Theoretical modeling of the RR Lyrae variables in NGC 1851
Loading...
Date
2015
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
The RR Lyrae instability strip (IS) in NGC 1851 is investigated, and a model is presented which reproduces the pulsational properties of the RR Lyrae population. In our model, a stellar component within the IS that displays minor helium variations (Y∼0.248-0.270) is able to reproduce the observed periods and amplitudes of the RR Lyrae variables, as well as the frequency of fundamental and first-overtone RR Lyrae variables. The RR Lyrae variables therefore may belong to an He-enriched second generation of stars. The RR Lyrae variables with a slightly enhanced helium (Y∼0.270-0.280) have longer periods at a given amplitude, as is seen with Oosterhoff II (OoII) RR Lyrae variables, whereas the RR Lyrae variables with Y∼0.248-0.270 have shorter periods, exhibiting properties of Oosterhoff I (OoI) variables. %.