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 object ESO456-SC38 (Djorgovski 2) is one of the globular clusters that isclosest to the Galactic center. It is on the blue horizontal branch and has amoderate metallicity of [Fe/H]~-1.0. It is thus similar to the very old innerbulge globular clusters NGC 6522, NGC 6558, and HP 1, and therefore appears tobe part of the primeval formation stages of the Milky Way. The aim of this workis to determine an accurate distance and metallicity for ESO456-SC38, as wellas orbital parameters, in order to check similarities with other clusters inthe inner bulge that have previously been well studied in terms of spectroscopyand photometry. This is a considerably fainter cluster that is contaminated bya rich stellar field; it is also quite absorbed by the dusty foreground. Weanalyzed ESO456-SC38 based on Hubble Space Telescope photometry, with thefilters F606W from ACS, F110W and F160W from WFC3,and photometry in V and Ifrom FORS2 at the VLT. We combined this with identified stars that are coveredby Gaia Data Release 2. The isochrone fitting was carried out with thestatistical Markov chain Monte Carlo method. We derive an accurate distance ofdSun = 8.75+-0.12 kpc and a reddening of E(B-V)=0.81^+0.02_-0.02. Thebest-fitting BaSTI isochrones correspond to an age of 12.70^{+0.72}_{-0.69} Gyrand a metallicity of [Fe/H]=-1.11^{+0.03}_{-0.03}. ESO 456-SC38 adds to thelist of moderately metal-poor globular clusters located in the inner bulge. Itis on the blue horizontal branch and is very old. The cluster is confined tothe bulge and bar region, but it does not support the Galactic bar structure.The old stellar population represented by clusters like this has to be takeninto account in models of Galactic bulge formation. Studying them also providesindications on the formation times of the globular clusters themselves.

Another relic bulge globular cluster: ESO 456-SC38 (Djorgovski~2)