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.; Krenn, A.; Hoyer, S.; Santerne, A.; Ehrenreich, D.; Alibert, Y.; Alonso, R.; Anglada, G.; Bárczy, T.; Barrado y Navascues, D.; Barros, S. C. C.; Baumjohann, W.; Beck, M.; Beck, T.; Benz, W.; Billot, N.; Bonfils, X.; Borsato, L.; Brandeker, A.; Broeg, C.; Cabrera, J.; Charnoz, S.; Corral van Damme, C.; Csizmadia, Sz.; Davies, M. B.; Deleuil, M.; Deline, A.; Delrez, L.; Demangeon, O. D. S.; Demory, B. -O.; Erikson, A.; Fortier, A.; Fossati, L.; Gandolfi, D.; Gillon, M.; Güdel, M.; Heng, K.; Isaak, K. G.; Kiss, L. L.; Laskar, J.; Lecavelier des Etangs, A.; Magrin, D.; Munari, M.; Nascimbeni, V.; Olofsson, G.; Ottensamer, R.; Pagano, I.; Pallé, E.; Peter, G.; Piotto, G.; Pollacco, D.; Queloz, D.; Ragazzoni, R.; Rando, N.; Rauer, H.; Ribas, I.; Rieder, M.; Santos, N. C.; Ségransan, D.; Smith, A. M. S.; Steinberger, M.; Steller, M.; Szabó, Gy. M.; Thomas, N.; Udry, S.; Walton, N. A.; Wolter, D.
Bibliographical reference

Astronomy and Astrophysics

Advertised on:
2
2023
Number of authors
86
IAC number of authors
2
Citations
15
Refereed citations
12
Description
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.

Full Table F.1 and a copy of the data are available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (ftp://130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/670/A24

Related projects
Helio and Asteroseismology
Helio and Astero-Seismology and Exoplanets Search
The principal objectives of this project are: 1) to study the structure and dynamics of the solar interior, 2) to extend this study to other stars, 3) to search for extrasolar planets using photometric methods (primarily by transits of their host stars) and their characterization (using radial velocity information) and 4) the study of the planetary
Savita
Mathur
Projects' name image
Exoplanets and Astrobiology
The search for life in the universe has been driven by recent discoveries of planets around other stars (known as exoplanets), becoming one of the most active fields in modern astrophysics. The growing number of new exoplanets discovered in recent years and the recent advance on the study of their atmospheres are not only providing new valuable
Enric
Pallé Bago