Magnetic cycles of the planet-hosting star τ Bootis - II. A second magnetic polarity reversal

R. Fares, J. F. Donati, C. Moutou, D. Bohlender, C. Catala, M. Deleuil, Evgenya Shkolnik, A. C. Cameron, M. M. Jardine, G. A H Walker

Research output: Contribution to journalArticle

105 Citations (Scopus)

Abstract

In this paper, we present new spectropolarimetric observations of the planet-hosting star τ Bootis, using ESPaDOnS and Narval spectropolarimeters at Canada-France-Hawaii Telescope and Telescope Bernard Lyot, respectively. We detected the magnetic field of the star at three epochs in 2008. It has a weak magnetic field of only a few gauss, oscillating between a predominant toroidal component in January and a dominant poloidal component in June and July. A magnetic polarity reversal was observed relative to the magnetic topology in 2007 June. This is the second such reversal observed in 2 years on this star, suggesting that τ Boo has a magnetic cycle of about 2 years. This is the first detection of a magnetic cycle for a star other than the Sun. The role of the close-in massive planet in the short activity cycle of the star is questioned. τ Boo has a strong differential rotation, a common trend for stars with shallow convective envelope. At latitude 40°, the surface layer of the star rotates in 3.31 d, equal to the orbital period. Synchronization suggests that the tidal effects induced by the planet may be strong enough to force at least the thin convective envelope into corotation. τ Boo shows variability in the Ca ii H & K and Hα throughout the night and on a night-to-night time-scale. We do not detect enhancement in the activity of the star that may be related to the conjunction of the planet. Further data are needed to conclude about the activity enhancement due to the planet.

Original languageEnglish (US)
Pages (from-to)1383-1391
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Volume398
Issue number3
DOIs
StatePublished - Sep 2009
Externally publishedYes

Fingerprint

magnetic reversal
planets
polarity
planet
stars
cycles
night
magnetic field
envelopes
topology
telescopes
surface layer
corotation
conjunction
augmentation
timescale
polarimeters
France
Canada
magnetic fields

Keywords

  • Planetary systems
  • Stars: activity
  • Stars: individual: τ Boo
  • Stars: magnetic fields

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Fares, R., Donati, J. F., Moutou, C., Bohlender, D., Catala, C., Deleuil, M., ... Walker, G. A. H. (2009). Magnetic cycles of the planet-hosting star τ Bootis - II. A second magnetic polarity reversal. Monthly Notices of the Royal Astronomical Society, 398(3), 1383-1391. https://doi.org/10.1111/j.1365-2966.2009.15303.x

Magnetic cycles of the planet-hosting star τ Bootis - II. A second magnetic polarity reversal. / Fares, R.; Donati, J. F.; Moutou, C.; Bohlender, D.; Catala, C.; Deleuil, M.; Shkolnik, Evgenya; Cameron, A. C.; Jardine, M. M.; Walker, G. A H.

In: Monthly Notices of the Royal Astronomical Society, Vol. 398, No. 3, 09.2009, p. 1383-1391.

Research output: Contribution to journalArticle

Fares, R, Donati, JF, Moutou, C, Bohlender, D, Catala, C, Deleuil, M, Shkolnik, E, Cameron, AC, Jardine, MM & Walker, GAH 2009, 'Magnetic cycles of the planet-hosting star τ Bootis - II. A second magnetic polarity reversal', Monthly Notices of the Royal Astronomical Society, vol. 398, no. 3, pp. 1383-1391. https://doi.org/10.1111/j.1365-2966.2009.15303.x
Fares, R. ; Donati, J. F. ; Moutou, C. ; Bohlender, D. ; Catala, C. ; Deleuil, M. ; Shkolnik, Evgenya ; Cameron, A. C. ; Jardine, M. M. ; Walker, G. A H. / Magnetic cycles of the planet-hosting star τ Bootis - II. A second magnetic polarity reversal. In: Monthly Notices of the Royal Astronomical Society. 2009 ; Vol. 398, No. 3. pp. 1383-1391.
@article{0809ea8dcd954b1cb2a5860803caabd9,
title = "Magnetic cycles of the planet-hosting star τ Bootis - II. A second magnetic polarity reversal",
abstract = "In this paper, we present new spectropolarimetric observations of the planet-hosting star τ Bootis, using ESPaDOnS and Narval spectropolarimeters at Canada-France-Hawaii Telescope and Telescope Bernard Lyot, respectively. We detected the magnetic field of the star at three epochs in 2008. It has a weak magnetic field of only a few gauss, oscillating between a predominant toroidal component in January and a dominant poloidal component in June and July. A magnetic polarity reversal was observed relative to the magnetic topology in 2007 June. This is the second such reversal observed in 2 years on this star, suggesting that τ Boo has a magnetic cycle of about 2 years. This is the first detection of a magnetic cycle for a star other than the Sun. The role of the close-in massive planet in the short activity cycle of the star is questioned. τ Boo has a strong differential rotation, a common trend for stars with shallow convective envelope. At latitude 40°, the surface layer of the star rotates in 3.31 d, equal to the orbital period. Synchronization suggests that the tidal effects induced by the planet may be strong enough to force at least the thin convective envelope into corotation. τ Boo shows variability in the Ca ii H & K and Hα throughout the night and on a night-to-night time-scale. We do not detect enhancement in the activity of the star that may be related to the conjunction of the planet. Further data are needed to conclude about the activity enhancement due to the planet.",
keywords = "Planetary systems, Stars: activity, Stars: individual: τ Boo, Stars: magnetic fields",
author = "R. Fares and Donati, {J. F.} and C. Moutou and D. Bohlender and C. Catala and M. Deleuil and Evgenya Shkolnik and Cameron, {A. C.} and Jardine, {M. M.} and Walker, {G. A H}",
year = "2009",
month = "9",
doi = "10.1111/j.1365-2966.2009.15303.x",
language = "English (US)",
volume = "398",
pages = "1383--1391",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "3",

