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arXiv 1608.00746astro-ph.EPastro-ph.SR
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来自附近恒星的污染无法解释超短周期巨行星WASP-103 b的异常透射光谱

Contamination from a nearby star cannot explain the anomalous transmission spectrum of the ultra-short period giant planet WASP-103b

John Southworth, Daniel F. Evans

摘要:

WASP-103系统中的行星由于其大半径和高温而成为透射光谱的绝佳候选者。应用这一技术发现了半径随波长的变化,这种变化太强烈,无法用行星大气中的散射过程来解释。一颗微弱的邻近恒星随后被探测到,其对凌日光变曲线的污染可能解释了这种异常。我们提出了一个重新分析公布的数据,以确定暗淡的恒星,并评估其对测量的透射光谱的影响。这颗暗淡的恒星质量为0.72 +/- 0.08 Msun,几乎可以肯定是引力束缚在行星系上。我们发现,它对测量的行星和宿主恒星的物理性质的影响很小,相当于行星半径大0.6西格玛和行星密度小0.8西格玛。它对测量的透射光谱的影响要大得多:光谱现在在760 nm左右有一个最小值,不透明度上升到蓝色和红色波长。它与理论光谱的匹配较差,并且光谱斜率对于瑞利散射来说仍然太强。因此,附近微弱恒星的存在无法解释这颗炽热膨胀行星的光谱特性。我们主张对该系统进行进一步的观测,既要有高的空间分辨率,以改善暗星的测量特性,又要有更高的光谱分辨率,以确认行星的异常透射光谱。

英文摘要:

The planet in the WASP-103 system is an excellent candidate for transmission spectroscopy because of its large radius and high temperature. Application of this technique found a variation of radius with wavelength which was far too strong to be explained by scattering processes in the planetary atmosphere. A faint nearby star was subsequently detected, whose contamination of the transit light curves might explain this anomaly. We present a reanalysis of published data in order to characterise the faint star and assess its effect on the measured transmission spectrum. The faint star has a mass of 0.72 +/- 0.08 Msun and is almost certainly gravitationally bound to the planetary system. We find that its effect on the measured physical properties of the planet and host star is small, amounting to a planetary radius larger by 0.6 sigma and planetary density smaller by 0.8 sigma. Its influence on the measured transmission spectrum is much greater: the spectrum now has a minimum around 760 nm and opacity rises to both bluer and redder wavelengths. It is a poor match to theoretical spectra and the spectral slope remains too strong for Rayleigh scattering. The existence of the faint nearby star cannot therefore explain the measured spectral properties of this hot and inflated planet. We advocate further observations of the system, both with high spatial resolution in order to improve the measured properties of the faint star, and with higher spectral resolution to confirm the anomalous transmission spectrum of the planet.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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