Effects of a Burst of Formation of First‐Generation Stars on the Evolution of Galaxies

First-generation (Population III) stars in the universe play an importantrole inearly enrichment of heavy elements in galaxies and intergalactic mediumand thus affect the history of galaxies. The physical and chemical propertiesof primordial gas clouds are significantly different from those of present-daygas clouds observed in the nearby universe because the primordial gas clouds donot contain any heavy elements which are important coolants in the gas.Previous theoretical considerations have suggested that typical masses of thefirst-generation stars are between several $M_\odot$ and $\approx 10 M_\odot$although it has been argued that the formation of very massive stars (e.g., $>100 M_\odot$) is also likely. If stars with several $M_\odot$ are most popularones at the epoch of galaxy formation, most stars will evolve to hot (e.g.,$\gtrsim 10^5$ K), luminous ($\sim 10^4 L_\odot$) stars with gaseous and dustyenvelope prior to going to die as white dwarf stars. Although the duration ofthis phase is short (e.g., $\sim 10^5$ yr), such evolved stars could contributeboth to the ionization of gas in galaxies and to the production of a lot ofdust grains if the formation of intermediate-mass stars is highly enhanced. Wecompare gaseous emission-line properties of such nebulae with some interestinghigh-redshift galaxies such asIRAS F10214+4724 and powerful radio galaxies.Comment: 25 pages, 7 figures, ApJ, in pres