H-Alpha Imaging Survey of Early-Type(Sa-Sab) Spiral Galaxies

We are conducting an H-Alpha survey of a complete sample of 57 bright (m(B) < 12.1 mag.), nearby (D < 40 Mpc), early-type(Sa-Sab) spiral galaxies.


This survey is motivated by a recent analysis of the IRAS database by Devereux & Hameed 1997 (AJ 113, 599), which suggests that the global massive star formation rates in early-type spirals are comparable to the global massive star formation rates in late-type spirals.

WHY USE H-Alpha:

The use of the far infrared luminosity as a tracer of high mass star formation is still being debated in the literature. Therefore, we are imaging these galaxies in H-Alpha, which is a less controversial tracer of high mass star formation.

The H-Alpha images reveal the morphology and luminosity of the hydrogen gas. The H-Alpha flux provides a measure of the massive star formation rate, but it will be a lower limit because of extinction. The continuum images elucidate large scale morphological features such as stellar bars and bulges and evidence for interactions.

Images from the Survey

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