Long-term starspot activity of short-period RS canum venaticorum stars. 5: CG Cygni

Zeilik, M.; Gordon, S.; Jaderlund, E.; Ledlow, M.; Summers, D. L.; Heckert, P. A.; Budding, E.; Banks, Timothy

doi:10.1086/173647

Cited by 28 publications

(22 citation statements)

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“…The size of each circle shows the relative area of spotted regions, labeled by year of observation. It is clearly seen that there is an indication of two active regions on the primary star, which are located in two longitude zones centered around the quadrature points as reported by Zeilik et al (1994). One is located near 90 • and the other near 270 • (Fig.…”

Section: Analysis Of the Light Curvessupporting

confidence: 57%

“…The 1992 V-light curve and the computed curve by using the WD code. Zeilik et al (1994) and Kjurkchieva (2003) detected some depression on the light curves at different orbital phases.…”

Section: The Variation Of the Mean Brightnessmentioning

confidence: 93%

“…Hence, Zeilik et al (1994) concluded that the observed light fluctuations do not originate in the comparison star used, but that the rapid, small amplitude fluctuations are intrinsic to the system. Zeilik et al (1994) collected all the available photometric data from 1922 to 1991 and analysed for the orbital parameters of the system, as well as the starspot parameters. They found that the spots on CG Cyg tend to be located at two active longitude belts (ALB) at about 90 • and 270 • , i.e.…”

Section: The Variation Of the Mean Brightnessmentioning

confidence: 96%

“…The steps of our analysis are the same as those used by Zeilik et al (1994): (1) optimize a model eclipsing binary curve to the observations; (2) calculate the residuals by subtracting data points from the model to define the maculation wave; (3) optimize a model for the maculation wave to calculate the starspot parameters.…”

Section: Analysis Of the Light Curvesmentioning

confidence: 99%

“…Many of the V light curves that we model here have been previously modeled (Zeilik et al 1994;Heckert 1994Heckert , 1996Heckert , 1998 using the same ILOT method. Our new results are generally close to but not exactly the same as the previous results.…”

Section: Analysis Of the Light Curvesmentioning

confidence: 99%

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Long-term luminosity variations and period changes in CG Cygni

Afşar¹,

Heckert²,

İbanoǧlu³

2004

A&A

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Abstract.We report new photometry of CG Cyg from [1998][1999][2000][2001][2002]. We also analyze published photometry collected since 1965. An O-C analysis reveals evidence of a third body in the system having a 51 year orbital period. After removing the effects of the third body, we note a remaining 22.5 year cyclic variation in the O-C curve that is similar to the period of the luminosity variations. Modeling the spot activity for 28 V band light curves obtained between 1965 and 2002 confirms the presence of two active longitude belts (ALBs) at approximately 90 • and 270 • . Most of the spots occur at mid latitudes with a few at low latitudes. We note no spots at latitudes greater than 60 • .

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Section: Analysis Of the Light Curvessupporting

confidence: 57%

“…The 1992 V-light curve and the computed curve by using the WD code. Zeilik et al (1994) and Kjurkchieva (2003) detected some depression on the light curves at different orbital phases.…”

Section: The Variation Of the Mean Brightnessmentioning

confidence: 93%

Section: The Variation Of the Mean Brightnessmentioning

confidence: 96%

Section: Analysis Of the Light Curvesmentioning

confidence: 99%

Section: Analysis Of the Light Curvesmentioning

confidence: 99%

See 3 more Smart Citations

Long-term luminosity variations and period changes in CG Cygni

Afşar¹,

Heckert²,

İbanoǧlu³

2004

A&A

Self Cite

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Stability of magnetic flux tubes in close binary stars

Holzwarth

Schüßler

2000

Astron. Nachr.

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Photometric and Doppler imaging observations of active binaries indicate the existence of starspots at preferred longitudes (position angles with respect to the companion star). We investigate the stability of magnetic flux tubes in the convection zone of close, fast‐rotating binary stars and explore whether the observed preferred longitudes could be caused by tidal forces and the deformation of the active star. We assume a synchronized binary system with spin axes perpendicular to the orbital plane and a rotation period of a few days. The tidal force and the deviation from spherical structure are considered in lowest‐order perturbation theory. The magnetic field is in the form of toroidal magnetic flux rings, which are stored in mechanical equilibrium within the stably stratified overshoot region beneath the convection zone until the field has grown sufficiently strong for the undulatory instability to initiate the formation of rising loops. Frequencies and geometry of stable as well as growth rates of unstable eigenmodes are determined by linear stability analysis. Particular consideration is given to the question whether the effects of tidal forces and perturbations of the stellar structure can force a rising flux loop to enter the convection zone at specific longitudes.

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Spot signatures of a solar‐type dynamo in close binary stars

Holzwarth

2004

Astron Nachr

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Abstract. Magnetic activity signatures in the atmosphere of active stars can be used to place constrains on the underlying processes of flux transport and dynamo operation in its convective envelope. The 'solar paradigm' for magnetic activity suggests that the magnetic field is amplified and stored at the base of the convection zone. Once a critical field strength is exceeded, perturbations initiate the onset of instabilities and the growth of magnetic flux loops, which rise through the convection zone, emerge at the stellar surface, and eventually lead to the formation of starspots and active regions. In close binaries, the proximity of the companion star breaks the rotational symmetry. Although the magnitude of tidal distortions is rather small, non-linear MHD simulations have nevertheless shown in the case of main-sequence binary components that they can cause non-uniform surface distributions of flux tube eruptions. The present work extends the investigation to post-mainsequence components to explore the specific influence of the stellar structure on the surface pattern of erupting flux tubes. In contrast to the case of main-sequence components, where the consistency between simulation results and observations supports the presumption of a solar-like dynamo mechanism, the numerical results here do not recover the starspot properties frequently observed on evolved binary components. This aspect points out an insufficiency of the applied flux tube model and leads to the conclusion that additional flux transport and possibly amplification mechanisms have to be taken into account.

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Long-term starspot activity of short-period RS canum venaticorum stars. 5: CG Cygni

Cited by 28 publications

References 0 publications

Long-term luminosity variations and period changes in CG Cygni

Long-term luminosity variations and period changes in CG Cygni

Stability of magnetic flux tubes in close binary stars

Spot signatures of a solar‐type dynamo in close binary stars

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