Abstract
We investigate how the observed large-scale surface magnetic fields of low-mass stars (̃0.1-2M⊙), reconstructed through Zeeman-Doppler imaging, vary with age t, rotation and X-ray emission. Our sample consists of 104 magnetic maps of 73 stars, from accreting premain sequence to main-sequence objects (1 Myr ≲ t ≲ 10 Gyr). For non-accreting dwarfs we empirically find that the unsigned average large-scale surface field is related to age as t-0.655 ± 0.045. This relation has a similar dependence to that identified by Skumanich, used as the basis for gyrochronology. Likewise, our relation could be used as an age-dating method ('magnetochronology'). The trends with rotation we find for the large-scale stellar magnetism are consistent with the trends found from Zeeman broadening measurements (sensitive to large-and small-scale fields). These similarities indicate that the fields recovered from both techniques are coupled to each other, suggesting that small-and large-scale fields could share the same dynamo field generation processes. For the accreting objects, fewer statistically significant relations are found, with one being a correlation between the unsigned magnetic flux and rotation period. We attribute this to a signature of star-disc interaction, rather than being driven by the dynamo.
Original language | English |
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Pages (from-to) | 2361-2374 |
Number of pages | 14 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 441 |
Issue number | 3 |
DOIs | |
Publication status | Published - Jun 2014 |
Externally published | Yes |
Keywords
- Planetary systems
- Stars: Activity
- Stars: Evolution
- Stars: Magnetic field
- Stars: Rotation
- Techniques: Polarimetric
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science