# The World Builder's Handbook - It Is Here!

Apologies if this has been covered before: for star age calculations are subdwarf (Class VI) stars treated the same as main sequence stars? Thanks in advance!
Yes. Under Main Sequence lifespan on page 20 it says:
the ‘normal’ phase of a star’s life is similarly determined for Class Ia, Ib, II, V and VI stars.

The 'lower half' of subdwarfs is all under 0.9 Sol, so their actual age can be determined by the Small Star Age equations on p. 21, and those odd duck hot O and B subdwarfs (as well as all Class Ia, Ib, and II) would use the Large Star Age equations on the same page.

I'll have to be honest and say that I don't know what those odd duck hot subdwarfs evolve into, but the G-M subdwarfs, if the universe where older, would go through a VI -> IV -> III -> White Dwarf life cycle, similar to the main sequence stars.

Thanks mate, makes for an easy code change, just change if star.starClass = 'V' to if star.starClass in ['V', 'VI']

Ok, I am just looking for clarification in regards to the star position codes from page 25.

Primary =Aa
Companion of Primary = Ab
Close = Ba
Companion of Close = Bb
Near = Ca
Companion of Near = Cb
Far = Da
Companion of Far = Db

So each stars position is a 2 digit code, skipping missing stars, dropping the upper case 'a' for companions if doing a short form?

ie Single star = A
Single star with a close companion, short form = Aab

I hope I am understanding this correctly.

Ok, I am just looking for clarification in regards to the star position codes from page 25.

Primary =Aa
Companion of Primary = Ab
Close = Ba
Companion of Close = Bb
Near = Ca
Companion of Near = Cb
Far = Da
Companion of Far = Db

So each stars position is a 2 digit code, skipping missing stars, dropping the upper case 'a' for companions if doing a short form?

ie Single star = A
Single star with a close companion, short form = Aab

I hope I am understanding this correctly.
Looks correct in general, but in fact that would only be strictly true for an eight star system. locations without stars don't get letters.

For example, if all there was a single primary and Far secondary with companion, it would be A, Ba, and Bb, with circumbinary worlds around the Far stars being Bab, and a world which orbited the primary beyond the Far stars being designated roman numerals after AB (or ABab for the pedantic).

Looks correct in general, but in fact that would only be strictly true for an eight star system. locations without stars don't get letters.

For example, if all there was a single primary and Far secondary with companion, it would be A, Ba, and Bb, with circumbinary worlds around the Far stars being Bab, and a world which orbited the primary beyond the Far stars being designated roman numerals after AB (or ABab for the pedantic).
Was there a reason why you didn't just go with a positional notation?
ie
0 is the primary,
1 is the primaries companion,
2 is close,
3 is close companion
4 is near
5 is near companion
6 is far
7 is far companion
8 is close to far
9 is close to far companion
A is near to far
B is near to far companion
C is distant
D is distant companion
E is close to distant
F is close to distant companion
G is near to distant
H is near to distant companion

So it would be a single digit per star position, instead of two. No need for a simplification step.
For those who like profiles, first digit is the star position, followed by a dash, followed by the star type ie 0-G2V etc

Originally, I thought you were following the astronomy standard, but Aa is not the primary nor is Ba the close if you are following the standard

This is why I had suggested going by barycenter vs star as it is less confusing than basing orbits on stars.
Most of the nomenclature is based upon barycenters.

There have been many systems discovered with more than 8 stars, for example
which has 10 stars.

I was just confused by your use of the Aa/Ab style nomenclature without following it. Most people would not have picked up on it and for the average gamer, it does not matter, but, for someone who tries to follow this stuff, it is confusing.
For the average gamer, a simple digit as a placeholder without the need for simplification, should suffice.

I am not trying to tear apart your excellent work, just trying to understand your reasoning.

Best regards
Dalton

On the subject of trade numbers, is there any modifier for neighbors or trade routes? For instance, Serendip Belt is Importance 5. Neubayern is Importance 4. Presumably they trade with each other. But they are 5 parsecs apart and the two systems between them are Importance -2 and Importance -3.

