In the framework of an ongoing project aimed at searching for and studying eXtremely Metal-Poor ( XMP ) very gas-rich blue dwarfs in nearby voids , we conducted spectroscopy with the 11-m Southern African Large Telescope ( SALT ) of 26 candidates , preselected in the first paper of this series ( PEPK19 ) .
For 23 of them , we detected Oxygen lines , allowing us to estimate the gas O/H ratio .
For ten of them , the oxygen abundance is found to be very low , in the range of 12+ \log ( O/H ) =6.95–7.30 dex .
Of those , four void dwarfs have 12+ \log ( O/H ) < 7.19 , or Z < Z _ { \odot } /30 .
For the majority of observed galaxies , the faint line [ O iii ] \lambda 4363 Å used to estimate O/H with the direct T _ { e } method appeared either too noisy or was not detected .
We therefore use the semi-empirical method of Izotov & Thuan ( 19 ) for these spectra , or , when applicable , the new ’ Strong line ’ method of Izotov et al .
( 2019b ) .
We present and discuss the results for all void dwarfs observed in this work .
We also compare their O/H values with O/H values of \sim 140 void galaxies available from our recent papers .
We address the properties of the newly found unusual void XMP dwarfs and compare them with those for ten known prototype void XMP objects .
The latter small group is outstanding based on their very small mass fraction of stars ( only 0.01–0.02 of the baryonic mass ) , the blue colours of stars in the outer body ( indicating a non-cosmological age for the main star-forming episode ) , and the low gas metallicity ( several times lower than expected for their luminosity ) .