Suppose we used Gliese 832 C in a Traveller Campaign.

[Tom Kalbfus]

I figure this planet would have a surface gravity between 1.7 and 2 g. Lets suppose it is a
terrestrial super Earth with an atmosphere breathable to humans. What would be th starport code
of this planet? What would be its size digit?, lets assume a 5, 6, 7, or 8 atmosphere, the
atmosphere would probably tend toward the higher number. Hydrographic percentage would be
from 5 to A most likely. Population, I don't know, who do you think would live here, some kind of
modified human or one of the Traveller Aliens, an which alien do you think would be most
confortable here? Then of course there is government, law level, and tech level.

http://phl.upr.edu/press-releases/gliese832
Press Releases >

A Nearby Super-Earth with the Right Temperature but Extreme Seasons
posted Jun 25, 2014, 4:53 AM by Abel Mendez Torres [ updated 5 hours ago ]

Artistic representation of the potentially habitable Super-Earth Gliese 832 c against a stellar
nebula background. Credit: PHL @ UPR Arecibo, NASA Hubble, Stellarium.

UPDATE: Check figure 5 for an alternative version.




Gliese 832 c is the nearest best habitable world candidate so far





An international team of astronomers, led by Robert A. Wittenmyer from UNSW Australia, report
the discovery of a new potentially habitable Super-Earth around the nearby red-dwarf star Gliese
832, sixteen light years away. This star is already known to harbour a cold Jupiter-like planet,
Gliese 832 b, discovered on 2009. The new planet, Gliese 832 c, was added to the Habitable
Exoplanets Catalog along with a total of 23 objects of interest. The number of planets in the
catalog has almost doubled this year alone.




Gliese 832 c has an orbital period of 36 days and a mass at least five times that of Earth's (≥ 5.4
Earth masses). It receives about the same average energy as Earth does from the Sun. The
planet might have Earth-like temperatures, albeit with large seasonal shifts, given a similar
terrestrial atmosphere. A denser atmosphere, something expected for Super-Earths, could easily
make this planet too hot for life and a "Super-Venus" instead.




The Earth Similarity Index (ESI) of Gliese 832 c (ESI = 0.81) is comparable to Gliese 667C c (ESI
= 0.84) and Kepler-62 e (ESI = 0.83). This makes Gliese 832 c one of the top three most Earth-
like planets according to the ESI (i.e. with respect to Earth's stellar flux and mass) and the closest
one to Earth of all three, a prime object for follow-up observations. However, other unknowns
such as the bulk composition and atmosphere of the planet could make this world quite different
to Earth and non-habitable.

So far, the two planets of Gliese 832 are a scaled-down version of our own Solar System, with an
inner potentially Earth-like planet and an outer Jupiter-like giant planet. The giant planet may
well have played a similar dynamical role in the Gliese 832 system to that played by Jupiter in our
Solar System. It will be interesting to know if any additional objects in the Gliese 832 system
(e.g. planets and dust) follow this familiar Solar System configuration, but this architecture
remains rare among the known exoplanet systems.



Contacts
Original Research: Robert A. Wittenmyer (rob@phys.unsw.edu.au), Mikko Tuomi (miptuom@utu.fi)

Habitable Exoplanets Catalog: Abel Méndez (abel.mendez@upr.edu)




Additional Resources
•Paper: GJ 832c: A super-earth in the habitable zone
•Habitable Exoplanets Catalog

Images

Figure 1. Artistic representation of the potentially habitable exoplanet Gliese 832 c as compared with Earth. Gliese 832 c is represented here as a temperate world covered in clouds. The relative size of the planet in the figure assumes a rocky composition but could be larger for a ice/gas composition. Credit: PHL @ UPR Arecibo.

