What is exactly happening when instantiating with 'new'?

Let's consider the following code:

class a {
    public $var1;
    function disp(){
        echo $this->var1;
        }    
    }

$obj1 = new a;
echo '<br/>After instantiation into $obj1:<br/>';    
xdebug_debug_zval('obj1');  

$obj1->var1 = "Hello ";
echo '<br/><br/>After assigning "Hello" to  $obj->var1:<br/>';
$obj1->disp();

echo "<br/><br/>";  
xdebug_debug_zval('obj1');  

The output:

After instantiation into $obj1:
obj1: (refcount=1, is_ref=0)=class a { public $var1 = (refcount=2, is_ref=0)=NULL }

After assigning "Hello" to $obj->var1:
Hello

obj1: (refcount=1, is_ref=0)=class a { public $var1 = (refcount=1, is_ref=0)='Hello ' }

One by one:

After instantiation into $obj1:
obj1: (refcount=1, is_ref=0)=class a { public $var1 = (refcount=2, is_ref=0)=NULL }

Why does $obj1->var1 have refcount=2 when there is only one object of class a?

Is it because of how the new operator makes assignment? PHP does assignment with references. When instantiated with new, no symbol/variable name is associated with that instance. But, the class properties do have names. Is the recount=2 because of this?

If that is the case then a C.O.W (copy on write) has occurred with a shallow copy WRT the class instance. While the properties are still pointing to the zval's of properties created during the instantiation using new.

Now,

After assigning "Hello" to $obj->var1:
Hello

obj1: (refcount=1, is_ref=0)=class a { public $var1 = (refcount=1, is_ref=0)='Hello ' }

So, when I assign a value to the property $obj1->var1 a new zval container for that property and hence the refcount=1