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 study the dynamical properties of halo stars located in the SolarNeighbourhood. Our goal is to explore how the properties of the halo depend onthe selection criteria used for defining a sample of halo stars. Once this isunderstood we proceed to measure the shape and orientation of the halo'svelocity ellipsoid and we use this information to put constraints on thegravitational potential of the Galaxy. We use the recently released Gaia DR1catalogue cross-matched to the RAVE dataset for our analysis. We develop adynamical criterion based on the distribution function of stars in variousGalactic components, using action integrals to identify halo members, andcompare this to metallicity and to kinematically selected samples. With thisnew method, we find 1156 stars in the Solar Neighbourhood to be likely membersof the stellar halo. Our dynamically selected sample consists mainly of distantgiants on elongated orbits. Their metallicity distribution is rather broad,with roughly half of the stars having [M/H] $\ge -1$ dex. The use of differentselection criteria has an important impact on the characteristics of thevelocity distributions obtained. Nonetheless, for our dynamically selected andfor the metallicity selected samples, we find the local velocity ellipsoid tobe aligned in spherical coordinates in a Galactocentric reference frame: thissuggests that the total gravitational potential is rather spherical in theregion spanned by the orbits of the halo stars in these samples.

The dynamically selected stellar halo of the Galaxy with Gaia and the tilt of the velocity ellipsoid