Extragalactic abstracts - IRSA - California Institute of Technology

Spitzer_Approved_Extragalactic
Mar 25, 10 16:24 Page 33/742
Spitzer Space Telescope − General Observer Proposal #3578
Infrared Extinction in the Magellanic Clouds
Principal Investigator: Karl Misselt
Institution: University of Arizona
Technical Contact: Karl Misselt, University of Arizona
Co−Investigators:
Karl Gordon, University of Arizona
Geoff Clayton, Louisiana State University
JD Smith, University of Arizona
Kate Su, University of Arizona
Science Category: local group galaxies
Observing Modes: IracMap IrsStare
Hours Approved: 20.7
Abstract:
We propose to examine the infrared extinction curve in the Magellanic Clouds.
As our nearest galactic neighbors, the Clouds provide an ideal laboratory for
the study of dust properites in environments very different from the Galaxy. We
will use IRAC imaging in conjunction with IRS spectra for selected targets to
explore the shape of the infrared extinction curve as well as the nature of the
dust grains in both the Large and Small Magellanic Clouds. All of our targets
have extensive data in the vacuum ultraviolet as well as optical and hence
correlations of the IR properties of the dust (shape of the extinction curve
from IRAC + IRS, mineralogy from IRS) will provide previously unavailable
insight into the nature of grains in diverse environments. In addition, the IRAC
images will provide information on the surrounding environment and its effect on
grain properties. With the IRS spectra covering the stong aborption feature of
silicate dust at 9.7 micron, we will be able to address recent evidence that
silicon is undepleted into a solid state in the SMC. Previous studies of the UV
extinction in extragalactic environments indicate that dust grains and their
attendant extinction of starlight vary significantly with environment. In
particular, the dust in the Magellanic Clouds, especially the SMC, appears
similar to that found in starburst and high redshift galaxies. Hence,
understanding how grain properties and hence their attenuation of starlight
varies in the Clouds will provide valuable tools in interpreting data from the
distant universe.
Spitzer_Approved_Extragalactic
Printed_by_SSC
Mar 25, 10 16:24 Page 34/742
Spitzer Space Telescope − Archive Research Proposal #50029
Extragalactic Cepheids from Spitzer Archival Data
Principal Investigator: Chow Choong Ngeow
Institution: University of Illinois, Urbana−Champaign
Technical Contact: Chow Choong Ngeow, UIUC
Co−Investigators:
Shashi Kanbur, SUNY at Oswego
Lucas Macri, NOAO
Science Category: local group galaxies
Dollars Approved: 25000.0
Abstract:
We have recently derived the Cepheid Period−Luminosity (PL) relations in the
IRAC bands using archival Spitzer data from the SAGE project. These PL relations
can be used in future distance scale studies with the James Webb Space
Telescope, which will mainly operate in the near and mid infrared. We propose to
test the suitability of the LMC IRAC band PL relations for extragalactic work by
applying them to extragalactic Cepheids present in archival Spitzer observations
of three nearby galaxies: WLM, IC 1613 and M33. We request a funding of $25,000
to carry out this proposal.
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