The following document lists the file abstract/GSPEAR_GS_BM_1.abs
from catalogue VI/111.
A plain copy of the file
(without headers/trailers) may be downloaded.
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.