HIGH PRECISION ABUNDANCES IN THE 16 Cyg BINARY SYSTEM: A SIGNATURE OF THE ROCKY CORE IN THE GIANT PLANET

Author(s)

Maia, Marcelo Tucci ^[1] ; Melendez, Jorge ^[1] ; Ramirez, Ivan ^{[2, 3]}

Affiliation

^[1] Univ Sao Paulo, Dept Astron IAG, BR-05508900 Sao Paulo - Brazil

^[2] Univ Texas Austin, Dept Astron, Austin, TX 78712 - USA

^[3] Univ Texas Austin, McDonald Observ, Austin, TX 78712 - USA

• Document type: Journal article
• Source: Astrophysical Journal Letters; v. 790, n. 2 AUG 1 2014.
• Web of Science Citations: 52

Abstract

We study the stars of the binary system 16 Cygni to determine with high precision their chemical composition. Knowing that the component B has a detected planet of at least 1.5 Jupiter masses, we investigate if there are chemical peculiarities that could be attributed to planet formation around this star. We perform a differential abundance analysis using high resolution (R = 81,000) and high S/N (similar to 700) CFHT/ESPaDOnS spectra of the 16 Cygni stars and the Sun; the latter was obtained from light reflected of asteroids. We determine differential abundances of the binary components relative to the Sun and between components A and B as well. We achieve a precision of sigma less than or similar to 0.005 dex and a total error similar to 0.01 dex for most elements. The effective temperatures and surface gravities found for 16 Cyg A and B are T-eff = 5830 +/- 7 K, log g = 4.30 +/- 0.02 dex, and T-eff = 5751 +/- 6K, log g = 4.35 +/- 0.02 dex, respectively. The component 16 Cyg A has ametallicity ({[}Fe/H]) higher by 0.047 +/- 0.005 dex than 16 Cyg B, as well as a microturbulence velocity higher by 0.08 km s(-1). All elements show abundance differences between the binary components, but while the volatile difference is about 0.03 dex, the refractories differ by more and show a trend with condensation temperature, which could be interpreted as the signature of the rocky accretion core of the giant planet 16 Cyg Bb. We estimate a mass of about 1.5-6 M-circle times for this rocky core, in good agreement with estimates of Jupiter's core. (AU)

• FAPESP's process: 12/24392-2 - High precision spectroscopy: impact in the study of planets, stars, the galaxy and cosmology
• Grantee: Jorge Luis Melendez Moreno
• Support Opportunities: Research Projects - Thematic Grants