NOAO > Observing Info > Approved Programs > 2002B-0023
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NOAO > Observing Info > Approved Programs > 2002B-0023 |
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PI: Edward G. Schmidt, Universtiy of Nebraska-Lincoln, eschmidt1@unl.edu
Address: Lincoln, NE 68588-0111, USA
CoI: Kevin M. Lee, University of Nebraska-Lincoln
Title: The Pulsational Properties of Type II Cepheid Variable Stars
Abstract:
We have undertaken a photometric study of the pulsational properties
of Population II or Type II Cepheid variable stars. Although in
principle the Type II Cepheids are a well defined group, distinguishing
between Type II Cepheids and the more numerous Classical Cepheids on the
basis of easily observed properties is often ambiguous and can not be
trusted in many cases. There are also significant differences among the
properties of individual Type II Cepheids which confuse classification
and need to be understood to relate them to theory.
To provide a firm basis for the investigation of the pulsation, we
are approaching the classification of Cepheids in a new way. We will
assemble a database of parameters for each of about 50 presumed Type II
Cepheids and 20 Classical Cepheids. Cluster analysis will then be used
to find groups of stars which can be associated with Type II and
Classical Cepheids and perhaps with subgroups among the Type II stars.
Many of the parameters will come from photometry done at Behlen
Observatory (such as Fourier coefficients, rise times, slopes of color-
magnitude plots, etc.) but others, such as the presence of emission
lines and line doubling or broadening, will be derived from spectra.
Seven nights were allocated to the program in July 2001. About
forty-five percent of the needed spectra were obtained.
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360
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NOAO > Observing Info > Approved Programs > 2002B-0023 |
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