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The HST/ACS star formation history of the Tucana dwarf spheroidal galaxy: Clues from the horizontal branch

Savino, A, Tolstoy, E, Salaris, M, Monelli, M and De Boer, TJL (2019) The HST/ACS star formation history of the Tucana dwarf spheroidal galaxy: Clues from the horizontal branch. Astronomy and Astrophysics, 630. ISSN 0004-6361

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We report a new star formation history for the Tucana dwarf spheroidal galaxy, obtained from a new look at a deep HST/ACS colour-magnitude diagram. We combined information from the main sequence turn-off and the horizontal branch to resolve the ancient star formation rates on a finer temporal scale than previously possible. We show that Tucana experienced three major phases of star formation, two very close together at ancient times and the last one ending between 6 and 8 Gyr ago. We show that the three discrete clumps of stars on the horizontal branch are linked to the distinct episodes of star formation in Tucana. The spatial distribution of the clumps reveals that each generation of stars presents a higher concentration than the previous one. The simultaneous modelling of the horizontal branch and the main sequence turn-off also allows us to measure the amount of mass lost by red giant branch stars in Tucana with unprecedented precision, confirming dwarf spheroidals to be excellent laboratories to study the advanced evolution of low-mass stars.

Item Type: Article
Uncontrolled Keywords: 0201 Astronomical and Space Sciences
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: EDP Sciences
Date Deposited: 05 Nov 2019 14:37
Last Modified: 04 Sep 2021 08:32
DOI or Identification number: 10.1051/0004-6361/201936077
URI: https://researchonline.ljmu.ac.uk/id/eprint/11688

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