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The CARMENES search for exoplanets around M dwarfs: benchmarking the impact of activity in high-precision radial velocity measurements

<i>Context.<i/> Current exoplanet surveys using the radial velocity (RV) technique are targeting M dwarfs because any habitable zone terrestrial-mass planets will induce a high RV and orbit on shorter periods than for more massive stars. One of the main caveats is that M dwarfs show a wi...

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Main Authors: Jeffers, Sandra (Author) , Barnes, J. R. (Author) , Schöfer, P. (Author) , Quirrenbach, Andreas (Author) , Zechmeister, M. (Author) , Amado, P. J. (Author) , Caballero, J. A. (Author) , Fernández, M. (Author) , Rodríguez, E. (Author) , Ribas, I. (Author) , Reiners, A. (Author) , Guillén, C. Cardona (Author) , Cifuentes, C. (Author) , Czesla, S. (Author) , Hatzes, A. P. (Author) , Kürster, Martin (Author) , Montes, D. (Author) , Morales, J. C. (Author) , Pedraz, S. (Author) , Sadegi, S. (Author)
Format: Article (Journal)
Language:English
Published: 8 July 2022
In: Astronomy and astrophysics
Year: 2022, Volume: 663, Pages: 1-28
ISSN:1432-0746
DOI:10.1051/0004-6361/202141880
Online Access:Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1051/0004-6361/202141880
Verlag, lizenzpflichtig, Volltext: https://www.aanda.org/articles/aa/abs/2022/07/aa41880-21/aa41880-21.html
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Author Notes:S.V. Jeffers, J.R. Barnes, P. Schöfer, A. Quirrenbach, M. Zechmeister, P.J. Amado, J.A. Caballero, M. Fernández, E. Rodríguez, I. Ribas, A. Reiners, C. Cardona Guillén, C. Cifuentes, S. Czesla, A.P. Hatzes, M. Kürster, D. Montes, J.C. Morales, S. Pedraz, and S. Sadegi
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Summary:<i>Context.<i/> Current exoplanet surveys using the radial velocity (RV) technique are targeting M dwarfs because any habitable zone terrestrial-mass planets will induce a high RV and orbit on shorter periods than for more massive stars. One of the main caveats is that M dwarfs show a wide range of activity levels from inactive to very active, which can induce an asymmetry in the line profiles and, consequently, a spurious RV measurement.<i>Aims.<i/> We aim to benchmark the impact of stellar activity on high-precision RV measurements using regular-cadence CARMENES visible and near-infrared observations of the active M3.5 dwarf EV Lac.<i>Methods.<i/> We used the newly developed technique of low-resolution Doppler imaging to determine the centre-of-light, or spot-induced RV component, for eight observational epochs.<i>Results.<i/> We confirm a statistically significant and strong correlation between the independently measured centre-of-light and the chromatic index, which is a measure of the amplitude variation with wavelength of the RVs. We also find circular “closed-loop” relations of several activity indices with RV for a subset of data that covers only several rotation periods. We also investigate the implications of large phase gaps in the periodograms of activity indicators. Finally, by removing the spot-induced RV component we improve the planet-mass sensitivity by a factor of at least three.<i>Conclusions.<i/> We conclude that for active M stars, a regular-cadence observing strategy is the most efficient way to identify and eliminate sources of correlated noise.
Item Description:Gesehen am 12.08.2022
Physical Description:Online Resource
ISSN:1432-0746
DOI:10.1051/0004-6361/202141880

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