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Brown Dwarfs?

plop101

Absent Friend
What are Brown Dwarfs exactly?
They seem to be important in 2300. What would be there utility for the other Traveller systems?
 
A brown dwarf is a failed star, it hasn't accumulated enough mass to become a star. A typical star has at least 80 time the mass of Jupiter. A brown dwarf has less than the minimum mass to become a star, but has many times the mass of Jupiter. Like a gas giant, its possible for a starship to refuel by skimming its atmosphere, it must not skim too deeply however because while Jupiter has a gravity field of 2.5g, the typical gravity of a brown dwarf may run from 20g to 100g, this attraction exceeds the acceleration capacity of a typical traveller maneuver drive.
A Brown Dwarf is a member of a family of substellar objects, that may be of use for refueling purposes and in crossing rifts where there are no stars present. These things should really be on subsector maps. Other types of objects are gas giants, rogue planets, and interstellar comets, they can all be used as refueling stops where there are no star present.
Interstellar comets are hard to spot since they are small and there is very little light to reveal them. Terrestrial planets are hard to find, but gas giants and brown dwarfs emit more radiation that the receive, they should be easier to spot with an infrared or radio telescope. The denizens of the OTU should be very interested in the locations of these objects.
 
Thanks for the reply! I wonder what the frequency of Brown Dwarfs would be? 1 per sector? 1 per subsector?
I now in 2300 that finding a BD was a really big deal, super difficult to locate.
 
"Thanks for the reply! I wonder what the frequency of Brown Dwarfs would be? 1 per sector? 1 per subsector? I now in 2300 that finding a BD was a really big deal, super difficult to locate."


Mr. Roseberry,

I can't even guess what the frequency of brown dwarfs per subsector may be. Some schools of thought finger them for a nice, albeit low, percentage of the 'missing mass' of the universe.

Spotting them has been difficult enough in the Real World to make them more theorized about than actually spotted. This doesn't mean they don't exist however, we have the same theory vs. spotting trouble with black holes after all. Given the canonical abilities of sensors in the 57th century OTU, I'd think spotting them would be trivial.

As for using them as refueling points, I'd be more then a little leery. This isn't due to the gravitational problems Mr. Kalbfus pointed out; contra-grav technology puts that concern to rest, I'm more worried about the energy output from the things. They may be 'failed' stars, but that doesn't mean they aren't emitting EMS wave lengths of various nasty kinds; RF, IR, etc.

Their utility in the 2300AD setting had to do with their providing gravity wells for sutterwarp drive discharges. Stutterwarp drives required a number of hours discharging a charge build up after 7.7 ly (IIRC). This discharge could only be done at certain gravitational gradient; something like 0.01 gee IIRC. FTL vessels in 2300AD could only cross 7.7 ly gaps, they had to discharge after that distance or risk destruction.

The ways around this 7.7 ly restriction were limited. You could use stutterwarp tugs; they carried your vessel out ~3.85 ly, dropped you off to travel the next 7.7, and returned ~3.85 ly. You could use extra stutterwarp engines; use Set A to travel 7.7 ly, take them off line, and then use Set B to travel the next 7.7 ly. Finally, you could discover a brown dwarf and use it's gravitational gradient as a discharge point. This final option was the one that was being counted to 'open' the 'closed' American Arm in 2300AD. (Tugs and shuttles were used too.)

If YTU requires gravity wells for jump precipitation; i.e. no deep space jumps, brown dwarfs are a necessity to cross those big rifts. However if all you need is hydrogen for your next jump, I'd look for other fuel sources. Skimming a failed star with Traveller technology might be too dangerous if it not actually impossible.


