arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2007.11013astro-ph.EPastro-ph.IMastro-ph.SR
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在近红外用正演模拟技术精确测量径向速度

Precision radial velocity measurements by the forward-modeling technique in the near-infrared

Teruyuki Hirano, Masayuki Kuzuhara, Takayuki Kotani, Masashi Omiya, Tomoyuki Kudo, Hiroki Harakawa, Sébastien Vievard, Takashi Kurokawa, Jun Nishikawa, Motohide… 展开作者

Teruyuki Hirano, Masayuki Kuzuhara, Takayuki Kotani, Masashi Omiya, Tomoyuki Kudo, Hiroki Harakawa, Sébastien Vievard, Takashi Kurokawa, Jun Nishikawa, Motohide Tamura, Klaus Hodapp, Masato Ishizuka, Shane Jacobson, Mihoko Konishi, Takuma Serizawa, Akitoshi Ueda, Eric Gaidos, Bun'ei Sato

摘要:

在近红外中精确的径向速度(RV)测量是探测和表征低质量恒星或具有较高磁活动的年轻恒星周围的系外行星的有力工具。然而,在近红外中随时间显著变化的强的大地吸收线和发射谱线的存在可以防止通过经典技术从这些光谱中提取RV信息,经典技术忽略或掩蔽大地线。我们提出了一种方法和流水线,以获得精确的RV从近红外光谱使用前向建模技术。我们将其应用于光谱与宽波长覆盖(Y,J,和H波段,同时),采取了斯巴鲁8.2米望远镜的红外多普勒(IRD)摄谱仪。我们的管道提取每个光谱段的光谱仪的瞬时仪器配置文件,基于与恒星光同时注入光谱仪的激光频率梳的参考光谱。这些配置文件是用来获得的内在恒星模板光谱,这是免费的仪器加宽和大地特征,以及模型和适合个人观察到的光谱在RV分析。实施了一系列的数值模拟,使用理论光谱,模仿IRD数据,我们测试的管道,并表明IRD可以实现$<2$ m s $^{-1}$精度缓慢旋转中晚期M矮星的信噪比$> 100$每像素在1000 nm。RV精度对各种恒星参数的依赖性(例如,$T_{\rm eff}$,$v\sin i$,[Fe/H])的混合,以及碲线混合对RV精度的影响。我们还将RV分析管道应用于GJ 699和TRAPPIST-1的观测光谱,表明摄谱仪和管道能够至少在几个月的时间尺度上具有$<3$ m s $^{-1}$的RV精度。

英文摘要:

Precision radial velocity (RV) measurements in the near-infrared are a powerful tool to detect and characterize exoplanets around low-mass stars or young stars with higher magnetic activity. However, the presence of strong telluric absorption lines and emission lines in the near infrared that significantly vary in time can prevent extraction of RV information from these spectra by classical techniques, which ignore or mask the telluric lines. We present a methodology and pipeline to derive precision RVs from near-infrared spectra using a forward-modeling technique. We applied this to spectra with a wide wavelength coverage (Y, J, and H bands, simultaneously), taken by the InfraRed Doppler (IRD) spectrograph on the Subaru 8.2-m telescope. Our pipeline extracts the instantaneous instrumental profile of the spectrograph for each spectral segment, based on a reference spectrum of the laser-frequency comb that is injected into the spectrograph simultaneously with the stellar light. These profiles are used to derive the intrinsic stellar template spectrum, which is free from instrumental broadening and telluric features, as well as model and fit individual observed spectra in the RV analysis. Implementing a series of numerical simulations using theoretical spectra that mimic IRD data, we test the pipeline and show that IRD can achieve $<2$ m s$^{-1}$ precision for slowly rotating mid-to-late M dwarfs with a signal-to-noise ratio $> 100$ per pixel at 1000 nm. Dependences of RV precision on various stellar parameters (e.g., $T_{\rm eff}$, $v\sin i$, [Fe/H]) and the impact of telluric-line blendings on the RV accuracy are discussed through the mock spectra analyses. We also apply the RV-analysis pipeline to the observed spectra of GJ 699 and TRAPPIST-1, demonstrating that the spectrograph and the pipeline are capable of an RV accuracy of $<3$ m s$^{-1}$ at least on a time scale of a few months.

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