English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We investigate the orbital motions of dwarf spheroidal galaxies (dSphs) inthe halo of the Milky Way (MW) to understand their possible effects on thediversity of the star formation histories seen in these MW satellites. In thiswork, we explicitly consider a time-varying gravitational potential due to thegrowth of the MW's dark halo mass to calculate the long-term orbital evolutionsof the dSphs, guided with {\it Gaia} DR2 proper motions, over the past 13.5billion years. We find that the infall time of a satellite, defined at whichthe galaxy first crosses within the growing virial radius of the MW's halo,coincides well with the time when the star formation rate (SFR) is peaked forthe sample of classical dSphs. On the other hand, ultra-faint dSphs alreadyfinished their SF activity prior to their infall times as already suggested inprevious works, but there is a signature that their earlier SF histories areaffected by interaction with the growing MW's halo to some extent. We alsofind, for classical dSphs, that the relative fraction of stars formed after thepeak of the SFR to the current stellar mass is smaller for the smallerpericentric radius of the galaxy at its first infall. These results suggestthat the infalling properties of the dSphs into the MW and the resultantenvironmental effects such as ram-pressure stripping and/or tidal disturbancein the MW's dark halo containing hot gas play important roles in their starformation histories.

Long-term orbital evolution of Galactic satellites and the effects on their star formation histories