http://arxiv.org/abs/2201.03780
The radial velocity (RV) detection of exoplanets is complicated by stellar spectroscopic variability that can mimic the presence of planets, as well as by instrumental instability. These distort the spectral line profiles and can be misinterpreted as apparent RV shifts.
We present the improved FourIEr phase SpecTrum Analysis (FIESTA a.k.a. $\mathit{\Phi}$ESTA) to disentangle apparent RV shifts due to a line deformation from a true Doppler shift.
$\mathit{\Phi}$ESTA projects stellar spectrum’s cross correlation function (CCF) onto the truncated Fourier basis functions. Using the amplitude and phase information from each $\mathit{\Phi}$ESTA mode, we can trace the line variability at different CCF width scale robustly to identify and mitigate multiple sources of RV contamination.
We test $\mathit{\Phi}$ESTA metrics on the SOAP 2.0 solar simulations and find some strong correlations with the apparent RVs induced by sunspots. We apply $\mathit{\Phi}$ESTA to 3 years HARPS-N solar observations and demonstrate that $\mathit{\Phi}$ESTA is capable of identifying multiple sources of the spurious solar RV variations, including stellar rotation, the long-term trend from the solar magnetic cycle, instrumental instability and apparent solar rotation rate changes. Applying a simple multi-linear regression model, $\mathit{\Phi}$ESTA reduces the weighted RMS from 1.89~m/s to 0.98~m/s, a 48% reduction in the weighted RMS, better than applying a similar multi-linear regression to FWHM and BIS.
J. Zhao and E. Ford
Wed, 12 Jan 22
45/89
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