Figure 2. Orbital analysis of Gliese 832 c, a potentially habitable world around the nearby red-dwarf star Gliese 832. Gliese 832 c orbits near the inner edge of the conservative habitable zone. Its average equilibrium temperature (253 K) is similar to Earth (255 K) but with large shifts (up to 25K) due to its high eccentricity (assuming a similar 0.3 albedo). Credit: PHL @ UPR Arecibo.

Figure 3. The Habitable Exoplanets Catalog now has 23 objects of interest including Gliese 832 c, the closest to Earth of the top three most Earth-like worlds in the catalog. Credit: PHL @ UPR Arecibo.

Figure 4. Stellar map with the position of all the stars with potentially habitable exoplanets including now Gliese 832 (lower left). Credit: PHL @ UPR Arecibo, Jim Cornmell.

Figure 5. Artistic representation of the potentially habitable Super-Earth Gliese 832 c with an actual photo of its parent star (center) taken on June 25, 2014 from Aguadilla, Puerto Rico by Efrain Morales Rivera of the Astronomical Society of the Caribbean. Original annotated image available here. Credit: Efraín Morales Rivera, Astronomical Society of the Caribbean, PHL @ UPR Arecibo.h t

 

[Reynard]

Useful information gleaned:
Star - M1 5
Orbital distance - 0.134-0.192AU (0.1617AU average)
Orbit period - 36 days
Same energy from its sun as Earth from Sol, large seasonal shifts
1.75 x Earth diameter, 5x Earth density
Dense atmosphere (possible Super-Venus)
Temperature about 253K +/- 25K(Earth 255K
Albedo 0.3

Time to use MegaTraveller's detailed worldgen and translate back to as close as possible to MgT. It would be interesting if at least our part of the galaxy favored these superEarths and the average on the UWP scale would need to move size closer to 8 or 9.

Considering the size comparison chart, I'm a bit disappointed we haven't detected more worlds closer to Earth (or smaller). Too bad the only exoplanet around Alpha centauri is a hot superworld UNLESS we can't detect smaller worlds at only one parsec away..

 

[GypsyComet]

1.75 x Earth diameter, 5x Earth density

That should probably be 5x Earth mass. If it was 5 times the density the whole planet would need to be made of out of something denser than solid gold (which is less than 4 times as dense as Earth).

In Traveller terms, Gleise 832 C is a Size 14.

Assuming the round numbers above and an Earth-like density, I'm getting about 1.6G at the surface.

 

[sideranautae]

Considering the size comparison chart, I'm a bit disappointed we haven't detected more worlds closer to Earth (or smaller).

It has almost 5X the mass of Earth. It was detected because of its mass acting on its small sun. So, no need to be disappointed at all. Under the same parameters Earth would NOT have been detected...

Only highly modified humans could live there. Otherwise some other alien race (not any of the majors).

 

[Reynard]

Considering our own crowded solar system, I would hope these so called 'terran worlds' are the elephant in the room and there could still be more worlds not vying to be the big boy. Sounds like these worlds will be the awesome landmark in a system then we go check out the actually useable worlds not detectable at distance.

This would fit with the FTL starship topic. Either the ship goes to each system in priority of distance to take a peek or by data compiled by Earth observance as to being an interesting priority. Since a fission power plant and a warp drive make travel more casual, you don't need a gas giant at both ends to refuel, I'd say Choice A unless something really stands out. So far 832C as Best Hope for a terran shows these big worlds are not promising but not a deterrent to exploring.

 

[sideranautae]

Considering our own crowded solar system, I would hope these so called 'terran worlds' are the elephant in the room and there could still be more worlds not vying to be the big boy. Sounds like these worlds will be the awesome landmark in a system then we go check out the actually useable worlds not detectable at distance.

This would fit with the FTL starship topic. Either the ship goes to each system in priority of distance to take a peek or by data compiled by Earth observance as to being an interesting priority. Since a fission power plant and a warp drive make travel more casual, you don't need a gas giant at both ends to refuel, I'd say Choice A unless something really stands out. So far 832C as Best Hope for a terran shows these big worlds are not promising but not a deterrent to exploring.