Sincerely,
Bill

P.S. BTW, Hi! 8^)
 
I can't even guess what the frequency of brown dwarfs per subsector may be. Some schools of thought finger them for a nice, albeit low, percentage of the 'missing mass' of the universe.
At a guess, I'd say they are more common than Class M stars. Remember the stellar sequence Oh Be A Fine Girl Kiss Me? or O, B, A, F, G, K, M? These spectral classes are in order of decreasing mass and increasing frequency, there are more 'B's than 'O's, more 'A's than 'B's, more 'F's than 'A's, more 'G's than 'F's, more 'K's than 'G's, and more 'M's than 'K's. Continuing this progression there should be more Brown Dwarfs than class M stars, more Gas giants than Brown Dwarfs, more terrestrial planets than gas giants and more comets than planets.
As for using them as refueling points, I'd be more then a little leery. This isn't due to the gravitational problems Mr. Kalbfus pointed out; contra-grav technology puts that concern to rest, I'm more worried about the energy output from the things. They may be 'failed' stars, but that doesn't mean they aren't emitting EMS wave lengths of various nasty kinds; RF, IR, etc.
Gravity is a problem because traveller rules only cover maneuver drives with accelerations of up to 6g. The rules state that when accelerating away from a planet or other gravitational body, you must subtract the planets gravity from your acceleration before applying it to your starship.
As for the EMS, that depends on the size and age of the brown dwarf. Brown Dwarfs are powered by their own internal contraction. As the gases contract toward the core of the brown dwarf, heat is generated, heat rises warming the outer atmosphere of the star. A recently formed brown dwarf will be glowing just like a red dwarf star, as is gets older it glows in the infrared frequence, then microwaves, and finally radiowaves. A suitable aged brown dwarf will have a 'room temperature' outer atmosphere and might even have water clouds.
The most important thing is that brown dwarfs are likely to have planets or perhaps you could call them moons in orbit around them, those would be easier refueling points than the brown dwarf it self. Any planet that formed in interstellar space is likely to be covered with ice which means lots of hydrogen to refuel your starship with.
 
"Gravity is a problem because traveller rules only cover maneuver drives with accelerations of up to 6g. The rules state that when accelerating away from a planet or other gravitational body, you must subtract the planets gravity from your acceleration before applying it to your starship."


Mr. Kalbfus,

No. If that were true every Traveller starship would require a maneuver drive rated greater then 1 gee simply to leave Earth-sized planets. Given contra-grav and a sufficiently dense atmosphere, Traveller ships can actually float in mid-air.

Traveller ships have contra-gravity which somehow negates the attraction of the body they are thrusting away from. Don't confuse this handwave technology with those other two handwave technologies; inertial dampers and gravitic compensation. They provide gee fields within a ship or structure and allow the occupants to ignore unwanted vectors.


Sincerely,
Larsen
 
I remember reading the Classic Traveller rules (Book 2) for space combat. It says your supposed to make planetary templates. First you draw the planets diameter and you calculate its surface gravity. Then you draw a circle around that that is the nearest multiple of 0.25g less than the surface gravity and you keep on drawing larger circles around it at intervals 0.25g less than the immediate inside circle until you reach the outermost circle of 0.25g. A spaceship that moves within the 0.25g circle must add a vector to its movement that's 25mm long and pointing toward the center of its planet. Likewise a spaceship within the 0.5g circle must add a 50mm long vector to its movement each 1000 second turn. To negate this the starship needs to add an equal vector pointing away from the planet, this reduces the amount of vector left for maneuvering any particular turn within the circle. A spaceship can escape a planet by flying out of its atmosphere if the ship is a lifting body or has wings, it then accelerates to orbital velocity. In a Brown Dwarf's atmosphere this orbital velocity is extremely high. Atmospheric friction is a concern. Also I'm not sure about how much gravity
 
"I remember reading the Classic Traveller rules (Book 2) for space combat." (snip of LBB2 space combat movement example)


Mr. Kalbfus,

I remember reading them too, both in '78 and after I bought the Reprints. We're discussing apples and oranges here; lift-off vs. effects on space combat movement at orbit and beyond.

Mayday has you take planetary gravity into effect when engaged in space combat too. Mayday also has you lift off from any body in one turn by placing your ship counter in any hex next to the planet's hex, no matter what your m-drive rating or the size of the planet.

"A spaceship can escape a planet by flying out of its atmosphere if the ship is a lifting body or has wings, it then accelerates to orbital velocity."

Good. Now explain how this is done on a planet without an atmosphere. If your take on the subject is to be believed, every 1gee Beowulf is suddenly faced with a whole bunch worlds that are now off-limits.

