Settings in the Stars

M24 - Small Sagittarius star cloud

I was a science fiction reader before I dipped my toe into the vast ocean of romance. More than that, I like space opera. Yes, I'm a Star Wars fan, despite the rather ordinary science. What attracts me is the aliens and the space ships and the amazing different worlds out there. And after all, with current estimates for the number of habitable worlds in the Milky Way – those with liquid water – at up to five billion (New Scientist Nov 2020), why not?

Although my Ptorix Empire series and Morgan Selwood series are set in an indeterminate part of the galaxy, when I decided to write stories for the Dryden franchise, I wanted somewhere real in our very own Milky Way. My Dryden stories had an Empire and a number of sentient aliens, some space-faring, some not. I wanted a region of real space where the planets were closer together so that a cohesive Empire could form.

Accordingly, I did some homework on star clusters. Globular clusters, it seemed, were not the best fit. The stars are very old first generation, and gravitationally bound to each other. Current knowledge suggested that mitigates against planetary systems, both because of the forces, and also because the material from which planets (and we humans) are formed comes from supernova debris, and these clusters are poor in such material.

However, open clusters are very different. The stars are younger, without being too young for planetary systems to have formed. They form in the usual stellar nurseries like the gas clouds of the mighty Orion Nebula. From there, they remain in a more 'open' gravitational relationship until they leave home on their own. Our sun was probably part of an open cluster when it was a teenager. You can find out more about open clusters here.

I eventually settled on M24. According to the article in the Messier objects website, M24 is in the constellation Sagittarius and it's pretty big - ten to sixteen thousand light years across. There are thousands and thousands and thousands of stars in there, relatively close together, so it seems to be an ideal place for an author to set up a civilization. Yay me.

But then I discovered that M24 isn't any sort of cluster. It's a window. This 8 minute video explains it better than I could (well worth a watch if you like astronomy).

So my Dryden Universe books are set in somewhere a lot like the previous understanding of M24. It's fiction, after all.

NGC 1980 *

 I used another open cluster for my Ptorix Empire book, The Stuff of Legend. For the purposes of my story I wanted the gas clouds that you see around Orion as part of the legends associated with my cluster. I went back to research, and discovered that an open cluster that had been thought to be part of the Orion Nebula, was in fact a different entity, situated in front of the nebula. Here's the story of NGC 1980.  It was perfect. So my story takes place with regard to a star cluster that has some similarities to NGC 1980.

I love astronomy.

* NGC 1980 photo By Donald Pelletier - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=53485691