General Carchemish - Kukulkan subsector

[Duke Craig]

Locus Kukulkan subsector (Solomani Rim 2536)

Introduction
This is mostly a frozen world, however at several times during the 63.2 day orbital period it becomes a hot world.
There is indigenous life in the oceans and on land.
The native life (more on that elsewhere) is highly adapted to wild temperature swings and there maybe a research institute on the planet supported and maintained by SolSec.

Stellar Data
binary stellar system in close orbit
an M3 V Mass = 0.354, Luminosity = 0.027
and M2 V Mass = 0.386, Lumoinosity = 0.035
The M3 V star located in close orbit 15Mkm to the M2V star.

System Planetary Data
M2V/M3V binary system
Orbit 0.8 Carchemish 2536 D778169-7 Lo 403 So
Orbit 2 SGG named Hydrospar
Orbit 3 Cee X840000-9
Orbit 4 Dee X610000-0
Orbit 5 SGG named Heliospa
Orbit 6 LGG named Interdicted no fueling (not surveyed)
<source=https://wiki.travellerrpg.com/Carchemish_(world)>
Empty Orbits
11, 10, 9, 8, 7

System Notes:
The M2V/M3V stars are in close orbit. This binary system has one gas giant each in orbit 2 (0.7 AU), 5 (2.7 AU) and 6 (5.0 AU).
Carchemish orbits in a highly irregular orbit around orbital zero point eight.
There are two other uninhabited planets found in orbit 3 (0.97 AU) and 4 (1.55 AU).
The planet designated Cee has a nuclear pile communication array with a recorded message advising interstellar travellers on frontier refueling parameters.
An automated refueling station providing unrefined fuel is available on a moon of Hydrospar.

Distance between the planet Carchemish to the gas giant, Hydrospar in light seconds equals 250 + (4d6-4) times 15 light seconds. Average distance is 400 light seconds.
Average travel time from planet to gas giant assuming a ten hour 1G burn is nearly 100 hours (4 days).
Average is ten hours to refuel with an average piloting check.

The many moons of the three Gaseous giants remain unsurveyed.

Planetary Orbital Data
The planet Carchemish orbits the binary pair (eccentricity = 21%). During the planetary orbit, Carchemish has two periapsis points, both around 0.18 AU (closest point) to one of the two stars. At the periapsis the temperature rises gradually up to nearly 100 degrees C at the equator.
It experiences two apoapsis points and is occasionally tugged further away from the binary barycenter by the gaseous giant in orbit 2 and the temperature drops suddenly to below -70 degrees C.

Planetary Physical Data:
Carchemish 2536 D778169-7 Lo 403 So

Starport: Class II.
Diameter: 6,700 miles (10,700 km). Gravity: 0.84g.
Atmosphere: Standard oxygen-nitrogen (Tainted).
Hydrographics: 66%.
Climate: Normal.
Population: 40.
Government: Captive (Pavel).
Control Level: 6.
Tech Level: 11.
World Trade Number: 2
<source=https://wiki.travellerrpg.com/Carchemish_(world)>

Carchemish Notes
The planet is located in orbit 0.8, some 48.9 Mkm around the main stellar pair.
Carchemish receives mainly infrared light from it's twin cool and higly active red main sequence stars.

The atmosphere has a sulphur taint caused by volcanism. There are at least 9 active volcanoes on the planet and another 20 inactive volcanoes. The planet has deep oceans of H2O probably containing a multitude of life (not researched yet). The human (or other) inhabitants are likely involved in the research of the native life.

It is NOT tidally locked.
Orbital Period = 63.2 days = 0.1733 years
Orbital Eccentricity = 0.21
Axial Tilt = 25 degrees
Day/Night Cycle = 39.46 hours

The temperature of the planet was determined to be within the range 222.4 K (-50.75 C) and 325.2 K (51.85 C). This is a normal planet prone to wide variations during two irregular hot seasons, lasting between 3-6 days each and at least one frozen season, lasting between 6-11 days. The seasons are not regular throughout the year due to a highly irregular orbit.

The Starport is an automated landing beacon only. There are no repair or maintenance facilities. There is a reinforced and insulated warehouse for long term storage of supplies adjacent to the research station.

The research station is an underground mined facility capable of supporting around 40 individuals. Research is conducted on the native life found near river systems.

Thanks for reading.

 

[BRover]

I'm curious about this system, and similar close stars. T5 has the 100 diameter rule, which produces a stellar exclusion zone, as well as planetary exclusion zones. Would it matter if two zones overlap? It might not here, where the stars are low mass--but what if they were, say, F stars, with more than one solar mass each? Should there be an "extra" cushion--say, WAG of 120 diameters to safe jump distance?

