Being greater in mass, the primary is the first of the pair to evolve onto the asymptotic giant branch, where the star's envelope expands considerably.

At an age of about 1.7 billion years, the outer envelope of the star has expanded to almost 34 times the Sun's radius.

Kochab has reached a state in its evolution where the outer envelope has expanded to 42 times the girth of the Sun.

To compensate for the temperature increase, the outer envelope expanded to many times the radius it possessed as a main sequence star.

In the process, the star's outer envelope has expanded to form a deep, convective, hydrogen burning layer that is generating a magnetic field.

Its molecular envelope is expanding at a rate of 25 km/s.

The envelope will expand further, seeking a new balance between gravity and radiation pressure.

At this stage of the star's evolution, the outer envelope has expanded to around 100 times the size of the Sun.

With close to twice the mass of the Sun, the outer envelope has expanded until it is around ten times the Sun's radius.

It is 19% more massive than the Sun, but the outer envelope has expanded to around 11 times the Sun's radius.