A Spider Stellar Engine Could Move Binary Stars Halfway Across a Galaxy

by Evan Gough, Universe Today

Illustration of a millisecond pulsar consuming material from a companion star. Pulsars that evaporate their companions rather than consuming them could serve as stellar engines. Credit: NASA / GSFC SVS / Dana Berry

Eventually, every stellar civilization will have to migrate to a different star. The habitable zone around all stars changes as they age. If long-lived technological civilizations are even plausible in our universe, migration will be necessary, eventually.

The Concept of Stellar Engines

Could Extraterrestrial Intelligences (ETIs) use stars themselves as stellar engines in their migrations? In broad terms, a stellar engine uses a star to generate work. A simple example is solar panels, which use the sun's radiation to generate electricity that we use to perform work. But the scaled-up idea is to use the star to produce thrust, which could be used to move the star itself. An ETI capable of doing that would be termed a Type II civilization on the Kardashev Scale.

The stellar engine idea dates back to science fiction author Olaf Stapledon. A couple of decades after Stapledon, astronomer Fritz Zwicky also discussed manipulating stars with advanced technology, even turning them into spacecraft. In the decades since, the thought process behind stellar engines has persisted, with advances made by various scholars. Notably, in 1988, Leonid Shakdov developed the first detailed model of a stellar engine, termed the Shakdov Thruster.

Exploration of the Spider Stellar Engine

In recent research, Clement Vidal from Vrije Universiteit in Brussels, Belgium, delves into how an advanced civilization could use a binary star as a stellar engine. His paper titled "The Spider Stellar Engine: a Fully Steerable Extraterrestrial Design?" is available on the arXiv preprint server.

Understanding Spider Pulsars

Vidal introduces the concept of utilizing spider pulsars—binary stars comprising one millisecond pulsar and a low-mass companion star—as stellar engines. He aims to characterize the potential technosignatures emitted by these systems due to various types of maneuvers such as acceleration, deceleration, steering, and gravitational assists or captures.

According to Vidal, the emissions from the spider pulsar can provide various signals indicative of the type of engine that powers it—specifically, signatures that might arise from attempts to steer the engine using its radiation. He emphasizes the potential for observable technosignatures within our galaxy.

Stellar Engine Concepts

Vidal's study critically assesses the potential of a binary stellar engine as a propulsion system for advanced civilizations. He reasons that as the binary pair orbits their common center of gravity, the radiative energy from the pulsar strikes the companion star, generating thrust beneficial for the ETIs.

Mechanism of the Spider Stellar Engine

The mechanism relies on the companion star being used as the propellant. Mass from this star is expelled, thus allowing the binary system to move. The following critical aspects are highlighted:

• Thrust Generation: The pulsar generates thrust by expelling matter stripped from its companion star.
• Activation of Thrusters: The ETI would need technology sophisticated enough to manipulate the emitted radiation to effectively control thrust direction.
• Steering Mechanisms: The idea conveys that specific phases of the binary orbit can be exploited for better directional thrust by selectively evaporating the companion star.

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Potential Discoveries

Vidal's research opens avenues toward understanding technosignatures. Until recently, astrophysical studies focused largely on hypervelocity stars and their potential link to advanced technologies. However, his work suggests that candidate systems such as spider pulsars should be considered, as they possess distinctive features conducive to producing observable signals.

“Could our galaxy host a kind of fully steerable binary stellar engine that we proposed? This is a plausible hypothesis in the context of the stellivore hypothesis, which reinterprets some observed accreting binary stars as advanced lifeforms,” Vidal posits.

Insight into Stellivore Civilizations

According to Vidal, a stellivore civilization—a civilization that consumes its home star—has a unique evolutionary pathway. Rather than complete consumption of their home star’s energy, these civilizations might optimize mass from a lower-mass companion star as a method for propulsion:

This conceptualization could reshape our understanding of civilizations capable of exceptional advancements. It challenges the limits of what humans might think is possible regarding interstellar migration and technology.

Conclusion

In conclusion, the potential existence of spider stellar engines opens an intriguing line of inquiry into how ETIs might manipulate their environments utilizing available stellar resources. It’s a combination of science fiction and current speculative physics, with promising implications for the search for technosignatures elsewhere in the universe. As we plunge deeper into astrophysics, who knows what other planetary engineering possibilities await?

For more information, visit:

• University of Michigan Scientific Research.
• NASA's Overview on Stellar Engines NASA.
• Astrobiology Research Center Astrobiology.

Provided by Universe Today

Citation: Gough, E., (2024). A Spider Stellar Engine Could Move Binary Stars Halfway Across a Galaxy. Retrieved from Physical Science News.