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arXiv 0705.0272astro-ph
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近红外光谱搜索近轨道行星HD 75289 b

Near infrared spectroscopic search for the close orbiting planet HD 75289b

J. R. Barnes, C. J. Leigh, H. R. A. Jones, Travis S. Barman, D. J. Pinfield, A. Collier Cameron, J. S. Jenkins

摘要:

我们提出了一个搜索的近红外光谱特征的近轨道太阳系外的巨行星HD 75289 b。我们使用南双子座的凤凰光谱仪在2.18 - 2.19微米的波长范围内获得了约230个光谱。通过考虑直接光谱,来自照射模型大气,我们搜索的吸收轮廓签名存在于合并的恒星和行星的光。由于行星光谱是分离的恒星光谱在大多数阶段,我们应用相位相关的轨道模型和层析技术来搜索的吸收签名。由于吸收特征隐藏在单次曝光的噪声中,我们对可用的谱线应用多线反卷积,以提高数据的有效S/N比。80埃的波长覆盖范围预计将包含约100条行星线,使去卷积后能够实现信噪比约为800的平均线。然而,我们无法在数据中检测到行星的存在,并进行进一步的模拟,以表明更广泛的波长覆盖范围应该能够以99.9%(4 sigma)的置信度检测到像HD 75289 b这样的行星。我们调查我们的方法的灵敏度和估计观测和模型行星大气之间的不匹配的检测公差。

英文摘要:

We present a search for the near infrared spectroscopic signature of the close orbiting extrasolar giant planet HD 75289b. We obtained ~230 spectra in the wavelength range 2.18 - 2.19 microns using the Phoenix spectrograph at Gemini South. By considering the direct spectrum, derived from irradiated model atmospheres, we search for the absorption profile signature present in the combined star and planet light. Since the planetary spectrum is separated from the stellar spectrum at most phases, we apply a phase dependent orbital model and tomographic techniques to search for absorption signatures. Because the absorption signature lies buried in the noise of a single exposure we apply a multiline deconvolution to the spectral lines available in order to boost the effective S/N ratio of the data. The wavelength coverage of 80 angstroms is expected to contain ~100 planetary lines, enabling a mean line with S/N ratio of ~800 to be achieved after deconvolution. We are nevertheless unable to detect the presence of the planet in the data and carry out further simulations to show that broader wavelength coverage should enable a planet like HD 75289b to be detected with 99.9 per cent (4 sigma) confidence. We investigate the sensitivity of our method and estimate detection tolerances for mismatches between observed and model planetary atmospheres.

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