MT, TNE, GURPS, and (AFAIK) T20 all suppose contra-grav lifters to assist with ship lift-off to orbit. CT may not mention them explicitly, but their existence is rather strongly implied, otherwise PCs could not use their ships in the manner CT describes.


Sincerely,
Bill
 
I have doubts that an antigrav device can simply turn off an objects gravity no matter how strong it is. I think it can negate a certain amount of gravity and thats it. Carrying your logic to its extreme, if a contragrav vehicle can simply ignore gravity, why not land on a neutron star, hover a few feet above the event horizon of a black hole, or even go inside a black hole's event horizon and come out again, these are after all only effects of gravity. I think 1g Free traders do have planets that are off limits. Most 1g planets that they'd want to visit would have atmospheres. Those planets without atmospheres usually have less than 1g. A 1g vaccum world is a problem for a free trader and thats too bad, but no starship can be expected to do everything. Remember the ANNIC NOVA couldn't land on any planet, it had no landing gear, such starships have launches or an air/raft will serve to get from low orbit to the surface and back again.
 
"I have doubts that an antigrav device can simply turn off an objects gravity no matter how strong it is. I think it can negate a certain amount of gravity and thats it."


Mr. Kalbfus,

Which is precisely what the contra-grav lifters, mentioned or implied in all the various versions of Traveller, are said to do. They negate a very high percentage of the local gravity field within a certain volume, but not the entire gravity field.

"Carrying your logic to its extreme, if a contragrav vehicle can simply ignore gravity, why not land on a neutron star, hover a few feet above the event horizon of a black hole, or even go inside a black hole's event horizon and come out again, these are after all only effects of gravity."

Sorry, no. I failed to fully explain Traveller's contra-grav technology to you; CG negates a percentage of the field, not the entire field. None of the objects you wrote about could be visited using Traveller's CG technology.

"I think 1g Free traders do have planets that are off limits."

Good for you. That's the bedrock strength of Traveller, it's malleability. There is an OTU, a MTU, and a YTU. Use whatever options in YTU you please, but don't assume those options also apply to the OTU because they don't.

"Most 1g planets that they'd want to visit would have atmospheres. Those planets without atmospheres usually have less than 1g. A 1g vaccum world is a problem for a free trader and thats too bad, but no starship can be expected to do everything."

Yes, too bad and never mentioned in any Traveller material. The PCs Beowulfs and Maravas are expected to get them every place their jump drives can take them. There is no mention of 'airless' size 8+ worlds being off limits because of a vessel's m-drive rating. OTU ships in Traveller use CG lifters. If ships IYTU don't, that's fine too.

"Remember the ANNIC NOVA couldn't land on any planet, it had no landing gear, such starships have launches or an air/raft will serve to get from low orbit to the surface and back again."

Apples and oranges. We're talking about the basic PC starship, the Beowulf, and not various one-offs or special cases. Also, I wouldn't pin any explanations or handwaves on 'Annic Nova' either. That adventure was written well before most of the OTU was fashioned and it contains several canon busting aspects, not the least of which is a jump drive that uses no fuel. What's more, you can't even build an Annic Nova-style vessel using any of Traveller's published ship construction rules(1). So Annic Nova can't be used as an example of anything I'm afraid.

Yes, by design, there are plenty of starships in the OTU that don't land on planets. There are LASH freighters, dispersed structure battle tenders, and many other examples which are kept in orbit by, among other thigns, their streamlining rating. (If you want to read some mind numbing stuff, find the old threads discussing what people think streamlined, partially streamlined, and unstreamlined mean!) However, capabilities of those vessels are completely irrelevent to the discussion at hand; the canonical abilities of PC-crewed vessels.

Our Olde Game has been around for over 25 years and folks plenty smarter than me tackled this problem decades ago. For 1-gee vessels to behave as described in Traveller, they must have CG lifters. Period.

If you don't like CG, don't use CG In Your Traveller Universe. You'll still be having fun and you'll still be playing Traveller! Remember, YTU, MTU, and the OTU. It's all Traveller and it's all good.


