Lumenna-Súnáris System (4): Sialhaith

I/3. Sialhaith

Class: Sialhain
Orbit (period): 0.58 au (161.3 T-days)
Orbit (ecc.): 0.02
Radius: 3,680 miles
Mass: 4.3 x 1024 kg
Density: 4.96 g/cm3
Surface gravity: 0.84 g

Axial tilt: 7.9°
Rotation period:
  23.1 T-hours

Black-body temperature: 347 K
Surface temperature (avg.): 1,015 K

Atmosphere: Extremely dense, furnace-hot, primarily CO2.
Atmospheric pressure (sfc.): 117.6 atm
Hydrographic coverage: 21%

Satellites: None.

Sialhaith may not actually be one of the less pleasant hells, but if you wanted to build one, it would undoubtedly be where you’d go real-estate shopping.

It’s a “wet greenhouse”, consisting of furnace-heat over eroded rocky deserts, moistened by small oceans of boiling acid, with an atmosphere primarily of carbon dioxide and water vapor, mercifully concealed from space by its impenetrable belts of caustic, lemon-yellow, sulphuric-acid smog clouds. (They wrapped probes in platinum hulls just to find that much out.) If it is not the single least hospitable place in the entire System, the Sialhaith Extreme Tourism Advocacy Branch would like to know.

Naturally, in the future, people tried to ecopoese it. It didn’t stick: in the end, the residents of the aerostats – it’s very easy to build cities that are naturally buoyant in the Sialhain atmosphere – that were intended to monitor the ecopoesis process ended up buying out the project, having decided that they liked their lifestyle and its uniqueness just the way it was.

There’s very little on the surface itself but some minor scientific and resource-gathering outposts, and small-scale dome-warrens belonging to the sort of person who demands that their lifestyle be the absolutely most challenging available.

Oh, and Fort Inferno, because Legionary drill instructors also demand a lifestyle that’s the absolutely most challenging available.


Lumenna-Súnáris System (3): Toramir

I/2. Toramir

Class: Eurymic
Orbit (period): 0.32 au (66.12 T-days)
Orbit (ecc.): 0.00
Radius: 826.9 miles
Mass: 5.996 x 1022 kg
Density: 6.07 g/cm3
Surface gravity: 0.4 g

Axial tilt: 12.1°
Rotation period: 43.3 T-days

Black-body temperature: 467 K
Surface temperature (avg.): 453 K

Atmosphere: None.
Hydrographic coverage: 0%

Satellites: None.

The second planet of Lumenna, Toramir, is actually a much better Mercury-as-it-actually-is analog than Eurymir is.

Namely, Toramir is a sun-seared rockball with a long, long day. It’s sun-searedness makes it another great place for energy production, but also its high density (the highest of any planet in the Lumenna-Súnáris System) makes it a rich world, specifically rich in heavy metals and power metals. (It is, in fact, probably the richest of all Lumenna’s worlds in readily accessible metals, radioactives, and other heavy elements, along with not-insignificant regolith deposits of lighter elements and solar-wind collectibles.)

In short, prospectors just leapt at it. (Toramir’s own gravity well is relatively shallow, and despite its depth within Lumenna’s well, the total Δv required to get elsewhere in the system remains below launch costs from most other planets. It is unfortunately impracticable to construct an orbital elevator on Toramir, due to its slow rotation.) Shortly thereafter, so did shipbuilders and other heavy macroindustries, and Toramir’s orbitals in the modern era are crammed full of cageworks, macroforges, and autofacs.

The major groundside settlement is Sírtirias Lemisef, or translating approximately, Crawlerberg. That’s because it moves to stay out of the sunlight: the city itself and its smelters are a giant turtle built atop the biggest damned dual set of treads in the System that drives very slowly but continuously around the equatorial loop to stay on the shady side of the planet.

And the -berg? That would be the gunspire of the huge mass driver on its back that fires building-sized slugs of refined metal into orbit for the local industry to pick up.

The future colonists of this particular rockball were not in the habit of thinking small.


Lumenna-Súnáris System (2): Eurymir

(Or maybe a little more often, if I happen to feel like it; also, a shout out to Wolfram Alpha, whose fine facilities make running the necessary calculations a great deal easier.)

I/1. Eurymir

Class: Eurymic
Orbit (period): 0.21 au (35.15 T-days)
Orbit (ecc.): 0.05
Radius: 1,758.5 miles
Mass: 4.712 x 1023 kg
Density: 4.96 g/cm3
Surface gravity: 0.4 g

Axial tilt: 3.9°
Rotation period: 35.15 T-days (tide-locked)

Black-body temperature: 577 K
Surface temperature (avg., sunside): 672 K
Surface temperature (avg., nightside): 56 K

Atmosphere: None.
Hydrographic coverage: 0%

Satellites: None.

