Patterns of Variation among Sun‐like Stars

Radick, R. R.; Lockwood, G. W.; Skiff, B. A.; Baliunas, S. L.

doi:10.1086/313135

Cited by 276 publications

(344 citation statements)

References 22 publications

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“…Elsewhere, Radick et al (1998) found that the luminosity variation of young stars was anti-correlated with their chromospheric emission, in the sense that young stars are fainter near their activity maxima. This suggests that the long-term variability of young stars is spot-dominated, whereas older stars are faculae-dominated (Lockwood et al 2007).…”

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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“…In such a case hot photospheric faculae dominate the color variation. Again, this could be interpreted in the framework of the scenario proposed by Radick et al (1998), Lockwood et al (2007), and Hall et al (2009) in which young and rapidly rotating stars arrange their surface magnetic flux predominantly into dark spots, whereas, when stars age and their rotation slows down, bright facula-like structures are favored.…”

Section: Rapidly Rotating Starsmentioning

confidence: 64%

“…Stellar magnetic activity studies require long term monitoring projects both from the ground and space. Among the observing programs providing bulks of fundamental data for stellar magnetic activity studies I recall the Mount Wilson Observatory Ca ii H&K (e.g., Baliunas et al 1998), and the Lowell & Fairborn Observatories (e.g., Radick et al 1998, Messina & Guinan 2002, Lockwood et al 2007 projects, both aimed to the detection of chromospheric variability in solar-like stars, the latter dedicated also to observations of the photospheric signatures of magnetic activity. Photometric and spectroscopic monitoring have been carried out in several European observatories and institutes to get maps of spotted photospheres (e.g., Rodonò 1992, Rodonò & Cutispoto 1994, Lanza et al 1998, Rodonò et al 2000, Messina 2008, Vida et al 2007Strassmeier 2009), and of magnetic field patterns (e.g., Donati et al 2003a, Donati et al 2003b.…”

Section: Sources Of Long-term Data On Magnetic Activitymentioning

confidence: 99%

Long-term stellar variability

Pagano

2009

Proc. IAU

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Abstract. Stars with significant subsurface convection zones develop magnetic loop structures that, arising from the surface upward to the external atmospheres, cause flux variability detectable throughout the whole electromagnetic spectrum. In fact, diagnostics of magnetic activity are in radio wavelengths, where gyrosincrotron radiation arises from the quiescent and flaring corona; in the optical region, where important signatures are the Balmer lines, the Ca ii IRT and H&K lines; in the UV and X ray domains, the latter mainly due to coronal thermal plasma. The zoo of different magnetic features observed for the Sun -spots, faculae, flares, CMEs -are characterized by different temporal evolution and energetics, both in quantity and quality. As a consequence, the time scale of variability, the amount of involved energy and the quality of the involved photons are used as fingerprints in interpreting the observed stellar variability in the framework of the solar-stellar analogy. Here I review main results from long-term multiwavelength observations of cool star atmospheres, with emphasis to similarities and differences with the solar case.

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“…Overlap with MWO targets allowed the comparison of photometric variability in the combined bandpass ((b + y)/2) to Ca ii H & K activity expressed with the R HK index, the ratio of HK flux to the bolometric luminosity. Lockwood et al (1997) generally found that active stars (high R HK ) have larger rms photometric variability, and Radick et al (1998) found a power law relationship between the two quantities. Furthermore, Radick et al (1998) found that stars were either faculae-dominated, with a positive correlation between brightness and H & K activity, or spot-dominated, with a negative correlation.…”

Section: Introductionmentioning

confidence: 93%

Evolution of Long Term Variability in Solar Analogs

Egeland

Soon

Baliunas³

et al. 2016

Proc. IAU

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Abstract. Earth is the only planet known to harbor life, therefore we may speculate on how the nature of the Sun-Earth interaction is relevant to life on Earth, and how the behavior of other stars may influence the development of life on their planetary systems. We study the long-term variability of a sample of five solar analog stars using composite chromospheric activity records up to 50 years in length and synoptic visible-band photometry about 20 years long. This sample covers a large range of stellar ages which we use to represent the evolution in activity for solar mass stars. We find that young, fast rotators have an amplitude of variability many times that of the solar cycle, while old, slow rotators have very little variability. We discuss the possible impacts of this variability on young Earth and exoplanet climates.

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Patterns of Variation among Sun‐like Stars

Cited by 276 publications

References 22 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

Long-term stellar variability

Evolution of Long Term Variability in Solar Analogs

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