The Brightest Stars of Irregular and Low-Mass Spiral Galaxies

search for a correlation between the luminosities of the brightest stars and luminosities of their host galaxies was carried out on archival Hubble Space Telescope (HST) F606W or F555W ( V ) and F814W ( I ) images of 150 nearby galaxies. The sample contains only galaxies with ongoing star formation and with known distances we derived with the TRGB-method. We correlated the average absolute luminosities of the three brightest blue and the three brightest red stars with the luminosity of a host. We find a linear relation for both the blue and the red stars in irregular and low-mass spiral galaxies. Their scatters are sufficiently small ( 0.^m4 ) to make these relations useful for distance determination for low-mass galaxies. We found that all 31 dwarf galaxies (M_B > - 13^m) in our sample lack bright massive stars (M_V(BS) < - 7.^m0) , probably due to the physical conditions that prevent their birth. For galaxies with higher an average luminosity in the range - 18^m < M_B < - 13^m , there is an asymmetry in the distribution of the number of galaxies relative to the linear dependence, indicating an increase in the fraction of galaxies with bright stars.