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The connection between stellar activity cycles and magnetic field topology

Catalog Data

Petit, P.  Search this
Fares, R.  Search this
Vidotto, A. A.  Search this
Jardine, M.  Search this
Marsden, S. C.  Search this
Morin, J.  Search this
Donati, J. -F  Search this
Moutou, C.  Search this
Jeffers, S. V.  Search this
Boro Saikia, S.  Search this
do Nascimento, J. D.  Search this
Folsom, C. P.  Search this
Gregory, S. G.  Search this
Hussain, G.  Search this
See, V.  Search this
Waite, I. A.  Search this
Bouvier, J.  Search this
Object Type:
Smithsonian staff publication
Electronic document
Zeeman-Doppler imaging (ZDI) has successfully mapped the large-scale magnetic fields of stars over a large range of spectral types, rotation periods and ages. When observed over multiple epochs, some stars show polarity reversals in their global magnetic fields. On the Sun, polarity reversals are a feature of its activity cycle. In this paper, we examine the magnetic properties of stars with existing chromospherically determined cycle periods. Previous authors have suggested that cycle periods lie on multiple branches, either in the cycle period-Rossby number plane or the cycle period-rotation period plane. We find some evidence that stars along the active branch show significant average toroidal fields that exhibit large temporal variations while stars exclusively on the inactive branch remain dominantly poloidal throughout their entire cycle. This lends credence to the idea that different shear layers are in operation along each branch. There is also evidence that the short magnetic polarity switches observed on some stars are characteristic of the inactive branch while the longer chromospherically determined periods are characteristic of the active branch. This may explain the discrepancy between the magnetic and chromospheric cycle periods found on some stars. These results represent a first attempt at linking global magnetic field properties obtained from ZDI and activity cycles.
See, V., Jardine, M., Vidotto, A. A., Donati, J. -F, Boro Saikia, S., Bouvier, J., Fares, R., Folsom, C. P., Gregory, S. G., Hussain, G., Jeffers, S. V., Marsden, S. C., Morin, J., Moutou, C., do Nascimento, J. D., Petit, P. and Waite, I. A. 2016. The connection between stellar activity cycles and magnetic field topology. <i>Monthly Notices of the Royal Astronomical Society<i>, 462: 4442-4450. doi:10.1093/mnras/stw2010
Astronomy  Search this
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Smithsonian Libraries