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Geir
Emperor Mongoose
Not that simple, because if you use the smallest size for the white dwarf it has an older main sequence lifespan which can be in the order of 10+ billion. You should assume that the age of the system is the total lifespan experienced by the white dwarf.
Yeah I updated the post, used the highest instead of lowest Mass. At a Mass of 0.11, just the main sequence lifespan is 44.5+ Gyrs and that's using the highest D3+2 roll; assuming the lowest instead, it's 10/(0.11 * 3)^2.5 which is nearly 160 Gyrs...
bartlebyfosco
Mongoose
I very much appreciate your going through this in detail. Thank you. I will keep an eye on the error you said you made when I go through on my end.
bartlebyfosco
Mongoose
Oh, so the formula as written does make some white dwarfs with overly inflated ages?
That does indeed appear to be the case. p20 even states that:
Which, doing the math, yeah, 3162 Gyrs... but post-stellar objects multiply their dead-star mass by 3 to 5, so the smallest they could be for that calculation is 0.3 (technically 0.33), which is where I got that 160 Gyr number from.
I'm not sure would be a good way to handle that while maintaining the assumption of a < 14 Gyr universe. Maybe increase the 3-5x multiplier, or change the formula for White Dwarf Mass on p227 to give them more mass there.
I wonder what the minimum mass is that we've observed for a WD in real life? Maybe our understanding of how they form and/or age isn't complete. A rabbit-hole, to be sure.
bartlebyfosco
Mongoose
OK so it does jibe with with my original calculations. My test sector using RAW had a couple 20+ Gyr white dwarfs and that led me to posting here.
Yep. And paraphrasing Wikipedia: https://en.wikipedia.org/wiki/White_dwarf#Formation
So, in the end, it may be better to simply ignore Post-Stellar object age when generated as secondaries and assume any with lower mass got that way through some process other than going supernova.
Geir
Emperor Mongoose
Well white dwarfs never form after a supernova (though they may cause one, but that's another issues altogether). A quick and lazy search tells me that the smallest observed white dwarf is ~0.14 Sol, but that is likely because of some mass stripping process in a multi-star system. If we stick within the formulas in the book, a progenitor star of any existing white dwarf not subject to external effects was barely smaller than the sun, and likely bigger. So if this table makes any sense:
Ages are in billions of years. The smallest white dwarf that is feasible in the rules is 0.1962 Sol, with a progenitor of 0.981 sol and an age suggesting it formed only 70 million years after the big bang (maybe a little too soon, but at least 'possible'. That comes from a 5x mass reduction from the process and a Main Sequence Life of about 10.5 billion years followed by 2.1 as a subgiant and 1.1 as a giant. So maybe I ought to have limited the size... to 0.2-1.4 for white dwarfs and capped the system age as 13.7, but someone would then point out that smaller ones exist, but hey, nothing is perfect. If the formulas are close to being correct that one at 0.14 lost a good chunk of mass somewhere in its dying or post-life phase.
| x3 | x5 | x3 | x5 | x3 | x5 | |
| rolled | rolled | observed | observed | limit | limit | |
| WD | 0.11 | 0.11 | 0.14 | 0.14 | 0.327 | 0.1962 |
| x# | 3 | 5 | 3 | 5 | 3 | 5 |
| MS Mass | 0.33 | 0.55 | 0.42 | 0.7 | 0.981 | 0.981 |
| MSL | 159.8509 | 44.5752 | 87.47355 | 24.39242 | 10.49126 | 10.49126 |
| SGLS | 36.91707 | 9.796747 | 19.7904 | 5.189877 | 2.106255 | 2.106255 |
| GLS | 444.8088 | 26.792 | 118.0671 | 7.111493 | 1.111272 | 1.111272 |
| Total age: | 641.5768 | 81.16395 | 225.3311 | 36.69379 | 13.70878 | 13.70878 |
bartlebyfosco
Mongoose
Sounds like interference from the Ancients to me.
p50, Step 7, am I understanding correctly that when determining a random Orbit# for an anomalous planet, the 2D-2 roll is intended to be used as is for the Orbit# (before adding +/-D6s if out of bounds), ranging from Orbit# 0.0 to Orbit#10.0?
What is the reason for doing it that way rather than using an Orbit# guaranteed to be between the min and max?
For example, we could use the same roll divided by 10, (or D100/100) and multiply that by (max - min), then add that to MAO, and the result will not only be within the allowed Orbit#s, but also allows for generating Orbit#s beyond 10.0 when they are allowed.
What is the reason for doing it that way rather than using an Orbit# guaranteed to be between the min and max?