 

[Duke Craig]

I'm curious about this system, and similar close stars. T5 has the 100 diameter rule, which produces a stellar exclusion zone, as well as planetary exclusion zones. Would it matter if two zones overlap? It might not here, where the stars are low mass--but what if they were, say, F stars, with more than one solar mass each? Should there be an "extra" cushion--say, WAG of 120 diameters to safe jump distance?

Thanks for this comment and the interesting question raised.
I don't know the answer to your question but I'd suggest sticking with 100 diameters. All versions of Traveller, that I am aware of, use the 100 diameters rule for entering and exiting Jumpspace.
I agree that planetary and stellar overlap zones could exist. So let's have a look at a couple of potential candidates.

Stars are categorized by heat, luminosity and size.
Class OABFGKM and Type Ia,Ib,II,III, IV,V,D. A numerical identifier is added because there are a lot of different types of stars.

Class defines the star's "surface" temperature and Type defines the star's relative size.
I'm using CT Book 6 Scouts, TNE The Regency Sourcebook: Spinward Marches data and an excel spreadsheet.

Firstly Earth.

Earth orbits a G2V class/type of star. This star called the Sun has a surface temperature of around 5830 K.
Diameter = 2 x 696,342 km equatorial radius = 1,392,684 km,

A hundred times the Sun's diameter = 139,268,400 km.
One hundred diameters is around One hundred and thirty-nine million km.

The Earth's Diameter is 12,740 km times 100 = 1,274,000 km

Earth Orbits at 150 million km. So no overlap.


Second, we'll have a look at Regina.

Star called Lusor is an F7V Class/type.
Probable radius = 1.25 sol so diameter = 2.5 x 696,342 km = 1,740,855 km

One hundred diameters of Lusor 174,085,500 km.

Regina orbits a LGG in orbit 4.

Orbit 4 is around 225 million km from the star.

Lets call the LGG Assiniboia (canon). For argument's sake we'll say that Assiniboia is 145,000 km diameter.

145,000 km times 100 diamters is 14,500,000.

225 million minus 174 million is 51 million which is greater than 14.5 million.

Again no overlap.


We need to have a look around the Spinward Marches to find another type of star. But we don't have to look too far to find the possible candidate. There are many to choose from...

Narsil in the Sword Worlds is the capital and orbits an M0II Class/Type star. Possibly with a binary close dwarf star orbiting (not determined).

The MOII class probable radius = 237 sol for a diameter = 696342km x 237 sol radii x 2 = 330,066,108 km diameter. Narsil star is one big star. A red giant.

100 diameters (narsil star) = 33,006,610,800 km
33 billion km.

It is possible that Narsil is a satellite (undetermined)

Narsil is probably in the habitable zone since it has water. Habitable zone around an M0II star is 67 AU.
Let's place the planet in Orbit 10 at 77 AU. So it would be quite cool.

Narsil Orbital distance = 77 AU x 150 million km is 11.5 billion km.

But 100 diameters of the Narsil star is 33 billion km.

And the planet Narsil orbits at 11.5 billion km.

Clearly, 11.5 billion km is less than 33 billion km.

Therefore Narsil is far within the gravity field of the Narsil star.

After exiting Jump a starship would have to traverse some 21.5 billion km (at least) to reach Narsil.

How long would that take? That is the subject of another post...


Thanks for reading.

 

[BRover]

Duke Craig,

I get all that. I'm wondering if having two close stellar masses would change the equation--might you get out the requisite 100 stellar diameters from both, only to find that the "gravity gradient" is still too steep for a safe jump? I'm thinking it might--terrestrial planets max out at about 1-2G, Jupiter and its ilk are higher--2.5+G easily. Stars proper get even higher surface Gs, and so even 100 diameters out would have a higher "residue" of gravity. After all, with the inverse square law, 100 diameters = 200 radius, giving 0.0025% surface gravity--but if you start at, say, 5G, it's still higher than comfortable--and if you start with two similar fields. . . .

Or is is just the proximity of a substantial mass too close that is somehow the problem? (And what might be the cause that reaches out such a distance?)

I think that math seems right . . .

 

[Duke Craig]

Duke Craig,

I get all that. I'm wondering if having two close stellar masses would change the equation--might you get out the requisite 100 stellar diameters from both, only to find that the "gravity gradient" is still too steep for a safe jump? I'm thinking it might--terrestrial planets max out at about 1-2G, Jupiter and its ilk are higher--2.5+G easily. Stars proper get even higher surface Gs, and so even 100 diameters out would have a higher "residue" of gravity. After all, with the inverse square law, 100 diameters = 200 radius, giving 0.0025% surface gravity--but if you start at, say, 5G, it's still higher than comfortable--and if you start with two similar fields. . . .

