Evolving magnetic lives of Sun-like stars. I. Characterisation of the large-scale magnetic field with Zeeman-Doppler imaging

Autor(en)

S. Bellotti, M. Gudel, S. Boro Saikia, C. P. Folsom, P. Petit, J. Morin, M. Gudel, J.-F. Donati, E. Alecian

Abstrakt

Planets orbiting young, solar-type stars are embedded in a more

energetic environment than that of the solar neighbourhood. They

experience harsher conditions due to enhanced stellar magnetic activity

and wind shaping the secular evolution of a planetary atmosphere. This

study is dedicated to the characterisation of the magnetic activity of

eleven Sun-like stars, with ages between 0.2 and 6.1 Gyr and rotation

periods between 4.6 and 28.7 d. Based on a sub-sample of six stars, we

aim to study the large-scale magnetic field, which we then use to

simulate the associated stellar wind and environment. Finally, we want

to determine the conditions during the early evolution of planetary

habitability. We analysed high-resolution spectropolarimetric data

collected in 2018 and 2019 with Narval. We computed activity diagnostics

from chromospheric lines such as CaII H&K, H$α$, and the CaII

infrared triplet, as well as the longitudinal magnetic field from

circularly polarised least-squares deconvolution profiles. For six stars

exhibiting detectable circular polarisation signals, we reconstructed

the large-scale magnetic field at the photospheric level by means of

Zeeman-Doppler imaging (ZDI). In agreement with previous studies, we

found a global decrease in the activity indices and longitudinal field

with increasing age and rotation period. The large-scale magnetic field

of the six sub-sample stars displays a strength between 1 and 25 G and

reveals substantial contributions from different components such as

poloidal (40-90 %), toroidal (10-60 %), dipolar (30-80 %), and

quadrupolar (10-40 %), with distinct levels of axisymmetry (6-84 %) and

short-term variability of the order of months. Ultimately, this implies

that exoplanets tend to experience a broad variety of stellar magnetic

environments after their formation.

Organisation(en)

Institut für Astrophysik

Journal

Astronomy & Astrophysics

ISSN

0004-6361

Publikationsdatum

07-2025

Peer-reviewed

Ja

ÖFOS 2012

103004 Astrophysik

Schlagwörter

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