Sincerely,
Bill

1 - Except, maybe, by FF&S1? I can't remember if an Annic Nova-style drive is mentioned among the FTL variants there.
 
On Brown Dwarfs, and other stellar objects...

IMTU: I've developed a procedure that allows for worlds (habitable and otherwise) that orbit every star class from black holes to Methane Dwarfs. A few assumptions are made to keep it simple:

1) Wolf-Rayet stars (type W) are so rare as to be ignored. They may also be considered as "peculiar" O-type stars.

2) R, N, and S-type stars are "peculiar" M-type stars.

3) Any star cooler than type K8-V would have the habitable zone so close to the star, that any planet would be tide-locked, with a limited habitable area on the planet, thus limiting the POP rating. Also, these stars would produce insufficient U/V to support photosynthesis.

4) Any star warmer than F0 might have too much U/V radiation to support photsynthesis.

5) Rolling two ten-sided dice to set up a Traveller game is not heresy. However, during the game is another matter... ;)

Procedure:

1) Roll 2d10 as a percentage.

99 = Black hole, neutron star, black or white dwarf.
96 to 98 = O-type
91 to 95 = B-type
84 to 90 = A-type
75 to 83 = F-type
64 to 74 = G-type
51 to 63 = K-type
36 to 50 = M-type (Red Dwarf)
19 to 35 = L-type (Brown Dwarf)
00 to 18 = T-type (Methane Dwarf)

There are modifiers for a planet's SIZ, ATM, and HYD (but it may be too complex for posting here), A G2-V star is considered ideal so modifiers would tend to eventually reduce POP at either end of the classification scale.

Anyway, that's my 20 millicredits' worth.
 
Originally posted by thrash:
Current thinking is that brown dwarfs may be up to twice as common as regular stars; maybe half of those would be "free field" brown dwarfs, not part of any larger stellar system. There are three known (including one around Epsilon Indi) and four more suspected brown dwarfs (vs. ~320 stars) within 10 pc, all discovered within the last 8 years.
Whatever the truth in the Real Universe, the history of the Traveller Universe makes it clear that such objects are either exceedingly rare or very difficult to detect in deep space. Otherwise the big problems with crossing the rifts would be even more of a non-problem than it is in the TU (where you at least have to lay out deep space fuel depots by hand before crossing).

Hans
 
thinking,
a Dyson shpeere similar to the one from that ST:TNG episode (where they found scotty) would be detectable in the infared (weaker than a normal star) but not in the visable and could be mistaken for a brown dwarf for melenia, until someone actually went there and seen for themselves...
 
By working out the size of the capacitors atached to the jump drives (this is in the black globe section of FFS1) and by providing an alternative power source I was able to design a version of the Annic Nova at TL12. The design also generated the reason why battery powered vessels did not sweep the fuel guzzling jump drives from the market. The batteries have a total charge allowing 8 days at maximum drive and take 7 days to recharge in the life zone. This would make the vessel of limited utility. (I use her as a training ship in my Alston League navy).

An implication of the design is that the building race did not have fission or fusion power technology (or did not use it, perhaps religious objections?) The small craft found with the Annic Nova were imperial standard so I have postulated that these were not the vessels original away craft.
 
Whatever the truth in the Real Universe, the history of the Traveller Universe makes it clear that such objects are either exceedingly rare or very difficult to detect in deep space. Otherwise the big problems with crossing the rifts would be even more of a non-problem than it is in the TU (where you at least have to lay out deep space fuel depots by hand before crossing).