So the raw figures show thousands of tradeships a week at Neubayern & Serendip, with only 1 per week at Topas and Berlichingen. Which you need to pass through to trade between the two.

Obviously, I can massage outcomes as is a general expectation for any RPG system. That's no big deal. I just wondered if there was anything I was overlooking as far as guidance on that.

Was there a reason why you didn't just go with a positional notation?
ie
0 is the primary,
1 is the primaries companion,
2 is close,
3 is close companion
4 is near
5 is near companion
6 is far
7 is far companion
8 is close to far
9 is close to far companion
A is near to far
B is near to far companion
C is distant
D is distant companion
E is close to distant
F is close to distant companion
G is near to distant
H is near to distant companion

So it would be a single digit per star position, instead of two. No need for a simplification step.
For those who like profiles, first digit is the star position, followed by a dash, followed by the star type ie 0-G2V etc

Originally, I thought you were following the astronomy standard, but Aa is not the primary nor is Ba the close if you are following the standard

View attachment 1221
This is why I had suggested going by barycenter vs star as it is less confusing than basing orbits on stars.
Most of the nomenclature is based upon barycenters.

There have been many systems discovered with more than 8 stars, for example
which has 10 stars.

I was just confused by your use of the Aa/Ab style nomenclature without following it. Most people would not have picked up on it and for the average gamer, it does not matter, but, for someone who tries to follow this stuff, it is confusing.
For the average gamer, a simple digit as a placeholder without the need for simplification, should suffice.

I am not trying to tear apart your excellent work, just trying to understand your reasoning.

Best regards
Dalton
Mainly I went the route I did to maintain compatibility with the way Orbits and multiple star systems have already been described in Traveller - specifically the T5 notation and its notion of secondary and companion stars. I toyed with 'fixing' it using barycentres and the tree-like multi-star paradigm, but it buys very little game benefit at the cost of more complex calculation and incompatibility with decades of material.

For a 'clean slate' design system, I would use a barycentre-based tree-like model without the artificial constraints of primary, secondaries, and their companions. I would also dispense with Orbits and handle planetary atmospheres differently. But if I did all that, it wouldn't be Traveller.

Mainly I went the route I did to maintain compatibility with the way Orbits and multiple star systems have already been described in Traveller - specifically the T5 notation and its notion of secondary and companion stars. I toyed with 'fixing' it using barycentres and the tree-like multi-star paradigm, but it buys very little game benefit at the cost of more complex calculation and incompatibility with decades of material.

For a 'clean slate' design system, I would use a barycentre-based tree-like model without the artificial constraints of primary, secondaries, and their companions. I would also dispense with Orbits and handle planetary atmospheres differently. But if I did all that, it wouldn't be Traveller.
I understand. I don't know if I would have done it much differently from you in this regard except for the placement notation vs the Aa/Ab notation. I have been looking at orbits as multiples of star diameter, etc, in the same manner you approached moons.
Perhaps once the new ORC or OGL or whatever is released, I may post my own material on this.

I understand. I don't know if I would have done it much differently from you in this regard except for the placement notation vs the Aa/Ab notation. I have been looking at orbits as multiples of star diameter, etc, in the same manner you approached moons.
Perhaps once the new ORC or OGL or whatever is released, I may post my own material on this.
Yeah, orbits, planetary diameters and all that... mass is a more constant arbiter if you want purity - sure mass will gradually shrink a little as the star ages (and then a lot in the giant stage), but diameter can vary to a much greater extent. Only the Roche limit really depends on the diamater and even that's not strictly true. Mass determines Hill sphere distances, not only for moons, for differing stars and even planets - look how big the Hill sphere of Neptune is, for instance: the radius is more than 0.75 AU, so no other planets could occupy orbits which approached the planet more closely than that - probably out to 2 or more AU would be unstable.

I note that the World Builders Handbook Forms and Templates.pdf does not include the system overview graph that is shown in WBH pgs 64, 66, 68.
Will there be an update to the template file to include this?

I note that the World Builders Handbook Forms and Templates.pdf does not include the system overview graph that is shown in WBH pgs 64, 66, 68.
Will there be an update to the template file to include this?
Is page 12 of the forms and templates what you're looking for?

