It has an estimated average median radius of 1,708 solar radii , or a diameter of 2.4 billion km ( 1.5 billion mi ; 15.9 AU ) ; thus a volume 5 billion times that of the Sun .
The star has an estimated average median radius of 1,708 times that of the Sun , or a diameter of 2.4 billion km ( 1.5 billion mi ; 15.9 AU ) ; thus a volume 5 billion times that of the Sun .