Hans
The rifts are devoid of matter, whatever matter there is goes toward comets, planets, brown dwarfs and stars. The Traveller mapping conventions don't include the star type that the planet orbits or even if there is a star at all! A single solitary planet, in interstellar space, would get the same treatment as a planet orbiting another star. An inhabitable planet would presumably orbit another star, but an uninhabitable planet could be by itself. A rogue planet would be treated as an ice capped vacuum world without a gas giant. Player's looking at the subsector map wouldn't know it was a rogue planet until they got there. Gas giants usually have moons. In the case of a rogue gas giant with moons, the map hex would detail one of the gas giant's moons and indicate that a gas giant is present. The world would again be an ice-capped vacuum world, or perhaps a moon with a nitrogen atmosphere like Titan. Tidal heating might keep the world from being completely frozen. Again the PCs don't know that there is no star until they get there. Brown Dwarfs can have planets just like other stars do. Many of the blank hexes on rift maps may contain interstellar comets, rogue planets, or brown dwarves that haven't been detected yet. It is very hard to search an entire hex. That is the problem with rifts, it is finding where the interstellar comets, rogue planets, gas giants and brown dwarfs drifting in space are. Once the first such object is found the search stops as they now have their required fuel supply for traversing the rift. the next hex is then searched and the process continues until you have a path across the rift. Rifts aren't well explored as there is little there of interest other than what's required to get through them. That's my explaination anyway.
 
Originally posted by Tom Kalbfus:
The Traveller mapping conventions don't include the star type that the planet orbits or even if there is a star at all! A single solitary planet, in interstellar space, would get the same treatment as a planet orbiting another star. An inhabitable planet would presumably orbit another star, but an uninhabitable planet could be by itself. A rogue planet would be treated as an ice capped vacuum world without a gas giant. Player's looking at the subsector map wouldn't know it was a rogue planet until they got there.
I don't consider the maps and UWPs published in a game supplement to be exact facsimilies of the information available to the characters in the Traveller universe. If an interstellar object is listed in a library database, then an description of its nature is also available. Maybe not in great detail -- that would depend on the nature of the database -- but any PC in any campaign of mine would be able to know it was a rogue planet long before he got there.

(That is one of the big problems with an SF universe. The amount of information that would logically be available to the PCs is hugely, vastly, mind-bogglingly bigger than the amount of information any GM can be expect to have the time to make up.)


Anyway, unless brown dwarfs and similar objects are either extremely rare or extremely hard to detect (or both), there would exist lists of those objects and crossing the rifts (and smaller gaps for that matter) wouldn't be the problem that it canonically is.


Hans
 
Originally posted by rancke:
(That is one of the big problems with an SF universe. The amount of information that would logically be available to the PCs is hugely, vastly, mind-bogglingly bigger than the amount of information any GM can be expect to have the time to make up.)
Indeed. But that information needs not

a) be available in an ordered, ready-to-use way. The players are just looking for the answer to a technical question? The net search returns a zillion related pages. Sorting them out to get at the info they actually need would take too much time. Let's say, until next session.

b) be available for free. You want world climate reports for the whole subsector. Of course, at your fingertips, sir, it will be 10,000 Credits.
 
The characters would know if the target world was a rogue planet, but their player's wouldn't unless they asked. The player's would have to specifically ask the Referee whether the planet their characters were heading to had a star or not. If the planet cannot support life without a vacc suit, then it makes little difference whether the planet has a star or not. In the Traveller Universe solar energy is not required to build a dome and an artificial light source powered by fusion. Most planets that formed in interstellar space would have plenty of hydrogen, not only in the form of water ice, but also of methan ice and even free gasious hydrogen. Hydrogen freezes at 14k and it liquifies at 21k, so liquid hydrogen might exist on the surface.
 
"But that information needs not

a) be available in an ordered, ready-to-use way. The players are just looking for the answer to a technical question? The net search returns a zillion related pages. Sorting them out to get at the info they actually need would take too much time. Let's say, until next session.

b) be available for free. You want world climate reports for the whole subsector. Of course, at your fingertips, sir, it will be 10,000 Credits."


Sir,

Indeed indeed! A very neat explanation and a nifty GM 'tool' I'm sure we've all used a time or three before!


Sincerely,
Bill
 
Mr. Tom Kalbfus wrote:

"The characters would know if the target world was a rogue planet, but their player's wouldn't unless they asked. The player's would have to specifically ask the Referee whether the planet their characters were heading to had a star or not. If the planet cannot support life without a vacc suit, then it makes little difference whether the planet has a star or not. In the Traveller Universe solar energy is not required to build a dome and an artificial light source powered by fusion. Most planets that formed in interstellar space would have plenty of hydrogen, not only in the form of water ice, but also of methan ice and even free gasious hydrogen. Hydrogen freezes at 14k and it liquifies at 21k, so liquid hydrogen might exist on the surface."


