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

Among the nearest most metal-poor starburst-dwarf galaxies known, SBS0335-052E is the most luminous in integrated nebular He II {\lambda}4686emission. This makes it a unique target to test spectral synthesis models andspectral interpretation tools of the kind that will be used to interpret futurerest-frame UV observations of primeval galaxies. Previous attempts to reproduceits He II {\lambda}4686 emission luminosity found that X-ray sources, shocks,and single Wolf-Rayet stars are not main contributors to the He II-ionizingbudget; and that only metal-free single rotating stars or binary stars with atop-heavy IMF and an unphysically-low metallicity can reproduce it. We presentnew UV (COS) and optical (MUSE) spectra which integrate the light of four superstar clusters in SBS 0335-052E. Nebular He II, [C III], C III], C IV, and OIII] UV emission lines with equivalent widths between 1.7 and 5 {\AA}, and a CIV {\lambda}{\lambda}1548, 1551 P-Cygni like profile are detected. Recentextremely-metal poor shock + precursor models and binary models fail toreproduce the observed optical emission-line ratios. We use different sets ofUV and optical observables to test models of constant star formation withsingle non-rotating stars which account for very massive stars, as blueshiftedO V {\lambda}1371 absorption is present. Simultaneously fitting the fluxes ofall high-ionization UV lines requires an unphysically-low metallicity. Fittingthe P-Cygni like + nebular components of C IV {\lambda}{\lambda}1548, 1551 doesnot constrain the stellar metallicity and time since the beginning of starformation. We obtain 12+log(O/H)=7.45\pm0.04 and log(C/O)=-0.45(+0.03)(-0.04)for the galaxy. Model-testing would benefit from higher spatial resolution UVand optical spectroscopy of the galaxy.

Stars and gas in the most metal-poor galaxies I: COS and MUSE observations of SBS 0335-052E