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The relation between stellar magnetic field geometry and chromospheric activity cycles – II The rapid 120-day magnetic cycle of τ Bootis.
- Source :
- Monthly Notices of the Royal Astronomical Society; Oct2018, Vol. 479 Issue 4, p5266-5271, 6p
- Publication Year :
- 2018
-
Abstract
- One of the aims of the BCool programme is to search for cycles in other stars and to understand how similar they are to the Sun. In this paper, we aim to monitor the evolution of τ Boo’s large-scale magnetic field using high-cadence observations covering its chromospheric activity maximum. For the first time, we detect a polarity switch that is in phase with τ Boo’s 120-day chromospheric activity maximum and its inferred X-ray activity cycle maximum. This means that τ Boo has a very fast magnetic cycle of only 240 days. At activity maximum τ Boo’s large-scale field geometry is very similar to the Sun at activity maximum: it is complex and there is a weak dipolar component. In contrast, we also see the emergence of a strong toroidal component which has not been observed on the Sun, and a potentially overlapping butterfly pattern where the next cycle begins before the previous one has finished. [ABSTRACT FROM AUTHOR]
- Subjects :
- STELLAR magnetic fields
STELLAR chromospheres
POLARIMETRY
STARSPOTS
ASTRONOMY
Subjects
Details
- Language :
- English
- ISSN :
- 00358711
- Volume :
- 479
- Issue :
- 4
- Database :
- Complementary Index
- Journal :
- Monthly Notices of the Royal Astronomical Society
- Publication Type :
- Academic Journal
- Accession number :
- 131309435
- Full Text :
- https://doi.org/10.1093/mnras/sty1717