arXiv 1309.19982013-09-08astro-ph.EPastro-ph.SR

90台transit主机的新的和更新的恒星参数。地表重力的影响

New and updated stellar parameters for 90 transit hosts. The effect of the surface gravity

A. Mortier, N. C. Santos, S. G. Sousa, J. M. Fernandes, V. Zh. Adibekyan, E. Delgado Mena, M. Montalto, G. Israelian

备注：: 12 pages, 6 figures, 5 tables, accepted to A&A
DOI：: 10.1051/0004-6361/201322240

摘要：

上下文在系外行星研究中，精确的恒星参数是正确确定行星参数的关键。对于有凌日行星的恒星，行星的质量和半径取决于恒星的质量和半径，而恒星的质量和半径又取决于大气中的恒星参数。不同的方法可以提供不同的结果，从而导致不同的行星特征。}%光谱表面重力已被证明是不好的约束，但过境行星的测光可以提供一个独立的测量表面重力。目标。在本文中，我们使用一个统一的方法，光谱推导恒星大气参数，化学丰度，恒星质量和恒星半径的90个过境主机的样本。表面重力也可以用光度学方法从光变曲线导出的恒星密度导出。我们研究了使用这些不同的表面重力的化学丰度和恒星的质量和半径的测定的效果。方法.基于LTE中的Kurucz模式，通过MOOG代码进行光谱分析，以获得大气参数和化学丰度。测光表面重力是通过等时线拟合和使用直接从光变曲线确定的恒星密度来确定的。恒星的质量和半径通过校准公式确定。结果光谱学和光度学的表面重力不同，但这对我们在光谱分析中精确测定恒星质量的影响很小。恒星半径，以及行星半径，受表面重力差异的影响最大。对于化学丰度，正如预期的那样，差异仅适用于通过分析电离物质线获得的丰度。

英文摘要：

Context. Precise stellar parameters are crucial in exoplanet research for correctly determining of the planetary parameters. For stars hosting a transiting planet, determining of the planetary mass and radius depends on the stellar mass and radius, which in turn depend on the atmospheric stellar parameters. Different methods can provide different results, which leads to different planet characteristics.}%Spectroscopic surface gravities have shown to be poorly constrained, but the photometry of the transiting planet can provide an independent measurement of the surface gravity. Aims. In this paper, we use a uniform method to spectroscopically derive stellar atmospheric parameters, chemical abundances, stellar masses, and stellar radii for a sample of 90 transit hosts. Surface gravities are also derived photometrically using the stellar density as derived from the light curve. We study the effect of using these different surface gravities on the determination of the chemical abundances and the stellar mass and radius. Methods. A spectroscopic analysis based on Kurucz models in LTE was performed through the MOOG code to derive the atmospheric parameters and the chemical abundances. The photometric surface gravity was determined through isochrone fitting and the use of the stellar density, directly determined from the light curve. Stellar masses and radii are determined through calibration formulae. Results. Spectroscopic and photometric surface gravities differ, but this has very little effect on the precise determination of the stellar mass in our spectroscopic analysis. The stellar radius, and hence the planetary radius, is most affected by the surface gravity discrepancies. For the chemical abundances, the difference is, as expected, only noticable for the abundances derived from analyzing of lines of ionized species.

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