The CARMENES search for exoplanets around M dwarfs. Convective shift and starspot constraints from chromatic radial velocities

Context. Variability caused by stellar activity represents a challenge to the discovery and characterization of terrestrial exoplanets and complicates the interpretation of atmospheric planetary signals. Aims. We aim to use a detailed modeling tool to reproduce the effect of active regions on radial...

Descripción completa

Detalles Bibliográficos
Autores: Baroch, David, Morales, Juan Carlos, Ribas, Ignasi, Herrero, Enrique, Rosich, Albert, Perger, M., Anglada-Escudé, Guillem, Reiners, Ansgar, Caballero, J. A., Quirrenbach, Andreas, Amado, Pedro J., Jeffers, Sandra V., Cifuentes, C., Passegger, V.M., Schweitzer, Andreas, Lafarga, M., Bauer, Florian Franz, Béjar, Victor J. S., Colomé, J., Cortés-Contreras, M., Dreizler, Stefan, Galadí-Enriquez, D., Hatzes, Artie P., Henning, Thomas, Kaminski, Adrian, Kürster, M., Montes, David, Rodríguez-López, Cristina, Zechmeister, Mathias
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2020
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/221067
Acceso en línea:http://hdl.handle.net/10261/221067
Access Level:acceso abierto
Palabra clave:Convection
Stars: activity
Stars: late-Type
Starspots
Techniques: radial velocities
Descripción
Sumario:Context. Variability caused by stellar activity represents a challenge to the discovery and characterization of terrestrial exoplanets and complicates the interpretation of atmospheric planetary signals. Aims. We aim to use a detailed modeling tool to reproduce the effect of active regions on radial velocity measurements, which aids the identification of the key parameters that have an impact on the induced variability. Methods. We analyzed the effect of stellar activity on radial velocities as a function of wavelength by simulating the impact of the properties of spots, shifts induced by convective motions, and rotation. We focused our modeling effort on the active star YZ CMi (GJ 285), which was photometrically and spectroscopically monitored with CARMENES and the Telescopi Joan Oró. Results. We demonstrate that radial velocity curves at different wavelengths yield determinations of key properties of active regions, including spot-filling factor, temperature contrast, and location, thus solving the degeneracy between them. Most notably, our model is also sensitive to convective motions. Results indicate a reduced convective shift for M dwarfs when compared to solar-Type stars (in agreement with theoretical extrapolations) and points to a small global convective redshift instead of blueshift. Conclusions. Using a novel approach based on simultaneous chromatic radial velocities and light curves, we can set strong constraints on stellar activity, including an elusive parameter such as the net convective motion effect. © ESO 2020.

Similares en LA Referencia