For example, we could use the same roll divided by 10, (or D100/100) and multiply that by (max - min), then add that to MAO, and the result will not only be within the allowed Orbit#s, but also allows for generating Orbit#s beyond 10.0 when they are allowed.
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Geir
Emperor Mongoose
Historical reasons... I carried forward an old "roll 2D" for the orbit from Classic Traveller (Book 6), but did 2D-2 to allow for closer "Captured Planets". I suppose I could have made it more complicated:
Step 1: Find the spots where a planet could go (for any single star system, this would be essentially anywhere - it's just the multiple star systems that get wonky)
Step 2: Come up with some formula that fits a potential discontinuous set of regions - which will be different for each special case.
Step 3: roll some dice
I just decided to skip to Step 3 and only deal with situations that didn't work rather than trying to find a consistent way to deal with the multiple star systems.
Having a little trouble parsing the Axial Tilt variance:
But for Extreme, also add the 1D roll? That seems to be what the Zed Prime example on p105 did.
So roll 1D-1 for tens digit, 1D10 for ones digit, and, in general, add those directly as arc minutes and arc seconds.
But for Extreme, also add the 1D roll? That seems to be what the Zed Prime example on p105 did.
Geir
Emperor Mongoose
So you mean the 1D on the Extreme Axial Chart? Then yes. The example skips a roll (a 4), I think. It should be:
Roll on the Axial Tilt Table -> get a 10
Roll on the Extreme Axial Table -> get a 3, which is 30+1D x 10
Roll 1D -> get a 4, which is 30+4x10 = 70
And then roll a bunch more dice (d10 = 3, d6-1 = 3, d10 = 9) to get it to 73° 39' (or you could roll d10 for a 3 and then d100 for a 65 to get 73.65°)
Geir
Emperor Mongoose
That's the intent. 80-100 have an effective DM-10
Seem to be running into an edge case calculating solar year, but maybe I'm doing it wrong.
Solar Days in a local year = (Years(hours) / Sideral Day(hours)) - 1
Years(hours) = Orbit Period * 8766
Sidereal Day (hours) = Basic Day Length formula, possibly modified by Tidal Lock
I've rolled up a world with the following data:
Orbit Period: 0.2168693327005174
Year Length: 1901.0765704527355 (calculated as above)
Sidereal Day: 3600 (modified tidal lock roll of 10, so Retrograde Rotation and Siderial = 50 * 24 * D6)
Axial Tilt: 145.21194444444444
Plugging those numbers in, I get -0.47 as the number of days per solar year.
If I treat the sidereal days as negative, I get -1.53 days per year instead.
Now, that's not really a big deal, I suppose, but it's screwing me up when I try to use the Solar Period to calculate High/Low Temperature. Should I just treat it as 1.0 as if it were in a 1:1 tidal lock with its sun?
Solar Days in a local year = (Years(hours) / Sideral Day(hours)) - 1
Years(hours) = Orbit Period * 8766
Sidereal Day (hours) = Basic Day Length formula, possibly modified by Tidal Lock
I've rolled up a world with the following data:
Orbit Period: 0.2168693327005174
Year Length: 1901.0765704527355 (calculated as above)
Sidereal Day: 3600 (modified tidal lock roll of 10, so Retrograde Rotation and Siderial = 50 * 24 * D6)
Axial Tilt: 145.21194444444444
Plugging those numbers in, I get -0.47 as the number of days per solar year.
If I treat the sidereal days as negative, I get -1.53 days per year instead.
Now, that's not really a big deal, I suppose, but it's screwing me up when I try to use the Solar Period to calculate High/Low Temperature. Should I just treat it as 1.0 as if it were in a 1:1 tidal lock with its sun?
Geir
Emperor Mongoose
In this case: rather odd, a retrograde rotation and an axial tilt more than 90 should, logically be the same as rotating prograde. (two flips are better than one??) and the day is longer than the year which is annoying, but happens . It should be equivalent to a prograde rotation based on 34.788 degrees and so treating the rotation as effectively positive, that yields -0.47. Which means the sunrise to sunrise period experienced on the surface is 3600/-0.47 = -7628.36 hours... for which the absolute value should be correct from a temperature perspective and the sun still goes backwards, rising in the east (at the 34.788 axial tilt, prograde, assumption (I guess it would be west in upside-down logic- but it would behave that way looking at the sky - ouch my head hurts, but I think that's right - effectively three flips. I'd have to build an orrery* to test it.)
*okay, in this case ChatGPT was helpful, correctly answering "what's the name of that thing with the sun in the center and the planets rotating on stilts?"
