December 01, 2016

Star lifting to mine star matter could explain dimming of Tabby's star

Arxiv - A physically inspired model of Dip d792 and d1519 of the Kepler light curve seen at KIC8462852, by Eduard Heindl1 , Furtwangen University, Germany

The star KIC 8462852 shows a very unusual and hard to comprehend light curve. The dip d7922 absorbs 16% of the starlight. The light curve is unusually smooth but the very steep edges make it hard to find a simple natural explanation by covering due to comets or other well-known planetary objects. We describe a mathematical approximation to the light curve, which is motivated by a physically meaningful event of a large stellar beam which generates an orbiting cloud. The data might fit to the science fiction idea of star lifting, a mining technology that could extract star matter. We extend the model to d1519 and d1568 using multiple beams and get an encouraging result that fits essential parts of the dips but misses other parts of the measured flux. We recommend further exploration of this concept with refined models.

Stars have deep gravity wells, so the energy required for such operations is large. For example, lifting solar material from the surface of the Sun to infinity requires 2.1 × 10^11 J/kg. This energy could be supplied by the star itself, collected by a Dyson sphere; using only 10% of the Sun's total power output would allow 5.9 × 10^21 kilograms of matter to be lifted per year (0.0000003% of the Sun's total mass), or 8% of the mass of Earth's moon.

Our Sun has 99.8 percent of the solar system's mass.

Star Lifting with Heating to boost solar wind

The simplest system for star lifting would increase the rate of solar wind outflow by directly heating small regions of the star's atmosphere, using any of a number of different means to deliver energy such as microwave beams, lasers, or particle beams – whatever proved to be most efficient for the engineers of the system. This would produce a large and sustained eruption similar to a solar flare at the target location, feeding the solar wind.

The resulting outflow would be collected by using a ring current around the star's equator to generate a powerful toroidal magnetic field with its dipoles over the star's rotational poles. This would deflect the star's solar wind into a pair of jets aligned along its rotational axis passing through a pair of magnetic rocket nozzles. The magnetic nozzles would convert some of the plasma's thermal energy into outward velocity, helping cool the outflow. The ring current required to generate this magnetic field would be generated by a ring of particle accelerator space stations in close orbit around the star's equator. These accelerators would be physically separate from each other but would exchange two counterdirected beams of oppositely charged ions with their neighbor on each side, forming a complete circuit around the star.

A mechanism for "harvesting" solar wind (RC = ring current, MN = magnetic nozzles, J = plasma jet).

Harvesting lifted mass

The material lifted from a star will emerge in the form of plasma jets hundreds or thousands of astronomical units long, primarily composed of hydrogen and helium and highly diffuse by current engineering standards. The details of extracting useful materials from this stream and storing the vast quantities that would result have not been extensively explored. One possible approach is to purify useful elements from the jets using extremely large-scale mass spectrometry, cool them by laser cooling, and condense them on particles of dust for collection. Small artificial gas giant planets could be constructed from excess hydrogen and helium to store it for future use.

Super advanced aliens managing the resources of a star

The lifespan of a star is determined by the size of its supply of nuclear "fuel" and the rate at which it uses up that fuel in fusion reactions in its core. Larger stars have a larger supply of fuel, but the increased core pressure resulting from that additional mass increases the reaction rate even more; large stars have a significantly shorter lifespan than small ones. Current theories of stellar dynamics also suggest that there is very little mixing between the bulk of a star's atmosphere and the material of its core, where fusion takes place, so most of a large star's fuel will never be used naturally.

As a star's mass is reduced by star lifting its rate of nuclear fusion will decrease, reducing the amount of energy available to the star lifting process but also reducing the gravity that needs to be overcome. Theoretically, it would be possible to remove an arbitrarily large portion of a star's total mass given sufficient time. In this manner a civilization could control the rate at which its star uses fuel, optimizing the star's power output and lifespan to its needs. The hydrogen and helium extracted in the process could also be used as fusion reactor fuel. Alternatively, the material could be assembled into additional smaller stars, to improve the efficiency of its use.

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