Connecting photometric and spectroscopic granulation signals with CHEOPS and ESPRESSO

Sulis, S.; Lendl, M.; Cegla, H. M.; Rodríguez Díaz, L. F.; Bigot, L.; Van Grootel, V.; Bekkelien, A.; Cameron, A. Collier; Maxted, P. F. L.; Simon, A. E.; Lovis, C.; Scandariato, G.; Bruno, G.; Nardiello, D.; Bonfanti, A.; Fridlund, M.; Persson, C. M.; Salmon, S.; Sousa, S. G.; Wilson, T. G.; ... (2023). Connecting photometric and spectroscopic granulation signals with CHEOPS and ESPRESSO. Astronomy and astrophysics, 670 EDP Sciences 10.1051/0004-6361/202244223

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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 K 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:

Journal Article (Original Article)


08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences > Theoretical Astrophysics and Planetary Science (TAPS)
08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences
08 Faculty of Science > Physics Institute
10 Strategic Research Centers > Center for Space and Habitability (CSH)
08 Faculty of Science > Physics Institute > NCCR PlanetS

UniBE Contributor:

Simon, Attila, Alibert, Yann Daniel Pierre, Beck, Thomas, Benz, Willy, Broeg, Christopher, Demory, Brice-Olivier Denys, Fortier, A., Heng, Kevin, Rieder, Martin, Thomas, Nicolas


000 Computer science, knowledge & systems
500 Science > 520 Astronomy
500 Science > 530 Physics
600 Technology > 620 Engineering




EDP Sciences




Agnès Véronique Schär Vuillemin

Date Deposited:

04 Apr 2024 14:39

Last Modified:

04 Apr 2024 14:47

Publisher DOI:


Uncontrolled Keywords:

Techniques: radial velocities and photometric - Sun: granulation - stars: atmospheres - Methods: data analysis




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