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 Tools annual

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 monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

The first and second moments of stellar velocities encode importantinformation about the formation history of the Galactic halo. However, due tothe lack of tangential motion and inaccurate distances of the halo stars, thevelocity moments in the Galactic halo have largely remained "known unknowns".Fortunately, our off-centric position within the Galaxy allows us to estimatethese moments in the galacto-centric frame using the observed radial velocitiesof the stars alone. We use these velocities coupled with the HierarchicalBayesian scheme, which allows easy marginalisation over the missing data (theproper-motion, and uncertainty-free distance and line-of-sight velocity), tomeasure the velocity dispersions, orbital anisotropy ($\beta$) and streamingmotion ($v_{\rm rot}$) of the halo main-sequence turn-off (MSTO) and K-giant(KG) stars in the inner stellar halo (r $\lesssim 15$ kpc). We study themetallicity bias in kinematics of the halo stars and observe that thecomparatively metal-rich ([Fe/H]$>-1.4$) and the metal-poor ([Fe/H]$\leq -1.4$) MSTO samples show a clear systematic difference in $v_{\rm rot} \sim20-40$ km s$^{-1}$, depending on how restrictive the spatial cuts to cull thedisk contamination are. The bias is also detected in KG samples but with lesscertainty. Both MSTO and KG populations suggest that the inner stellar halo ofthe Galaxy is radially biased i.e. $\sigma_r>\sigma_\theta$ or $\sigma_\phi$and $\beta \simeq 0.5$. The apparent metallicity contrariety in the rotationvelocity among the halo sub-populations supports the co-existence of multiplepopulations in the galactic halo that may have formed through distinctformation scenarios, i.e. in-situ versus accretion.

Galactic googly: the rotation-metallicity bias in the inner stellar halo of the Milky Way