Stellification is a theoretical process by which a brown dwarf star or Jovian-class planet is turned into a star, or by which the luminosity of dim stars is greatly magnified.
The fusion reaction of stars is strongly dependent upon temperature. For proton-proton reactions such as found in Earth's sun, the reaction rate scales with the fourth power of temperature (T4). For other reactions such as the CNO cycle, the proportionality can be as high as T20. Thus, increasing the temperature of the star even a small amount (for example by using reflective solar sails), would create a large increase in power output, resulting in a much higher equilibrium temperature, and therefore luminosity, of the star.
Brown dwarf stars and gas-giant planets do not achieve sustained fusion, as they contain insufficient mass to gravitationally compress the reactants to the degree required to initiate a reaction. If the density of the star or planet could be increased, fusion could be initiated. One such method is to "seed" the body with a black hole. Although the black hole would initially start swallowing the body, the huge output of radiation caused by this would resist the flow of further material. The rate of infall is bound by the Eddington limit, which shows that the luminosity of the resultant star (in Watts) would be equal to approximately six times its mass (in kilograms).
It has been suggested that a black hole could be moved into position by placing an asteroid in orbit around the black hole, and using a mass driver to direct a stream of matter into it. This could be used to move the black hole either via simple conservation of momentum, or by harnassing the power generated as a result. Zubrin (1999) suggests that a luminosity 1/10,000th that of our own sun would be required to create Earth-like temperatures on planets in close orbit to a brown dwarf, thus requiring a black hole with a mass of 6.1 × 1021 kg (about 8% the mass of Earth's moon).
It is well established that Jovian-class planets consist mostly of hydrogen and helium. It is theorised that concentrations of hydrogen and helium isotopes at certain depths of a gas-giant planet may be sufficient to support a fusion chain reaction, if sufficient energy can be delivered to ignite the reaction. Scientists have proposed that a nuclear warhead, heavily shielded and able to withstand pressures of up to 1,000 MPa (150,000 psi) may be able to reach a depth of 1,000 km (620 mi) in the atmosphere of Jupiter, potentially deep enough to reach high concentrations of isotopes and ignite a fusion reaction.In Arthur C. Clarke's 2010: Odyssey Two, an alien construct transforms the hydrogen of Jupiter's atmosphere directly into heavier elements, leading to a subsequent ignition of the planet.
In The Saga of Seven Suns by Kevin J. Anderson, humanity uses alien technology to ignite a gas giant, inadvertently wiping out a race of gaseous aliens who dwelt within and thus initiating an interstellar war.
In Star Maker by Olaf Stapledon, the eponymous "star maker" is depicted as a rational artist, akin to a god.