Wilson, David J., Gänsicke, B. T. (Boris T.), Farihi, Jay and Koester, Detlev (2016) Carbon to oxygen ratios in extrasolar planetesimals. Monthly Notices of the Royal Astronomical Society, 459 (3). pp. 3282-3286. doi:10.1093/mnras/stw844

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Abstract

Observations of small extrasolar planets with a wide range of densities imply a variety of planetary compositions and structures. Currently, the only technique to measure the bulk composition of extrasolar planetary systems is the analysis of planetary debris accreting onto white dwarfs, analogous to abundance studies of meteorites. We present measurements of the carbon and oxygen abundances in the debris of planetesimals at ten white dwarfs observed with the Hubble Space Telescope, along with C/O ratios of debris in six systems with previously reported abundances. We find no evidence for carbon-rich planetesimals, with C/O < 0.8 by number in all 16 systems. Our results place an upper limit on the occurrence of carbon-rich systems at < 17 percent with a 2 σ confidence level. The range of C/O of the planetesimals is consistent with that found in the Solar System, and appears to follow a bimodal distribution: a group similar to the CI chondrites, with log(<C/O>) = −0.92, and oxygen-rich objects with C/O less than or equal to that of the bulk Earth. The latter group may have a higher mass fraction of water than the Earth, increasing their relative oxygen abundance.

Item Type:	Journal Article
Subjects:	Q Science > QB Astronomy
Divisions:	Faculty of Science > Physics
Library of Congress Subject Headings (LCSH):	Extrasolar planets, White dwarf stars
Journal or Publication Title:	Monthly Notices of the Royal Astronomical Society
Publisher:	Oxford University Press
ISSN:	0035-8711
Official Date:	9 May 2016
Dates:	Date Event 9 May 2016 Published 14 April 2016 Available 11 April 2016 Accepted 20 August 2015 Submitted
Date of first compliant deposit:	19 April 2016
Volume:	459
Number:	3
Number of Pages:	7
Page Range:	pp. 3282-3286
DOI:	10.1093/mnras/stw844
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Funder:	European Research Council (ERC), Seventh Framework Programme (European Commission) (FP7), Science and Technology Facilities Council (Great Britain) (STFC), United States. National Aeronautics and Space Administration (NASA)
Grant number:	ERC Grant Agreement no 320964 WDTracer (FP7), NAS 5-26555 (NASA)

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