~76% Main Sequence Stars are Red Dwarfs

[The Pakkrat]

Live via satellite, this is the Pakkrat for NET-7 News! There was chaos in Stellar Cartography today as an error in Habitable Zone Orbit locations was found in relation to the Mainworlds to their parent, Red Dwarf stars, forcing many populated worlds to suddenly realize they were lacking Twilight Zone and Tidally Locked Trade Classifications.

:CoW:

1. Look at any given T5SS ‘official’ Sector data list. Find all the solar primary bodies with M V, M VI and M D star types, e.g. M3 V.

2. Consult the chart on Traveller⁵, pages 400 and 413 HZ Habitable Zone Orbits.

3. Note on those twin charts that M V, VI and M D stars have the Habitable Zone (HZ) in Orbit 0 (zero).

4. Every HZ mainworld in Charted Space with a solar primary of M V, M VI and M D type has to be changed.

4a. Every HZ mainworld orbiting a secondary, tertiary or quarternary M V, M VI or M D star is also to be changed.

5. Change all Mainworlds in Orbit 0 or 1 to Twilight Zone World (Tz).

6. Change all Mainworlds in Orbit 0 to Tidal Locked (Lk).

7. Enjoy the headache and increased blood pressure across all canon Charted Space. :devil:

8. Have a nice day.

This information brought to you by Stellar Classification on Wikipedia. Please, someone, tell me I'm reading this wrong and save the cartographers of this Highport from jumping out the nearest airlock. For NET-7 News, this is the Pakkrat running for heartburn meds.

 

[whulorigan]

Live via satellite, this is the Pakkrat for NET-7 News! There was chaos in Stellar Cartography today as an error in Habitable Zone Orbit locations was found in relation to the Mainworlds to their parent, Red Dwarf stars, forcing many populated worlds to suddenly realize they were lacking Twilight Zone and Tidally Locked Trade Classifications.

:CoW:

1. Look at any given T5SS ‘official’ Sector data list. Find all the solar primary bodies with M V, M VI and M D star types, e.g. M3 V.

2. Consult the chart on Traveller⁵, pages 400 and 413 HZ Habitable Zone Orbits.

3. Note on those twin charts that M V, VI and M D stars have the Habitable Zone (HZ) in Orbit 0 (zero).

4. Every HZ mainworld in Charted Space with a solar primary of M V, M VI and M D type has to be changed.

4a. Every HZ mainworld orbiting a secondary, tertiary or quarternary M V, M VI or M D star is also to be changed.

5. Change all Mainworlds in Orbit 0 or 1 to Twilight Zone World (Tz).

6. Change all Mainworlds in Orbit 0 to Tidal Locked (Lk).

7. Enjoy the headache and increased blood pressure across all canon Charted Space. :devil:

8. Have a nice day.

This information brought to you by Stellar Classification on Wikipedia. Please, someone, tell me I'm reading this wrong and save the cartographers of this Highport from jumping out the nearest airlock. For NET-7 News, this is the Pakkrat running for heartburn meds.

Keep in mind that not all worlds need be in the habitable zone for any given stellar type. Only worlds otherwise described as "Earth-like" or possessing breathable atmosphere and "shirtsleeve" environment would need to be in the habitable zone. Vacuum worlds, trace-atmo worlds, as well as exotic, corrosive, or insidious atmospheres could be in any orbital zone potentially.

 

[Garnfellow]

Well, not quite. The Tz classification is for planets, while the Lk classification is reserved for satellites in near orbit. They are mutually exclusive.

Further, you could have a mainworld that is a satellite orbiting a hot Jupiter gas giant or BigWorld in orbit 0 or 1 that would have neither the Tz or Lk classification.

But that pedantry aside, your general point is right: based on T5 worldgen, most mainworlds of size 1+ orbiting an red dwarf should probably have the twilight zone classification.

(Personally, I just assume that any mainworld of size 5+ and atmo 456789 orbiting a single M class star is tide-locked to the primary.)

It would impossible to usefully apply this observation to the T5SS dataset without generating planet/satellite and specific orbit position for all mainworlds in order to know which ones are in the HZ and which ones are satellites.

 

[The Pakkrat]

So,
Who wants to ret-con all the canon, Charted Space worlds already written up and that will require revision to tack on Twilight Zone (Tz) across the rest of Charted Space. How many populations will be standing on the wrong side of the mainworld when Tz gets dropped on them? The casualties projections are staggering, viewers.

"I felt a disturbance in the Force..."

Though thirty duplicate M dwarfs of the original 132 need to be re-rolled in Knoellighz Sector that I have been revising and developing, it will be an unrelated chore. The remainder original M V, MVI and M D primaries will have to looked at again for the mainworld's position in the system. Then each will have to be checked against Earth-like, habitable stats as to whether the planet is either a Satellite or a normal planet in the Habitable Zone be it HZ-1, HZ or HZ+1.

