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Description
At the start of the solar activity cycle, a few spots appear at high latitudes. These spots gradually migrate toward mid-latitudes as activity peaks and eventually approach the equator by the cycle's end. This progression illustrates how spots at various phases of the magnetic cycle trace distinct latitudes.
This work presents a chromospheric and photometric analysis of HIP12653 to explore its differential rotation. Matching HARPS archival spectra with MARCS-Amber theoretical templates, we derive the stellar parameters Teff, log g, [Fe/H], and vsini of the target. The S-index, a magnetic activity indicator derived from CaII H & K line emissions, is fitted to determine rotation periods. At the minimum activity, between November 20 and 28, 2006, we estimate a rotation period of 4.7 days, which contrasts with a 7.6-day period obtained when these low-activity measurements are excluded. This discrepancy suggests that the two periods correspond to different latitudes.
To validate this hypothesis, we fit the TESS light curve, for sectors S2 S3, S29 S30, and S69, with a different number of harmonics to model multiple spot configurations. This approach successfully identifies rotation periods associated with distinct spot latitudes, confirming the 4.7-day period and demonstrating that differential rotation can be inferred from period searches at different magnetic cycle phases.
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