Hi All

Paul Birch has a series of online papers that discuss how he re-engineers the planets and mines the Sun for mass...

How to Spin a Planet

How to Move a Planet

...and if you really want to move star you can try the old stellar rocket design which uses half-a-Dyson sphere to reflect the star's own light as a giant photon-rocket. Thrust is a gargantuan 12x10^17 Newtons, but the acceleration is miniscule. Enough to shift the Sun by a light year over a billion years. Integrated over the Sun's total fusion energy output and its final velocity is over 2000 km/s, enough to escape the Galaxy and roam intergalactic space. Controlling core-convection and luminosity will be a very delicate job. Distance travelled when the gas runs out ~ 638 million light years. Fusing helium would add ~ 30% to burn time but it's even harder to control... (temp)^17 sensitivity and all that.

Faster travel would require total conversion and/or using Sun's mass as reaction mass. If we could use 45% - more than 50% cuts the planets loose - of its mass then about 0.5 c is feasible. Of course the planets would be converted into a Dyson Cloud which could maneuver in closer as the mass fell allowing a higher mass-fraction.

Next: Moving Galactic Black-holes...

Adam