (XUV) flux 5 or giant impacts 6 . Although there is some evidence for the former 7,8 , there are no unambiguous findings so far about the occurrence of giant impacts in an exoplanet system. Here, we characterize the two innermost planets of the compact and near-resonant system Kepler-107 (ref. 9 ). We show that they have nearly identical radii (about 1.5–1.6R ⊕ ), but the outer planet Kepler-107 c is more than twice as dense (about 12.6 g cm –3 ) as the innermost Kepler-107 b (about 5.3 g cm −3 ). In consequence, Kepler-107 c must have a larger iron core fraction than Kepler-107 b. This imbalance cannot be explained by the stellar XUV irradiation, which would conversely make the more-irradiated and less-massive planet Kepler-107 b denser than Kepler-107 c. Instead, the dissimilar densities are consistent with a giant impact event on Kepler-107 c that would have stripped off part of its silicate mantle. This hypothesis is supported by theoretical predictions from collisional mantle stripping 10 , which match the mass and radius of Kepler-107 c.

UR - http://www.scopus.com/inward/record.url?scp=85065653360&partnerID=8YFLogxK

U2 - 10.1038/s41550-018-0684-9

DO - 10.1038/s41550-018-0684-9

M3 - Letter

AN - SCOPUS:85065653360

SN - 2397-3366

VL - 3

SP - 416

EP - 423

JO - Nature Astronomy

JF - Nature Astronomy

IS - 5

ER -

A giant impact as the likely origin of different twins in the Kepler-107 exoplanet system

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