Change the behaviour of the initial stellar birth time overwrite parameter.

examples/SubgridTests/CosmologicalStellarEvolution/stellar_evolution.yml

@@ -40,7 +40,8 @@ SPH:
 
 # Properties of the stars
 Stars:
-  birth_time:  0.00991   # Give the star in the ICs a decent birth time
+  overwrite_birth_time: 1
+  birth_time:           0.00991   # Give the star in the ICs a decent birth time
   
 # Parameters related to the initial conditions
 InitialConditions:

examples/SubgridTests/StellarEvolution/stellar_evolution.yml

@@ -34,7 +34,8 @@ SPH:
 
 # Properties of the stars
 Stars:
-  birth_time:  0.   # Give the star in the ICs a decent birth time
+  overwrite_birth_time: 1
+  birth_time:           0.   # Give the star in the ICs a decent birth time
   
 # Parameters related to the initial conditions
 InitialConditions:

examples/parameter_example.yml

@@ -54,7 +54,8 @@ Stars:
   h_tolerance:          1e-4     # (Optional) Relative accuracy of the Netwon-Raphson scheme for the smoothing lengths. Defaults to the SPH value.
   max_ghost_iterations: 30       # (Optional) Maximal number of iterations allowed to converge towards the smoothing length. Defaults to the SPH value.
   max_volume_change:    1.4      # (Optional) Maximal allowed change of kernel volume over one time-step. Defaults to the SPH value.
-  birth_time:           -1       # (Optional) Initial birth time of *all* the stars. If not -1, this value will overwrite all the values read from the ICs.
+  overwrite_birth_time:  0       # (Optional) Do we want to overwrite the birth time of the stars read from the ICs? (default: 0).
+  birth_time:           -1       # (Optional) Initial birth times of *all* the stars to be used if we are overwriting them. (-1 means the stars remain inactive feedback-wise througout the run).
 
 # Parameters for the self-gravity scheme
 Gravity:

src/stars/EAGLE/stars.h

@@ -65,7 +65,7 @@ __attribute__((always_inline)) INLINE static void stars_first_init_spart(
   sp->time_bin = 0;
   sp->birth_density = 0.f;
   sp->f_E = -1.f;
-  if (stars_properties->spart_first_init_birth_time != -1.f)
+  if (stars_properties->overwrite_birth_time)
     sp->birth_time = stars_properties->spart_first_init_birth_time;
 
   stars_init_spart(sp);

src/stars/EAGLE/stars_io.h

@@ -217,8 +217,11 @@ INLINE static void stars_props_init(struct stars_props *sp,
   else
     sp->log_max_h_change = logf(powf(max_volume_change, hydro_dimension_inv));
 
-  /* Read birth time to set all stars in ICs to (defaults to -1 to indicate star
-   * present in ICs) */
+  /* Do we want to overwrite the stars' birth time? */
+  sp->overwrite_birth_time =
+      parser_get_opt_param_int(params, "Stars:overwrite_birth_time", 0);
+
+  /* Read birth time to set all stars in ICs */
   sp->spart_first_init_birth_time =
       parser_get_opt_param_float(params, "Stars:birth_time", -1.f);
 }
@@ -244,6 +247,10 @@ INLINE static void stars_props_print(const struct stars_props *sp) {
 
   message("Maximal iterations in ghost task set to %d",
           sp->max_smoothing_iterations);
+
+  if (sp->overwrite_birth_time)
+    message("Stars' birth time read from the ICs will be overwritten to %f",
+            sp->spart_first_init_birth_time);
 }
 
 #if defined(HAVE_HDF5)

src/stars/EAGLE/stars_part.h

@@ -144,7 +144,7 @@ struct stars_props {
   /*! Smoothing length tolerance */
   float h_tolerance;
 
-  /*! Tolerance on neighbour number  (for info only)*/
+  /*! Tolerance on neighbour number  (for info only) */
   float delta_neighbours;
 
   /*! Maximal number of iterations to converge h */
@@ -153,7 +153,10 @@ struct stars_props {
   /*! Maximal change of h over one time-step */
   float log_max_h_change;
 
-  /*! Value to set birth time of stars read from ICs if not set to -1 */
+  /*! Are we overwriting the stars' birth time read from the ICs? */
+  int overwrite_birth_time;
+
+  /*! Value to set birth time of stars read from ICs */
   float spart_first_init_birth_time;
 };