high refinement memory error

In [24]: data=cg['density']
---------------------------------------------------------------------------
MemoryError                               Traceback (most recent call last)
<ipython-input-24-ca3058876a5b> in <module>()
----> 1 data=cg['density']

/opt/apps/yt/yt-x86_64/src/yt-hg/yt/data_objects/data_containers.py in __getitem__(self, key)
    251                 return self.field_data[f]
    252             else:
--> 253                 self.get_data(f)
    254         # fi.units is the unit expression string. We depend on the registry
    255         # hanging off the dataset to define this unit object.

/opt/apps/yt/yt-x86_64/src/yt-hg/yt/data_objects/construction_data_containers.py in get_data(self, fields)
    598         fill, gen, part, alias = self._split_fields(fields_to_get)
    599         if len(part) > 0: self._fill_particles(part)
--> 600         if len(fill) > 0: self._fill_fields(fill)
    601         for a, f in sorted(alias.items()):
    602             self[a] = f(self)

/opt/apps/yt/yt-x86_64/src/yt-hg/yt/data_objects/construction_data_containers.py in _fill_fields(self, fields)
    878             if level == 0 and tot != 0:
    879                 raise RuntimeError
--> 880             self._update_level_state(ls)
    881         for name, v in zip(fields, ls.fields):
    882             if self.level > 0: v = v[1:-1,1:-1,1:-1]

/opt/apps/yt/yt-x86_64/src/yt-hg/yt/data_objects/construction_data_containers.py in _update_level_state(self, level_state)
    949         new_fields = []
    950         for input_field in level_state.fields:
--> 951             output_field = np.zeros(ls.current_dims, dtype="float64")
    952             output_left = level_state.global_startindex + 0.5
    953             ghost_zone_interpolate(rf, input_field, input_left,

MemoryError: