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arXiv 1306.5937astro-ph.SR
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用PAVO @ CHARA进行早型星的光学干涉测量。I.恒星基本性质

Optical Interferometry of early-type stars with PAVO@CHARA. I. Fundamental stellar properties

V. Maestro, X. Che, D. Huber, M. J. Ireland, J. D. Monnier, T. R. White, Y. Kok, J. G. Robertson, G. H. Schaefer, T. A. Ten Brummelaar, P. G. Tuthill

摘要:

本文利用CHARA阵列的PAVO合束器对7颗主序星和3颗巨星进行了干涉观测,光谱类型从B2到F6。我们直接测定了这些天体的角直径,平均精度为2.3%。我们还计算了辐射热通量使用现有的测光在可见光和红外波长,以及空间紫外光谱。结合精确的\textit{Hipparcos}方程,我们导出了一组恒星的基本性质,包括线半径、光度和有效温度。拟合后者计算等时线模型,我们推断的质量和年龄的恒星。得到的有效温度是在良好的协议(在3%的水平)与几乎独立的温度估计光谱。他们验证了最近的六阶多项式(B-V)- $T_\mathrm{eff}$经验关系\citep{Boyajian2012a},但建议更保守的三阶解\citep{vanBelle2009}可以充分描述光谱类型为A0及以后的主序星的(V-K)- $T_\mathrm{eff}$关系。最后,我们已经比较了质量值结合表面重力与推断的恒星半径(\textit{gravity mass}),并作为计算的光度和温度值与恒星演化模型(\textit{isochrone mass})的比较结果。观测到的恒星之一,$γ$ \,天琴座,等时线和重力质量之间的强烈差异,表明恒星大气参数的测定应加以修订。

英文摘要:

We present interferometric observations of 7 main-sequence and 3 giant stars with spectral types from B2 to F6 using the PAVO beam combiner at the CHARA array. We have directly determined the angular diameters for these objects with an average precision of 2.3%. We have also computed bolometric fluxes using available photometry in the visible and infrared wavelengths, as well as space-based ultraviolet spectroscopy. Combined with precise \textit{Hipparcos} parallaxes, we have derived a set of fundamental stellar properties including linear radius, luminosity and effective temperature. Fitting the latter to computed isochrone models, we have inferred masses and ages of the stars. The effective temperatures obtained are in good agreement (at a 3% level) with nearly-independent temperature estimations from spectroscopy. They validate recent sixth-order polynomial (B-V)-$T_\mathrm{eff}$ empirical relations \citep{Boyajian2012a}, but suggest that a more conservative third-order solution \citep{vanBelle2009} could adequately describe the (V-K)-$T_\mathrm{eff}$ relation for main-sequence stars of spectral type A0 and later. Finally, we have compared mass values obtained combining surface gravity with inferred stellar radius (\textit{gravity mass}) and as a result of the comparison of computed luminosity and temperature values with stellar evolutionary models (\textit{isochrone mass}). The strong discrepancy between isochrone and gravity mass obtained for one of the observed stars, $γ$\,Lyr, suggests that determination of the stellar atmosphere parameters should be revised.

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