Celestia Forums

Hello again!
I've decided against using Beta Hydri as the star for the setting of my science fiction scenario, and switched to the more sun-like 82 Eridani. Using StarGen (http://www.eldacur.com/~brons/NerdCorner/StarGen/StarGen.html), a planetary system "modeler" of sorts (it generate planets based on data on the chosen star, or input data for fictional ones), I generated several system models. Here is the result I'm going with http://fast-times.eldacur.com/cgi-bin/StarGen.pl?Catalog=w&Dole=12&SolStation=12&Mass=0.97&Output=all&Seed=230&Count=1&Incr=1&Gas=on&Moon=off&SVG=off#10 (I checked the system out in GravitySimulator, and the eight planet, as I thought, was kicked out. So I've since removed this planet and will probably add an asteroid belt in it's place) I've modified the planet's information slightly for what I want (I also thought their eccentricity values were a bit too high for some of them.)
I chose 82 Eridani for several reasons. Firstly, it is relatively sun-like. It's a little cooler and a little dimmer, but otherwise seems like a good candidate to support life-baring planets. It has a high metalicity, which should give it a much higher chance at having formed terrestrial planets. Secondly, it is only 19.7 light-years away. Since there is no FTL in my science fiction scenario, this is very important. The ships used are based on the Valkyrie design (http://www.projectrho.com/rocket/rocket3aj.html#valkyrie), which, while it requires absurd amounts of antimatter (For my story, I'm assuming that an affordable solution to generating and storing large amounts of antimatter is discovered in the next century or 2), could in theory be made to accelerate to nearly 90% c.
The system has 11 planets, one of which is habitable and fairly Earth-like. From my knowledge of planetary formation and mechanics, the current set-up I have looks fairly realistic. I've checked the current set up as well in GravitySimulator, and it seems to be stable over the long term with minimal shifting in the outermost planets. Here is the current .ssc:


When I'm "finished" (I really never am...I always have to go and tweak things...), I'll upload the file on the "Add-On Release" Forum. I still need to finish the moons for several planets, as well as some textures, asteroids, and other components that need a few finishing touches before it is ready for consumption.

Also, while it is still kind of bare-bones right now, the homepage of my scenario is here, for those curious: http://upbringer.webs.com/

If it helps, I've used 82 Eridani as well. Look in the Motherlode, under Fictional --> ArcBuilders. It's an older version.

82 Eridani is a good star to use. There are *some* arguments against it, mainly being its age (possibly older than 10 billion years, and it's metallicity is relatively low, but still somewhat enriched for a star of that age; I've seen estimates that range between 29% and 100% of Sol). But these are easily overcome; I look forward to seeing the visualization of this system!

...John...

Is there a way to calculate or estimate the perihelion and aphelion of a given planet's orbit, given the semi-major axis and eccentricity? I've been trying to get a very rough estimate by going to the surface of 82 Eridani and selecting one of my planets, then recording their closest approach and furthest approach, finally adding the value of 82 Eridani's radius to those numbers. Is there a better, more accurate way?

Greetings, Sen,

This should help.

Where a = semimajor axis, b = semiminor axis and e = eccentricity:
c = sqrt( (a^2) - (b^2) )
or
c = ae.
Aphelion Distance = a + c.
Perihelion distance = a - c.

-Gary

Ah, thank you very much VikingTechJPL. That should come in handy for my data tables.

Also, for everyone's viewing pleasure, here is a screenshot of Tiamat, the fourth planet out from 82 Eridani and the only habitable planet in the system.

In addition, the planets can be viewed here: (shameless act of self-promotion ) http://upbringer.webs.com/planets.htm

The site looks great... and your gas giants look absolutely beautiful. I know *I'm* jealous!

...John...

Thank you, Dollan!
Yeah, a lot of my textures are pretty high-res (Tiamat's texture is 8192x4096), so they do look pretty nice. Which is why I'm thinking of perhaps uploading two versions of the system, a low-res and a high-res. The gas giant textures were made by overlaying other textures from our own solar system, Saturn being the most popular, again here using high-res versions...but the atmospheres were a bit tricky to scale correctly to get the desired effects. I still have to finish up the moons for everything, and then add in a few representative dwarf planets, asteroids, and comets. Maybe sometime in the future I'll add some satellites and spaceships...

Tiamat seems a little chilly for a habitable world....

Anyways, I agree with Dollan, great gas giants!