}

TY - JOUR

T1 - Magnetic cycles of the planet-hosting star τ Bootis - II. A second magnetic polarity reversal

AU - Fares, R.

AU - Donati, J. F.

AU - Moutou, C.

AU - Bohlender, D.

AU - Catala, C.

AU - Deleuil, M.

AU - Shkolnik, Evgenya

AU - Cameron, A. C.

AU - Jardine, M. M.

AU - Walker, G. A H

PY - 2009/9

Y1 - 2009/9

N2 - In this paper, we present new spectropolarimetric observations of the planet-hosting star τ Bootis, using ESPaDOnS and Narval spectropolarimeters at Canada-France-Hawaii Telescope and Telescope Bernard Lyot, respectively. We detected the magnetic field of the star at three epochs in 2008. It has a weak magnetic field of only a few gauss, oscillating between a predominant toroidal component in January and a dominant poloidal component in June and July. A magnetic polarity reversal was observed relative to the magnetic topology in 2007 June. This is the second such reversal observed in 2 years on this star, suggesting that τ Boo has a magnetic cycle of about 2 years. This is the first detection of a magnetic cycle for a star other than the Sun. The role of the close-in massive planet in the short activity cycle of the star is questioned. τ Boo has a strong differential rotation, a common trend for stars with shallow convective envelope. At latitude 40°, the surface layer of the star rotates in 3.31 d, equal to the orbital period. Synchronization suggests that the tidal effects induced by the planet may be strong enough to force at least the thin convective envelope into corotation. τ Boo shows variability in the Ca ii H & K and Hα throughout the night and on a night-to-night time-scale. We do not detect enhancement in the activity of the star that may be related to the conjunction of the planet. Further data are needed to conclude about the activity enhancement due to the planet.

AB - In this paper, we present new spectropolarimetric observations of the planet-hosting star τ Bootis, using ESPaDOnS and Narval spectropolarimeters at Canada-France-Hawaii Telescope and Telescope Bernard Lyot, respectively. We detected the magnetic field of the star at three epochs in 2008. It has a weak magnetic field of only a few gauss, oscillating between a predominant toroidal component in January and a dominant poloidal component in June and July. A magnetic polarity reversal was observed relative to the magnetic topology in 2007 June. This is the second such reversal observed in 2 years on this star, suggesting that τ Boo has a magnetic cycle of about 2 years. This is the first detection of a magnetic cycle for a star other than the Sun. The role of the close-in massive planet in the short activity cycle of the star is questioned. τ Boo has a strong differential rotation, a common trend for stars with shallow convective envelope. At latitude 40°, the surface layer of the star rotates in 3.31 d, equal to the orbital period. Synchronization suggests that the tidal effects induced by the planet may be strong enough to force at least the thin convective envelope into corotation. τ Boo shows variability in the Ca ii H & K and Hα throughout the night and on a night-to-night time-scale. We do not detect enhancement in the activity of the star that may be related to the conjunction of the planet. Further data are needed to conclude about the activity enhancement due to the planet.

KW - Planetary systems

KW - Stars: activity

KW - Stars: individual: τ Boo

KW - Stars: magnetic fields

UR - http://www.scopus.com/inward/record.url?scp=70249130116&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=70249130116&partnerID=8YFLogxK

U2 - 10.1111/j.1365-2966.2009.15303.x

DO - 10.1111/j.1365-2966.2009.15303.x

M3 - Article

AN - SCOPUS:70249130116

VL - 398

SP - 1383

EP - 1391

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 3

ER -