Contents of: VI/111/./abstract/GSPEAR_GS_BM_1.abs

The following document lists the file abstract/GSPEAR_GS_BM_1.abs from catalogue VI/111.
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     We propose to observe selected Cepheids in the Large Magellanic
 Cloud (LMC) using the IRAS 12 micron band.  Using our previously
 established period-luminosity relation (PLR) at 12 microns for
 galactic Cepheids, we will derive a new and independent distance
 measurement for the LMC.  These ISO Cepheid observations will also
 enable us to determine a new 12 micron PLR for the LMC Cepheids.
 This will allow us to compare the galactic PLR with a PLR
 determined for Cepheids in an extragalactic system.  We will then
 search for systematic differences between these two relationships.
 This comparison will be significant since the LMC is known to be
 somewhat metal poor in comparison to the Milky Way galaxy.
     The PLR at the far-infrared wavelength of 12 microns effectively
 provides us with a new and powerful technique for determining
 galactic and extragalactic distances.  Because of the diminished
 amplitude and diminished asymmetry of the light variation for
 Cepheids in the infrared, reliable determinations of mean light
 levels are possible by employing a simple mean of several random-
 phase observations.  Furthermore, at a wavelength of 12 microns the
 interstellar dust produces no measurable effects, so uncertain
 corrections for interstellar extinction are not required.  Finally, the
 absence of metallic absorption features in this part of the spectrum
 should minimize any systematic effects due to chemical abundances.
     The observations we propose will enable us to demonstrate the
 power and the reliability of this new technique for determining
 galactic and extragalactic distances.  This technique requires
 minimal observations and is independent of interstellar extinction
 and differences in chemical composition.  The results from this
 proposal will be essential for studies of galactic structure and the
 local extragalactic distance scale which use data from IRAS, ISO,
 and SIRTF.

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