METALLICITIES OF PLANET-HOSTING STARS: A SAMPLE OF GIANTS AND SUBGIANTS

Journal Article · Fri Dec 10 04:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/725/1/721· OSTI ID:21474422

Ghezzi, L; Cunha, K ^[1]; Schuler, S C

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1. Observatorio Nacional, Rua General Jose Cristino, 77, 20921-400, Sao Cristovao, Rio de Janeiro, RJ (Brazil)

This work presents a homogeneous derivation of atmospheric parameters and iron abundances for a sample of giant and subgiant stars which host giant planets, as well as a control sample of subgiant stars not known to host giant planets. The analysis is done using the same technique as for our previous analysis of a large sample of planet-hosting and control sample dwarf stars. A comparison between the distributions of [Fe/H] in planet-hosting main-sequence (MS) stars, subgiants, and giants within these samples finds that the MS stars and subgiants have the same mean metallicity of ([Fe/H]){approx_equal} +0.11 dex, while the giant sample is typically more metal poor, having an average metallicity of [Fe/H] = -0.06 dex. The fact that the subgiants have the same average metallicities as the dwarfs indicates that significant accretion of solid metal-rich material onto the planet-hosting stars has not taken place, as such material would be diluted in the evolution from dwarf to subgiant. The lower metallicity found for the planet-hosting giant stars in comparison with the planet-hosting dwarfs and subgiants is interpreted as being related to the underlying stellar mass, with giants having larger masses and thus, on average, larger-mass protoplanetary disks. In core accretion models of planet formation, larger disk masses can contain the critical amount of metals necessary to form giant planets even at lower metallicities.

• OSTI ID: 21474422
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 725; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
ATMOSPHERES
DWARF STARS
ELEMENTS
EVOLUTION
GIANT STARS
IRON
MASS
METALS
PLANETS
PROTOPLANETS
STAR EVOLUTION
STARS
STELLAR ATMOSPHERES
TRANSITION ELEMENTS