Ok twitter, time to answer the age old question: which came first, the chicken or the egg? But to figure it out, we need science! Let’s introduce you to our contestants.

In this corner, we have the Running Chicken Nebula. As @emsque pointed out on our research group’s Slack (yeah, it’s awesome, yeah, you wish you were on it), it has Bok globules. Get it? Chicken? Bok?

It’s a cluckin’ good pun.

https://en.wikipedia.org/wiki/IC_2944 

So what is it? Well, it’s a cloud of gas and dust that’s being zapped by radiation from newborn massive stars! Those stars were cataloged in 1965, and the bluest (and most massive) has a spectral type of O6. All that means is the star is around 30-35 times the mass of the sun.

In the other corner, we have contestant number 2!! The Fried Egg Nebula!!

https://en.m.wikipedia.org/wiki/IRAS_17163%E2%88%923907

The Fried Egg Nebula is a shell of gas and dust surrounding a really peculiar kind of star. This star evolved from a bright blue star (similar to those in the Running Chicken) turned into an enormous red supergiant, then yeeted off its outer layers and turned yellow.

...did I use yeet right? That felt weird.

Anyway, it took us a while to figure that out, but after we got the distance to it (and thus it’s brightness), we figured out it is indeed a bona fide post-RSG, that is currently experiencing ~*dynamical instability*~ in its atmosphere. Hence the fried egg look.

Ahh sorry, gotta cite my sources: https://www.aanda.org/articles/aa/pdf/2011/10/aa17521-11.pdf

Anyway, all this implies that the star inside the Fried Egg Nebula was born with around 30-35 times the mass of the sun! Weird coincidence!

So what does that mean? The star inside the Fried Egg Nebula was born first*!

*i have made many assumptions, all of astronomy is just a leaning tower of assumptions, nothing we do is real

Great, we figured it out, the egg came first!

OR DID IT

See, remember that whole ~*dynamical instability*~ thing? Yellow supergiants like this are incredibly unstable, and don’t last long in this zone. They tend to shed enough mass here to become Wolf-Rayet stars (stars with no envelopes). This happens over 10-100 thousand years.

This is lightning fast on astronomical timescales. So while the star in the Fried Egg Nebula is older than the stars in the Running Chicken Nebula, the Fried Egg itself is really young!

Meanwhile, the Running Chicken is as old as the stars inside it: were talking millions of years rather than thousands.

So, with lots of assumptions, and some neat science, we’ve solved it: the chicken came first, even though the star in the egg is older! Thanks to @emsque @KathrynNeugent @eyyysh_lyn for encouraging me to tweet about science