spiral galaxies appear to exhibit a large range in properties such as disk surface brightness, disk scale length, star formation rate and gas surface density. most of the galaxies studied best so far are those with the highest surface brightness. it has become quite clear recently that galaxies with low surface brightness disks are at least as numerous as the well studied high surface brightness galaxies, and understanding their evolution is very crucial. we have good photometric data and hi imaging for a large number of galaxies over a range of 4 mag/arcsec^2 in surface brightness. for the interpretation of the photometry and other properties it is important to have a good measure of the fir spectral energy distribution of the galaxies. from our study we know that the star formation rate, the gas surface density and the metallicity of the inter stellar medium (ism) decrease with decreasing surface brightness of the disk. at the extreme end one has the genuinely low surface brightness (lsb) galaxies with very low gas surface densities, metallicities of 0.2 - 0.5 solar and extremely low star formation rates. little is known about how the dust properties in galaxies vary with the surface brightness of the disk. the lower surface brightness objects have not been detected in iras, probably because the dust is much cooler than in high surface brightness (hsb) galaxies and the gas-to-dust ratio may be down by a factor 10. we propose to observe a sample of 21 galaxies with central surface brightnesses of 20 - 24 b-mag/arcsec^2 at 60, 100, 135 and 200 micron in order to determine the properties of the dust as a function of surface brightness and star formation rate.
Instrument
PHT03 , PHT32
Temporal Coverage
1996-04-04T07:48:41Z/1997-06-03T06:43:45Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the world's first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
European Space Agency, 1999, Dust Temperatures In Galaxies As Function Of Their Surface Brightness, 1.0, European Space Agency, https://doi.org/10.5270/esa-sprz8ve
