Thuan, T. X.T. X.ThuanGoehring, K. M.K. M.GoehringHibbard, J. E.J. E.HibbardIzotov, Y. I.Y. I.IzotovHUNT, Leslie KippLeslie KippHUNT2020-05-082020-05-0820160035-8711http://hdl.handle.net/20.500.12386/24671We have obtained new H I observations with the 100 m Green Bank Telescope (GBT) for a sample of 29 extremely metal-deficient star-forming blue compact dwarf (BCD) galaxies, selected from the Sloan Digital Sky Survey (SDSS) spectral data base to be extremely metal-deficient (12 + log O/H ≤ 7.6). Neutral hydrogen was detected in 28 galaxies, a 97 per cent detection rate. Combining the H I data with SDSS optical spectra for the BCD sample and adding complementary galaxy samples from the literature to extend the metallicity and mass ranges, we have studied how the H I content of a galaxy varies with various global galaxian properties. There is a clear trend of increasing gas mass fraction with decreasing metallicity, mass and luminosity. We obtain the relation M(H I)/L<SUB>g</SUB>∝ L_g^{-0.3}, in agreement with previous studies based on samples with a smaller luminosity range. The median gas mass fraction f<SUB>gas</SUB> for the GBT sample is equal to 0.94 while the mean gas mass fraction is 0.90±0.15, with a lower limit of ∼0.65. The H I depletion time is independent of metallicity, with a large scatter around the median value of 3.4 Gyr. The ratio of the baryonic mass to the dynamical mass of the metal-deficient BCDs varies from 0.05 to 0.80, with a median value of ∼0.2. About 65 per cent of the BCDs in our sample have an effective yield larger than the true yield, implying that the neutral gas envelope in BCDs is more metal-deficient by a factor of 1.5-20, as compared to the ionized gas.STAMPAenArticle10.1093/mnras/stw22592-s2.0-85019766424000393568200058https://academic.oup.com/mnras/article/463/4/4268/26465022016MNRAS.463.4268TFIS/05 - ASTRONOMIA E ASTROFISICA