Chromospheric variations in main-sequence stars

Baliunas, S. L.; Donahue, R. A.; Soon, Willie; Horne, J. H.; Frazer, J.; Woodard-Eklund, L.; Bradford, M.; Rao, Lihua; Wilson, O. C.; Zhang, Qizhou; Bennett, W.; Briggs, J.; Carroll, S. M.; Duncan, D. K.; Figueroa, D.; Lanning, H. H.; Misch, T.; Mueller, J.; Noyes, R. W.; Poppe, D.; Porter, A. C.; Robinson, C. R.; Russell, J.; Shelton, J. C.; Soyumer, T.; Vaughan, A. H.; Whitney, J. H.

doi:10.1086/175072

Cited by 1,030 publications

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“…In a survey of stellar activity on 111 lower mainsequence stars, Baliunas et al (1995) used chromospheric Ca ii HK measurements as a proxy of the surface magnetic fields. They found that, of the stars with solar-like activity cycles, the measured activity cycle periods Pcyc ranged from 2.5 yr to the 25 yr maximum baseline of observations.…”

Section: Introductionmentioning

confidence: 99%

Roche tomography of cataclysmic variables – VII. The long-term magnetic activity of AE Aqr

Hill

Watson²,

Steeghs

et al. 2016

Mon. Not. R. Astron. Soc.

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We present a long-term study of the secondary star in the cataclysmic variable AE Aqr, using Roche tomography to indirectly image starspots on the stellar surface spanning 8 years of observations. The 7 maps show an abundance of spot features at both high and low latitudes. We find that all maps have at least one large high-latitude spot region, and we discuss its complex evolution between maps, as well as its compatibility with current dynamo theories. Furthermore, we see the apparent growth in fractional spot coverage, f s , around 45 • latitude over the duration of observations, with a persistently high f s near latitudes of 20 • . These bands of spots may form as part of a magnetic activity cycle, with magnetic flux tubes emerging at different latitudes, similar to the 'butterfly' diagram for the Sun. We discuss the nature of flux tube emergence in close binaries, as well as the activity of AE Aqr in the context of other stars.

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Section: Introductionmentioning

confidence: 99%

Roche tomography of cataclysmic variables – VII. The long-term magnetic activity of AE Aqr

Hill

Watson²,

Steeghs

et al. 2016

Mon. Not. R. Astron. Soc.

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“…This is the famous H&K project dedicated to the detection and study of stellar activity cycles. Its main results have been summarized by Baliunas et al (1995Baliunas et al ( , 1998. They find that about 60 percent of main-sequence stars with spectral types from F to early M show cycles.…”

Section: Stellar Cycles From Chromospheric Proxiesmentioning

confidence: 99%

Stellar magnetic cycles

Lanza

2009

Proc. IAU

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Abstract. The solar activity cycle is a manifestation of the hydromagnetic dynamo working inside our star. The detection of activity cycles in solar-like stars and the study of their properties allow us to put the solar dynamo in perspective, investigating how dynamo action depends on stellar parameters and stellar structure. Nevertheless, the lack of spatial resolution and the limited time extension of stellar data pose limitations to our understanding of stellar cycles and the possibility to constrain dynamo models. I briefly review some results obtained from disc-integrated proxies of stellar magnetic fields and discuss the new opportunities opened by space-borne photometry made available by MOST, CoRoT, Kepler, and GAIA, and by new ground-based spectroscopic or spectropolarimetric observations. Stellar cycles have a significant impact on the energetic output and circumstellar magnetic fields of late-type active stars which affects the interaction between stars and their planets. On the other hand, a close-in massive planet could affect the activity of its host star. Recent observations provide circumstantial evidence of such an interaction with possible consequences for stellar activity cycles.

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“…However, significant uncertainties in our current understanding of the solar dynamo mechanism motivates us to confront our theoretical ideas of magnetic field generation with the wider space parameters available from stellar activity observations (Noyes et al 1984a;Baliunas et al 1995;Giampapa 2005;Böhm-Vitense 2007;Oláh et al 2009;Donati and Landstreet 2009;Reiners 2012, and references therein). While, in principle, different stars with different properties may host distinct classes of MHD dynamos, a good starting assumption is that a reasonable model of solar and stellar magnetism should be able to reproduce the range of stellar activity taking into account appropriate changes in the internal driving mechanisms.…”

Section: Solar Dynamics and Magnetism In A Stellar Contextmentioning

confidence: 99%

The Solar-Stellar Connection

Brun¹,

García²,

Houdek³

et al. 2017

Space Sciences Series of ISSI

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We discuss how recent advances in observations, theory and numerical simulations have allowed the stellar community to progress in its understanding of stellar convection, rotation and magnetism and to assess the degree to which the Sun and other stars share similar dynamical properties. Ensemble asteroseismology has become a reality with the advent of large time domain studies, especially from space missions. This new capability has provided improved constraints on stellar rotation and activity, over and above that obtained via traditional techniques such as spectropolarimetry or CaII H&K observations. New data and surveys covering large mass and age ranges have provided a wide parameter space to confront theories of stellar magnetism. These new empirical databases are complemented by theoretical advances and improved multi-D simulations of stellar dynamos. We trace these pathways through which a lucid and more detailed picture of magnetohydrodynamics of solar-like stars is beginning to emerge and discuss future prospects.

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Chromospheric variations in main-sequence stars

Cited by 1,030 publications

References 0 publications

Roche tomography of cataclysmic variables – VII. The long-term magnetic activity of AE Aqr

Roche tomography of cataclysmic variables – VII. The long-term magnetic activity of AE Aqr

Stellar magnetic cycles

The Solar-Stellar Connection

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