Observations show that nearly all star clusters and stellar populations contain blue straggler stars ( BSs ) .
BSs in a cluster can significantly enhance the integrated spectrum of the host population , preferentially at short wavelengths , and render it much bluer in photometric colours .
Current theoretical simple stellar population ( SSP ) models constructed within the traditional framework of single and binary stellar evolution can not fully account for the impact of these objects on the integrated spectral properties of stellar populations .
Using conventional SSP models without taking into account BS contributions may significantly underestimate a cluster ’ s age and/or metallicity , simply because one has to balance the observed bluer colours ( or a bluer spectrum ) with a younger age and/or a lower metallicity .
Therefore , inclusion of BS contributions in SSP models is an important and necessary improvement for population synthesis and its applications .
Here , we present a new set of SSP models , which include BS contributions based on our analysis of individual star clusters .
The models cover the wavelength range from 91 Å to 160 \mu m , ages from 0.1 to 20 Gyr and metallicities Z = 0.0004 , 0.004 , 0.008 , 0.02 ( solar ) and 0.05 .
We use the observed integrated spectra of several Magellanic Cloud star clusters to cross-check and validate our models .
The results show that the age predictions from our models are closer to those from isochrone fitting in the clusters ’ colour-magnitude diagrams compared to age predictions based on standard SSP models .