1. Cluster & Association Members Ernst Paunzen IfA, Vienna

2. Why consider Clusters Members? Clusters offer astrophysical properties “for free”: Clusters offer astrophysical properties “for free”: 1. Age 2. Distance 3. Reddening Not depending on any temperature, log g, absolute magnitude calibration Not depending on any temperature, log g, absolute magnitude calibration

3. The BRITE HRD Without reddening: M(V) = -5 mag and V = 4 mag => distance = 630 pc -6; 4; 1000 -5; 4; 630 -4; 4; 400 -3; 4; 250 -2; 4; 160 -1; 4; 100 +0; 4; 65

4. Clusters within 750 pc -6; 4; 1000 -5; 4; 630 -4; 4; 400 -3; 4; 250 -2; 4; 160 -1; 4; 100 +0; 4; 65 log t < 8.0 (blue) log t < 9.0 (yellow) log t > 9.0 (red) Several Cluster Members in the BRITE sample! WEBDA: http://www.univie.ac.at/webda

5. Cluster Properties and Membership Cluster formation within a few Myrs Cluster formation within a few Myrs From one large Molecular Cloud From one large Molecular Cloud Membership criteria due to proper motions and radial velocities Membership criteria due to proper motions and radial velocities

6. Isochrones I Padova Isochrones

7. Isochrones II 280K Huge Errors!

8. Lines of Equal Masses 2.5 mag Error:  M(V) = 0.1 mag  Mass = 0.1 M(sun) + Error in log T eff Padova Isochrones

9. Precision of Age Determination Values from the Literature Paunzen & Netopil, 2006, MNRAS, 371, 1641

10. Why consider Clusters Members? Clusters offer astrophysical properties “for free”: Clusters offer astrophysical properties “for free”: 1. Age, error about 15% 2. Distance, error less than 10% 3. Reddening, error less than 5% Values can be improved! Values can be improved! “Only positive membership needed” “Only positive membership needed” Precise mass estimation possible Precise mass estimation possible Huge data base (WEBDA) in Vienna Huge data base (WEBDA) in Vienna