M. LlerenaR. AmorínF. CullenPENTERICCI, LauraLauraPENTERICCIA. CalabròR. McLureA. CarnallE. Pérez-MonteroF. MarchiBONGIORNO, ANGELAANGELABONGIORNOCASTELLANO, MARCOMARCOCASTELLANOFONTANA, AdrianoAdrianoFONTANAD. J. McLeodM. TaliaN. P. HathiP. HibonMANNUCCI, FILIPPOFILIPPOMANNUCCIA. SaxenaD. SchaererG. Zamorani2022-03-292022-03-2920220004-6361http://hdl.handle.net/20.500.12386/32058We study the mean properties of a large representative sample of 217 galaxies showing CIII] emission at $2<z<4$, selected from a parent sample of $\sim$750 main-sequence star-forming galaxies in the VANDELS survey. These CIII] emitters have a broad range of UV luminosities, thus allowing a detailed stacking analysis to characterize their stellar mass, star formation rate (SFR) and stellar metallicity, as a function of the UV emission line ratios, EWs, and the carbon-to-oxygen (C/O) abundance ratio. Reliable CIII] detections represent $\sim$30% of the parent sample. Extreme CIII] emitters (EW(CIII])$\gtrsim$8\r{A}) are exceedingly rare ($\sim$3%) in VANDELS. The UV line ratios of the sample suggest no ionization source other than massive stars. Stacks with larger EW(CIII]) show larger EW(Ly$\alpha$) and lower metallicity, but not all CIII] emitters are Ly$\alpha$ emitters. The stellar metallicities of CIII] emitters are not significantly different from that of the parent sample, increasing from $\sim$10% to $\sim$40% solar for stellar masses $\log$(M$_{\star}$/M$_{\odot})\sim$9-10.5. The stellar mass-metallicity relation of the CIII] emitters is consistent with previous works showing strong evolution from $z=0$ to $z\sim3$. The C/O abundances of the sample range 35%-150% solar, with a noticeable increase with FUV luminosity and a smooth decrease with the CIII] EW. We discuss the CIII] emitters in the C/O-Fe/H and the C/O-O/H planes and find they follow stellar and nebular abundance trends consistent with those of Milky Way halo and thick disc stars and local HII galaxies, respectively. A qualitative agreement is also found with chemical evolution models, which suggests that CIII] emitters at $z\sim$3 are experiencing an active phase of chemical enrichment.STAMPAenArticle10.1051/0004-6361/2021416512-s2.0-85125877764http://arxiv.org/abs/2107.00660v2https://www.aanda.org/articles/aa/abs/2022/03/aa41651-21/aa41651-21.htmlFIS/05 - ASTRONOMIA E ASTROFISICA