 July 23, 2010 - 6:41pm | The reason I'll asking the below questions deals with something else in the works but I dont want to clutter this thread with that topic but anyhow: In the original materials we were told details about the planets of the Frontier ie: the gravity of the planet and length of day What I was wondering for those of you up on astronomy and such what other details could be deduced from these facts? Sort of like math if x + y= z then what does knowing the gravity about a planet tell us about its density and diameter? In particular I was currious about if there was anyway to determine the length of a planet's year from the details we have? but other info is good too. I might not be a dralasite, vrusk or yazirian but I do play one in Star Frontiers! |
 July 25, 2010 - 10:22am | Well, gravity is proportional to mass divided by planetary radius squared and mass is proportional to the density times the radius cubed. So at best you could get a rlelation that limits one if you picked the other. On the other hand if you assume the average density is similar to that of the Earth (about 5.5 grams per cubic centimeter) you could then estimate the radius if you knew the gravity. For the lenght of year, there is nothing to directly allow you to figure it out. However, if you take the stellar type, you could look up the "habitable zone" for that kind of star. That would at least give you a smaller range of possible orbits to choose from. Then once you pick the orbital distance, the stellar type corresponds to a mass and you could figure out the orbital period. Ad Astra Per Ardua! My blog - Expanding Frontier Webmaster - The Star Frontiers Network & this site Founding Editor - The Frontier Explorer Magazine Managing Editor - The Star Frontiersman Magazine |
 July 25, 2010 - 9:48pm | Here's a simple way to calculate; Planetary Mass: Gravity x Diameter x Diameter Length of Year: y = 365.25 * sqrt(a^3/m) Where: y = Length of YearHope you don't mind, I'm posting the information I sent to you for the timeline. Thought other's could critique.
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July 26, 2010 - 7:38pm | No Woot I dont mind I'm just disappointed with the results concerning clarion having the longest year. there is a statement somewhere (module maybe) that clarion's monarchy is 900 years old and I was sort of hoping for a short year that would make that 900 year statement correct even while the frontier isn't 900 years old. I might not be a dralasite, vrusk or yazirian but I do play one in Star Frontiers! |
July 26, 2010 - 8:53pm | I just noticed that. Where did that spectral type and distance come from. Becuase phyically, there is no way that would work. Plus it doesn't jive with the Warriors of White Light (WOWL) module. M7 is okay, but I think that is a little small and cold. It should probably be an early K star (K0-K3). That would give it the correct color (red-orange, M stars are too red) and would place it's habitable zone in the right location (see below). Zeb's guide calls it a F7 star but that would be yellow hinting toward green or blue and brighter than our sun. Defintely not red-orange as the AD rules and WOWL module indicate. In the WOWL module there is a system map that places the orbit of Clarion 92 million km from White Light. That is 0.61 AU and closer to the White Light than Venus is to the sun. Since Clarion is habitable, it needs to fall in the habitable zone and that means the star has to be no bigger than about a G0 and no smaller than about a K5. Otherwise, it would be outside the habitable zone at that distance. Given other characteristics of the planet as described in the WOWL module (which I'm not sure I agree with but okay) it has a high carbon dioxide content in the atmosphere so there is a large green house effect. That means you probably want it at the outer edge of the habitable zone. More reason (besides just color) to go with a K star. I'd call it a K3 and be done. That gives it a mass of about 0.72 solar masses. So now that we have the mass and orbital distance, we can get the period. Using w00t's equation (which is correct) the orbital period of Clarion is 207.29 24 hour days. Since Clarion's day is 50 hours that corresponds to 99.49 days. The numbers can easily be tweaked to make it almost eactly 100 days if you wanted to. So a "year" on Clarion is only 100 days long local time. And ~250 standard days or 0.625 Standard years. So, in response to jedi's original question, I guess there was enough published material for this system to figure it out. WOWL says that the Leotus line has ruled for 400 years. If you take that to be local years, that corresponds to only 250 standard years. So if it is an unbroken dynasty from the original colonization and WL was one of the first systems colonized, it works out relatively well given that the Frontier is some 300-400 years old. Also, I think it should be a class V star (main sequence), not a class IV (sub-giant). Being a IV star would make the star larger (both in physical size and mass) and move the habitable zone further out. This doesn't really work with the published distance for the planet. It could, but could also mean that the planet has only become habitable in the last few million years as the star has started to evolve off the main sequence. I'd have to think more about this but I could probably come up with a plausable scenario to make it work. However, making it a main sequence star is more realistic I think. Ad Astra Per Ardua! My blog - Expanding Frontier Webmaster - The Star Frontiers Network & this site Founding Editor - The Frontier Explorer Magazine Managing Editor - The Star Frontiersman Magazine |
