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  #31  
Old March 9th, 2019, 03:05 AM
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Originally Posted by Straybow View Post
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Menorb is K2 V (typically ~0.8 Msol, 0.735 Rsol) which makes the 100.5 diameter jump shadow roughly 103M km. At 2√(D/A) that makes 1G (10m/s) travel time 56.4 hours (not days) to reach the star. Hab zone edge is approx 0.35AU = 52M km for a differential of only 51M km. Travel time at 1G is only 39.7 hours.
...
Menorb's primary used to be an M5 II, according to the old Spinward Marches Campaign. I suspect it was changed for precisely that reason. The giants made a royal mess of things when people started talking about stellar masking. They changed Cogri too, used to be an M1 II.
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  #32  
Old March 12th, 2019, 04:08 AM
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Doing some rough calcs, I think the person who made the list of travel times (to which Xerxes linked) may have mistakenly used 1 m/s instead of 9.8 m/s or 10 m/s.
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  #33  
Old March 13th, 2019, 09:30 AM
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Quote:
Originally Posted by Straybow View Post
Doing some rough calcs, I think the person who made the list of travel times (to which Xerxes linked) may have mistakenly used 1 m/s instead of 9.8 m/s or 10 m/s.
Menorb primary as originally conceived would have had a stellar diameter of 712 solar diameters per Book 6. Good ol' Sol is about 1.4 million kilometers in diameter. So, Menorb primary, as an M5 II, would have had a 100-diameter limit out at 712*1.4m*100= 99.6 billion kilometers. Habitable zone at 122 AU, or about 18.3 billion kilometers. So, 81.3 billion kilometers best case. I get T at 2,851,000 seconds from start to turnaround, then the same to decelerate, or about 66 days from 100D limit to mainworld at 1G, and that's rounding 1G up to 10 m/s2. I'm pretty sure the person who made the list was not using 1 m/s2
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  #34  
Old March 13th, 2019, 09:55 AM
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Is it fair to say that jump masking was a far bigger problem for earlier editions that had much wilder stellar results? So you had a bunch of high pop worlds with native life in the habitable zones of supergiants. Many of these stars have been reconned to something on the main sequence, and for those stars masking isn't much of an issue.
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  #35  
Old April 2nd, 2019, 03:52 AM
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Well, the simple solution to Menorb as type II is to say the 100D jump limit shadow only applies to solid, icy, or similarly dense matter that would include a main sequence (type V) star. Various subgiant, giant, and supergiant stars are so rarified that they've expanded to roughly the size of the star's main sequence lifetime jump shadow, yet the mass is probably a little bit less than the star's original mass. Perhaps the jump shadow might expand to double the main sequence lifetime shadow due to greater tidal shear, or maybe not even that much.
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  #36  
Old April 2nd, 2019, 02:28 PM
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Quote:
Originally Posted by Straybow View Post
Well, the simple solution to Menorb as type II is to say the 100D jump limit shadow only applies to solid, icy, or similarly dense matter that would include a main sequence (type V) star. Various subgiant, giant, and supergiant stars are so rarified that they've expanded to roughly the size of the star's main sequence lifetime jump shadow, yet the mass is probably a little bit less than the star's original mass. Perhaps the jump shadow might expand to double the main sequence lifetime shadow due to greater tidal shear, or maybe not even that much.
100D IS the simple solution.

Many suggest that it's really a tidal function related to mass of the object. That brings in lots of math about density and mass and other things.

Or, you can just take the diameter, multiply it by 100, quip "Boy, Jump Space sure is weird", and call it a day.

