The relation between stellar magnetic field geometry and chromospheric activity cycles - II The rapid 120-day magnetic cycle of τ Bootis

S. V. Jeffers; M. Mengel; C. Moutou; S. C. Marsden; J. R. Barnes; M. M. Jardine; P. Petit; J. H. M. M. Schmitt; V. See; A. A. Vidotto; BCool Collaboration

doi:10.1093/mnras/sty1717

The relation between stellar magnetic field geometry and chromospheric activity cycles - II The rapid 120-day magnetic cycle of τ Bootis

S. V. Jeffers^*, M. Mengel, C. Moutou, S. C. Marsden, J. R. Barnes, M. M. Jardine, P. Petit, J. H. M. M. Schmitt, V. See, A. A. Vidotto, BCool Collaboration

^*Corresponding author for this work

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

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-scalemagnetic 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.

Original language	English
Pages (from-to)	5266-5271
Number of pages	6
Journal	Monthly Notices of the Royal Astronomical Society
Volume	479
Issue number	4
Early online date	5 Jul 2018
DOIs	https://doi.org/10.1093/mnras/sty1717
Publication status	Published - 1 Oct 2018

Keywords

Stars: activity
Stars: individual: (τ Boo)
Stars: magnetic field
Stars: solar-type
Starspots
Techniques: polarimetric

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10.1093/mnras/sty1717

Jeffers_2018_MNRAS_activitycycles_FinalPubVersion
© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This work is made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at: https://doi.org/10.1093/mnras/sty1717
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https://arxiv.org/abs/1805.09769

Astronomy at St Andrews 2018-2021: Astronomy at St Andrews 2018-2021
Jardine, M. M. (PI), Bonnell, I. A. (CoI), Cameron, A. C. (CoI), Cyganowski, C. J. (CoI), Dominik, M. (CoI), Helling, C. (CoI), Horne, K. D. (CoI), Scholz, A. (CoI), Tojeiro, R. (CoI), Weijmans, A.-M. (CoI), Wild, V. (CoI), Woitke, P. (CoI), Wood, K. (CoI) & Zhao, H. (CoI)
1/04/18 → 31/03/22
Project: Standard
Astronomy at St Andrews 2015-2018: Astronomy at St Andrews 2015-2018
Jardine, M. M. (PI), Cameron, A. C. (CoI), Cyganowski, C. J. (CoI), Horne, K. D. (CoI) & Wood, K. (CoI)
Science & Technology Facilities Council
1/04/15 → 31/03/18
Project: Standard

Moira Mary Jardine
- mmjst-andrews.acuk
- School of Physics and Astronomy - Professor
Person: Academic

Cite this

Jeffers, S. V., Mengel, M., Moutou, C., Marsden, S. C., Barnes, J. R., Jardine, M. M., Petit, P., Schmitt, J. H. M. M., See, V., Vidotto, A. A., & BCool Collaboration (2018). The relation between stellar magnetic field geometry and chromospheric activity cycles - II The rapid 120-day magnetic cycle of τ Bootis. Monthly Notices of the Royal Astronomical Society, 479(4), 5266-5271. https://doi.org/10.1093/mnras/sty1717

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title = "The relation between stellar magnetic field geometry and chromospheric activity cycles - II The rapid 120-day magnetic cycle of τ Bootis",

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-scalemagnetic 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.",

keywords = "Stars: activity, Stars: individual: (τ Boo), Stars: magnetic field, Stars: solar-type, Starspots, Techniques: polarimetric",

author = "Jeffers, {S. V.} and M. Mengel and C. Moutou and Marsden, {S. C.} and Barnes, {J. R.} and Jardine, {M. M.} and P. Petit and Schmitt, {J. H. M. M.} and V. See and Vidotto, {A. A.} and {BCool Collaboration}",

note = "SJ acknowledges support from the German Science Foundation (DFG) Research Unit FOR2544 {\textquoteleft}Blue Planets around Red Stars{\textquoteright}, project JE 701/3-1. VS acknowledges funding fromt the European Research Council (ERC) under the European Unions Horizon 2020 research and innovtion programme (grant agreement No 682393 AWESoMeStars).",

year = "2018",

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doi = "10.1093/mnras/sty1717",

language = "English",

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journal = "Monthly Notices of the Royal Astronomical Society",

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Jeffers, SV, Mengel, M, Moutou, C, Marsden, SC, Barnes, JR, Jardine, MM, Petit, P, Schmitt, JHMM, See, V, Vidotto, AA & BCool Collaboration 2018, 'The relation between stellar magnetic field geometry and chromospheric activity cycles - II The rapid 120-day magnetic cycle of τ Bootis', Monthly Notices of the Royal Astronomical Society, vol. 479, no. 4, pp. 5266-5271. https://doi.org/10.1093/mnras/sty1717

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T1 - The relation between stellar magnetic field geometry and chromospheric activity cycles - II The rapid 120-day magnetic cycle of τ Bootis

AU - Jeffers, S. V.

AU - Mengel, M.

AU - Moutou, C.

AU - Marsden, S. C.

AU - Barnes, J. R.

AU - Jardine, M. M.

AU - Petit, P.

AU - Schmitt, J. H. M. M.

AU - See, V.

AU - Vidotto, A. A.

AU - BCool Collaboration

N1 - SJ acknowledges support from the German Science Foundation (DFG) Research Unit FOR2544 ‘Blue Planets around Red Stars’, project JE 701/3-1. VS acknowledges funding fromt the European Research Council (ERC) under the European Unions Horizon 2020 research and innovtion programme (grant agreement No 682393 AWESoMeStars).

PY - 2018/10/1

Y1 - 2018/10/1

N2 - 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-scalemagnetic 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.

AB - 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-scalemagnetic 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.

KW - Stars: activity

KW - Stars: individual: (τ Boo)

KW - Stars: magnetic field

KW - Stars: solar-type

KW - Starspots

KW - Techniques: polarimetric

U2 - 10.1093/mnras/sty1717

DO - 10.1093/mnras/sty1717

M3 - Article

AN - SCOPUS:85051484913

SN - 0035-8711

VL - 479

SP - 5266

EP - 5271

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 4

ER -

The relation between stellar magnetic field geometry and chromospheric activity cycles - II The rapid 120-day magnetic cycle of τ Bootis

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Keywords

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Astronomy at St Andrews 2018-2021: Astronomy at St Andrews 2018-2021

Astronomy at St Andrews 2015-2018: Astronomy at St Andrews 2015-2018

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Moira Mary Jardine

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