Two New Methods for Counting and Tracking the Evolution of Polar Faculae

Abstract Polar faculae are the footpoints of magnetic-field lines near Sun’s poles that seen as bright regions along edges granules. The time variation in number polar has been shown to correlate with strength magnetic field and be a predictor subsequent solar cycle. Due small size transient nature these features, combined different techniques observational factors, previous counts differ magnitude. Further, there were no scalable measure statistical properties faculae, such facular lifetime or activity. Using data from Helioseismic Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO), we present two new methods for tracking measuring their properties. In first, calculate pixel-by-pixel standard deviation HMI continuum intensity images over one day, visualizing streaks. facula is found by dividing angular length streaks latitude-dependent rotation rate. We apply this method more visible pole each day week every six months, September 2010 March 2021. Combining all measured lifetimes provides distribution mean 6.0 hours, FWHM 5.4 skew towards longer lifetimes, some lasting up 1 day. second method, overlay progressive magnetogram show close relationship between candidates field. results allow us distinguish motion due “proper motion” moving across surface, confirming participate convective motions at poles. Counts using both agree cycle These can extended automate identification measurement other which would daily measurements since SDO began operation 2010.