Mr. Kalbfus,

All very good points. Unfortunately, they have little to do with the question at hand or the explanation Mr. Rancke-Madsen was making. We're discussing the availability of wilderness refuelling in rift hexes and not the mechanics of settling 'sunless' bodies.

If the various objects you describe; brown dwarfs, rogue planets, KBOs, ice bodies, etc., are as prevelant in rift hexes as you suggest; they merely need to be looked for, then the history of the Official Traveller Universe would be very different. Please note, I'm referring to the Official Traveller Universe and not Your Traveller Universe.

As Mr. Rancke-Madsen pointed out, the Rifts, both Greater and Lesser, figure prominently in OTU history. They are all but impassable and that feature has has a strong effect on the ebb and flow of history in Traveller. The only fuel sources found within them are either stepping stone systems; like the Aslan jump5 Trans-Rift Route, or man-made depots, like TNE's calibration points. Unlike your assertions, fuel, or the objects you can refuel from, aren't simply there for the looking. No one has surveyed a rift hex, found an object to refuel from, moved onto the next hex, and begun the process all over again. And again, despite your assertions, this isn't because no one has tried.

I'll provide you with a few historical examples that make your supposition unworkable in the OTU:

- Control of the Aslan Jump5 Trans-Rift Route gives the clans that hold it great power. They can and do deny transit to the ihatei of any of the clans they wish. When faced with this denial of transit, a clan could begin the survey process you describe and eventually develop another route across the Rift relying on the various objects you propose exist there. However, in the thousands of years the Aslan have used the Jump5 route, no clan has surveyed another route across the Rift in the manner you propose despite the constant need to dispatch ihatei towards 'greener pastures'.

- The early Imperium psent over a century and untold trillions of credits on the Corridor campaigns, an effort to clear that sector of the Vargr or at least subjugate them. This effort was made to ensure safe communications and shipping routes between the Imperial core and the Imperium's only frontier; the Deneb, Spinward Marches, and Trojan Reach sectors. If, as you propsoe, surveying a path across a rift was only a matter of looking long enough for various deep space objects, the Corridor Campaign was completely unneccessary. The Imperium could have surveyed dozens of cross-rift routes for a fraction of the cost of the campaigns. In fact, the Imperium did look for these alternate routes. There are mentions in canon of a series of efforts by the IISS to survey other routes across the Rift, efforts that utterly failed.

- The rift in Windhorn in the Vargr extents had a great effect on history. First, it prevented the Vilani from contacting and conquering the Vargr during the Consolidation Wars. Later, it helped shield the Ziru Sirka from most of the Vargr. If that rift were passable, as you propose, the history of that region would have played very differently.

- In the Viral Era, the rift between the Regency and the fallen Imperial core is the primary defense of that region from the depredations of Virus. The Regency maintains and operates various calibration points; man-made fuel depots, within the rift to monitor the activities of Virus both within the rift and on the other side. This effort somewhat resembles the sapper/counter-sapper fighting in classical seige warfare. In it one side; Virus, tries to create depots; tunnels, that it can use to breach the defenses while the other; the Regency, uses it's own depots; counter-tunnels, to prevent that. Once again, as you propose, if a route across the rift is merely a matter of time and surveying, than the Regency's rift 'glacis' would have been porous to Virus infiltration.

Now, as I keep saying, this is all relative to the Official Traveller Universe *only*. Your TU can and should be something else entirely. However, for YTU with your take on trans-rift routes to have a history that even remotely resembles the history of the OTU, quite a bit of explaining needs to be done. In the OTU, rifts are all but impassable and the history of the OTU has been profoundly effected by this fact. If those same rifts can be crossed given time and surveying, as in your TU, a very different history will have occurred. If that history did not occur, you need to explain why no one bothered to survey those routes for over 5000 years and despite the known utility of the routes.

And, of course, the very idea of 'rifts' bares no resemblence to actual astronomy too!

Always glad to read your ideas. Thanks for sharing them.


Sincerely,
Bill
 
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