The hand of omega is a stellar manipulator.
Omega gave the time lords the power source, the ye of harmony, and got lost, but they thought he died.
I personally assumed from the language that one star powered the entire Time lord Civilization.
The movie kinda said that every Tardis had an eye of harmony.
After the timewar, the doctor no longer had access to the time lords singular power supply, which is why the ship needed rift energy to power up.
The last thing a star does before it collapses, is that it expands a couple hundred sizes.
How close to collapse is that sun?
Had it expanded, or was it only about to expand or had it collapsed a lot already and might be tiny on the way to being a complete nugget.
The Doctor knows where the Hand of Omega is hiding on Earth in 1963 where he can borrow it before destoying Skaro and make his own Eye of Harmony... The TARDIS might have hooked into the Eye after the seond Big Bang or when gallifrey came back mometarily?