The star formation history of the Sagittarius stream
T.J.L. de Boer, V. Belokurov, S. Koposov

TL;DR
This study analyzes the star formation history of the Sagittarius streams using SDSS data, revealing distinct epochs and metallicities that suggest different origins and stripping times for the streams.
Contribution
It provides the first detailed quantitative SFH of the Sagittarius streams, distinguishing between bright and faint components and their relation to the parent galaxy.
Findings
Star formation occurred in a well-mixed, enriched medium.
Sharp decline in star formation rates at 5-7 Gyr possibly due to MW accretion.
Faint stream stars are older and more metal-poor, stripped earlier from the outskirts.
Abstract
We present the first detailed quantitative study of the stellar populations of the Sagittarius (Sgr) streams within the Stripe 82 region, using photometric and spectroscopic observations from the Sloan Digital Sky Survey (SDSS). The star formation history (SFH) is determined separately for the bright and faint Sgr streams, to establish whether both components consist of a similar stellar population mix or have a distinct origin. Best fit SFH solutions are characterised by a well-defined, tight sequence in age-metallicity space, indicating that star formation occurred within a well-mixed, homogeneously enriched medium. Star formation rates dropped sharply at an age of ~5-7 Gyr, possibly related to the accretion of Sgr by the MW. Finally, the Sgr sequence displays a change of slope in age-metallicity space at an age between 11-13 Gyr consistent with the Sgr alpha-element knee,…
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Taxonomy
TopicsStellar, planetary, and galactic studies · Astrophysical Phenomena and Observations · Mechanics and Biomechanics Studies
