Star formation and chemical abundances in clumpy irregular galaxies.
Abstract
Clumpy irregular galaxies consist of several bright clumps which are huge H II complexes (about 100 times brighter and more massive than 30 Doradus) and contain about 100,000 O and B stars. Image-tube spectrograms with 1-3 A resolution have been obtained of the brightest emission regions of three clumpy galaxies and one candidate clumpy galaxy with the Mauna Kea 2.24 m telescope. The electron temperatures were found to be in the range 7000-9000 K and electron densities a few hundred per cu cm - quite typical for normal H II regions. The abundances of O, N, S in Mrk 432 are comparable to those in Orion, while the three clumpy galaxies are slightly deficient in O and S (by factors of 2 to 4) and N (by factors of 3 to 6). The galaxies appear to be normal (like Sc galaxies) in mass and composition. Supernovae remnants are indicated by the high forbidden S II/H alpha ratio. Possible triggering mechanisms for the exceptional star formation activity are discussed.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 1982
- DOI:
- 10.1086/159577
- Bibcode:
- 1982ApJ...252..487B
- Keywords:
-
- B Stars;
- Chemical Composition;
- Galactic Structure;
- O Stars;
- Star Formation;
- Abundance;
- Data Reduction;
- Electron Density (Concentration);
- Electron Energy;
- Galactic Nuclei;
- H Ii Regions;
- Nebulae;
- Supernova Remnants;
- Astrophysics