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Looking for RL near-Sol astronomical data

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Golan2072

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I am toying with the idea of compiling a (simplified) list of RL data about the near-Sol star systems; this would probably be posted later on at Stellar Reaches.

What I'm looking for is more game-useful "popular science", that is things which would come up in play (or in setting description), such as very basic astronomical data about the stars themselves, the star's age (which would affect the probability of having well-developed planets around, especially with life), coordinates (in relation to Sol, preferrably), known planets or other interesting phenomena.

I'd like you to recommend to me about web pages on which credible information on these subjects could be found.

Thanks in advance,
Omer Golan
 
An important factor will be the Metallicity of the star. This is basically how much non-Hydrogen, non-Helium stuff the star has. Below a certain point, there will not be enough "stuff" to form planets from. You might have Gas Giants and maybe icy worlds, but no rocky worlds. There is probably also a higher Metallicity that will be required for life to develop. I don't have the numbers, but that one factor could play a big part of what each system could look like.

For example:

Epsilon Eridani is known to have a couple of gas giants around it, it is a young star, BUT it has a very low metallicity and probably does not have rocky planets. PS: It might also have a planetary belt like the Asteroid Belt, but last I saw that was unconfirmed.
 
Sorry for the late reply, but I've once more become interested in such data.

Valarian, thanks for the links - they are VERY useful, even for a partial layman such as me


Plankowner, this metallicity information is interesting - and also VERY conductive to Traveller starsystem-building (it would tell you where the bigger planets would be, and where mining would be especially profitable). At wich level would you place the threshold beneath which planets would be unlikely?

And, aside from metallicity, at which other parameters should I look when thinking of the possibility of Earth-sized (very roughly - say CT size 1 to A) worlds to exist in a given system? In other words, what would be a reasonable minimum stellar age for solid and stable planets to form? Would a low luminocity cause most planets to be pretty much frozen? would a high luminocity scorch most planets?
 
Originally posted by Flynn in another thread:
Given that most historical empires on Earth began to fall apart with a time lag between capital and borders and back again of six months or more, and that none have ever survived a time lag of more than a year, this gives us a practical limit on a single polity size of six months round trip from capital to borders and back again.

For Jump-1, at 10 days per jump, that nine jumps out and nine jumps back, or an area roughly the size of a quadrant.

Given that a ship can travel 36 jumps in a year before starting to break down, that's a frontier range of about 18 jumps out, or roughly a quadrant of explored space beyond the borders of this large Jump-1 polity.
Click to expand...
So, translating this to lightyears, a "mature" setting with Jump-1 only would probably have its main polity within a 29 ly radious from Sol, with a few stray colonies or explored systems in the 29-58 ly radious from Sol and anything beyond that completely unexplored.

However, in a "younger" setting, a 10-parsec radius from Sol would work well, and would be quite managable; I could use Malenfant's starcharts, flatten them and add a few more systems.

By the way, is there another good source for metallucity other than the Encyclopedia of Suns? I'd like to know the metallucity of stars which are not on that list.

On another note, I've found soon good explanations of the criteria for possible Earthlike worlds in the encyclopedia of Suns, namely here and here. A very good site. By the way, are the coordinates given in its encyclopedia entries the kind of coordinates useful for Traveller starmapping?
 
I believe it took about 500 million years for things to settle down enough after the Sun ignited for the Earth to form and have a hard crust. Life formed almost as soon as the planet had cooled enough to allow Liquid Water on the surface.

So, for basic planets I would use 500 million years. Complex life took a couple of BILLION years to develop. I think the first land animals were about one billion years ago (3.5 billion year old planet). Things could be faster other places of course, but I would guess that it would take at least 1 billion years for complex life to develop and perhaps 2 billion for intelligent life (ish).

Stars brighter than about F5v would not last long enough for life to develop.

I personally recommend the Sol Station link above. I have used that resource a LOT and it seems to give me all the data that I needed for near stars.

