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C/O and Mg/Si Ratios of Stars in the Solar Neighborhood

Status Report From: arXiv.org e-Print archive
Posted: Wednesday, August 24, 2016

John M. Brewer, Debra A. Fischer
(Submitted on 22 Aug 2016)

The carbon to oxygen ratio in a protoplanetary disk can have a dramatic influence on the compositions of any terrestrial planets formed. In regions of high C/O, planets form primarily from carbonates and in regions of low C/O, the ratio of magnesium to silicon determines the types of silicates which dominate the compositions. We present C/O and Mg/Si ratios for 849 F, G, and K dwarfs in the solar neighborhood. We find that the frequency of carbon-rich dwarfs in the solar neighborhood is < 0.13% and that 156 known planet hosts in the sample follow a similar distribution as all of the stars as a whole. The cosmic distribution of Mg/Si for these same stars is broader than the C/O distribution and peaks near 1.0 with ∼60% of systems having 1≤ Mg/Si <2, leading to rocky planet compositions similar to the Earth. This leaves 40% of systems that can have planets that are silicate rich and may have very different compositions than our own.

Comments: 9 pages, 5 figures, 1 ancillary data table. Accepted for publication to ApJ
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1608.06286 [astro-ph.SR] (or arXiv:1608.06286v1 [astro-ph.SR] for this version)
Submission history
From: John M. Brewer
[v1] Mon, 22 Aug 2016 20:00:01 GMT (98kb,AD)
http://arxiv.org/abs/1608.06286

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