Please use this identifier to cite or link to this item:
http://hdl.handle.net/20.500.12386/28766
Title: | A giant impact as the likely origin of different twins in the Kepler-107 exoplanet system | Authors: | BONOMO, ALDO STEFANO Zeng, Li Damasso, Mario Leinhardt, Zoë M. Justesen, Anders B. Lopez, Eric Lund, Mikkel N. Malavolta, Luca Silva Aguirre, Victor Buchhave, Lars A. CORSARO, ENRICO MARIA NICOLA Denman, Thomas Lopez-Morales, Mercedes Mills, Sean M. Mortier, Annelies Rice, Ken SOZZETTI, Alessandro Vanderburg, Andrew AFFER, Laura Arentoft, Torben Benbakoura, Mansour Bouchy, François Christensen-Dalsgaard, Jørgen Collier Cameron, Andrew COSENTINO, Rosario Dressing, Courtney D. Dumusque, Xavier Figueira, Pedro Fiorenzano, Aldo F. M. García, Rafael A. Handberg, Rasmus HARUTYUNYAN, AVET Johnson, John A. Kjeldsen, Hans Latham, David W. Lovis, Christophe Lundkvist, Mia S. Mathur, Savita Mayor, Michel MICELA, Giuseppina MOLINARI, Emilio Carlo Motalebi, Fatemeh NASCIMBENI, VALERIO Nava, Chantanelle Pepe, Francesco Phillips, David F. Piotto, Giampaolo PORETTI, Ennio Sasselov, Dimitar Ségransan, Damien Udry, Stéphane Watson, Chris |
Issue Date: | 2019 | Journal: | NATURE ASTRONOMY | Number: | 3 | First Page: | 416 | Abstract: | Measures of exoplanet bulk densities indicate that small exoplanets with radius less than 3 Earth radii (R<SUB>⊕</SUB>) range from low-density sub-Neptunes containing volatile elements<SUP>1</SUP> to higher-density rocky planets with Earth-like<SUP>2</SUP> or iron-rich<SUP>3</SUP> (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<SUP>4</SUP>. Planet evolution may be especially affected by either photoevaporative mass loss induced by high stellar X-ray and extreme ultraviolet (XUV) flux<SUP>5</SUP> or giant impacts<SUP>6</SUP>. Although there is some evidence for the former<SUP>7,8</SUP>, 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. <SUP>9</SUP>). We show that they have nearly identical radii (about 1.5-1.6R<SUB>⊕</SUB>), but the outer planet Kepler-107 c is more than twice as dense (about 12.6 g cm<SUP>-3</SUP>) as the innermost Kepler-107 b (about 5.3 g cm<SUP>-3</SUP>). 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<SUP>10</SUP>, which match the mass and radius of Kepler-107 c. | URI: | http://hdl.handle.net/20.500.12386/28766 | URL: | https://www.nature.com/articles/s41550-018-0684-9 | ISSN: | 2397-3366 | DOI: | 10.1038/s41550-018-0684-9 | Bibcode ADS: | 2019NatAs...3..416B | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
Files in This Item:
File | Description | Size | Format | |
---|---|---|---|---|
Bonomoetal_2019.pdf | postprint | 2.27 MB | Adobe PDF | View/Open |
Nat. Astr. main. s41550-018-0684-9.pdf | [Administrators only] | 2.52 MB | Adobe PDF |
Page view(s)
84
checked on Mar 19, 2024
Download(s)
42
checked on Mar 19, 2024
Google ScholarTM
Check
Altmetric
Altmetric
Items in DSpace are published in Open Access, unless otherwise indicated.