The innermost planet of Lumenna, Eurymir is similar to Mercury as we once imagined it, which is to say, tide-locked, with a sunward face hot enough to have lakes of molten metal and roast anyone on even momentary exposure, and a dark face plunged into deepest chill, even occasionally to the extent of having water ice. The mind boggles…

Unlike Mercury, though, Eurymir can muster up some volcanic activity, especially on its sunward face: the tidal stresses also keep its core molten and perking right along.

(Being the fine, inhospitable world it is, it’s not all that populated even in the future. It houses a fascinating experimental a-life ecology, but apart from that, its principal use is as a gravity anchor for solar power stations and antimatter generators.

Its best-known settlement is actually a temple: because when you have a solar deity, where would be the best place to put that but the nearest solid ground to the eponymous sun?)


Lumenna-Súnáris System (1): The Stars

(So post. Such computation. Wow.)

Okay, folks, here we go, the Lumenna-Súnáris System. A little bit slower than expected, because it turns out that it actually takes quite a long time to gather up and re-double-check all my figures with great care.  Since I know you guys, y’know?

So starting with this post, which covers the suns, I’m going to try and hit up one planet a day, with its moons, other statistics, and a few interesting facts about it. Hopefully, it is planned, not to the exclusion of any other content.

So, let’s get started. To sum things up, first, the System is a Population I far binary (the stars vary in distance from 125 au to 358 au during their 2,864 local year orbit) which gives their worlds a nice “deep seasonal cycle” to pay attention to as well as their regular ones.

For convenience, in this description, we’re going to pretend that Lumenna is the center of the system and everything orbits around it rather than mucking about with barycenters. It has nine planets and an asteroid belt; Súnáris has eight planets and an asteroid belt; and then, of course, there is Múrcár. (If you’re into Kuiperians.)

Also, since if anyone does put this into a KSP mod it would be nice for them to start from the start, this is the system raw. Which is to say, this data reflects that status quo as of 2050, before anyone got clever ideas about strapping nuclear weapons to their ass and launching themselves into the wild black yonder, and certainly before people started colonizing other worlds, building habitats all over the place, moving inconvenient moons to better locations, girdling the equators of gas giants with supercolliders, reengineering the suns, or other cool stuff like that.

And a final word: through all of this, please pardon my eclectic mix of units; that’s just how I roll. Time units prefixed with T- indicate that I’m using your Earth hours/days/years, not the local calendar.

So let’s get started, shall we?

I. Lumenna

Mass: ~1.0 solar masses
Spectral class: G2V
Temperature: 5,800 K
Luminosity: 0.82 sol
Radius: 381,100 miles

“the Sun”; the yellow-white G2V star that everyone thinks of as the system primary even though it’s, technically, not really a concept that works all that well with binaries.

II. Súnáris

Mass: ~0.75 solar masses
Spectral class: K2V
Temperature: 4,900 K
Luminosity: 0.24 sol
Radius: 288,100 miles
Orbit (avg.): 242 au
Orbit (ecc.): 0.48
Orbit (period): 2,845.69 years
Perihelion: 125 au
Aphelion: 358 au

The system’s secondary star, slightly smaller and cooler than Lumenna, with light more orange. It’s name glosses as “shining one”, because its presence in the heavens overshadows all the other stars therein.


Imperial Fringe, or, Map Time

Today’s gift for y’all is… a new map! A bigger map! A better map!

This map:


Which basically quintuples the amount of the Worlds that has been mapped on a system-by-system basis by extending that from the Imperial Core to the entire Imperial Fringe. Enjoy! (Although it’s big, so be aware when you click through.)

Key and notes:

  • As is usual, it’s a link-graph map, i.e., like a metro map, and a projection of 3D space onto 2D space besides. Neither stellar distances nor relative positions are in the least accurate except in the most general possible sense.
  • Each of the constellations (the Imperial Core plus the five constellations of the Imperial Fringe) represented is represented as a box containing the associated star systems. At the edges, the little orange boxes with CAPITAL LETTERS inside them represent links out to the other constellations of the Worlds.
  • The majority of Imperial star systems are represented as GOLD nodes. The exceptions to this are:
    • Certain important systems highlighted in RED (the throneworld, the IN Prime Base, the Cirys sphere and Cirys swarm); and
    • The system dedicated to the Conclave of Galactic Polities, indicated in BLUE; and
    • Imperial conlegial systems, indicated in GREEN; and
    • The original Thirteen Colonies (reached subluminally) represented in PALE GOLD.
  • Non-Imperial star systems are represented as PURPLE nodes.
  • Stargate pairs connecting systems are represented as SOLID lines. Stargate pairs connecting entire constellations are represented as DASHED lines. Crossing lines, as per the symbology, don’t actually intersect.
  • Arterial routes, i.e., extra-high-capacity stargate pairs, are represented as THICK lines.
  • The ORANGE line represents one major interstellar trade route passing through the Empire, the Mercantile Corridor. The GREEN line represents the other, the Lethiaza Trade Spine.
  • GOLD systems with a RED border are Imperial systems that connect directly to non-Imperial systems and as such form part of the Interface Defense Matrix. Also, when you get there, you have to clear immigration.