Also, I have an Excel spreadsheet with a lot of data on nearby stars that I put together for another game. Send me an Email and I will be happy to share.
 
I have been doing the same research for MTU. Sadly, I have not found *the* definitive source of information. (Heck, I often can't get two databases to list a star at the same coordinates.)

You are probably already familiar with ChView. ChView is a good starting point for visualizing the stars in the local stellar neighborhood in a 25 ly to 250 ly radius around Sol. (I would just forget about the 250 ly radius: ChView has some 7522 stars in that data set and that is not even complete.) ChView is great because you can setup "routes" to see "jump distances" between stars. One parsec is "too hard" (hardly anything that close); three parsecs is "too soft" (too many that close); two parsecs is "just right."

Margaret Turnbull's articles and catalogs on "Habitable Stars" are excellent (though technical):

http://skye.as.arizona.edu/~turnbull/


The Terrestrial Planet Finder (TPF) website has an excellent and almost readable report:

http://planetquest.jpl.nasa.gov/TPF/TPFIswgReport2007.pdf


The TPF website is:

http://planetquest.jpl.nasa.gov/TPF/tpf_index.cfm


Finally, I would add the SIMBAD database, if only to find alternative identifiers for stars when the star you are checking out just isn't listed in your favorite list by the same name (and man does this happen often). Here it is:

http://simbad.u-strasbg.fr/simbad/sim-fid


SIMBAD also gives some good info.

I also found one good database of stars, in particular, but I can't remember where I picked it up. I could send if you are interested. I added a simple way to calculate the jump distances (and light years) between a star and all of the other stars in the list by simply checking the star.

I have other info and links if interested.
 
By the way, Wikipedia lists astronomical data for several stars (near-Sol ones, presumable); how reliable is its information?
 
Depends on how often it gets updated.

I know this seems hard to believe, but even Paralax data has been proven wrong before about nearby stars. I found two databases on the internet that gave differences in star location of over 20 ly and one of the values was within 30 ly of the Earth!

I would be VERY suspect of any info on Wikipedia with regards to distance. Data on size, color etc. is probably OK, but there are differences even there. More accurate info on nearby stars is coming out all the time and I just don't know how updated the entries on Wiki are in this area.

If has not been updated in the last year, it probably shouldn't be used.

Interestingly enough, I found differences between the SIMBAD Data and the PlanetQuest data, so go figure. Not much difference mind you, but differences.
 
An important lesson I've learned from reading about the nearby stars is that there is a massive amount of red dwarves around, typically with the following characteristics:

1) Extremely low luminocity (so no fluid water unless a planet is ultra-close to the star, and then it'll usually be torn apart by tidal forces).

2) Very low metallicity, so a very low chance for solid planets (except possibly for icy ones).

3) A tendency to be flare stars, bathing the system with massive amounts of radiation every now and then.

4) Little or no evidence of planets.

---

So, from a Traveller POV, I am thinking of doind one of the following:

1) Ignoring most M-type stars (i.e. red dwarves) and using a high jump-number to make travel between the remaining stars possible (as star density without them would be rather low).

2) Give some of them gas-giants (or frozen-hydrogen comets) to allow refueling; interstellar tarvel would take multiple jumps between inhabitated systems, with the red dwarves being refueling stops. Some red dwarves would have small spacestations built in orbit around their gas giants, with enough thrust to hide in the gas giant's shadow when the star flares.

I'm leaning towards the second option, possibly with automatic ship control during refuling and reliable cryo-sleep for maximum Alien effect
 
Hmmm... If these links are acurate, then you COULD have habitable planets around M-class dwarves; you might even have enough atmosphere (or magnetosphere) to deal with flares...

The big issue, though, would be metallicity - too low metallicity would prevent solid planets from forming. would 10% metallicity be a good minimal threshhold for planets to form, or is a higher metalicity required?

Also, UV ceti has the problem of the two stars getting quite close to each other (minimal distance around 8 au IIRC) - which could be probelmatic for the formaton of planets.
 
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