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arXiv 1608.08993astro-ph.EP
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膨胀的系外行星WASP-52 b的透射光谱学,以及恒星表面明亮区域的证据

Transmission spectroscopy of the inflated exoplanet WASP-52b, and evidence for a bright region on the stellar surface

J. Kirk, P. J. Wheatley, T. Louden, S. P. Littlefair, C. M. Copperwheat, D. J. Armstrong, T. R. Marsh, V. S. Dhillon

摘要:

我们用安装在4.2米威廉·赫歇尔望远镜上的ULTRACAM仪器,在SDSS u ',g'和以钠偶线(NaI)为中心的滤光片上同时进行测光观测,测量了极度膨胀的热木星WASP-52 b的透射光谱。我们发现,瑞利散射是不透明的行星大气内的主要来源,并找到一个传输光谱更一致的波长无关的不透明性,如从云。我们检测到的过境异常,我们归因于恒星活动的存在,并发现这一功能可以更简单地模拟为一个明亮的区域在恒星表面类似太阳光斑,而不是斑点。一个斑点模型需要一个显着更大的行星/恒星半径比发现在以前的研究。我们的研究结果突出的精度,可以实现地面测光误差小于一个大气尺度的高度,可比的HST观测的缩放行星半径。

英文摘要:

We have measured the transmission spectrum of the extremely inflated hot Jupiter WASP-52b using simultaneous photometric observations in SDSS u', g' and a filter centred on the sodium doublet (NaI) with the ULTRACAM instrument mounted on the 4.2m William Herschel Telescope. We find that Rayleigh scattering is not the dominant source of opacity within the planetary atmosphere and find a transmission spectrum more consistent with wavelength-independent opacity such as from clouds. We detect an in-transit anomaly that we attribute to the presence of stellar activity and find that this feature can be more simply modelled as a bright region on the stellar surface akin to Solar faculae rather than spots. A spot model requires a significantly larger planet/star radius ratio than that found in previous studies. Our results highlight the precision that can be achieved by ground-based photometry with errors in the scaled planetary radii of less than one atmospheric scale height, comparable to HST observations.

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