The distance-size ratio for the sun-nearest other star system is of an order of magnitude of

Proxima Centauri is the closest star to that of the sun and being 4.22 light years away from the earth having an apparent magnitude of 12.95.

Explanation:

Being a small and low mass star locate away from the sun in southern constellation being discovered in 1915 by Robert innings. Having an apparent magnitude of 11.3 having an Astronomical number of 12,950 from the orbital period of 550,000 years. Proxima Centauri is a red dwarf star with a mass of eight times that of sun, and an average density that of sun, more than 85%of the radiation is infrared and has the regular activity of starspots. Being closes to the sun around 32,000 years away. It thass an orbital period of 3.6 to 14 days.

Magma is outside the volcano  and lava is inside the volcano.