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Cluster & Association Members

Cluster & Association Members. Ernst Paunzen IfA, Vienna. Why consider Clusters Members?. Clusters offer astrophysical properties “for free”: Age Distance Reddening Not depending on any temperature, log g, absolute magnitude calibration. The BRITE HRD.

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Cluster & Association Members

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  1. Cluster & Association Members Ernst Paunzen IfA, Vienna

  2. Why consider Clusters Members? • Clusters offer astrophysical properties “for free”: • Age • Distance • Reddening • 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 • From one large Molecular Cloud • Membership criteria due to proper motions and radial velocities

  6. Isochrones I Padova Isochrones

  7. Isochrones II Huge Errors! 280K

  8. Lines of Equal Masses Error: DM(V) = 0.1 mag DMass = 0.1 M(sun) + Error in log Teff 2.5 mag 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”: • Age, error about 15% • Distance, error less than 10% • Reddening, error less than 5% • Values can be improved! • “Only positive membership needed” • Precise mass estimation possible • Huge data base (WEBDA) in Vienna

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