Metallicity of Young Stars of the NGC 4068 Galaxy

Abstract

Based on archival images from the Hubble Space Telescope, stellar photometry of the galaxy NGC 4068 was carried out. The resulting Hertzsprung-Russell diagram (CM diagram) shows branches of young and old stars. To estimate the metallicity of young stars, isochrones of different ages and metallicities were used. A combination of isochrones and the CM diagram of stars shows that the young stars of NGC 4068 have high metallicity, up to the metallicity of the Sun (\(Z=0.02\)). Since stars of high metallicity are observed throughout the body of the galaxy, we can talk about high metallicity of the entire galaxy, and not just one local region. The position of NGC 4068 among 105 irregular galaxies of different metallicities is shown on a diagram of the dependence between the metallicities of old and young stars. The almost linear dependence between these parameters indicates the absence of processes of rapid enrichment of galaxies with metals at the present stage of their evolution. The obtained results do not confirm the conclusion about the low metallicity of NGC 4068 reported earlier. For direct measurements of the metallicity of NGC 4068, the coordinates and fields of identification of the three brightest red supergiants with a high color index \((V-I)\), which indicates their high metallicity, are presented.