Paschen-alpha Imaging of a SIRTF-Selected Nearby Galaxy Sample
Abstract
We propose to carry out a NICMOS snapshot survey in the Paschen-alpha {PAlpha} emission line and H-band of the sample of galaxies being observed at 3.5 - 160 microns as part of SIRTF Nearby Galaxies Survey {SINGS} and a related guaranteed time survey of starburst galaxies. The PAlpha images, accessible only from HST, will be combined with groundbased HAlpha imaging to measure the extinction in the star-forming centers of these galaxies, and obtain robust, extinction- corrected maps of the massive star formation rate {SFR}. The PAlpha data by themselves will provide reliable `extinction- free' SFRs, and a cross-calibration of the {dust-affected} HAlpha- and UV-based SFRs. The PAlpha-based SFR measurements will extend the SFR-vs.-gas density law {Schmidt-law} to surface densities at least 30 times higher than what is accessible using HAlpha-based SFR measurements alone, bridging the gap between normal galaxies and IR-luminous starbursts. Furthermore, the combination of the HST PAlpha images with the SIRTF images and spectra, as well as ancillary ground-based UBVRIJHK images and GALEX UV images being obtained as part of the SINGS project, will provide a definitive study of the radiative transfer of starlight and dust heating in star-forming galaxies. The processed NICMOS images will be incorporated into the public SINGS Legacy Data Archive, to enable scores of follow-up studies by the astronomical community at large.
- Publication:
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HST Proposal
- Pub Date:
- July 2002
- Bibcode:
- 2002hst..prop.9360K