I was thinking about your explanation of the light curve and it gave me an idea about detecting alien lasers. It seems natural light sources should always have a curve, but Laser light doesn't. It's a specific wavelength that only deviates a few nanometres either way....Now I know there is a Laser SETI, but as far as i know they are looking for pulses of laser light and I'm guessing they could only detect a fairly strong source of light. This would need aliens to probably be intentionally aiming a beam at us or we wouldn't detect it. So just like Radio SETI it requires aliens to be doing something that they probably aren't doing. However maybe you could still detect a much more likely event. Such as Alien's communicating with an off world colony that just happens to have them aiming a beam in our direction.
If we looked at a light curve of their star system while they were transmitting and they were using say, a green 530nm laser we would possibly see a spike in that star's light curve at 530nm. Even though the individual pulses would be too weak and short to detect. As we spent hours observing and they spent hours transmitting, the 530nm spike should become more and more promanite. Possibly to the point it would show up in our data.
Just like your green star a sharp narrow spike maybe 10nm or so wide in a star's light curve (if it were big enough) seems like it would be hard to explain through natural means. Just like the green star maybe such a laser spike is hiding in observations we already made.
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