The fastest-moving stars in the galaxy may be piloted by intelligent aliens, new paper suggests

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To explore the galaxy and hunt for resources, intelligent aliens might need to turn their home stars into natural spaceships, a new paper suggests. A few known star systems might fit the bill.

An alien megastructure like a Dyson sphere doesn’t seem to be causing the weird dimming of one of the weirdest stars in our galaxy, Tabby's star.
An illustration of a Dyson Sphere, a hypothetical structure that aliens could use to harness the power of stars. (Image credit: dottedhippo/iStock/Getty Images Plus)

An advanced alien civilization may want to cruise around the galaxy, and the best way to do that is by steering their binary star system, a researcher proposes in a new paper.

Long-lived civilizations may have many motivations for wanting to move somewhere else in the galaxy. They may need to escape an impending supernova, for example. Maybe they need to scout our new natural resources. Or maybe they just feel like exploring.

Given the enormous distances between the stars, however, interstellar travel is tremendously difficult and time-consuming. So, instead of leaving their system, an intrepid alien species might decide to take their system with them. The main advantage of accelerating their own star would be that they get to keep it with them as they travel. They would do this by causing their star to either radiate or evaporate in just one direction, which would propel the star, along with all of its planets, to a new location in the galaxy.

Astronomers have investigated whether "hypervelocity" stars (which, as their name suggests, are stars with an extraordinarily high velocity) may have been purposefully launched by alien civilizations, but the known candidates show no signs of artificial interference.


Related: Astronomers Detect a Swarm of Tiny Objects Orbiting an Alien Sun

In a recent paper, Clement Vidal, a philosopher at the Vrije University Brussels in Belgium, pointed out that most stars are not solitary but rather belong to binary systems. This means we might be missing half of the potential artificially accelerated stars. Even better, binary systems offer many advantages over their solo counterparts, Vidal wrote in his paper, which has not been peer-reviewed or published in a scientific journal.

Vidal took a model system consisting of a neutron star with a low-mass star tightly orbiting it. This setup provides the most flexibility in steerability and thrust.

The alien civilization would have to figure out a way to eject material from the star. This could be from asymmetric magnetic fields or from some device that causes uneven heating on the stellar surface. No matter what, the goal would be to get the star to eject more material in one direction than another. This would create thrust, pushing the binary system in the opposite direction, Vidal explained.

If the civilization were to place the machinery on or near the neutron star, where the strong gravity could provide a ready source of energy, they could steer the binary system by carefully cycling the machine off and on. For example, if they activated the machine only at the exact same point in the orbit, they would send the binary system in one direction. If they left the machine activated slightly longer, they would adjust their course, pointing their movement in any direction they wished along the orbital plane.

They could even steer their system in new off-orbit directions by altering the direction in which their machine was pointed, effectively changing the orbit of the neutron star around its companion.

Amazingly, there are real systems in the universe that match these kinds of characteristics, like the "black widow" pulsar PSR J0610-2100 and the "redback" pulsar PSR J2043+1711. Both of those systems have significant accelerations. Although they are unlikely to be caused by alien engineering, they are worth looking into, Vidal concludes. At least, while they're still around.

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Paul Sutter
Paul Sutter
Space.com Contributor

Paul M. Sutter is an astrophysicist at SUNY Stony Brook and the Flatiron Institute in New York City. Paul received his PhD in Physics from the University of Illinois at Urbana-Champaign in 2011, and spent three years at the Paris Institute of Astrophysics, followed by a research fellowship in Trieste, Italy, His research focuses on many diverse topics, from the emptiest regions of the universe to the earliest moments of the Big Bang to the hunt for the first stars. As an "Agent to the Stars," Paul has passionately engaged the public in science outreach for several years. He is the host of the popular "Ask a Spaceman!" podcast, author of "Your Place in the Universe" and "How to Die in Space" and he frequently appears on TV — including on The Weather Channel, for which he serves as Official Space Specialist.