July 26, 2010 - 8:57pm | Oh, and another item. For basically all M stars, the habitable zone falls within the tidal lock zone meaning that a plaent in that location will be tidally locked to the star like the Moon is to the Earth or Mercury is to the Sun (Mercury is inside the Sun's tidal lock zone) i.e. it will always point the same face to the star or have some small interger ratio (2:1, 3:2) of orbital period to rotation period. That would make it very uninhabitable. It's actually hard to get habitable planets around M stars. Ad Astra Per Ardua! My blog - Expanding Frontier Webmaster - The Star Frontiers Network & this site Founding Editor - The Frontier Explorer Magazine Managing Editor - The Star Frontiersman Magazine |
July 26, 2010 - 9:00pm | Thats right there is a big discrepency between Zebs and the module on details about the WL system. very cool terl. I might not be a dralasite, vrusk or yazirian but I do play one in Star Frontiers! |
 July 27, 2010 - 8:21am | I think w00t just made up the star classification without checking with zeb's guide- but I think he would have been wrong if he did... zeb's called it an F7 which is wrong on the other side of the spectrum :-) I think w00t just rolled it up using the FS star doc, which can occasionally have results which are imperfect by our current understanding of spatial physics -- but always playable if you suspend disbelief or assume factors which are yet to be discovered or cataloged. I see no problem with adjusting the stats w00t threw out there - have fun with them. Make the LOY justify your needs, excellent idea! :-) 3. We wear sungoggles during the day. Not because the sun affects our
vision, but when you're cool like us the sun shines all the time. |
July 27, 2010 - 8:22am | btw, TerlObar... can you provide any type of function/formula/estimation of the "tidal lock zone" ? Could we just say anything in zone 1 of the star document is a tidal lock zone and state that any solid-core planetary body in that zone would be tidal-locked? 3. We wear sungoggles during the day. Not because the sun affects our
vision, but when you're cool like us the sun shines all the time. |
 July 29, 2010 - 1:56am | @w00t: thanks for the calculation, but I'm a little rusty. What function is "^"? If I ignore it, I get some pretty decent results, but I want to make sure I'm doing things right. So far I have just plugged in numbers I felt were right for orbits. :) Long live the Frontier! |
July 29, 2010 - 6:22am | It's signifies an exponent. x^y means x raised to the y power. So a^3 = a*a*a Ad Astra Per Ardua! My blog - Expanding Frontier Webmaster - The Star Frontiers Network & this site Founding Editor - The Frontier Explorer Magazine Managing Editor - The Star Frontiersman Magazine |
July 29, 2010 - 8:09am | You can plug that formula into Excel or Google Spreadsheet (free application). If fact Google might be a good host for people to work on projets that require data calculations. |
July 29, 2010 - 8:13am | Thanks w00t, that made quite a difference. Long live the Frontier! |
July 29, 2010 - 8:53am | I published a page on Google than anyone can edit. Some of the data is based of the Star Document I've been working on. I'm sure ppl like Terl, Iggy and others could really add some useful tools/data to this! :-) StarFrontiers Astrophysics |
August 6, 2010 - 1:47pm | Oh, I just found a little bit on galactic standard time in the SFAD Expanded rulebook, pg. 52. "One year in Galactic Standard Time is 8,000 hours long. A standard year is divided into 400 20-hour days. Each day is divided into a 10-hour work period and a 10-hour rest period." Of course, 60 seconds makes one minute, and 60 minutes make one hour. One second is "...defined as the length of time needed for a beam of light to travel 300,000 km through a vacuum." While I propose keeping 365.25 as the constant for the calculation of a planet's year (orbital period), when breaking it down into standard years, 400 should be the gst constant. Likewise, if one wants to discover the local day as regards to gst, divide the hours by 20. Oddly, this means that the UPF capital, Gran Quivera, has a day only 3/4 of a standard day long, and its year (which should be 546.25 standard days) is 1.365 standard years. I'd like to add that my article in SFMan 6 on Prenglar didn't use these calculations; days and years were simply guessed. I might post an update at some point with the corrected numbers. Long live the Frontier! |
September 3, 2010 - 10:04am | btw, TerlObar... can you provide any type of function/formula/estimation of the "tidal lock zone" ? Could we just say anything in zone 1 of the star document is a tidal lock zone and state that any solid-core planetary body in that zone would be tidal-locked? TerlObar? |