Will Charted Space and its inhabitable worlds look different after each sector has been combed for those criteria? Is this an overhaul of the consensual Traveler Universe as we thought we knew it?

Will this issue get swept under the rug of Errata despite the fact that, yes ~76% of Main Sequence stars are red dwarfs? Are we playing with sophonts' lives when suddenly their homeworld stops spinning in the face of its Type M star?

All we do know, viewers is that space may never be the same if this issue isn't Errata.

"Call your mate-spouses, cartographers. It's going to be a long night."

Via satellite, this is the Pakkrat.

 

[Ulsyus]

While it may not be regarded as a definitive source, I thought this article was interesting:

Previous studies determined that there are about six stars for every brown dwarf in our cosmic neighborhood. Those studies only looked at brown dwarfs within a range of about 1,500 light-years from Earth, where such faint and tiny objects are easier to spot. However, the entire Milky Way spans a much greater distance of about 100,000 light-years, and it turns out that our neck of the woods isn't exactly representative of the entire galaxy.

That would mean that even if there were meant to be more brown dwarf stars than represented in canon, the star charts of Traveller should be pretty safe for about 460 parsecs from Terra, which will cover charted space won't it?

As for the others in our vicinity, if they're satellite-less and stuck out there quiet and silent in space, why would a vessel travel there (except to reactivate the installation of cyborg-zombies left over from the Rule of Man...)

 

[whulorigan]

As for the others in our vicinity, if they're satellite-less and stuck out there quiet and silent in space, why would a vessel travel there . . .

If it is cool enough (i.e. Y-Type) one might be able to skim fuel from it like a gas giant. Which might create a "short-cut" across a small section of space otherwise less easily accessible.

 

[Ulsyus]

If it is cool enough (i.e. Y-Type) one might be able to skim fuel from it like a gas giant. Which might create a "short-cut" across a small section of space otherwise less easily accessible.

Nice.

They might have to be written out of the Rift though, just to keep it's impact the same. One would imagine that over the duration of the 3I astronomers may have noticed some brown dwarfs out there if they were to help cross it.

If not them, then some enterprising Aslan clan could surely have found them, couldn't they?

 

[whulorigan]

If not them, then some enterprising Aslan clan could surely have found them, couldn't they?

Presumably, yes.

 

[G. Kashkanun Anderson]

If it is cool enough (i.e. Y-Type) one might be able to skim fuel from it like a gas giant. Which might create a "short-cut" across a small section of space otherwise less easily accessible.

While theoretically possible, I would classify that as suicidal behavior at standard Traveller Tech Levels. A typical Type-Y brown dwarf will be up to 25% smaller in radius compared to Jupiter while being anywhere from 10-75 times more massive. This requires you to go much, much deeper into the body's gravity well in order to reach the hydrogen, forcing you to deal with exponentially higher wind shear and g-forces than you will find on a standard gas or ice giant.

A typical 20Mj Type-Y brown dwarf at skimming level should have a 'surface' gravity of over 100 g's. I imagine Grandfather-level tech can handle this, but I don't know that anything built by the Imperium could.

 

[Wol]

Is there a scientific way of determining how close the planet and star have to be, to be tidally locked?

Could it be that planets are at orbit 1.5, a bit colder, and that forms the Hz in such cases?

After all, the old standard orbits are a bit of make believe aren't they?

regards

 

[GypsyComet]

Take a closer look at T5's stellar generation process. It tends to generate a lot more companion stars than the UWP has room for. They are background noise, and they are red "dwarf" stars often enough that the OP's "problem" essentially vanishes.

A more apropos problem is that "Dwarf" has changed meanings over the years. In modern parlance Sol is a Dwarf, while Traveller has kept the older usage that centers around dwarf stars having left the Main Sequence (or never been on it).

 

[OjnoTheRed]

Live via satellite, this is the Pakkrat for NET-7 News! There was chaos in Stellar Cartography today as an error in Habitable Zone Orbit locations was found in relation to the Mainworlds to their parent, Red Dwarf stars, forcing many populated worlds to suddenly realize they were lacking Twilight Zone and Tidally Locked Trade Classifications.

:CoW:

1. Look at any given T5SS ‘official’ Sector data list. Find all the solar primary bodies with M V, M VI and M D star types, e.g. M3 V.

2. Consult the chart on Traveller⁵, pages 400 and 413 HZ Habitable Zone Orbits.

3. Note on those twin charts that M V, VI and M D stars have the Habitable Zone (HZ) in Orbit 0 (zero).

4. Every HZ mainworld in Charted Space with a solar primary of M V, M VI and M D type has to be changed.

4a. Every HZ mainworld orbiting a secondary, tertiary or quarternary M V, M VI or M D star is also to be changed.

