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TEMPORAL VARIATIONS OF THE GLOBAL SEISMIC PARAMETERS OF HD 49933 OVER A MAGNETIC CYCLE KCI 등재 SCOPUS
pp.129-137
It has been established that the acoustic mode parameters of the Sun and Sun-like stars vary over activity cycles. Since the observed variations are not consistent with an activity-related origin, even Sun-like stars showing out-of-phase changes of mode frequencies and amplitudes need to be carefully studied using other observational quantities. In order to test whether the presumed relations between the global seismic parameters are a signature of the stellar activity cycle, we analyze the photometric light curve of HD 49933 for which the rst direct detection of an asteroseismic signature for activityinduced variations in a Sun-like star was made, using observations by the CoRoT space telescope. We nd that the amplitude of the envelope signi cantly anti-correlates with both the maximum frequency of the envelope and the width of the envelope unless super are-like events completely contaminate the light curve. However, even though the photometric proxy for stellar magnetic activity appears to show relations with the global asteroseismic parameters, they are statistically insigni cant. Therefore, we conclude that the global asteroseismic parameters can be utilized in cross-checking asteroseismic detections of activity-related variations in Sun-like stars, and that it is probably less secure and efective to construct a photometric magnetic activity proxy to indirectly correlate the global asteroseismic parameters. Finally, we seismically estimate the mass of HD 49933 based on our determination of the large separation of HD 49933 with evolutionary tracks computed by the MESA code and nd a value of about 1:2M and a sub-solar metallicity of Z = 0:008, which agrees with the current consensus and with asteroseismic and non-asteroseismic data.
1. INTRODUCTION
2. DATA
3. GLOBAL SEISMIC PARAMETERS OF HD 49933
4. HD 49933 IN SEISMIC H–R DIAGRAM
5. SUMMARY AND CONCLUSIONS
REFERENCES
