Metallicity of objects refers to the amount of chemical elements present in it other than Hydrogen and Helium. Note: The other elements may or may not be actual ...
There are various modes of Cepheids like single modes: fundamental (F), first overtone (1O), and likewise. And then we have double modes: F/1O, 1O/2O etc. triple modes: 1O/2O/3O etc. ...