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aramis
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Stellar type data - real world - near stars

Tue 03 Dec 2019, 09:38

I went crawling for a few real world sources in short form for answering the questions needed to use the system gen...
For example, I wanted to find the data on Procyon...
Procyon B (DQA) orbits Procyon A (F5 IV-V) at 40.79 years per orbit, and 15.1 AU. The rough estimate life-zone is 2.53-3.65 AU for A, and 0.02-0.03 AU for B. (I also calculated B's hill sphere to about 7.1 AU and A's to 15.3, so there's probably nothing around 7.9-8.1 AU from A, as that pushes right onto the point of figure-8 orbits... and anything from 8 out is likely concentrated into B's orbit in either trojans or the dwarf itself.)

sharing the links...
Star lists
http://www.icc.dur.ac.uk/~tt/Lectures/G ... 50lys.html
http://www.johnstonsarchive.net/astro/nearstar.html
http://www.projectrho.com/public_html/s ... pindex.php
http://astropixels.com/stars/brightstars.html

Useful formulae:
https://www.planetarybiology.com/calcul ... _zone.html
http://hosting.astro.cornell.edu/academ ... solute.htm

Useful calculators:
https://www.omnicalculator.com/physics/orbital-velocity
https://www.omnicalculator.com/physics/orbital-period
https://www.artificial-gravity.com/sw/SpinCalc/
http://orbitsimulator.com/formulas/hillsphere.html
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Smith & Wesson: the original point and click interface...
 
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Vader
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Re: Stellar type data - real world - near stars

Tue 03 Dec 2019, 12:23

This one could come in useful, as well:

https://exoplanets.nasa.gov/exoplanet-catalog/
Before you use the word "XENOMORPH" again, you should read this article through:

https://www.wired.co.uk/article/aliens-throwaway-line-confusion
 
Bengt Petter
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Re: Stellar type data - real world - near stars

Thu 05 Dec 2019, 11:55

So, how would a list of useful stars look? How far out has planets been observed with the technology we have today?
 
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Gebohq
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Re: Stellar type data - real world - near stars

Fri 06 Dec 2019, 00:50

There may be stuff in this thread that is helpful as well!

viewtopic.php?f=103&t=5338
The Plothole: a home for amateur, inclusive, collaborative stories
http://forums.theplothole.net
 
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aramis
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Re: Stellar type data - real world - near stars

Fri 06 Dec 2019, 10:36

So, how would a list of useful stars look? How far out has planets been observed with the technology we have today?
The Game's map extends roughly 14 parsecs radius.
14 * 3.26 = 45.64 LY... so it's essentially the 50 LY range.

Real world direct imaging has been done on at least 2 dozen worlds, in at least 20 systems. the most distant of these I can easily find reference to is 470 LY.

Most distant exoplanet confirmed detected, Kepler 443B, is 2,540 LY away; a candidate has been pushed forward for KOI5889.and thats a bit over 5000 LY,.

Direct imaging is just that - put the image on the CCD, and see it separate from its star...  
Such as this one of 2m1207 a & b...
Image
a is the blue one, and is an M8 subdwarf of 0.025 Msol or 26.2 Mjupiter or 8325 MEarth
b is the orange one, estimated to be 3-10 Mjupiter. It orbits between 39.3 and 41.9 AU from a.

Image from: https://www.planetary.org/explore/space ... aging.html
Wikipedia page on known direct imaged exoplanets:https://en.wikipedia.org/wiki/List_of_d ... exoplanets

I'll try to remember to collate a list of ones on the map...

The star list...
A proper list would include the stellar type and size, an x/y/z column, and, for hab-zone, luminosity (preferably in multiples of Sol), presence of known exoplanets.
A second table with planets by star listing known mass, and separation from their primary.
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Bengt Petter
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Re: Stellar type data - real world - near stars

Fri 06 Dec 2019, 13:08

Thanks, Aramis. What I was thinking of was an actual list. I get that it would take some time to make such a list. I don’t have that time, but hopefully you or someone else here have that.

Since my astronomisk knowledge is limited, I don’t know how scientific the Alien universe is. But to me that’s not so important. It’s a fictional universe, but it has to feel realistic. That’s a part of the concept.

Having that in mind, it’s also interesting to consider how universe will appear in the future (but fictional) time frame we are talking about here. Certainly, a lot more will be known to mankind. How far out would it be possible to see with the help of a more advanced technology? It’s a hypothetical question of course, but still interesting because it kind of limits (?) what can be known in this game.

(An interesting twist could be if the telescope of the Pilot actually still works, and makes it possible to see a lot further out... Imagine how powerful such a tool would be!)
 
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aramis
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Re: Stellar type data - real world - near stars

Fri 06 Dec 2019, 20:35

Bengt:

The scientificness of the setting...