If we put in orbit newer/larger 'scopes we will be able to detect smaller planets (Earth sized). It is just a matter of funding. Not a high priority right now as there isn't much tangible to do with the data we collect...

 

[Reynard]

Funny if we were to build the starship first and no longer need the Big Eyes.

The only reason right now to build such detection system is to know if Earth is a one shot, rarity or representative. Could give the god people more ammo.

 

[sideranautae]

The only reason right now to build such detection system is to know if Earth is a one shot, rarity or representative. Could give the god people more ammo.

Also to provide employment for astronomers. I don't know any literalists like those you are referring to. Most are in the M.E. region of this planet. They might get a wee bit upset if we start finding Earth type planets under every rock. :lol:

 

[Reynard]

Finding Earth like planets with non-Earth life or, worst, sophonts could be a big problem for those who believe the we are given the universe by a higher power. On the other hand, about the ammo, the more we find no evidence life and, especially, sophonts the more it looks like the galaxy is meant for one intelligent species whether or not we ever can leave our system.

 

[sideranautae]

Finding Earth like planets with non-Earth life or, worst, sophonts could be a big problem for those who believe the we are given the universe by a higher power. On the other hand, about the ammo, the more we find no evidence life and, especially, sophonts the more it looks like the galaxy is meant for one intelligent species whether or not we ever can leave our system.

Well, we aren't going to find other sophonts with a telescope anyway. All we'll find out is if there are Earth like planets out there. A statistical certainty already.

 

[Tom Kalbfus]

Considering our own crowded solar system, I would hope these so called 'terran worlds' are the elephant in the room and there could still be more worlds not vying to be the big boy. Sounds like these worlds will be the awesome landmark in a system then we go check out the actually useable worlds not detectable at distance.

This would fit with the FTL starship topic. Either the ship goes to each system in priority of distance to take a peek or by data compiled by Earth observance as to being an interesting priority. Since a fission power plant and a warp drive make travel more casual, you don't need a gas giant at both ends to refuel, I'd say Choice A unless something really stands out. So far 832C as Best Hope for a terran shows these big worlds are not promising but not a deterrent to exploring.

I could come up with a Gliese 832 C Calendar, basically each orbital period is a 36 day month and there are 10 months in a year for a total of 360 days. The names of the months would go as follows:
January
February
March
April
May
June
September
October
November
December
Gliese 832 C experiences the entire seasonal cycle within a 36 day month, so there is no difference between December and May, the heat absorbing/releasing capacity of the oceans would average out the seasonal variations over a 36 day cycle.

 

[sideranautae]

I could come up with a Gliese 832 C Calendar, basically each orbital period is a 36 day month and there are 10 months in a year for a total of 360 days.

Do they know if it is tide locked or not?

 

[Reynard]

I believe that is a 36 day YEAR! Yeah, that fast. Then again the planet is an average of .1617 AUs from the sun (Earth - sun = 1 AU and Mercury - sun = .365 AUs). No rotational period is mentioned (or detectable) and it would need a moon to have months. Earth travels 1.6million miles per day while 832C moves around its sun at 1.3 million miles per day at 1/7 the radius. That close to a sun would probably force tidelocking.

 

[Tom Kalbfus]

I believe that is a 36 day YEAR! Yeah, that fast. Then again the planet is an average of .1617 AUs from the sun (Earth - sun = 1 AU and Mercury - sun = .365 AUs). No rotational period is mentioned (or detectable) and it would need a moon to have months. Earth travels 1.6million miles per day while 832C moves around its sun at 1.3 million miles per day at 1/7 the radius. That close to a sun would probably force tidelocking.

