S316p.32 — 10 distinct stellar populations in omega Centauri.

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Aug 10th at 6:00 PM until 7:30 PM

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Author(s): Andrea Bellini3, Jay Anderson3, Luigi R. Bedin1, Adrienne Cool2, Ivan R. King4, roeland p. van der marel3

Institution(s): 1. INAF-OAPd, 2. SFSU, 3. STScI, 4. Univ.Washington

We are constructing the most comprehensive catalog of photometry and proper motions ever assembled for a globular cluster. The core of omega Centauri has been imaged over 600 times through WFC3’s UVIS and IR channels for the purposes of detector calibration. There exist ~30 exposures each for 26 filters, stretching uniformly from F225W in the UV to F160W in the infrared. Furthermore, the 12-year baseline between this data and a 2002 ACS survey will more than triple both the accuracy and the number of well-measured stars compared to previous studies.
This totally unprecedented complete spectral coverage for over 400,000 stars, from the red-giant branch down to the white dwarfs, provides the best chance yet to understand the multiple-population phenomenon in any globular cluster. A preliminary analysis of the color-magnitude diagrams in different bands already allows us to identify 10 distinct sequences.