Also compute the feedback strength when a star's smoothing length is limited by its softening.

src/runner.c

@@ -282,7 +282,52 @@ void runner_do_stars_ghost(struct runner *r, struct cell *c, int timer) {
               ((sp->h <= stars_h_min) && (f > 0.f))) {
 
             stars_reset_feedback(sp);
-            feedback_reset_feedback(sp, feedback_props);
+
+            /* Only do feedback if stars have a reasonable birth time */
+            if (feedback_do_feedback(sp)) {
+
+              const integertime_t ti_step = get_integer_timestep(sp->time_bin);
+              const integertime_t ti_begin =
+                  get_integer_time_begin(e->ti_current - 1, sp->time_bin);
+
+              /* Get particle time-step */
+              double dt;
+              if (with_cosmology) {
+                dt = cosmology_get_delta_time(e->cosmology, ti_begin,
+                                              ti_begin + ti_step);
+              } else {
+                dt = get_timestep(sp->time_bin, e->time_base);
+              }
+
+              /* Calculate age of the star at current time */
+              double star_age_end_of_step;
+              if (with_cosmology) {
+                star_age_end_of_step =
+                    cosmology_get_delta_time_from_scale_factors(
+                        cosmo, (double)sp->birth_scale_factor, cosmo->a);
+              } else {
+                star_age_end_of_step = (float)e->time - sp->birth_time;
+              }
+
+              /* Has this star been around for a while ? */
+              if (star_age_end_of_step > 0.) {
+
+                /* Age of the star at the start of the step */
+                const double star_age_beg_of_step =
+                    max(star_age_end_of_step - dt, 0.);
+
+                /* Compute the stellar evolution  */
+                feedback_evolve_spart(sp, feedback_props, cosmo, us,
+                                      star_age_beg_of_step, dt);
+              } else {
+
+                /* Reset the feedback fields of the star particle */
+                feedback_reset_feedback(sp, feedback_props);
+              }
+            } else {
+
+              feedback_reset_feedback(sp, feedback_props);
+            }
 
             /* Ok, we are done with this particle */
             continue;