2022/03/10 by Annabella Meech, S. Aigrain, Suzanne Aigrain +2
Chemistry · Physics and Astronomy · #Amplitude #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Exoplanet #Gaussian #Gaussian process #Optics #Physics #Planet #Planetary system #Spectral line #Spectral resolution #Spectrograph #Spectroscopy and Chemometric Analyses #Stars #Stellar, planetary, and galactic studies #Very Large Telescope #astro-ph.EP #astro-ph.IM
paper · pdf · doi:10.1093/mnras/stac662
14 pages, 7 figures, 3 tables. Accepted for publication in MNRAS
openalex publication_date 2022/03/10 · arxiv created 2022/03/17 · arxiv updated 2022/03/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Observations of exoplanet atmospheres in high resolution have the potential to resolve individual planetary absorption lines, despite the issues associated with ground-based observations. The removal of contaminating stellar and telluric absorption features is one of the most sensitive steps required to reveal the planetary spectrum and, while many different detrending methods exist, it remains difficult to directly compare the performance and efficacy of these methods. Additionally, though the standard cross-correlation method enables robust detection of specific atmospheric species, it only probes for features that are expected a priori. Here we present a novel methodology using Gaussian process (GP) regression to directly model the components of high-resolution spectra, which partially addresses these issues. We use two archival CRIRES/VLT data sets as test cases, observations of the hot Jupiters HD 189733 b and 51 Pegasi b, recovering injected signals with average line contrast ratios of ∼ 4.37 × 10-3 and ∼ 1.39 × 10-3, and planet radial velocities ΔKp =1.45 ± 1.53 \mathrmkm s-1 and ΔKp=0.12±0.12 \mathrmkm s-1 from the injection velocities respectively. In addition, we demonstrate an application of the GP method to assess the impact of the detrending process on the planetary spectrum, by implementing injection-recovery tests. We show that standard detrending methods used in the literature negatively affect the amplitudes of absorption features in particular, which has the potential to render retrieval analyses inaccurate. Finally, we discuss possible limiting factors for the non-detections using this method, likely to be remedied by higher signal-to-noise data.