def METHOD_NAME(self, ptype):
    if ptype == "STAR":
        def _creation_time(field, data):
            return YTArray(
                data.ds._handle.tphys_from_tcode_array(data["STAR", "BIRTH_TIME"]),
                "yr",
            )
        def _age(field, data):
            return data.ds.current_time - data["STAR", "creation_time"]
        self.add_field(
            (ptype, "creation_time"),
            sampling_type="particle",
            function=_creation_time,
            units="yr",
        )
        self.add_field(
            (ptype, "age"), sampling_type="particle", function=_age, units="yr"
        )
        if self.ds.cosmological_simulation:
            def _creation_redshift(field, data):
                return (
                    1.0
                    / data.ds._handle.auni_from_tcode_array(
                        data["STAR", "BIRTH_TIME"]
                    )
                    - 1.0
                )
            self.add_field(
                (ptype, "creation_redshift"),
                sampling_type="particle",
                function=_creation_redshift,
            )
    super().METHOD_NAME(ptype)