The calendar is for humans living on Gliese 832 C, since that's planet's orbital period is about one tenth of a year, then ten of those should make a human year. For the purposes of humans on the planet keeping track of time and telling how old they are, then ten orbital periods of Gliese 832 C would make a convenient "year" for them. If Gliese 832 C is tidally locked it won't have an axial tilt anyway, the only seasons it will have would be due to its varying distance from Gliese 832, the same hemisphere would face the star at all times, we would count time by the varying intensity of the star's radiance as seen from the planet and the changes in angular diameter of the star's disk as seen in the planet's sky. On the night side of the planets, we can track the movements of the stars to tell what time of the "Month" it is. A Gliese 832 C seasonal period would have about 9 days for each season, 9 days for winter, 9 days for spring, 9 days for summer, ad 9 days for autumn. We can't grow food crops on such a short seasonal cycle, se we should therefore pick those spots on the planet where the temperature doesn't change much over the 36 day seasonal cycle. I think the oceans will absorb and release heat over such a short seasonal period and thus the temperature should average out despite they varying distances from the star. So it would be natural to divide up the Gliesian year into ten 36-day months, the Romans in fact did have a ten month calendar before they added the months July and August, so I suggest removing those months with the names 'July" and "August" and leaving the rest of the months as they are, a 360 day year is about right for humans even if 10 orbital periods is of no significance to the planet itself.

 

[Tom Kalbfus]

I could come up with a Gliese 832 C Calendar, basically each orbital period is a 36 day month and there are 10 months in a year for a total of 360 days.

Do they know if it is tide locked or not?

Its probably only locked if its a terrestrial planet, if its a small gas giant, then it has no reason to be tidally locked at all. A terrestrial planet is a solid object, and gas giant is a ball of gas, in between is the possibility that it is a water giant, an theoretical planet that is made mostly of water, much like Europa is only larger and without the icy crust on top. So one possibility is that Gliese 832 has a roughly Earthlike atmosphere about 100 km thick or so, on top of a global ocean that is thousands of km deep with a small rocky core in the center. Since water is less dense than rock, the same amount of mass in water would lead to a greater diameter and less gravity at the surface of this global ocean, this would make the planet more habitable for humans, so long as they have something to float on. To colonize such a planet, humans would need to live on floating platforms, much like the oil platforms that dot Earth's oceans only larger.

 

[Reynard]

Interesting. Using the information provider here, the graphic approximation of size and being 5x Earth's mass, I back-engineered with the help of the world Builder Handbook for Traveller data. 832C, has a density of approximately 0.93 Earth and we'll give it a molten core for argument sake. The gravity is 1.6 g. Not bad.

I used the calculations in the book. Its orbit is below Orbit 0. Still I can calculate the orbital period which turns out to be 34 days. Almost spot on! Orbital eccentricity, according to the above information, is going to be high. It's also on the hot edge of the habitable zone.

Going back to MgT world stats we see our first problem being atmosphere and hydrographics as everything is proportional to the Size factor rather than consideration of gravity. 832C will have an atmosphere between 9-19 meaning Thin, low will be most probable while it most likely is a water (fluid) world. Looking at the other 'likely terrestrial candidates', I'd say, for a Traveller game, they are way off the scale. Look elsewhere in those systems for smaller worlds or Earth sized moons orbiting the super terrestrials.

 

[Tom Kalbfus]

the Traveller system doesn't generate worlds larger than size A 16,000 km in diameter, a size A world has a gravity of about 1.25 g. I think someone needs to rethink that table in light of all these exoplanet discoveries. I really think rolling 3d6-2 for planet size would be better, and I think a separate roll to determine whether its an asteroid belt of a planet would be better.
World Size 3d6-2 the rest of the tables work fine as is, though hydrographics might need to be adjusted if you want something other than water worlds for large planet sizes
Digit
1 1600 km
2 3200 km
3 4500 km
4 6400 km
5 8000 km
6 9600 km
7 11,200 km
8 12,800 km
9 14,400 km
A 16,000 km
B 17,600 km
C 19,200 km
D 20,500 km
E 22,400 km
F 24,000 km
G 25,600 km

