NOAO > Observing Info > Approved Programs > 2010A-0311
|
NOAO > Observing Info > Approved Programs > 2010A-0311 |
|
PI: Ata Sarajedini, University of Florida, ata@astro.ufl.edu
Address: Astronomy Department, 211 Bryant Space Science Center, Gainesville, FL 32611-2055, United States
CoI: Shashi Kanbur, SUNY - Oswego
CoI: Karen Kinemuchi, University of Florida
CoI: Chow Choong Ngeow, National Central University
Title: Unlocking the Secrets of the Oosterhoff Effect: A Period-Amplitude-Color Analysis of RR Lyrae Variables
Abstract:
Within our Galaxy, globular clusters can be divided into two
distinct groups based on the properties of their RR Lyrae (RRL) variable
stars: Oosterhoff I and II (OoI and OoII). Fundamental mode RRL in the
two types of clusters exhibit not only different average periods (0.55
and 0.65 days, respectively, for OoI and OoII), but also very different
Period-Amplitude (PA) relations. One possible explanation in the
literature is that OoII clusters are more evolved than OoI. We propose
to construct well sampled multicolor observations of Galactic globular
clusters that currently have few time series observations. Adding these
observations to the existing data, we will formulate Period-Color (PC)
and Amplitude-Color (AC) relations as a function of pulsation phase and
Oosterhoff type. The resulting relations will permit a more detailed
comparison of RRL properties with Oosterhoff type. It can be
demonstrated that PA relations can be decomposed into PC and AC
relations at maximum and minimum light, which can be traced to the
interaction of the stellar photosphere and hydrogen ionization front,
which in turn, may depend on the evolutionary status of the star.
Further, our multiphase, multicolor observations will be able to place
significantly stronger constraints on the pulsation models of RRL stars
than has hitherto been possible.
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360
|
NOAO > Observing Info > Approved Programs > 2010A-0311 |
|