Completing The Census Of Activity And Rotation At 600 Myr With Praesepe

The relationship between stellar age, magnetic activity, and rotation has beencharacterized mainly from observations of <500Myrold open clusters.Investigations of stellar rotation and activity have also revealed the presenceof a saturation threshold where magnetic activity no longer correlates withRossby number. Measuring rotation periods and tracers of magnetic activity inolder open clusters is difficult, but essential to calibrating and understandingthe ageactivityrotation relation. We propose two 60 ksec observations thatwill complete our census of the virgul600 Myr open cluster Praesepe. Combining thesedata with our >550 optical spectra of Praesepe, we will test the coronalstripping model of saturation, while calibrating LX as an age estimator for field stars. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]