Stellar chromospheric activity in main-sequence stars

Stellar chromospheric activity in main-sequence stars

The research presented here presents a narrow slice of several largescale, ground-based astronomy surveys focused on chromospheric activity measurements of stars from the Keck Observatory. We conducted a comprehensive study analyzing chromospheric activity and its relationship with stellar properties in exoplanet host stars and solar neighborhood stars. By extracting chromospheric activity measurements from the California-Kepler Survey and the California Legacy Survey, we explored connections between stellar activity, rotation periods, and magnetic dynamos across a large sample of stars. Our analysis includes 879 planethosting stars and 710 solar neighborhood stars, providing insights into stellar rotation, magnetic braking, and activity cycles. We observed discrepancies between photometrically and activity-derived rotation periods, supporting the theory of weakened magnetic braking. Our study also identified potential Maunder Minimum-like states in some stars and suggested that stellar activity cycles are strongly correlated with effective temperature in younger stars but not in older, low-activity stars. Additionally, we found that average chromospheric activity remains nearly constant while variations in activity decrease significantly with age, indicating measurable changes in stellar dynamos that are not strongly correlated with average activity. These findings have implications for the age-dating of mature solar-type stars and the understanding of the impact of stellar activity on exoplanet detection.

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