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arXiv 1104.0041astro-ph.EPastro-ph.SR
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对来自凌日系外行星WASP-4 b的热辐射的地基KS波段探测

A ground-based Ks-band detection of the thermal emission from the transiting exoplanet WASP-4b

C. Caceres, V. D. Ivanov, D. Minniti, A. Burrows, F. Selman, C. Melo, D. Naef, E. Mason, G. Pietrzynski

摘要:

次食是直接测量太阳系外行星热辐射、确定其类型和物理参数的有力工具。我们开始了一个项目,以获得可靠的宽波段测量的热发射过境系外行星。利用地基高频差近红外相对测光技术,获得了1.12M J热木星WASP-4 b在1.34天轨道上的次食光变曲线。数据显示,在2.2 μm处,该行星的热辐射有一个清晰的~10-σ探测。计算得到的热辐射对应于0.185^{+0.014}-0.013}%的食分深度,对应的亮温为T_B = 1995 \pm 40 K,中心温度T_C = 2455102.61162^{+0.00071}-0.00077} HJD。我们可以对偏心率设定一个极限,e cos ω=0.0027 \pm 0.0018,与近圆轨道相容。计算出的亮温以及特定的模型表明,热量从行星的昼侧到夜侧的重新分配效率很低,因此主要从昼侧排放。高节奏地面技术能够探测太阳系外行星二次日食的微弱信号,使其成为天基中红外观测的宝贵补充。

英文摘要:

Secondary eclipses are a powerful tool to measure directly the thermal emission from extrasolar planets, and to constrain their type and physical parameters. We started a project to obtain reliable broad-band measurements of the thermal emission of transiting exoplanets. Ground-based high-cadence near-infrared relative photometry was used to obtain sub-millimagnitude precision light curve of a secondary eclipse of WASP-4b -- a 1.12 M_J hot Jupiter on a 1.34 day orbit around G7V star. The data show a clear ~10-σdetection of the planet's thermal emission at 2.2 μm. The calculated thermal emission corresponds to a fractional eclipse depth of 0.185^{+0.014}_{-0.013}%, with a related brightness temperature in Ks of T_B = 1995 \pm 40 K, centered at T_C = 2455102.61162^{+0.00071}_{-0.00077} HJD. We could set a limit on the eccentricity of e cos ω=0.0027 \pm 0.0018, compatible with a near-circular orbit. The calculated brightness temperature, as well as the specific models suggest a highly inefficient redistribution of heat from the day-side to the night-side of the planet, and a consequent emission mainly from the day-side. The high-cadence ground-based technique is capable of detecting the faint signal of the secondary eclipse of extrasolar planets, making it a valuable complement to space-based mid-IR observations.

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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