تقرير
A novel framework for semi-Bayesian radial velocities through template matching
| العنوان: | A novel framework for semi-Bayesian radial velocities through template matching |
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| المؤلفون: | Silva, A. M., Faria, J. P., Santos, N. C., Sousa, S. G., Viana, P. T. P., Martins, J. H. C., Figueira, P., Lovis, C., Pepe, F., Cristiani, S., Rebolo, R., Allart, R., Cabral, A., Mehner, A., Sozzetti, A., Mascareño, A. Suárez, Martins, C. J. A. P., Ehrenreich, D., Mégevand, D., Palle, E., Curto, G. Lo, Tabernero, H. M., Lillo-Box, J., Hernández, J. I. González, Osorio, M. R. Zapatero, Hara, N. C., Nunes, N. J., Di Marcantonio, P., Udry, S., Adibekyan, V., Dumusque, X. |
| المصدر: | A&A 663, A143 (2022) |
| سنة النشر: | 2022 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Solar and Stellar Astrophysics |
| الوصف: | The detection and characterization of an increasing variety of exoplanets has been in part possible thanks to the continuous development of high-resolution, stable spectrographs, and using the Doppler radial-velocity (RV) method. The Cross Correlation Function (CCF) method is one of the traditional approaches for RV extraction. More recently, template matching was introduced as an advantageous alternative for M-dwarf stars. In this paper, we describe a new implementation of template matching within a semi-Bayesian framework, providing a more statistically principled characterization of the RV measurements. In this context, a common RV shift is used to describe the difference between each spectral order of a given stellar spectrum and a template built from the available observations. Posterior probability distributions are obtained for the relative RV associated with each spectrum, after marginalizing with respect to the continuum. This methodology was named S-BART: Semi-Bayesian Approach for RVs with Template-matching, and it can be applied to HARPS and ESPRESSO. The application of our method to HARPS archival observations of Barnard's star allowed us to validate our implementation against HARPS-TERRA and SERVAL. Then, we applied it to 33 ESPRESSO targets, evaluating its performance and comparing it with the CCF method. We found a decrease in the median RV scatter of \sim 10\% and \sim 4\% for M- and K-type stars, respectively. S-BART yields more precise RV estimates than the CCF method, particularly in the case of M-type stars where a median uncertainty of \sim 15 cm/s is achieved over 309 observations. Further, we estimated the nightly zero point (NZP) of ESPRESSO, finding a weighted NZP scatter below \sim 0.7 m/s. As this includes stellar variability, photon noise, and potential planetary signals, it should be taken as an upper limit of the RV precision attainable with ESPRESSO data. Comment: 17 pages, 15 Figures, Accepted for publication by Astronomy & Astrophysics (A&A), Code available in https://github.com/iastro-pt/sBART |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1051/0004-6361/202142262 |
| URL الوصول: | http://arxiv.org/abs/2205.00067 |
| رقم الأكسشن: | edsarx.2205.00067 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1051/0004-6361/202142262 |
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