A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
Fading features found in the kinematics of the far-reaching Milky Way stellar halo
Tekijät: Sarah A. Bird, Chris Flynn
Kustantaja: Oxford University Press
Julkaisuvuosi: 2015
Journal: Monthly Notices of the Royal Astronomical Society
Tietokannassa oleva lehden nimi: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Lehden akronyymi: MON NOT R ASTRON SOC
Vuosikerta: 452
Numero: 3
Aloitussivu: 2675
Lopetussivu: 2679
Sivujen määrä: 5
ISSN: 0035-8711
eISSN: 1365-2966
DOI: https://doi.org/10.1093/mnras/stv1448
We test the long-term kinematical stability of a Galactic stellar halo model, due to Kafle et al. (2012), who study the kinematics of approximately 5000 blue horizontal branch stars in the Sloan Digital Sky Survey. The velocity dispersion sigma and anisotropy parameter beta of the stars have been determined as functions of Galactocentric radius, over the range 6 < R-GC < 25 kpc, and show a strong dip in the anisotropy profile at R-GC similar to 17 kpc. By directly integrating orbits of particles in a 3D model of the Galactic potential with these characteristics, we show that the sigma and beta profiles quickly evolve on a time-scale of a few x 10 Myr whereas the density rho profile remains largely unaffected. We suggest that the feature is therefore transient. The origin of such features in the Galactic halo remains unclear.