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 Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

In this paper we demonstrate how Stromgren uvby photometry can be efficientlyused to: 1. Identify red giant branch stars that are members in a dwarfspheroidal galaxy. 2. Derive age-independent metallicities for the same starsand quantify the associated errors. Stromgren uvby photometry in a 11 x 22arcmin field centered on the Draco dwarf spheroidal galaxy was obtained usingthe Isaac Newton Telescope on La Palma. Members of the Draco dSph galaxy wereidentified using the surface gravity sensitive c_1 index which discriminatesbetween red giant and dwarf stars. Thus enabling us to distinguish the (redgiant branch) members of the dwarf spheroidal galaxy from the foreground dwarfstars in our galaxy. The method is evaluated through a comparison of ourmembership list with membership classifications in the literature based onradial velocities and proper motions. The metallicity sensitive m_1 index wasused to derive individual and age-independent metallicities for the members ofthe Draco dSph galaxy. The derived metallicities are compared to studies basedon high resolution spectroscopy and the agreement is found to be very good. Wepresent metallicities for 169 members of the red giant branch in the Dracodwarf spheroidal galaxy (the largest sample to date). The metallicitydistribution function for the Draco dSph galaxy shows a mean [Fe/H] = -1.74 dexwith a spread of 0.24 dex. The correlation between metallicity and colour forthe stars on the red giant branch is consistent with a dominant old, and coevalpopulation. There is a possible spatial population gradient over the field withthe most metal-rich stars being more centrally concentrated than the metal-poorstars.

The usage of Strömgren photometry in studies of local group dwarf spheroidal galaxies