Episode 40 - globular clusters, extended disks, high redshift galaxies and aliens!

Okay.

So my first paper today is called Project Hephaistos IV: JWST Observations of Two Dyson Sphere Candidates.

[gasps] Dyson spheres.

Dyson spheres.

It's been a while.

Yeah.

Since we were here.

So, exactly.

So this is Zachrisan et al from MNRAS, and Zachrisan is based at Uppsala University.

And yeah, we have talked about Dyson spheres, I think in the very early Star Archive now, and these are very exciting.

We're effectively hunting for signs of alien, intelligent alien life, right? So the idea of a Dyson sphere is that you have found a way of building a mega structure around your star, which either completely or partially covers it, but is able to absorb a bunch of the radiation and use that to power your advanced civilization somehow, whether that's for your power needs, if it's for interstellar travel or communication, and things like that.

If you, obviously, if you can detect a Dyson sphere, then you've detected the signs of alien life.

It's a high-risk, high-reward area of study.

Now, we think we may be able to detect them if they do exist because they may be a little bit leaky.

So you'd have...

They, they, they're gathering all this energy from the star, but they may also leak energy in the infrared, which you then could use as an infrared signature around a star or in or c- like, in the same region of a star that could be the sign of waste heat coming from that Dyson sphere.

So with the, the types of observations we have these days going ac- across the full electromagnetic spectrum, it's possible that you could look at stars and look for signs of infrared excess as a way of trying to identify a Dyson sphere candidate and then see if you can follow it up and figure out if it's a real Dyson sphere.

So that sounds nice and straightforward, but it's actually very challenging.

So one of the main problems is that a lot of the previous infrared surveys looking in the spectral region that you're interested in have quite a low spatial resolution.

So stars are obviously point sources, and you may get an infrared detection at that particular star's location.

But you don't know for sure that it's actually at that same location as a star or if it's just adjacent to it.

So you could be looking at a background object, or you also have intrinsic astrophysical phenomena that could also produce an infrared excess in the same band that has nothing to do with a Dyson sphere.

Uh, so one of the main astrophysical sources that can mimic the IR signature you expect to find from Dyson spheres, dust-enshrouded young stars.

So you have a young star, but it's surrounded by dust and that's emitting in the infrared, and that could then be, uh, mimic a Dyson sphere.

Now, in the earlier work from this group, because we're on paper four now, they've managed to identify a number of the candidates that probably are these young stars by looking for signs of youth in this, the host star itself.