NOAO >   Observing Info >   Approved Programs >   2016B-0263

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Program Information for 2016B-0263


PI: Blair Conn, Gemini Observatory South, bconn@gemini.edu
Address: Gemini Observatory, Colina El Pino s/n, La Serena Chile

CoI: Helmut Jerjen, Australian National U.
CoI: Dongwon Kim, Australian National U.

Title: A Census of Satellites: Is Mass Segregation common in the smallest Milky Way Satellites?

Abstract: Various groups including the Stromlo Milky Way Satellite Survey team have reported more than 25 new ultra-faint Milky Way (MW) satellite stellar systems in the past two years. For most of these objects it still remains completely unclear whether they belong to the class of LCDM predicted, dark-matter dominated ultra-faint dwarf galaxies or tidally disrupted, dark-matter free star clusters. There are two avenues for determining their true nature, expensive spectroscopy with large optical telescopes or using an innovative new approach to search for evidence of extra-tidal stars and mass segregation, two signatures typical for low mass star clusters but unexpected for dark matter dominated MW satellite galaxies. We propose to obtain deep Gemini+GMOS photometry of all stellar systems that are located in the transition zone of the size-luminosity plane between star clusters and ultra-faint dwarf galaxies. The photometry will probe into the main sequence of these stellar systems. The measurements will (i) establish the main sequence mass function and estimate the binary fraction and (ii) provide more accurate fundamental parameters for each stellar system, including the total luminosity, age, metallicity, extra-tidal stellar features, and will crucially (iii) test mass segregation as new diagnostic tool to discriminate between dark matter dominated MW satellite galaxies and pure baryonic stellar systems. We will explore 9 of these systems as test cases to investigate the prevalence of Mass Segregation in these ultra-faint systems.

Program Type: Standard/Galactic

Scheduled Nights:
Run 1 (2016B):  GEM-SQ/GMOSS -- 9.4hrs band 1 (GS-2016B-Q-7)


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2016B-0263

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