Diversity of terrestrial planets: a link to the chemical makeup of their host stars
- 1Instituto de Astrofísica e Ciências do Espaço, Centro de Astrofísica da Universidade do Porto, 4150-762 Porto, Portugal (vadibekyan@astro.up.pt)
- 2Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, 4169-007 Porto, Portugal
- 3University of Zurich, Institut of Computational Sciences, CH-8057, Zurich, Switzerland
- 4Max-Planck-Institut für Astronomie, 69117 Heidelberg, Germany
- 5Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife, Spain
- 6Departamento de Astrofìsica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Spain
- 7Physikalisches Institut, University of Bern, 3012 Bern, Switzerland
- 8European Southern Observatory, Alonso de Córdova 3107, Vitacura, Región Metropolitana, Chile
- 9Center for Cosmology and Astrophysics, Alikhanian National Science Laboratory, 0036 Yerevan, Armenia
- 10Department of Physics, School of Medicine, Kurume University, Fukuoka 830-0011, Japan
- 11National Astronomical Observatory, Mitaka, Tokyo 181-8588, Japa
- 12Sōgō kenkyū daigakuin daigaku, The Graduate University for Advanced Studies, Mitaka, Tokyo 181-8588, Japan
- 13Instituto de Astronomía, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México, C.P. 04510, México
- 14Observatorio Astronómico de Córdoba, Universidad Nacional de Córdoba, X5000BGR Córdoba, Argentina
- 15Consejo Nacional de Investigaciones Científicas y Técnicas, C1425FQB Buenos Aires, Argentina
- 16Institut dÕAstrophysique de Paris, UMR7095 Centre national de la recherche scientifique, Sorbonne Université, 75014 Paris, France
- 17Laboratório Nacional de Astrofísica, Itajubá MG 37504-364, Brazil
With the swift advance in exoplanet sciences it is now possible to characterize not only the fundamental parameters (mass and radius) of planets but also their interior structure and bulk composition. The former is known to influence on the habitability conditions of terrestrial planets, and the latter in itself is a key aspect to understand planet formation processes and the origin of their diversity.
In order to accurately assess planetary internal composition, the derivation of the chemical abundances of the host stars is of extreme importance. In particualr, stellar abundances of Fe, Si, Mg are proposed as principal constraints to reduce degeneracy in exoplanet interior structure models under assumption of identical composition of these elements in the rocky planets and their host stars.
This regularly used assumption is based on our knowledge that stars and planets form from the same primordial gas and dust cloud. It is also supported by our Solar System observations for which we know that the composition of major rock forming elements (such as Mg, Si, and Fe) in the meteorites and telluric planets (with the exception of Mercury) is similar to that of the Sun. However, direct observational evidence for the aforementioned assumption for exoplanets is absent.
By using the largest possible sample of precisely characterized low-mass planets and their host stars, we show that the composition of the planet building blocks indeed correlates with the properties of the rocky planets (see Fig. 1). We also find that on average the iron-mass fraction of planets is higher than that of the primordial values, owing to the disk-chemistry and planet formation processes. Additionally, we show that super-Earths and super-Mercuries appear to be distinct populations with differing compositions, implying differences in their formation processes. We suggest that giant impact alone is not responsible for the high-densities of super-Mercuries.
I propose an oral contribution to speak about these very recent results published in Scinece.
Fig. 1 The iron-mass fraction of the planets inferred from the planets' mass and radius as a function of the iron-mass fraction of the protoplanetary disk, estimated from the host star abundances. Super-Mercuries (in brown) and super-Earths (in blue) appear as two distinct groups.
How to cite: Adibekyan, V., Dorn, C., Sousa, S., Santos, N., Bitsch, B., Israelian, G., Mordasini, C., Barros, S., Delgado Mena, E., Demangeon, O., Faria, J., Figueira, P., Hakobyan, A., Osagh, M., Soares, B., Kunitomo, M., Takeda, Y., Jofré, E., Petrucc, R., and Martioli, E.: Diversity of terrestrial planets: a link to the chemical makeup of their host stars, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-74, https://doi.org/10.5194/epsc2022-74, 2022.