Atmosphere 3d6-10+World Size
0 Vacuum
1 Trace 0.01 bar
2 Very Thin, tainted 0.1 bar
3 Very Thin 0.1 bar
4 Thin, Tainted 0.33 bar (20% oxygen, same as mount Everest approx.)
5 Thin 0.33 bar (60% Oxygen, can be breathed by humans without oxygen masks)
6 Standard 1 bar (20% oxygen, Same as Earth as Sea Level)
7 Standard, Tainted 1 bar (7% oxygen or less)
8 Dense 3 bars (7% oxygen, can be breathed without oxygen masks)
9 Dense, Tainted 3 bars (2% oxygen or less, requires air filter masks)
A Exotic 10 bars (oxygen masks required)
B Corrosive 100 bars (1 km beneath Earth's oceans)
C Insidious 100 bars combined with high temperatures (The surface of Venus)
D Dense, High Pressure 100 bars at surface, (same as Insidious at surface, but at a high altitude 50 km for example, the oxygen percentage is sufficient to allow for unassisted breathing, roll 1d6(1-2 Dense atmosphere at this altitude, 3-4 standard atmosphere, or 5-6 thin atmosphere)
E Ellipsoid (Standard, thin, or Dense atmospheres at certain latitudes, elsewhere th atmosphere is unbreathable without mechanical assistance)
F Thin, Low Pressure 0.33 bars with 60% oxygen(High gravity World, or a world with a dense gas acting as a moderator, Argon instead of Nitrogen for instance, air is breathable only at the lowest altitudes above sea level.
G Gas Dwarf 1000+ bars (Planet is in a transitory stage between terrestrial World and gas giant, the surface is inaccessible)

Hydrographics 3d6-10+World Size
0 0%
1 25%
2 30%
3 35%
4 40%
5 45%
6 50%
7 55%
8 60%
9 65%
A 70%
B 75%
C 80%
D 85%
E 90 %
F 95%
G 100%

 

[Reynard]

Marc already considered this in T5.

Again I like the MgT K.I.S.S. system. In my Traveller Universe, I use the actual stars surrounding Sol then generated the systems as standard. I can actually play the game until we get better sensors and/or starships. Let IXS Enterprise find all those Size 10 worlds!

 

[Tom Kalbfus]

My system isn't so different, for World sizes, it is basically a continuation of the ones that end at size 10, mine goes up to size 16, and rolling a 3d6 produces an average value of 10.5, subtracting 2 from it produces 8 and 9 size worlds as average, the old 2d6-2 produces an average of size 5 worlds. I think from an anthropocentric point of view, Earth sized worlds might be preferred and low gravity worlds might be discarded. Mars for instance us a size 4 world and has a trace atmosphere, it might be discarded in favor of a larger planet with a more massive atmosphere, so you have a bell cure with 3d6s. I transposed these tables to the designing a logical World creation system thread, I reproduce the refined version here:

World Size 3d6-2 the rest of the tables work fine as is, though hydrographics might need to be adjusted if you want something other than water worlds for large planet sizes
Digit
1 1600 km
2 3200 km
3 4500 km
4 6400 km
5 8000 km
6 9600 km
7 11,200 km
8 12,800 km
9 14,400 km
A 16,000 km
B 17,600 km
C 19,200 km
D 20,500 km
E 22,400 km
F 24,000 km
G 25,600 km

