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PHAT XX. AGB stars and other cool giants in M31 star clusters
Leo Girardi, Martha L. Boyer, L. Clifton Johnson +20
The presence of AGB stars in clusters provides key constraints for stellar models, as has been demonstrated with historical data from the Magellanic Clouds. In this work, we look f…
Light Element Discontinuities Suggest an Early Termination of Star Formation in the Globular Cluster NGC 6402 (M14)
Christian I. Johnson, Nelson Caldwell, R. Michael Rich +2
NGC 6402 is among the most massive globular clusters in the Galaxy, but little is known about its detailed chemical composition. Therefore, we obtained radial velocities and/or che…
Exploring the Chemical Composition and Double Horizontal Branch of the Bulge Globular Cluster NGC 6569
Christian I. Johnson, R. Michael Rich, Nelson Caldwell +4
Photometric and spectroscopic analyses have shown that the Galactic bulge cluster Terzan 5 hosts several populations with different metallicities and ages that manifest as a double…
Light and Heavy Element Abundance Variations in the Outer Halo Globular Cluster NGC 6229
Christian I. Johnson, Nelson Caldwell, R. Michael Rich +1
NGC 6229 is a relatively massive outer halo globular cluster that is primarily known for exhibiting a peculiar bimodal horizontal branch morphology. Given the paucity of spectrosco…
Chemical Complexity in the Eu-enhanced Monometallic Globular Cluster NGC 5986
Christian I. Johnson, Nelson Caldwell, R. Michael Rich +4
NGC 5986 is a poorly studied but relatively massive Galactic globular cluster that shares several physical and morphological characteristics with "iron-complex" clusters known to e…
A Chemical Composition Survey of the Iron-Complex Globular Cluster NGC 6273 (M 19)
Christian I. Johnson, Nelson Caldwell, R. Michael Rich +5
Recent observations have shown that a growing number of the most massive Galactic globular clusters contain multiple populations of stars with different [Fe/H] and neutron-capture…