Star-forming complexes in a sample of spiral and irregular galaxies

Citation
Dm. Elmegreen et Jj. Salzer, Star-forming complexes in a sample of spiral and irregular galaxies, ASTRONOM J, 117(2), 1999, pp. 764-777
Citations number
62
Categorie Soggetti
Space Sciences
Journal title
ASTRONOMICAL JOURNAL
ISSN journal
00046256 → ACNP
Volume
117
Issue
2
Year of publication
1999
Pages
764 - 777
Database
ISI
SICI code
0004-6256(199902)117:2<764:SCIASO>2.0.ZU;2-K
Abstract
Over 300 star-forming complexes in 11 intermediate- and late-type spiral an d irregular galaxies have been observed in the B, I, and Ha bands to determ ine their luminosity functions, ages, sizes, and masses. The total Ha lumin osity from complexes compared with the total galaxy H alpha luminosity rang es from 20% to 70%, but the percentage is nearly constant at 7% in the B ba nd for most galaxies. A comparison of the colors and luminosities of the co mplexes with published cluster evolutionary models suggests that the comple xes range in age from a few times 10(6) yr to nearly 10(9) yr; the majority have ages of less than 1 to 2 x 10(7) yr. The complex masses range from 10 (4) to 10(7) M-. The luminosity functions for the complexes follow a power law with an exponent of approximately -2; late-type galaxies have slightly shallower slopes than intermediate-type galaxies. The sizes of the largest complexes in each galaxy scale approximately with the square root of the ga laxy luminosity, confirming previous studies. The complexes may have a frac tal size distribution that is consistent with values predicted by theoretic al turbulence models of the interstellar medium.