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|Title:||The GAPS programme with HARPS-N at TNG. X. Differential abundances in the XO-2 planet-hosting binary||Authors:||BIAZZO, Katia
BONOMO, ALDO STEFANO
LANZA, Antonino Francesco
MALDONADO PRADO, Jesus
PILLITTERI, Ignazio Francesco
Santos, N. C.
Zanmar Sanchez, R.
|Issue Date:||2015||Journal:||ASTRONOMY & ASTROPHYSICS||Number:||583||First Page:||A135||Abstract:||Binary stars hosting exoplanets are a unique laboratory where chemical tagging can be performed to measure the elemental abundances of both stellar components with high accuracy, with the aim to investigate the formation of planets and their subsequent evolution. Here, we present a high-precision differential abundance analysis of the XO-2 wide stellar binary based on high-resolution HARPS-N at TNG spectra. Both components are very similar K-dwarfs and host planets. Since they formed presumably within the same molecular cloud, we expect that they possess the same initial elemental abundances. We investigated whether planets can cause some chemical imprints in the stellar atmospheric abundances. We measure abundances of 25 elements for both stars with a range of condensation temperature T<SUB>C</SUB> = 40-1741 K, achieving typical precisions of ~0.07 dex. The northern component shows abundances in all elements higher by +0.067 ± 0.032 dex on average, with a mean difference of +0.078 dex for elements with T<SUB>C</SUB> > 800 K. The significance of the XO-2N abundance difference relative to XO-2S is at the 2σ level for almost all elements. We discuss that this result might be interpreted as the signature of the ingestion of material by XO-2N or depletion in XO-2S that is due to locking of heavy elements by the planetary companions. We estimate a mass of several tens of M<SUB>⊕</SUB> in heavy elements. The difference in abundances between XO-2N and XO-2S shows a positive correlation with the condensation temperatures of the elements, with a slope of (4.7 ± 0.9) × 10<SUP>-5</SUP> dex K<SUP>-1</SUP>, which could mean that both components have not formed terrestrial planets, but first experienced the accretion of rocky core interior to the subsequent giant planets. <P />Based on observations made with the Italian Telescopio Nazionale Galileo (TNG), operated on the island of La Palma by the INAF - Fundación Galileo Galilei at the Roche de los Muchachos Observatory of the Instituto de Astrofísica de Canarias (IAC) in the framework of the large programme Global Architecture of Planetary Systems (GAPS; P.I. A. Sozzetti).Final reduced spectra (FITS) are only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (ftp://184.108.40.206) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/583/A135">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/583/A135</A>||Acknowledgments:||This Italian GAPS project acknowledges support from INAF through the “Progetti Premiali” funding scheme of the Italian Ministry of Education, University, and Research. We thank the TNG staff for help with the observations. K.B. also thanks V. D’Orazi and C. Sneden for fruitful discussions of heavy elements.||URI:||http://hdl.handle.net/20.500.12386/23290||URL:||https://www.aanda.org/articles/aa/abs/2015/11/aa26375-15/aa26375-15.html||ISSN:||0004-6361||DOI:||10.1051/0004-6361/201526375||Bibcode ADS:||2015A&A...583A.135B||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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