Stellar Populations in Early-Type Galaxies with Nuclear Star-Bursts
Abstract
Strong nuclear star-bursts are occurring in a significant fraction of SO and early-type spiral galaxies, particularly barred galaxies. I have used IRAS far infrared colors and fluxes to find galaxies with the strongest on-going bursts. I have taken U, B, R, I, and H-alpha images and long-slit spectra of these galaxies to find the most optically intense bursts and to characterize their stellar populations. Three of the galaxies have particularly deep Balmer absorption lines due to optically-dominant A star populations, and strong Balmer line emission powered by O and B stars. The spectra and images directly indicate the number Of A stars present in the bursts, but only limited and indirect information about the more massive stars can be obtained from this data. Short wavelength SWP spectra are needed to determine the mix of O and B main sequence stars, and possibly massive evolved stars, in the bursts. This mix will be determined chiefly from the absorption (and possibly emission) equivalent widths of the Si IV and C IV features at 1400 and 1550 Angstroms. The deduced numbers of O, B, and A main sequence stars can then be compared to models of continuous bursts with different initial mass functions, and to models of multiple bursts, to characterize this particular type of star-burst.
- Publication:
-
IUE Proposal
- Pub Date:
- 1992
- Bibcode:
- 1992iue..prop.4226D