Atmosphere 3d6-10+World Size
0 Vacuum
1 Trace 0.01 bar
2 Very Thin, tainted 0.1 bar
3 Very Thin 0.1 bar
4 Thin, Tainted 0.33 bar (20% oxygen, same as mount Everest approx.)
5 Thin 0.33 bar (60% Oxygen, can be breathed by humans without oxygen masks)
6 Standard 1 bar (20% oxygen, Same as Earth as Sea Level)
7 Standard, Tainted 1 bar (7% oxygen or less)
8 Dense 3 bars (7% oxygen, can be breathed without oxygen masks)
9 Dense, Tainted 3 bars (2% oxygen or less, requires air filter masks)
A Exotic 10 bars (oxygen masks required)
B Corrosive 100 bars (1 km beneath Earth's oceans)
C Insidious 100 bars combined with high temperatures (The surface of Venus)
D Dense, High Pressure 100 bars at surface, (same as Insidious at surface, but at a high altitude 50 km for example, the oxygen percentage is sufficient to allow for unassisted breathing, roll 1d6(1-2 Dense atmosphere at this altitude, 3-4 standard atmosphere, or 5-6 thin atmosphere)
E Ellipsoid (Standard, thin, or Dense atmospheres at certain latitudes, elsewhere th atmosphere is unbreathable without mechanical assistance)
F Thin, Low Pressure 0.33 bars with 60% oxygen(High gravity World, or a world with a dense gas acting as a moderator, Argon instead of Nitrogen for instance, air is breathable only at the lowest altitudes above sea level.
G Gas Dwarf 1000+ bars (Planet is in a transitory stage between terrestrial World and gas giant, the surface is inaccessible)

Hydrographics 3d6-10+World Size
0 0% to 24% = old 0 to 2
1 25% = old 3
2 30% = old 3
3 35% = old 4
4 40% = old 4
5 45% = old 5
6 50% = old 5
7 55% = old 6
8 60% = old 6
9 65% = old 7
A 70% = old 7
B 75% = old 8
C 80% = old 8
D 85% = old 9
E 90% = old 9
F 95% = old A
G 100% = old A

You roll 3d6-2 for World Size
You roll 3d6-10 + World Size to determine Atmosphere according to the table above, the atmospheric codes haven't been changed except to the addition of the digit code G for Gas Dwarf, basically a Type G atmosphere is the intermediate stage between a Terrestrial planet and a gas giant, the "size" of the planet in this case would be the radius at which a 1 bar atmosphere exists, the actually solid surface below would be inaccessible as there is at least 100 km of atmosphere below this altitude and an atmospheric pressure at that surface of around 1000 bar or greater.
Your roll 3d6-10 + World Size to determine hydrographic percentage, and if you wish to translate it to the old digit I have that on the table as well. Generally anything with less than 25% water coverage is considered a Desert World. Small worlds such as Size 1 or 2 can have any hydrographic percentage up to and including 100% water coverage even if it has no atmosphere, under this category the Jupiter Satellite Europe has 100% water coverage, its just that the surface is frozen in the form of water ice.. I'm not considering any other fluid other than water, so oceans of liquid methane don't count as part of the hydrographic percentage. Titan by this definition would be considered a water world even though its water is frozen.. I believe its atmosphere would be destructive to an unprotected human I think low temperature might qualify it as corrosive. I don't know the tables above don't consider cold outer planet environments, except that if it has water coverage in a vacuum then it must be a frozen ice ball, and the World has to be moved outwards a few orbits beyond the habitable zone to make that happen.

As for the social data, population, Government, Law Level, and Tech Level that stays the same. The question arises as to who would live on a size 14 world (22,400 km diameter) Perhaps an alien race could be designed that could live on a world such as this, its physical strength would have to be high for its size, maybe a +3 or +4 modifier should be added when rolling its initial Physical Strength attribute. A creature such as this would be great at jumping on Earth sized worlds, would probably do well in physical brawling, but it might be a bit clumsy in a low gravity environment to it which would be Earth.

 

[sideranautae]

I believe that is a 36 day YEAR! Yeah, that fast. Then again the planet is an average of .1617 AUs from the sun (Earth - sun = 1 AU and Mercury - sun = .365 AUs). No rotational period is mentioned (or detectable) and it would need a moon to have months. Earth travels 1.6million miles per day while 832C moves around its sun at 1.3 million miles per day at 1/7 the radius. That close to a sun would probably force tidelocking.

Okay. Interesting stuff!