Or is is just the proximity of a substantial mass too close that is somehow the problem? (And what might be the cause that reaches out such a distance?)

I think that math seems right . . .

You have covered a fair bit of ground there.

I think that math seems right . . .

Thanks BRover.

I'm wondering if having two close stellar masses would change the equation--might you get out the requisite 100 stellar diameters from both, only to find that the "gravity gradient" is still too steep for a safe jump?

Its a good question. The maths for that question is here.
https://en.wikipedia.org/wiki/N-body_problem


This also might help with that problem: Chapter 2 Gravitational Dynamics https://home.strw.leidenuniv.nl/~spz/publ/Chapter2.pdf
It would also be an integral of that problem based on relative positions of the bodies. I'm not likely to run through that problem on here. I don't think anyone would care to read it. o: It would more than likely be part of a PhD Thesis in astrophysics.


Thanks for reading.

 

[whartung]

While some objects overlap, once you're out of "100D from anything", you're safe -- overlap or no. Now, is the overlap zone "extra" perilous? i.e. if there's a chance for mishap when 100D from one object, what is it when you're within the zone for more than one object.

That would be the more interesting question.

I don't know if there's a gradient of DMs based on how far you are from objects.

If the DM is "+0" for 100D, what is it for 99D? What is it for 1D? Are they different?

Is jump simply "impossible" at a certain close distance, or is it simply destined to fail. Most misjumps actually jump, just either to the wrong place or never return. Is there some area where it doesn't even start?

And there are several systems that are shrouded by their primaries and (in theory) you have to transit out past the 100D of the star to jump, not just the planet. Isn't Rhylanor one of these? Or is it Regina? One of the "common" systems is pretty deep in to its primaries well.

 

[BRover]

While some objects overlap, once you're out of "100D from anything", you're safe -- overlap or no. Now, is the overlap zone "extra" perilous? i.e. if there's a chance for mishap when 100D from one object, what is it when you're within the zone for more than one object.

That would be the more interesting question.

I don't know if there's a gradient of DMs based on how far you are from objects.

If the DM is "+0" for 100D, what is it for 99D? What is it for 1D? Are they different?

Is jump simply "impossible" at a certain close distance, or is it simply destined to fail. Most misjumps actually jump, just either to the wrong place or never return. Is there some area where it doesn't even start?

And there are several systems that are shrouded by their primaries and (in theory) you have to transit out past the 100D of the star to jump, not just the planet. Isn't Rhylanor one of these? Or is it Regina? One of the "common" systems is pretty deep in to its primaries well.

Just off the top of my head, I recall at least one ruleset had a higher misjump chance for <10 diam. vs. <100 diam. Details escape me, however.

Still, "Inquiring minds want to know!"

 

[PVernon]

As I remember it there is a bit of color text about one of the Azanti class cruisers, where the ship is half destroyed and is falling into a star so the captain orders the ship to jump at like 10 diameters from the star. As I remember it, it does not end well. But the point is that you can jump as close to an object as you want, results may now be very good in the end.

 

[Condottiere]

The option exists.

You certainly don't want to try it while dirtside, or within orbit.

I presume, depending on the edition, after ten diameters it becomes feasible, especially when Scotty's onboard, for a mono or micro jump, to avoid any Imperial entanglements.

 

[Grav_Moped]

Just off the top of my head, I recall at least one ruleset had a higher misjump chance for <10 diam. vs. <100 diam. Details escape me, however.

Still, "Inquiring minds want to know!"

LBB2 2nd Ed. p.6:
Misjump (roll 2D): 13+
Destroyed: 16+
Unrefined fuel: DM+1
<100D but more than 10D: DM+5
<10D DM+15

So, best case (refined fuel), <10D is always "ship is destroyed".
Between 10 dia. and 100 dia., results on the base 2D roll are:
2-7: normal jump
8-10: misjump
11+: ship destroyed

If you're a considerate referee, you might be willing to lower the +DMs the closer a ship is to the 100D limit, but that's not rules as written.

Also, IMTU (and arguably for OTU) that's the main defense tactic for Type S Scouts. Keep the tanks full, and be ready to sprint to the 10D limit popping off sandcasters like confetti then bang out a J1 and roll the dice. 42% of the time it's a normal Jump, but only an 8% chance of immediate doom. Allow the TCS power-down rule to apply during Jump (Pn->1) and even after a 6-week misjump the ship still has enough fuel for a Jump-1 and 1 week of Pn-1 afterwards (15Td) it can use to reach a fuel source.

Because, bluntly, a Type S is a terrible combat platform.