Navegando por Autor "Marsden, S."
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Artigo Stellar magnetism: empirical trends with age and rotation(Royal Astronomic Society, 2014-02-28) Vidotto, A. A; Gregory, S. G.; Jardine, M.; Donati, J. F.; Petit, P.; Morin, J.; Folsom, C. P.; Bouvier, J.; Cameron, A. C.; Hussain, G.; Marsden, S.; Waite, I. A.; Fares, R.; Jeffers, S.; Nascimento Júnior, José Dias doWe 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 Xray emission. Our sample consists of 104 magnetic maps of 73 stars, from accreting premain sequence to main-sequence objects (1Myr 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