Special extra challenges for the detail-oriented reader with some time to kill:

…how many different ante-Eldraeic roots for “world, place, land, planet, etc.” can you identify from the names of the various Imperial worlds seen on this map? And how many of those are actually exotic-species routes?

…how many and which extra-Imperial polities can you draw lines around based on commonalities of name scheme among the non-Imperial worlds?

Answers and questions in comments, please!

(P.S. Yes, that’s “Kerbol System” down there in the High Verge; having thrown that reference in as an homage, I’m hardly going to reverse myself now. Any assumptions one might make, however, about its planets, inhabitants, space program, or other details, however, are distinctly non-canonical.)

Author’s Note: Astrography

So let’s talk a little about the setting of our ongoing fiction, the Associated Worlds.

First: they’re big. Really, really frakkin’ big. Sci-fi writers with a sense of scale big. I mean, you may think it’s a long way down the road to the chemists’, but…

Ahem. Enough of that.

So, let me draw you a picture. The free-space volume of the Associated Worlds is an irregular mostly-oblate spheroid. Along its major axes, it’s about 3,300 light years from core to rim, 4,100 light years from spinward to trailing, and 2,000 light years from acme to nadir. To put some perspective on those numbers, that means that at its tallest part, much of the center, it completely fills the galactic disk top to bottom. Meanwhile, the Lethíäza arm of the galaxy in which it is located is approximately 3,500 light years across, and since one slightly-flattened end of the spheroid – expansion having slowed, although not stopped, to coreward on encountering the inter-arm gap – is pressed up against its coreward side, it lacks only about 200 light years of running into the rimward side of the arm, too.

As those of you with calculators will already know, that’s approximately 27 billion cubic light years of volume, which contains approximately 100 million stellar bodies of various kinds. Like I said, big.

Of course, on the cosmic scale, or even the galactic scale, it’s still a barely significant mote. Space is like that.

The kicker, of course, is that most of that is unused and only explored astronomically. The expansion pattern of the Worlds has been, essentially, to look for interesting things, and then fire off a long-range stargate to a system near them and weave a constellation from there. The one black hole in our neighborhood? That counts. The blue-white supergiant? That counts, too. Any system which appears to have signs of intelligent and usually technological life? That definitely counts, as maybe we can sell ’em something. That sort of thing.

That process has resulted in maybe 10,000 star systems over that whole enormous volume being actually connected to the stargate plexus and thus readily visitable. That would be roughly 0.01% of the stellar bodies in that volume. The rest would be the “Inner Periphery” of systems that didn’t seem so interesting at the time but which are likely to be hooked up if and when they become interesting, or if and when polities in inner constellations feel like expanding locally, rather than out in the ecumene, and also feel like paying for it.

So when you think of the Associated Worlds, think of a cobweb. The strands are long-distance wormholes. The dewdrops clinging to the points where they intersect are local constellations, where constellation in this case is defined as maybe fifty systems linked together with short-range stargates with three or four long-range gates connecting to it at various points. And the empty spaces are not-quite-empty space.

To hang some numbers on that, the Empire has all of one constellation (the Imperial Core), and about half each of five more (the Imperial Fringe), close to 250 worlds in total if you include its colonies out in the ecumene. Which is to say, it’s the tiny kernel at the heart of the big nut – although that said, it’s nearest competitors, the Photonic Network and the League of Meridian, are only 120-150 world polities. To divide up the rest, in the divisions Where’s Where in the Galaxy would offer you, these six constellations and 73 more make up the “true” Associated Worlds, the well-developed, comfortable, and stable metropolitan regions.

109 more constellations surrounding those make up the Expansion Regions, which are a bit less developed but not actually frontier. They tend to be the places where most of the action is, when there’s astropolitical action.

And the 23 constellations of the Periphery, found all around except to acme, nadir, and along the border with the Republic, are the wild and wooly frontier.

Leaving the Worlds proper for a moment, the Voniensa Republic, featuring rather heavily at the moment, is located spinward and slightly to rimward. It has about 8,000 worlds in its volume, although by no means all of those are politically part of the Republic. (More than a few of them belong to people who are currently being Prime Directed, for a start.) It’s also substantially smaller than the Worlds in free-space volume, because while they’re not quite as bad at insisting territorial volumes make sense in space as the members of the Interstellar League of Tribal Chiefdoms, they do pursue a much more consolidate-y expansionary policy.

And finally to note, cutting through the rimward systems of Lethíäza, and thus both the rimward side of the Republic and the fringe Periphery – only a few stargates at the far edge of the rimward Periphery breach it – is the Shadow Veil, which is a vast dark nebula of opaque gas and dust that does a fine job of obscuring both the view further rimward from most of the Worlds, and vice versa.

(So even if its still flexible galactic location turns out to be directly coreward of us, there’s still a reason why our astronomers *there* aren’t getting all excited about those distinct signs of someone building megastructures and operating pion drives. Heh.)