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

The velocity distribution of nearby stars contains many "moving groups" thatare inconsistent with the standard assumption of an axisymmetric,time-independent, and steady-state Galaxy. We study the age and metallicityproperties of the low-velocity moving groups based on the reconstruction of thelocal velocity distribution in Paper I of this series. We perform stringent,conservative hypothesis testing to establish for each of these moving groupswhether it could conceivably consist of a coeval population of stars. Weconclude that they do not: the moving groups are not trivially associated withtheir eponymous open clusters nor with any other inhomogeneous star formationevent. Concerning a possible dynamical origin of the moving groups, we testwhether any of the moving groups has a higher or lower metallicity than thebackground population of thin disk stars, as would generically be the case ifthe moving groups are associated with resonances of the bar or spiralstructure. We find clear evidence that the Hyades moving group has higher thanaverage metallicity and weak evidence that the Sirius moving group has lowerthan average metallicity, which could indicate that these two groups arerelated to the inner Lindblad resonance of the spiral structure. Further wefind weak evidence that the Hercules moving group has higher than averagemetallicity, as would be the case if it is associated with the bar's outerLindblad resonance. The Pleiades moving group shows no clear metallicityanomaly, arguing against a common dynamical origin for the Hyades and Pleiadesgroups. Overall, however, the moving groups are barely distinguishable from thebackground population of stars, raising the likelihood that the moving groupsare associated with transient perturbations. [abridged]

The velocity distribution of nearby stars from Hipparcos data II. The nature of the low-velocity moving groups