• DOI:10.3847/1538-4357/aadf91
• Corpus ID: 55274010

The First Tidally Disrupted Ultra-faint Dwarf Galaxy?: A Spectroscopic Analysis of the Tucana III Stream

@article{Li2018TheFT,
  title={The First Tidally Disrupted Ultra-faint Dwarf Galaxy?: A Spectroscopic Analysis of the Tucana III Stream},
  author={T. S. Li and Joshua D. Simon and Kyler W. Kuehn and Andrew B. Pace and Denis Erkal and Keith C. Bechtol and Brian Yanny and Alex Drlica-Wagner and Jennifer L. Marshall and Christopher E. Lidman and Eduardo Balbinot and Daniela Carollo and S. J. Jenkins and Clara E. Mart{\'i}nez-V{\'a}zquez and Nora Shipp and K. M. Stringer and Anna Katherina Vivas and Alistair R. Walker and Risa H. Wechsler and Filipe B. Abdalla and Sahar Allam and James T. Annis and Santiago {\'A}vila and Emmanuel Bertin and David Brooks and Elizabeth Buckley-Geer and David L. Burke and Aurelio Carnero Rosell and Matias Carrasco Kind and Jorge Carretero and Carlos E. Cunha and Chris D'Andrea and Luiz Nicolaci da Costa and C. L. Davis and Juan de Vicente and Peter Doel and T. F. Eifler and August E. Evrard and Brenna L. Flaugher and Joshua A. Frieman and Juan Garc{\'i}a-Bellido and Enrique Gazta{\~n}aga and David W. Gerdes and Daniel Gruen and Robert A. Gruendl and Julia Gschwend and Gaston R. Guti{\'e}rrez and William G. Hartley and Devon L. Hollowood and Klaus Honscheid and David J. James and E. Krause and Marcio A. G. Maia and M March and Felipe Menanteau and Ramon Miquel and Andreas Alejandro Plazas and Eusebio S{\'a}nchez and Bas{\'i}lio Xavier Santiago and Victor E. Scarpine and Rafe H. Schindler and Michael S. Schubnell and Ignacio Sevilla-Noarbe and M. Smith and R. C. Smith and Marcelle Soares-Santos and Flavia Sobreira and Eric Suchyta and Mollye E. C. Swanson and Gregory G. Tarl{\'e} and Douglas L. Tucker},
  journal={The Astrophysical Journal},
  year={2018},
  volume={866}
}

• T. Li, J. Simon, +68 authors D. Tucker
• Published 20 April 2018
• Physics
• The Astrophysical Journal

We present a spectroscopic study of the tidal tails and core of the Milky Way satellite Tucana III, collectively referred to as the Tucana III stream, using the 2dF+AAOmega spectrograph on the Anglo-Australian Telescope and the IMACS spectrograph on the Magellan Baade Telescope. In addition to recovering the brightest nine previously known member stars in the Tucana III core, we identify 22 members in the tidal tails. We observe strong evidence for a velocity gradient of over at least 3° on the sky. Based on the continuity in velocity, we confirm that the Tucana III tails are real tidal extensions of Tucana III. The large velocity gradient of the stream implies that Tucana III is likely on a radial orbit. We successfully obtain metallicities for four members in the core and 12 members in the tails. We find that members close to the ends of the stream tend to be more metal-poor than members in the core, indicating a possible metallicity gradient between the center of the progenitor halo and its edge. The spread in metallicity suggests that the progenitor of the Tucana III stream is likely a dwarf galaxy rather than a star cluster. Furthermore, we find that with the precise photometry of the Dark Energy Survey data, there is a discernible color offset between metal-rich disk stars and metal-poor stream members. This metallicity-dependent color offers a more efficient method to recognize metal-poor targets and will increase the selection efficiency of stream members for future spectroscopic follow-up programs on stellar streams.