Question: Guran’s [comment](https://worldbuilding.stackexchange.com/a/60304/885)

> 
> Perhaps they are tinkering with the solar activity, turning stars into Yotta-watt, nano-bit/second beakons. (We would see the pattern eventually, but not before we looked at century-spanning data)
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makes me think of [astroseismology](https://en.wikipedia.org/wiki/Asteroseismology) which is a newly available field of study since new instruments can resolve this for stars [beyond our sun](https://en.wikipedia.org/wiki/Helioseismology).

![star vibrations](https://upload.wikimedia.org/wikipedia/commons/e/ec/Helioseismology_pmode1.png)

Rather than building huge power-hungry transmitters, how could an advanced civilization induce and modulate vibrations in their star that could be observed at interstellar distances but are the most miserly in energy consumption to cause?

Answer: 
The only way I can think of to modulate the star would be to modify the mechanism used for "[star lifting](http://www.orionsarm.com/eg-article/47897e8b1947c)"

Since you want to induce vibrations in the star, the so called "[huff and puff](https://www.youtube.com/watch?v=pzuHxL5FD5U)" method of star lifting which periodically "squeezes" and "releases" the star using an orbiting magnetic field generator. Rather than using the device in a regular pulsating cycle to pump plasma out of the stellar poles, the pulsations are done in a sequence which imparts information on the regular vibration patterns already existing in the star.

[![enter image description here](https://i.stack.imgur.com/ftgqH.png)](https://i.stack.imgur.com/ftgqH.png)

*Star Lifting mechanism*

Given the vast size of a star, the pattern of vibrations will be incredibly slow, and modulating the "squeeze and release" cycle of the star lifting mechanism will most likely have to take place over a period of years even to attempt to imprint information using binary code.

The other issue would be since the astroseismology signals are not obvious, even to a civilization like ours, how do you use this to signal people who are not looking for it? This seems to be a means to send information to your *own* colonies, rather than to send information to the Universe like the Library of Alexandria for all viewers.
Find a neutron star, turn it into an x-ray pulsar
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First off, no one is going to cause vibrations detectable at light years distance to their own star. Assuming they want their home planet (circling said star) to be habitable, they aren't going to put their planet through a freeze/fry cycle.

[X-ray pulsars](https://en.wikipedia.org/wiki/X-ray_pulsar) release the potential energy of accreted gasses falling to the surface of the (neutron) star giving a continuous x-ray release. As long as the neutron star is spinning with its magnetic axis (where the gas falls) tilted with respect to its spin axis, then anyone looking at the start will see the cyclic appearance and disappearance of of the x-ray beams.

To make this happen, you want to modulate the spin of the pulsar to what you desire. You can do this by accreting mass to the neutron star, which can either increase or reduce angular momentum. The best candidate for accretion mass for modulating and powering your pulsar would be another star, but I suppose a Jupiter or Super-Jupiter would work, just not for as long of a time.

Sure moving a Jupiter (or a star) to a Neutron star isn't the least energy intensive thing you can think of, but it is probably the least energy intensive way to make a galactic scale cyclic transmitter.