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- Title
Metallicity of Young and Old Stars in Irregular Galaxies.
- Authors
Tikhonov, N. A.
- Abstract
Based on archived images obtained with the Hubble Space Telescope, stellar photometry for 105 irregular galaxies has been conducted. We have shown the red supergiant and giant branches in the obtained Hertzsprung-Russel diagrams. Using the TRGB method, distances to galaxies and metallicity of red giants have been determined. The color index (<italic>V</italic> − <italic>I</italic>) of the supergiant branch at the luminosity level <italic>M</italic><italic>I</italic> = −7 was chosen as the metallicity index of red supergiants. For the galaxies under study, the diagrams have been built, in which the correlation can be seen between the luminosity of galaxies (<italic>M</italic><italic>B</italic>) and metallicity of red giants and supergiants. The main source of variance of the results in the obtained diagrams is, in our opinion, uncertainty inmeasurements of galaxy luminosities and star-forming outburst. The relation between metallicity of young and old stars shows that main enrichment of galaxies with metals has taken place in the remote past. Deviations of some galaxies in the obtained relation can possibly be explained with the fall of the intergalactic gas on them, although, this inconsiderably affects metallicities of the stellar content.
- Subjects
STELLAR structure; IRREGULAR galaxies; HUBBLE Space Telescope (Spacecraft); STELLAR photometry; HR diagrams
- Publication
Astrophysical Bulletin, 2018, Vol 73, Issue 1, p22
- ISSN
1990-3413
- Publication type
Article
- DOI
10.1134/S1990341318010029