تقرير
Stellar magnetism: empirical trends with age and rotation
| العنوان: | Stellar magnetism: empirical trends with age and rotation |
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| المؤلفون: | 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 Jr, J. D. do |
| سنة النشر: | 2014 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Earth and Planetary Astrophysics |
| الوصف: | We investigate how the observed large-scale surface magnetic fields of low-mass stars (~0.1 -- 2 Msun), reconstructed through Zeeman-Doppler imaging (ZDI), vary with age t, rotation and X-ray emission. Our sample consists of 104 magnetic maps of 73 stars, from accreting pre-main 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 <|Bv|> is related to age as $t^{-0.655 \pm 0.045}$. This relation has a similar dependence to that identified by Skumanich (1972), 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. Comment: 15 pages, 7 figures. Accepted to MNRAS |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1093/mnras/stu728 |
| URL الوصول: | http://arxiv.org/abs/1404.2733 |
| رقم الأكسشن: | edsarx.1404.2733 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1093/mnras/stu728 |
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