How does 100D apply to a black hole? is D the event horizon?
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  #37  
Old April 2nd, 2019, 08:27 PM
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Originally Posted by whartung View Post
How does 100D apply to a black hole? is D the event horizon?
100D from the event horizon of a stellar black hole is about 1000-5000 km. I do NOT want to be there under any circumstances. About 1x106 g's even by classical Newtonian calculation, and tidal forces of about 0.1 g/m unless I miscalculated.
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Last edited by whulorigan; April 3rd, 2019 at 05:52 AM.. Reason: I did miscalculate.
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  #38  
Old April 2nd, 2019, 10:32 PM
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Quote:
Originally Posted by Straybow View Post
Well, the simple solution to Menorb as type II is to say the 100D jump limit shadow only applies to solid, icy, or similarly dense matter that would include a main sequence (type V) star. Various subgiant, giant, and supergiant stars are so rarified that they've expanded to roughly the size of the star's main sequence lifetime jump shadow, yet the mass is probably a little bit less than the star's original mass. Perhaps the jump shadow might expand to double the main sequence lifetime shadow due to greater tidal shear, or maybe not even that much.
Menorb primary as an M5 II was 16 solar masses. If we assume it's an older star that's moved off the main sequence, and if we use CT Book 6 as a guide, then it was a bit smaller than a B0 V before it expanded, and the original diameter would have been a bit under 10 solar diameters ... and the star's original habitable world froze up when the star moved off main sequence and expanded. Habitable zone moved inward from orbit 12 to orbit 11, covering a world that had originally been baked. It's an interesting idea, but I'm not certain a world originally in a Venusian orbit would still have any water to speak of by the time things cooled down. Maybe the Ancients flew some ice-teroids into it in a terraforming experiment. But, putting that aside, it would be a cool history; it means Menorb system has a frozen world that might once have had a living ecology. There's adventure fodder in that. Makes it a shame to have changed it - though the idea might be workable elsewhere.

At one time Aramis proposed this idea where the 100-diameter limit evolved from the cube root of some function or another. I wish I could recall the details; I thought it was rather clever.
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  #39  
Old April 3rd, 2019, 12:59 AM
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Quote:
Originally Posted by Carlobrand View Post
... and the star's original habitable world froze up when the star moved off main sequence and expanded. Habitable zone moved inward from orbit 12 to orbit 11, covering a world that had originally been baked.
I confess this is the opposite of what I expected to happen when a star moves off the Main Sequence to Giant phase. For instance, Heya, in the Marches in Regina subsector is an Ag world that orbits a K6 III orange Giant. Ive been playing for years that millennia ago Heya was a frozen world like Europa or Enceladus and the stars expansion to Giant phase shifted the HZ outward, immolating the old HZ and thawing out Heya, releasing the budding ecosystems locked under the ice.

Running the numbers with stellar data approximated from GURPS First In, I get an orbital period of over 50 years, creating some interesting flora and fauna life cycles, as well as an interesting and different culture to interact with.

Of course (back to the OT) TL 5, star port B Heya is, under this paradigm, several days travel inside the stars jump shadow for 2G ships, almost a week for 1G vessels... on the coreward Imperial border where many Vargr raiders prowl.

If I am mistaken about how stars leave the Main Sequence and their energy output when they do so, well... Heyas too much fun to fix IMTU.
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  #40  
Old April 3rd, 2019, 05:50 AM
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Quote:
Originally Posted by Carlobrand View Post
At one time Aramis proposed this idea where the 100-diameter limit evolved from the cube root of some function or another. I wish I could recall the details; I thought it was rather clever.
I believe the 100D limit and the "cube root" being referred to has to do with the gravitational tidal force.

G-Field (Gravitational acceleration):
  • ag = -GM/R2 (in mks-units, divide by 10 for units in g's)
Tidal acceleration:
  • Tg = ∆ag = D x -GM/R3, where D is the length (or diameter) of the object experiencing the tidal force. (in mks-units, divide by 10 for units in g's per meter)

So in this interpretation, it is not necessarily the g-field itself that is the problem, but rather the change in intensity of the field with respect to distance across the dimensions of the ship (i.e. the gravitational gradient). This also means that an accelerating ship would potentially have no problem jumping (as the acceleration would potentially be the same at any point on the ship under acceleration). See: Equivalence principle.
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Baroness of NorthammonDENE 0921 Northammon B764667-AMCGx2 - For Conspicuous Gallantry @ The Assaults on Dinomn & Denotam

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Last edited by whulorigan; April 3rd, 2019 at 08:36 AM..
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