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High resolution spectroscopy of stars in the outskirts of the Tucana II ultra-faint dwarf galaxy

Published online by Cambridge University Press:  30 October 2025

A. Chiti Open the ORCID record for A. Chiti [Opens in a new window]
A. Chiti*
Affiliation:
Department of Astronomy & Astrophysics, University of Chicago, 5640 S Ellis Avenue, Chicago, IL 60637, USA Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637, USA
*
email: achiti@uchicago.edu
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Abstract

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We discuss recent results from high-resolution Magellan/MIKE spectroscopy of five stars in the outskirts (up to ∼ 1 kpc) of the Tucana II ultra-faint dwarf galaxy (UFD), complemented by prior observations of seven stars closer to the galaxy’s center. These outer stars were identified via their low SkyMapper photometric metallicities and consistent Gaia DR2 proper motions, and their membership was confirmed through follow-up medium-resolution spectroscopy. The high-resolution spectroscopy presented here provides detailed chemical abundances and more precise velocities, facilitating a revised dynamical analysis for signs of tidal disruption and a collective analysis of the detailed chemistry to evaluate astrophysical scenarios for the origin of the spatially extended feature. We discuss these signatures here and assess the evidence for several formation scenarios for the extended feature of Tucana II, highlighting how such studies of the outskirts of the UFD population as a whole can inform which scenarios may be preferred.

Keywords

Galaxy: haloGalaxy: starsStars: abundances

Information

Type
Contributed Paper
Information
Proceedings of the International Astronomical Union , Volume 19 , Symposium S379: Dynamical Masses of Local Group Galaxies , December 2023 , pp. 154 - 159
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Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
Copyright
© The Author(s), 2025. Published by Cambridge University Press on behalf of International Astronomical Union

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