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S.A.Bates J.A. Holtzman R.A.M. Walterbos SDSS M31 collaborators APO May 2004

S.A.Bates J.A. Holtzman R.A.M. Walterbos SDSS M31 collaborators APO May 2004. APO 3.5m Follow UP Of SDSS Observations: Confirmation of Newly Discovered Globular Clusters in the Andromeda Galaxy. M31 has population of globular clusters like Milky Way, but more of them

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S.A.Bates J.A. Holtzman R.A.M. Walterbos SDSS M31 collaborators APO May 2004

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  1. S.A.Bates J.A. Holtzman R.A.M. Walterbos SDSS M31 collaborators APO May 2004 APO 3.5m Follow UP Of SDSS Observations: Confirmation of Newly Discovered Globular Clusters in the Andromeda Galaxy

  2. M31 has population of globular clusters like Milky Way, but more of them Distribution of GCs in Milky Way suggests distant GCS in M31 may have yet to be found Recent INT survey (Huxor et al.)found several new clustesr at largedistances SDSS scanned 2.6x18 degrees along M31 major axis in fall 2002, but no followup spectroscopy Distant clusters potentially important to constrain formation mechanism (clusters and galaxy) and mass/mass distribution in M31 ARC 3.5m well suited for spectroscopic followup/confirmation

  3. Identifcation Procedure • Match known clusters to SDSS objects in photometry catalog • 2 arcsec distance • Nearest in brightness to known cluster • Inspect clusters in multi-dimensional parameter space • Structural parameters (object type, Petrosian radius, ellipticity, concentration • Population parameters (colors) • Determine regions of parameter space inhabited by known clusters • Other objects in selected regions are cluster candidates • Additional filtering/quality control from visual inspection • Confirm candidates spectroscopically with 3.5m • Initial observation in February 2005 of 2 clusters appears to confirm them!

  4. Structural parameters Colors

  5. SDSS Images of Previously Known Clusters

  6. SDSS Images of New Candidate Clusters

  7. ARC 3.5m DIS Spectra of Candidates Short exposures of moderately bright objects on moderately cloudy night Clear detection of strongest absorption features (Ca HK, G band, H beta Velocities near systemic velocity of M31

  8. Location of New Clusters in M31 New clusters at large projected galactocentric radii, 52 and 56 kpc!! Possibly several dozen more to come!

  9. Future Work Follow-up spectroscopy of additional candidates at ARC 3.5m this fall Population studies using SDSS 5-color photometry and spectroscopic line strengths Dynamical modelling using 3.5m velocities

  10. ARC 3.5m as a follow-up tool for SDSS • High redshift quasars • Dynamical properties of galaxies • Supernovae type confirmation and spectroscopic light curves • Many others....

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