XMP gas-rich dwarfs in nearby voids: results of BTA spectroscopy

We present the second part of results on-going project searching for and studying eXtremely Metal-Poor (XMP, adopted as those with Z(gas) <~ Zo/30, or 12+log(O/H) 7.21~dex) very gas-rich blue dwarfs in voids.They were first identified course 'unbiased' study galaxy population nearby Lynx-Cancer void. These rare unusual galaxies seem to be best proxies so-called Very Young Galaxies (VYGs) defined recently model simulations by Tweed et al. To date, 16 preselected void XMP candidates, we obtained SAO 6-m telescope (BTA) spectra suitable determination O/H. For majority observed galaxies, principal line [OIII]4363 used direct classical T_e method O/H determination, is undetected. Therefore, estimate O/H, use a new 'Strong-lines' Izotov This appears most accurate empirical estimator range < 7.4-7.5. higher objects, semi-empirical Thuan our modification accounting variance excitation parameter O32. Six candidates are found confident dwarfs. In addition, eight studied somewhat less metal-poor, = 7.24-7.33. They also can fall into category VYG candidates. With account published us previously known (9 prototype galaxies) findings increase number this type total 19.