9 Comments Comment from the forums
  • Unclear Engineer
    "They would do this by causing their star to either radiate or evaporate in just one direction, which would propel the star, along with all of its planets, to a new location in the galaxy."

    But, that would propel just the star, not the planets. The planets would have to tag along because of being attracted by the star's gravity. But, that would seriously disrupt the orbits of those planets! It would be the same effect on their orbits as if they were all accelerated in one direction at the same time while the star stood still.

    Maybe by using only extremely slow acceleration rates for the star, so that the planets could keep getting back into sync and not develop too much eccentricity in their orbits?

    But then the "trip" would take far longer than if a space craft accelerated just itself.

    Now, if you want to imagine "tractor beams" with the power to pull stars around, then those could also bring along planets with ease, even those bigger than Jupiter, by using the beams on the planets as well as the star.

    (Who thinks up this stuff?)
    Reply
  • Mojo Jojo
    Unclear Engineer said:
    "They would do this by causing their star to either radiate or evaporate in just one direction, which would propel the star, along with all of its planets, to a new location in the galaxy."

    But, that would propel just the star, not the planets. The planets would have to tag along because of being attracted by the star's gravity. But, that would seriously disrupt the orbits of those planets! It would be the same effect on their orbits as if they were all accelerated in one direction at the same time while the star stood still.

    Maybe by using only extremely slow acceleration rates for the star, so that the planets could keep getting back into sync and not develop too much eccentricity in their orbits?

    But then the "trip" would take far longer than if a space craft accelerated just itself.

    Now, if you want to imagine "tractor beams" with the power to pull stars around, then those could also bring along planets with ease, even those bigger than Jupiter, by using the beams on the planets as well as the star.

    (Who thinks up this stuff?)
    My train of though says that if a society has a Dyson sphere, they're probably self sufficient in space without a planet? Maybe orbiting the sun or the society could be built on the Dyson sphere itself. And if we remove our ethical qualms about the planets and say "screw the planets," all they would need when they travel is the star?

    The original post is very cool, I never thought of this application for advanced societies! Thank you OP!
    Reply
  • Unclear Engineer
    Still won't work as described in the article.

    A "Dyson sphere" is not anchored to the star, physically. And, any "thrust" from the star would impinge on the sphere, pushing it in the opposite direction compared to where the star would move. So, the sphere would end up with the star hitting it! Even if the stars "exhaust" producing the thrust did not hit the sphere, say because they put a hole in exactly the right place, the star would still move relative to the sphere unless they also somehow applied thrust to the sphere. It would probably be easier to move just a planet in phase with the star than to move a whole Dyson sphere.

    By the way, I am no fan of the Dyson sphere concept either.

    Remember, that sphere must somehow allow the entire energy production of the star to pass through it, while extracting some work from it. Otherwise, it would just keep heating up until it vaporized. You can actually calculate the outer temperature of the sphere by taking the energy production of the star and the surface area of the sphere (at whatever radius it is designed for) and calculating the black body temperature needed to radiate that much energy from that much surface.

    So, if we want to look for Dyson spheres, we should do that calc and look for the proper temperature signature.

    I seriously doubt we are going to find any.

    For one thing, it would take a lot of mass to surround a star with a sphere. A sphere the radius of Earth's orbit has an area of about 2.8 x10^23 square meters, and the total mass of Mars, Earth, Venus and Mercury is about 1.2 x10^25 kg. So, assuming that the entire masses were materials that could be used to make structure, the Dyson shell would be about 42.5 kg/m^2. Since most of that would be iron, I use the density of iron (7,870 kg/m^3) to calculate a thickness of the sphere as 5.4 mm thick. And that is an upper limit, because a lot of the masses of those plants is not iron.

    Yes, they could make the diameter smaller, but that would make the temperature hotter.

