Milky Way halo stars ages and kinematics Virtual Observatory Resource

Authors
  1. Das P.
  2. Hawkins K.
  3. Jofre P.
  4. Published by
    CDS
Abstract

We exploit the [Mg/Mn]-[Al/Fe] chemical abundance plane to help identify nearby halo stars in the 14th data release from the APOGEE survey that have been accreted on to the Milky Way. Applying a Gaussian Mixture Model, we find a 'blob' of 856 likely accreted stars, with a low disc contamination rate of about 7 percent. Cross-matching the sample with the second data release from Gaia gives us access to parallaxes and apparent magnitudes, which place constraints on distances and intrinsic luminosities. Using a Bayesian isochrone pipeline, this enables us to estimate new ages for the accreted stars, with typical uncertainties of 20 percent. Our new catalogue is further supplemented with estimates of orbital parameters. The blob stars span a metallicities between -0.5 to -2.5, and [Mg/Fe] between -0.1 to 0.5. They constitute 30 percent of the metal-poor ([Fe/H]<-0.8) halo at metallicities of -1.4. Our new ages are mainly range between 8 to 13Gyr, with the oldest stars the metal-poorest, and with the highest [Mg/Fe] abundance. If the blob stars are assumed to belong to a single progenitor, the ages imply that the system merged with our Milky Way around 8 Gyr ago and that star formation proceeded for 5Gyr. Dynamical arguments suggest that such a single progenitor would have a total mass of 10^11^M_{sun}_, similar to that found by other authors using chemical evolution models and simulations. Comparing the scatter in the [Mg/Fe]-[Fe/H] plane of the blob stars to that measured for stars belonging to the Large Magellanic Cloud suggests that the blob does indeed contain stars from only one progenitor.

Keywords
  1. Milky Way Galaxy
  2. Halo stars
  3. Chemical abundances
  4. Stellar ages
Bibliographic source Bibcode
2020MNRAS.493.5195D
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/493/5195
IVOA Identifier IVOID
ivo://CDS.VizieR/J/MNRAS/493/5195

Access

Web browser access HTML
http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/493/5195
https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/493/5195
http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/493/5195
IVOA Table Access TAP
http://tapvizier.cds.unistra.fr/TAPVizieR/tap
Run SQL-like queries with TAP-enabled clients (e.g., TOPCAT).
IVOA Cone Search SCS
For use with a cone search client (e.g., TOPCAT).
http://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/493/5195/blob?
https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/493/5195/blob?
http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/493/5195/blob?

History

2020-08-03T08:53:09Z
Resource record created
2020-08-03T08:53:09Z
Created
2023-06-05T11:54:07Z
Updated

Contact

Name
CDS support team
Postal Address
CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France
E-Mail
cds-question@unistra.fr