5. Change all Mainworlds in Orbit 0 or 1 to Twilight Zone World (Tz).

6. Change all Mainworlds in Orbit 0 to Tidal Locked (Lk).

7. Enjoy the headache and increased blood pressure across all canon Charted Space. :devil:

8. Have a nice day.

This information brought to you by Stellar Classification on Wikipedia. Please, someone, tell me I'm reading this wrong and save the cartographers of this Highport from jumping out the nearest airlock. For NET-7 News, this is the Pakkrat running for heartburn meds.

I agree this is a problem. Let's just narrow it down, though, to worlds attracting the Trade Codes "Ag", "Ga", or "Ri" in the Spinward Marches where the primary star is a red dwarf. That leaves this list:

0103 Errere
0133 Emape
0301 Rio
0425 Engrange*
0538 Wonstar*
0605 Algebaster
0618 Dekalb*
0710 Stave*
0904 Chwistyoch*
0921 Hrunting*
1006 Emerald
1123 Joyeuse*
1138 Tarsus
1204 Mongo
1340 Motmos
1434 Tarkine
1523 Durendal*
1525 Sting*
1706 Alell*
1924 Ianic
2112 Rech*
2402 Heya*
2414 Tureded
2419 Cogri
2602 Corfu
2701 Lablon
2715 POROZLO*
2833 Pepernium
2933 Raydrad
3118 Cipatwe*
1529 Steel

* = population of 7 or more.

All of these I initially imagine to be bread baskets, full of parks and gardens, wealthy and highly human compatible worlds.

Except they are all Twilight Zone worlds if they are placed in the HZ.

Notice that Tarsus - a highly detailed and published world - is on this list!

And if they are placed in the next orbit out, they are at least as cold as Mars - and if this still places them in Orbit 1, they are still tidally locked!

I don't have the tidal-locking formula to hand, but it's on a world-building book or website somewhere (edit: found it! see further reply below), and there's no question the 5-billion year locking limit is in orbits 0 and 1 for main sequence stars, further for larger stars.

For some of these worlds I think a change to a star of F, G or K is in order. The lower population (Ni or Lo) we can justify as "Ag", "Ri" or "Ga" because that's the experience of those worlds based on the population huddling in the TZ around the starport. Porozlo is particularly problematic - A867A74-B Hi Ga according to T5SS - because it's 10s of billions of people possible packed into a twilight Zone whose UWP otherwise is just like Earth's!

Other worlds of Population 7 or more we can introduce native intelligent life under the rules - they will meet the criteria. That does tend towards the OTU becoming a Star Wars Cantina, something I've read that Marc Miller doesn't want. But it would work for me; I'm happy with a discover-a-new-minor-race-on-many-worlds campaign.

There are probably people here who are much better qualified to comment on what a Tz world would be like, but the following is gathered from keeping up with science journalism out of interest.

There are other problems with a Twilight Zone world up snug and close to a Red Dwarf - solar flares and other activity to bake them. Let alone the solar wind probably blowing away their atmosphere. Then even ignoring those problems, the (probably highly fluctuating) pressure differential between the hot baked side and the the freezing cold side would surely generate hurricane-strength winds at the Twilight Zone.

There are a couple of ways to rationalise this. One is just to hand-wave the science and accept that parts of our setting aren't completely realistic. This can be done in the spirit of playing the game in a 'period science fiction' setting of the 1970s in a similar way to Space 1889. Twilight Zone worlds with a red dwarf star dominating the horizon and a Douglas Adams' style holiday resort with beaches towards the sun-side, lunch restaurants in the middle, and night-clubs towards the cold side.

Another might be to imagine most of the population living in orbit, or crowded into the Twilight Zone but underground with wind shelter, or mountains in the Twilight Zone being prized wind-breaks, with solar flares causing regular crises on the planet, perhaps ameliorated by technological solutions.

 

[OjnoTheRed]

Is there a scientific way of determining how close the planet and star have to be, to be tidally locked?

Could it be that planets are at orbit 1.5, a bit colder, and that forms the Hz in such cases?

After all, the old standard orbits are a bit of make believe aren't they?

regards

A formula I have read in a world building book is 0.0161 x ((number of years to test for tidal locking) x (star mass in Solar Masses)^2 / (density in g / cm^3))^1/6 will give you the distance in AU from the star mass where a world will be tidally locked given the number of years entered. Generally use 5,000,000,000 years, but you could adjust this up or down depending on the lifetime of the star which can be derived from its mass.

For example, using 4.1 billion years as our age, a stellar mass of 1.46 Sol, and a planet density of 0.94 Earths (x 5.515 g / cm^3) yields a tidal locking limit of 0.56 AU for that star - i.e. Orbits 0 and 1 are tidally locked and Orbits 2 and further are not. I've repeated this calculation ad nauseum seeing if I can find a sweet spot where the planet is not too cold but is not tidally locked, and it comes out as "somewhere between orbit 1 and 2" in nearly all cases.