    I'll leave it to somebody else to do the calcs to try to find a Dyson sphere design for our own solar system that seems physically plausible, considering both structural material availability and temperature constraints.
    Reply
  • Frank Sterle Jr
    Admin said:
    To explore the galaxy and hunt for resources, intelligent aliens might need to turn their home stars into natural spaceships, a new paper suggests. A few known star systems might fit the bill.

    The fastest-moving stars in the galaxy may be piloted by intelligent aliens, new paper suggests : Read more
    With the human race desperately needing a unifying common cause, perhaps a vicious extraterrestrial attack is what we collectively need to brutally endure in order to survive the long-term from ourselves.

    Humanity could all unite for the first time ever to defend against, attack and defeat the humanicidal multi-tentacled ETs, the latter needing to be an even greater nemesis than our own formidably divisive politics and perceptions of differences, both real and perceived — especially those involving race and nationality.

    During this much-needed human alliance, we’d be forced to work closely side-by-side together and experience thus witness just how humanly similar we are in the ways that really count.


    Still, maybe some five or more decades later when all traces of the nightmarish ET invasion are gone, we'll inevitably revert to those same politics to which we humans seem so collectively hopelessly prone — including those of scale: the intercontinental, international, national, provincial or state, regional and municipal. And again we slide downwards.
    Reply
  • Dave
    Intelligent lifeforms capable of interstellar travel have unity and are beyond our social understanding. They would not be socially aggressive . It will be up to us to find a way, a way to unite, to integrate ideologies. There is only one race. The human race. If any of us were to stand on top of the world you will see what is truly real. No borders. There is no atlas. You will see an incredible diversity of life in its many forms, and you will see humanity. Carl Sagan showed us the pale blue dot. War, poverty and climate change stymie us because they are human problems. We are a collection of countries (tribes) that need to act as one tribe. Human.

    Using a star for travel is a clever idea. However, a triple star system such as Alpha Centauri may serve future humankind better than our own star. There would be more powerful energy sources. This is of course assuming that these resources are not already being used. Proxima b is a good candidate for both life and intelligent life.
    Reply
  • Unclear Engineer
    I think that Frank Sterle Jr is right to worry that even humans united against a vanquished common enemy invader would later splinter into warring tribes. That is what we have always done in the past. And it is what other social species do when their populations grow too large.

    To me, the solution is to recognize that our own emotional traits lead to overpopulation that is destructive to both our own societies and the environments in which we all have to live. As Walt Kelly wrote in his "Pogo" comic strip over half a century ago, "We have met the enemy, and he is us."

    Unless and until we can internalize the reality that we create our own problems, we will continue to suffer from them.

    But, even in a single family, there are too often individuals with destructive instead of destructive behaviors for the family itself. It is "society" that attempts to establish and enforce norms of behavior that lead to a stable and beneficial society - the large "family". And, it seems that some bad actors are born, not made by the problems that already exist. So, we will probably always have some fraction of our population being "bad actors". And we will likely never have complete agreement on what is actually "bad" and what is "tolerable".

    Society and technical progress might stagnate with complete conformity.

    So, what norms we establish and how we are able to enforce them will determine our destiny.

    And, the scary thing is that doing so involves "politics".
    Reply
  • motie
    Any inhabited body flying through a solar system at very high speed relative to the local system is going to have a lot of "stuff" flying at it with very high speeds and very high impact energies.
    Reply
  • George²
    But what speed have the fastest known star moving through the Milky Way?
    Reply
  • Unclear Engineer
    George² said:
    But what speed have the fastest known star moving through the Milky Way?
    Something like 1.3 million mph, "which is almost three times as fast as the speed of the sun in its orbit around the heart of the Milky Way. " See https://www.livescience.com/space/astronomy/something-kicked-this-hypervelocity-star-racing-through-the-milky-way-at-13-million-miles-per-hour

    (Apparently they can't put periods in link URLs)
    Reply