Program: GS-2011A-Q-13
Title: | Confirming The Dual Nature of Ultra Compact Dwarfs |
PI: | Mark Norris |
Co-I(s): | Sheila Kannappan, Juan Carlos Forte, Favio Faifer |
Abstract
Ultra compact dwarfs (UCDs) are an enigmatic class of stellar system with properties intermediate between globular clusters (GCs) and dwarf galaxies. Circumstantial evidence hints that UCDs are a mixed population, composed of objects formed in a manner similar to GCs in major galaxy mergers, plus a second population consisting of the remnant nuclei left after the stripping of companion galaxies during minor mergers. Conclusive evidence of this scenario has proved elusive, in part because the majority of UCDs studied to date reside in galaxy cluster environments, where the uniformly old nature of the stellar populations makes it difficult to separate objects formed by the two routes.
We have recently discovered the first case of a young UCD (located around a field S0) with strong circumstantial evidence for a stripping origin. Additionally, around a group elliptical we have found multiple UCDs, which for equally strong reasons we believe to be the result of GC-like formation. We propose to spectroscopically measure the stellar populations, masses, and mass-to-light ratios of the UCDs in these two galaxies and to compare the stellar populations of their GCs and UCDs, in order to perform a definitive test of the existence of two distinct UCD formation channels.
Publications using this program's data
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[data]
[ADS] The globular cluster kinematics and galaxy dark matter content of NGC 3923
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[data]
[ADS] The AIMSS Project - I. Bridging the star cluster-galaxy divide
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[data]
[ADS] The AIMSS Project II: dynamical-to-stellar mass ratios across the star cluster-galaxy divide
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[data]
[ADS] An extended star formation history in an ultra-compact dwarf
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[data]
[ADS] The AIMSS Project - III. The stellar populations of compact stellar systems
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[data]
[ADS] Field/isolated lenticular galaxies with high SN values: the case of NGC 4546 and its globular cluster system