The formula was derived from this Wikipedia entry (not by me).

 

[Wol]

Outstanding. Thanks for the link also. I will have a play too to see if modifying the albedo and greenhouse can warm them up a bit.

Appreciate the detailed response. I will put in a link when I find it again regarding the habitability of TL worlds.

Here it is, no idea how much it reflects current thinking

https://arxiv.org/pdf/1405.1025.pdf

regards

 

[whulorigan]

I don't have the tidal-locking formula to hand, but it's on a world-building book or website somewhere (edit: found it! see further reply below), and there's no question the 5-billion year locking limit is in orbits 0 and 1 for main sequence stars, further for larger stars.

Note that in our Solar System, Mercury is in Orbit 1 (Orbit 0 is empty), and it is NOT tidally locked. That is because it is in a 3:2 - rotation:revolution orbital resonance.

That is a possible explanation for some of the above worlds, but would quickly become overused as a common explanation, unless one were to argue that an intelligent agency deliberately altered the planetary rotation period of many worlds (perhaps specifically to produce garden worlds for mass-agriculture). .

 

[Wol]

Note that in our Solar System, Mercury is in Orbit 1 (Orbit 0 is empty), and it is NOT tidally locked. That is because it is in a 3:2 - rotation:revolution orbital resonance.

That is a possible explanation for some of the above worlds, but would quickly become overused as a common explanation, unless one were to argue that an intelligent agency deliberately altered the planetary rotation period of many worlds (perhaps specifically to produce garden worlds for mass-agriculture). .

I understood that the 3:2 ratio was not stable in the long term, and would decay over millions of years. I could (easily) be wrong about this.

 

[jcrocker]

That is a possible explanation for some of the above worlds, but would quickly become overused as a common explanation, unless one were to argue that an intelligent agency deliberately altered the planetary rotation period of many worlds (perhaps specifically to produce garden worlds for mass-agriculture). .

I have always imagined Scouts across the Spinward Marches sitting down with a cup of brew to check the latest survey results, getting down a few lines, then doing a spit-take on their drink at the data in front of them and yelling out "curse you, Ancients!" with a fair bit of regularity.

 

[The Pakkrat]

All this came about because I was developing a world in Knoellighz Sector that was the largest producing of Resource Units, RU or aryu, at 3900. When I saw its red dwarf star and the fact that the mainworld - not a Satellite - sat in Orbit 0, it got me thinking about how the Vargr there cranked out that much. The highest producing world in that Sector has a Twilight Zone (Tz) Trade Classification and still puts the others to shame.

Now, I understand that the RU of a world is not entirely dependent on the mainworld. Some to most can be from giants, belts and other planets. But still....

Then, after I saw the other worlds I had written up, I had to backtrack on all that had a Dwarf primary. My gut sank and took my heart with it. Then I looked at the Spinward Marches and saw the potential for for ret-con of history as well as data. Would this data revision change worlds and the desire to wage war for them?

I had to retreat back to Knoellighz and not become agitated. But the problem is still there even if downplayed.

 

[inexorabletash]

Twilight Zone worlds with a red dwarf star dominating the horizon and a Douglas Adams' style holiday resort with beaches towards the sun-side, lunch restaurants in the middle, and night-clubs towards the cold side.

I adore this.

 

[OjnoTheRed]

Note that in our Solar System, Mercury is in Orbit 1 (Orbit 0 is empty), and it is NOT tidally locked. That is because it is in a 3:2 - rotation:revolution orbital resonance.

That is a possible explanation for some of the above worlds, but would quickly become overused as a common explanation, unless one were to argue that an intelligent agency deliberately altered the planetary rotation period of many worlds (perhaps specifically to produce garden worlds for mass-agriculture). .

Although I could be corrected by someone who knows more, I think the extent of its eccentricity would probably present even more problems for those Ag, Ga or Ri worlds. Seasonal variations would be quite extreme, alternately baking and freezing the planet in an 80 day year, and resonate in interesting ways with the long days and nights from the 3:2 rotation in relation to the sun. Mercury would not attract an Ag, Ri or Ga classification (more like Va) and so it is not as difficult to reconcile the result anyway.

Further, if the planet has an atmosphere that is earth-like (say, 6 or 8), this implies a sufficient magnetic core to at least resist solar activity. In turn this implies an active core and hence seismic activity. The variation in seismic stress would be very large and make life ... interesting for the 10,000,000,000 inhabitants of Porozlo, for example.

I think the "Ancients wot dunnit" defence is more viable here. After all, they transplanted humans in many systems and wide-scale terraforming in favour of human-habitable worlds makes sense. But motive? Unless human conditions are favoured by Ancients/Droyne as well.