Is page 12 of the forms and templates what you're looking for?
Ah, I see that the PDF has been updated. My earlier copy stops at page 11!

Rogue planet plot ideas from the literature
• Dark Eden: a planet lit and heated by geothermal “trees”. In the books, inhabited by the descendants of the first explorers
• Beyond the Aquila Rift: an “empty” hex where many misjumping ships end up.
Are there others?

@Geir
I was doing a little searching on black hole diameters and found this

It seems, well, far too simple to be true, but, the source being nasa and specfically about black hole diameter and math.......

But if so, 12km diameter per solar mass makes calculations very simple.

Have you found anything that specifically addresses the diameter of a black hole?

@Geir
I was doing a little searching on black hole diameters and found this

It seems, well, far too simple to be true, but, the source being nasa and specfically about black hole diameter and math.......

But if so, 12km diameter per solar mass makes calculations very simple.

Have you found anything that specifically addresses the diameter of a black hole?
That math problem doesn't cite any sources, so I'm not sure how accurate it is. Can't do a lot of research today, but both Wikipedia and the magic question box (chatGPT - which I give even less credence to than Wikipedia - and which the Google spell check wants to change to 'catgut') give answers of just less than 3 km per solar mass and a smaller radius if spinning, though I suppose that could be the 'polar' radius being smaller and the 'equatorial' radius being larger.

That math problem doesn't cite any sources, so I'm not sure how accurate it is. Can't do a lot of research today, but both Wikipedia and the magic question box (chatGPT - which I give even less credence to than Wikipedia - and which the Google spell check wants to change to 'catgut') give answers of just less than 3 km per solar mass and a smaller radius if spinning, though I suppose that could be the 'polar' radius being smaller and the 'equatorial' radius being larger.
I have found ChatGPT (I and subscribed and have access to GPT4) has been getting worse. The quality of it's answers are not as good as they were even a month ago.
That is why I was trying to find from a more "confident" source ie fermilab, nasa, etc.,
But, the only thing I found so far was that work sheet.

I was hoping in your research you may have found some of these things.
One of the best resources I use happens to be
but I would love to find something that is just as in depth for other objects.
For colours, (for my autogeneration of star images) I use

If anyone is interested, I can post actual, updated stellar details for use in your games.

Schwarzschild radius of a stellar mass black hole is:
Rs=2GM/c^2

so Rs is 2x((6.7x10^-11)x(2x10^30))/9x10^16 = 3000m

diameter is 6km.

Schwarzschild radius of a stellar mass black hole is:
Rs=2GM/c^2

so Rs is 2x((6.7x10^-11)x(2x10^30))/9x10^16 = 3000m

diameter is 6km.
You sir are a genius, do you have a resource material that can be cited? I don't use Wikipedia as a trusted resource, nor do I trust references used in wikipedia. So a non-wiki based source is what I am looking for.

Also, I have the gaia gedr3 data which I have converted into galactic X/Y/Z coordinates but I have not found a way to convert the data for each star into the Morgan Keenan classification system. Any insights on how to do that?

Last edited:
Schwarzschild radius of a stellar mass black hole is:
Rs=2GM/c^2

so Rs is 2x((6.7x10^-11)x(2x10^30))/9x10^16 = 3000m

diameter is 6km.
Well of all the @*(&*^#. I actually confused radius with diameter in the book. Diameter should absolutely be 5.9km x mass, not 2.95 as I wrote on page 228... hopefully not too late to fix.

Well of all the @*(&*^#. I actually confused radius with diameter in the book. Diameter should absolutely be 5.9km x mass, not 2.95 as I wrote on page 228... hopefully not too late to fix.
^This
This is why we need access to the pdf BEFORE it goes to print.

This is an extremely complex and detailed document, and we all want it to be as close to perfect as possible.

We need an August Update to the WBH to ensure we can get one more read through before it goes to the printers - I doubt anyone (myself included) who paid in advance would mind if it was held up for editing.

Replies
80
Views
4K
Replies
24
Views
1K
Replies
20
Views
2K
Replies
107
Views
4K
Replies
5
Views
529