in this proposals we will make an attempt to get an indication for the supernovae rates in the hii regions of m33. we will use feii emission as an indicator for the supernovae rates. two prime questions asked are, does the supernovae rate depend on the galactocentric radius and is the supernovae rate directly connected with the slope of the radio spectral index. a radio continuum study of hii regions in m33, lahuis and van der hulst (in preparation) has shown that the spectra of hii regions are often not thermal. on the contrary, the spectral indices range from -0.1 to -0.8, in the latter case the spectra appear to be largely non-thermal. the excess of 20cm flux over 6cm flux ranges from a few tenth to a few tens of a mjy. there also appears to be a steepening of the spectral index with increasing galactocentric radius. the origin of this non-thermal radiation is not quite clear. one of the possibilities thought of is the supernova activity within the hii regions. that this could give a great contribution is demonstrated in a radio continuum study of known supernovea by duric. he found that the excess of 20cm flux over 6cm flux is of the order of a few tenth of a mjy to a few mjy. to check this we need to know the supernovae rates within individual hii regions. the use of feii emission has previously been suggested as an indicator for the supernovae rates in starburst galaxies (e.g. lumsden and puxley, 1993). we would like to try this for some individual hii regions using sws on three feii lines. since several of the transitions between the low lying levels of feii lie within the sws range we now have an ideal opportunity to do this.
Instrument
CAM01 , SWS02
Temporal Coverage
1998-01-31T10:52:08Z/1998-01-31T11:18:16Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the worlds 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, LAHUIS et al., 1999, 'HII REGIONS IN M33 comma SUPERNOVAE RATES', 1.0, European Space Agency, https://doi.org/10.5270/esa-d8e8bp6