The big disconnects are that we are presented no Z-axis data on the map nor in the book, and that most star lists use polar coordinates instead of cartesian, because the polar makes pointing telescopes easier. But for travel between,  cartesian coordinates (2D x,y or 3D x,y,z) are easier.

Still, most of the names on the map match real systems, tho' not always in the correct positions. There are several systems which are 400+ light years out in reality that are on the map as within 15 Pc (48.9 LY).

HD numbers are the Henry Draper Catalogue numbers. (HD numbers are sequential on Epoch 1900 Right Ascension.)
HIP numbers are the Hipparchos Catalogue numbers, for items measured by the same named ESA satellite.
GL, GI, GJ, WO, NN: Giese catalogues. 
  • GL (1-915) <20 Pc, 1957. 
  • GI (1-915, plus a fraction) for 1500 or so stars, 22 Pc, 1969.
  • WO (9001–9850) Wolsey & Associates extension to the 1969, 25 Pc, 1970. 
  • GJ (1-915, 1000-1294, 2000-2159, 9001-9850) Gliese-Jahreiß  1979 
  • NN (3000-4388) 1991 additions to the Gliese catalogue. "No Name"... 1991 
2M, 2m, 2mass: Two Micron All-Sky Survey. 2003, more than 300 million objects.... 

The size categories in system gen are based upon the Yerkes size classes... which combine with the Harvard system to give the MKK system.
Yerkes: 0, Ia, Ib, II, III, IV, V, VI (or SD), VII (or D) (Yerkes is a revision of Secchi's classes, and is sometimes called that.)
Harvard (as extended) O B A F G K M L T Y. That sequence runs from hot (O, B) to pretty close to room temp (Y2 is about 300 Kelvin Y3 is literally about room temp). T has methane absorption lines, and overlaps L somewhat.
The type category is usually letter-arabic numeral - roman numeral, and alpha suffixes. Such as G2V or G2v 

The System gen uses the yerkes roman numeral - no 0, Ia, Ib, nor II are within the mapped region.
The exception being for hot (O, B, A)  or cold (M) harvard classes in Yerkes size V. So, for game purposes, you're just looking for the size, and the first letter.
Note also, the above posted pic is of a "red" dwarf... to the eye, they're not really reddish until M5 or cooler, and Y's won't even glow in visible light. 

So, overall, it's "scientificish" - it's presenting a reasonably realistic (if somewhat abstract) system generation. It avoids much of the controversial by just giving a number of worlds of various types. It does better than Star Trek... and the non-realism elements are pretty clearly for playability.
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Bengt Petter
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Re: Stellar type data - real world - near stars

Mon 16 Dec 2019, 11:23

To me, it’s all about creating believable fiction. In a fictional setting where some kind of realism is included, you have to breake down scientific data into concepts.

Quite often real world science can offer creative impulses that would be hard to imagine just by making things up. Today i read about this very remote galaxy, MAMBO-9: https://edition.cnn.com/2019/12/12/worl ... NZvyPpWTkI

What could be known about this galaxy and other remote galaxies in the Alien universe? Probably a lot more than we know now. Probably it’s simply to far out for any kind of communication, but just the thought of knowing a lot (?) more about what is now almost beyond reach of human knowledge, could open up for new perspectives. For example, there should be at least some kind of signals sent through space... Or maybe just other traces of distant life...

So, what I’m actually saying is that it’s interesting from a conceptual point of view how big the known universe is - and what’s known about the known universe. The map included in the game is, I guess, a map of places that can be visited. But the known universe must be a lot bigger, probably still growing rapidly. I find it thought provoking what that growing knowledge could mean from an in-game perspective. Probably the corporations are not eager to share all of their deep space knowledge. Translating this to in-game material it could mean new star (or galaxy) maps, lists of rumours from the stars, signals from intergalactic expeditions, observations of bizarre alien spaceships far away, a sudden signal from a distant alien civilization...
 
S.M
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Re: Stellar type data - real world - near stars

Tue 17 Dec 2019, 01:05

For reference the game starmap is based on this map I made - https://alientimeline.files.wordpress.c ... 305&zoom=2

That was based on this map by Winchell Chung - http://www.projectrho.com/public_html/s ... _Large.png
And the list of stars for that map is here - http://www.projectrho.com/public_html/s ... YG50ly.csv
 
Bengt Petter
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Re: Stellar type data - real world - near stars

Sat 01 Feb 2020, 11:48

I think we all get that this map (or actually maps, there are several, only one is included in the game). has been created through quite extensive work. Thanks for that, S. M and others! The map does for sure bring value to the game.

So it’s based on info from a lot of novels and comic books, right? Has Fria Ligan and/or Gaska added stuff to the map too? I’m curious on the history of the map itself. It’s worldbuilding in it’s most literal sense.

By the way, for some reason I couldn’t open the star list link (maybe because of my phone). But there are more stars there than on the map in the actual game, right?
Last edited by Bengt Petter on Sat 01 Feb 2020, 11:53, edited 1 time in total.

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