Polar Magnetic Activity and Spin-down on the Lower Main Sequence

摘要: On the Sun, magnetic activity is essentially restricted to latitudes within 45° of equator. However, active stars, such as RS CVn systems, and T Tauri stars generally show polar activity. I model evolution a toroidal flux tube it rises from base convection zone in various lower main-sequence that, on main sequence, more likely for less massive stars. For example, 1 M☉ star must rotate with ω > 5 ω☉ order develop significant flux, while 0.4 will generate predominantly 0.5 ω☉. This leads expectation that all M should display polar, rather than equatorial, A similar effect expected giant An important consequence this inhibition angular momentum loss these systems. lost via interaction stellar field outflowing wind. if regions strong are confined poles, spin-down rates can be reduced dramatically, by up factor 3 or early Examination open clusters presence rapidly rotating at ages beyond those previously expected.