Young stars in the outer HI disc of NGC 6822
Date
2003
Authors
de Blok, Willem
Walter, F.
Journal Title
Journal ISSN
Volume Title
Publisher
Blackwell Publishing Ltd
Abstract
We present wide-field optical imaging covering the entire neutral hydrogen disc of the Local Group dwarf galaxy NGC 6822. These observations reveal the presence of numerous blue, young stars at large galactocentric radii well beyond R25. Blue stars are also found that are associated with NGC 6822's companion H I cloud, indicating that star formation was triggered in the companion in the last 108 yr. In general, blue stars are present where the H I surface densities reach values ≳ 5 × 1020 cm-2. However, over one-third of the blue stars detected within the H I disc are found at lower surface densities. The young stars trace the distribution of the neutral hydrogen in the inner disc, but seem to be avoiding the supergiant H I shell in NGC 6822, setting a lower limit for its age of 108 yr. The extended distribution of young stars implies that stars can form at large galactocentric radii in dwarf galaxies; the H I is therefore not necessarily much more extended than the stellar population. This finding has important consequences for the chemical enrichment of the interstellar medium throughout (dwarf) galaxies.
Description
Keywords
Keywords: Galaxies: dwarf; Galaxies: evolution; Galaxies: individual: NGC 6822; Galaxies: stellar content
Citation
Collections
Source
Monthly Notices of the Royal Astronomical Society
Type
Journal article
Book Title
Entity type
Access Statement
License Rights
Restricted until
2037-12-31
Downloads
File
Description