Sulis, S, Lendl, M, Cegla, HM, Diaz, LFR, Bigot, L, Van Grootel, V, Bekkelien, A, Cameron, AC, Maxted, PFL, Simon, AE, Lovis, C, Scandariato, G, Bruno, G, Nardiello, D, Bonfanti, A, Fridlund, M, Persson, CM, Salmon, S, Sousa, SG, Wilson, TG, Krenn, A, Hoyer, S, Santerne, A, Ehrenreich, D, Alibert, Y, Alonso, R, Anglada, G, Barczy, T, Barrado y Navascues, D, Barros, SCC, Baumjohann, W, Beck, M, Beck, T, Benz, W, Billot, N, Bonfils, X, Borsato, L, Brandeker, A, Broeg, C, Cabrera, J, Charnoz, S, van Damme, CC, Csizmadia, S, Davies, MB, Deleuil, M, Deline, A, Delrez, L, Demangeon, ODS, Demory, B-O, Erikson, A, Fortier, A, Fossati, L, Gandolfi, D, Gillon, M, Guedel, M, Heng, K, Isaak, KG, Kiss, LL, Laskar, J, des Etangs, AL, Magrin, D, Munari, M, Nascimbeni, V, Olofsson, G, Ottensamer, R, Pagano, I, Palle, E, Peter, G, Piotto, G, Pollacco, D, Queloz, D, Ragazzoni, R, Rando, N, Rauer, H, Ribas, I, Rieder, M, Santos, NC, Segransan, D, Smith, AMS, Steinberger, M, Steller, M, Szabo, GM, Thomas, N, Udry, S, Walton, NA and Wolter, D (2023) Connecting photometric and spectroscopic granulation signals with CHEOPS and ESPRESSO. Astronomy and Astrophysics, 670 (A24). ISSN 0004-6361

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Context. Stellar granulation generates fluctuations in photometric and spectroscopic data whose properties depend on the stellar type, composition, and evolutionary state. Characterizing granulation is key for understanding stellar atmospheres and detecting planets.

Aims. We aim to detect the signatures of stellar granulation, link spectroscopic and photometric signatures of convection for main-sequence stars, and test predictions from 3D hydrodynamic models.

Methods. For the first time, we observed two bright stars (Teff = 5833 and 6205 K) with high-precision observations taken simultaneously with CHEOPS and ESPRESSO. We analyzed the properties of the stellar granulation signal in each individual dataset. We compared them to Kepler observations and 3D hydrodynamic models. While isolating the granulation-induced changes by attenuating and filtering the p-mode oscillation signals, we studied the relationship between photometric and spectroscopic observables.

Results. The signature of stellar granulation is detected and precisely characterized for the hotter F star in the CHEOPS and ESPRESSO observations. For the cooler G star, we obtain a clear detection in the CHEOPS dataset only. The TESS observations are blind to this stellar signal. Based on CHEOPS observations, we show that the inferred properties of stellar granulation are in agreement with both Kepler observations and hydrodynamic models. Comparing their periodograms, we observe a strong link between spectroscopic and photometric observables. Correlations of this stellar signal in the time domain (flux versus radial velocities, RV) and with specific spectroscopic observables (shape of the cross-correlation functions) are however difficult to isolate due to S/N dependent variations.

Conclusions. In the context of the upcoming PLATO mission and the extreme precision RV surveys, a thorough understanding of the properties of the stellar granulation signal is needed. The CHEOPS and ESPRESSO observations pave the way for detailed analyses of this stellar process.

Item Type: Article
Additional Information: Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This article is published in open access under the Subscribe-to-Open model. Subscribe to A&A to support open access publication.
Uncontrolled Keywords: methods: data analysis; Sun: granulation; stars: atmospheres; techniques: photometric; techniques: radial velocities
Subjects: Q Science > QB Astronomy
Q Science > QB Astronomy > QB460 Astrophysics
Q Science > QB Astronomy > QB600 Planets. Planetology
Q Science > QB Astronomy > QB799 Stars
Divisions: Faculty of Natural Sciences > School of Chemical and Physical Sciences
Related URLs:
Depositing User: Symplectic
Date Deposited: 23 Mar 2023 09:11
Last Modified: 14 Apr 2023 11:55

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