Tiamat's temperature range is in Celsius. In Fahrenheit, it would be between 11.3 - 116.06 degrees, fairly similar to Earth. Although, this may not hold exactly true, as there would be a little more powerful of a greenhouse effect due to higher water vapor content in the atmosphere, and the higher atmospheric density. Also, I got those temperatures from the same planet generation program that I based the planets off of, so it is a very rough estimate anyways.

Thanks for the compliments on the Gas Giants!

My next challenge is to start coming up with some realistic xenobiota to populate it with...

Sen wrote:My next challenge is to start coming up with some realistic xenobiota to populate it with...

Yes, that is a true challenge. I've had the planet in my avatar (in various forms around various stars. long story.) in Celestia since at least 2003, and all I've been able to come up with are cats with blue fur, which is most likely not very realistic.

As for Tiamat's temperatures, I simply mis-read the temperature definition on your website... My apologies.

That's ok!

It is quite the challenge indeed, but it's as enjoyable as it is frustrating. But humans too will be difficult to design for Tiamat. I still haven't decided in what manner we've colonized Tiamat, whether by genetic seeder ships overseen with parent AIs, or with hibernating adult humans... And I need to determine how many are actually human and how many are, well, posthuman. It's going to be an interesting story, that's for sure!

PlutonianEmpire wrote:

Sen wrote:My next challenge is to start coming up with some realistic xenobiota to populate it with...

Yes, that is a true challenge. I've had the planet in my avatar (in various forms around various stars. long story.) in Celestia since at least 2003, and all I've been able to come up with are cats with blue fur, which is most likely not very realistic.

You might consider using the Spore creatures editor

You might consider using the Spore creatures editor

That actually looked very interesting. I kind of want to get Spore, but I haven't gotten around to that yet...

Actually I have produced a few preliminary sketches of some alien life, but to me they seem too Earth-like. I guess that's because I have somewhat of a bias, being born on Earth and all...

I think this system is almost at the point where I could feel comfortable releasing it soon (at least in a low-res version first). Just need to add in a few asteroids and comets, and of course scale back the textures. If it's popular enough, I might upload the high-res (what I'm using right now).

Sen wrote:That actually looked very interesting. I kind of want to get Spore, but I haven't gotten around to that yet...

Spore's pretty cool. The Spaceship Creator is great for designing ships for various reasons (I recreated the Enterprise... ).

W0RLDBUILDER wrote:

Sen wrote:That actually looked very interesting. I kind of want to get Spore, but I haven't gotten around to that yet...

Spore's pretty cool. The Spaceship Creator is great for designing ships for various reasons (I recreated the Enterprise... ).

Whoa, same here.

I apologize for my absence. I have finished and packaged the lower resolution version of this system. How do I upload it to the forum? I assume I have to upload onto another site and then provide a link?

Go to the motherlode and on the right side toward the bottom is the Upload Form. And it's pretty self-explanatory from there.

Ok. But it says that if my file is over 8 Mb (which it is, it's about 40.2 compressed), I need to use a FTP-program. I did a google search and found FileZilla, but I have no idea what to do with it. How do I use an FTP-program to upload the add-on? Is there an alternative method of uploading besides the motherlode?

Sen wrote:Ok. But it says that if my file is over 8 Mb (which it is, it's about 40.2 compressed), I need to use a FTP-program. I did a google search and found FileZilla, but I have no idea what to do with it. How do I use an FTP-program to upload the add-on? Is there an alternative method of uploading besides the motherlode?

FTP programs have to be configured like POP 3 client, in which the email address is substituted by "host". After the generic name "Motherlode" or whatelse as account name, under the textbox "host" you must place: "ftp.ibiblio.org" (without quote)
with the password "anonymous" (usually there is a checkbox already). When you are connected to the server, you will see the root in which to place your add-on: "\incoming\celestia". That's it.
Note that all the explanations above are shown in Motherlode when you accomplish the upload.

EDIT LATER:
FTP programs are then structured like File Manager, with your root on one side and the host on the other. File menu, buttons or right mouse menu copy/move the files.

Hey all, sorry for my extended absence. Anyway, I made an account on 4shared and uploaded the add-on to it. Here is the link (let me know if the download works, and don't forget to leave some feedback on the add-on!)

82 Eri.zip

Hahaha, I just now realized that the texture for Qingu is actually out-of-date...
I'll just include the new texture in a later release or by itself, along with the completed location file for Tiamat.