Star Trek's Bajor System in Detail

[Whirligig Girl]

According to Memory Alpha, the Bajoran Sun is host to 14 planets. The Bajoran Homeworld is the 11th planet, and the largest in the system. There exists a plasma field around the orbit of Deep Space Nine, and it holds the unique Bajoran Wormhole.

The Sun: Bajor System

Taking the Blue channel value from this image of the Bajoran Sun and comparing it to the thermal color spectrum with this calculator gives us a color that corresponds to 5250, or a G9 type Main Sequence Star.

Its mass is about 0.84 Solar masses and it has a luminosity of 0.6 Solar luminosities. Its habitable zone lies between 0.736 and 1.06 Astronomical Units. There are no planets massive enough to be gas giants, implying a vast system of comets and icy asteroids are retained outside the frost line.

Its planetary system is tightly packed, and many of them are so hot as to be rendered uninhabitable mercury-like objects. These are likely dark grey, heavily cratered objects. The innermost two objects may be partially molten at the surface.

The sun glows fairly evenly. No pictures of it exist showing sunspot activity. This could mean that the Bajoran sun has a very long rotation period and thus a very long solar activity cycle, and during the events of DS9 it has been at solar minimum.

There is one known comet, designated Comet Alpha, which appears to have a semi-major axis of around 0.5 AU and an eccentricity of around 0.4-0.6.

The Bajoran Wormhole

The Bajoran Wormhole is a massive spacetime portal between Bajor and deep space on the other side of the galaxy. Within itself is an incredible and mysterious power source which heats up a gas torus that it emits. The Bajoran Wormhole is massive enough to have its own gravity, and bright enough to be visible to Bajor when it is open. DS9 orbits the Bajoran Sun at the Sun-Wormhole L1 point. The wormhole appears to glow unevenly when open, between around 4500 Kelvin and 10,000 Kelvin. (Yellow and blue) At its brightest, it may outshine the Sun when viewed from Bajor. If in fact the Wormhole's glow is not Thermal, but is instead an emission spectrum or some other method of generating yellow and blue light, DS9 may simply orbit the wormhole itself.

The plasma torus, also known as the Denorios Belt, seems to have a significant effect on starships navigating to DS9 according to Memory Alpha. The composition of the torus appears to be Hydrogen, given the purple-pink glow of the belt in this image.

The Denorios Belt stretches from 0.62 to 0.7 AU.

The Planet: Bajor Homeworld and its Satellites

Bajor is a Terrestrial Minshara-Class planet. It has five moons.

• Derna: 0.158 Bajor Radii, Near the roche limit and very close.
• Three unnamed, probably asteroid moons. I suspect the innermost of these is within 4 or 5 Bajor radii distant, and are close together in their orbits to one another.
• Jerrado: A moon large enough to have a habitable atmosphere. I'd wager it's about 0.25 Earth masses minimum to hold onto that atmosphere, so I would suspect it must be fairly distant from Bajor.

This is important to finding a good guess at Bajor's characteristics. If Bajor wants to hold onto its four other moons without them being destablized (which would be disastrous in Derna's case) then Jerrado must orbit a fair distance away. However, if Bajor orbited right at 0.77 AU where Earth would to get as much light as it would from the Sun, Bajor's sphere of gravitational influence would be smaller than Earth's. Bajor must therefore be more massive and relatively further away from its sun than Earth. The tectonic and volcanic activity from Derna's extremely close orbit, as well as a higher-than-Earth-level of greenhouse gasses can make up for the loss in temperature that we get by moving it out to 0.93 AU (1.2x the Earth region)

Derna presents another challenge. It looks like Derna orbits one Derna-Diameter from the surface of Bajor. We'll throw this away. We can not accept that in any reasonable planet. Instead, we'll make Bajor less dense than Earth (4.8 g/cm³ instead of 5.51 g/cm^3.) and we'll make Derna denser. (6.0 g/cm³⁾

This puts the Derna-Bajor roche limit at 2.42 * 7679 km * (4.8/6)^1/3 = 17251.1 km.

Bajoran Homeworld

• Space Engine Class = Temperate Terra with Life
• Star Trek Class = M
• Radius = 7679 km, 1.205 Earth radii
• Density = 4.8 g/cm³
• Gravity = 0.915 Eg
• Mass = 1.3286 M-earth
• Semi Major Axis = 0.93 AU

Derna

• Space Engine Class = Temperate Selena
• Star Trek Class = D
• Radius = 1212 km
• Density = 6 g/cm³
• Gravity = 0.207 Eg
• Mass = 0.0075 M-earth
• Semi Major Axis = 21,963 km

Jerrado

• Space Engine Class = Temperate Terra with extinct Life
• Star Trek Class = H, formerly M?
• Radius = 4778 km
• Density = 3.4 g/cm³
• Gravity = 0.4628 Eg
• Mass = 0.26 M-earth
• Semi Major Axis = 1,521,161,000 km

I'm not completely sure Jerrado is small enough not to interfere with the orbits of the inner four satellites. If needed, Jerrado can be shrunk to 0.1 Earth masses.

Other Planets in the Bajoran System

This LCARS display shows the Bajoran system, presumably to scale.

From this we can get some reasonable values for size and mass. Radius is taken from chart relative to Bajor, Density is chosen pseudo-randomly based upon proximity to star. Gravity and Mass are calculated from the former two characteristics using the Earth-relative equation G = M/(R²⁾ = R*D. Albedo is chosen pseudo-randomly. Semi-Major-Axis (distance from the sun) is measured from the chart. Temperature is based on Albedo and SMA, but I may have made a mistake with it. Most of these planets are throwaway moon-like bodies, perhaps harvestable for minerals at best. The innermost two worlds likely have molten regions. Planets 1-6 or 7 are likely tidally locked to the sun, and might have an ice-coated permanent dark side.

We know that Planet 11 is the habitable Bajor, and that Planet 8 is habitable enough to be colonized. Unfortunately these do not fit within the habitable zone as we know it. I've given the planet a thick cloud cover and thus a higher albedo so it reflects as much light as possible, but its still too darn hot. The other possibility is to retcon Planet 8 so that it is actually either Planet 10 or Planet 12, both of which are in the habitable zone. Realistically Planet 8 should either have a Venus-like or hot Mars-like atmosphere. Possible fixes: Prophet Magic and/or star-shade at Planet8/BajorSun L1 point.

Bajor I

• Space Engine Class = Scorched Selena
• Star Trek Class = D
• Radius = 1745 km, 0.2272 Bajor
• Density = 5.6 g/cm³
• Gravity = 0.278 Eg (Earth Gravity)
• Mass = 0.021 M-earth
• Semi Major Axis = 0.1142105 AU

Bajor II

• Space Engine Class = Scorched Selena
• Star Trek Class = D
• Radius = 1745 km, 0.2272 Bajor
• Density = 5.6 g/cm³
• Gravity = 0.278 Eg (Earth Gravity)
• Mass = 0.021 M-earth
• Semi Major Axis = 0.13868 AU

Bajor III

• Space Engine Class = Hot Selena
• Star Trek Class = D
• Radius = 2443 km, 0.318 Bajor
• Density = 5.55 g/cm³
• Gravity = 0.3827 Eg
• Mass = 0.0568 M-earth
• Semi Major Axis = 0.19579 AU

Bajor IV

• Space Engine Class = Hot Selena
• Star Trek Class = D
• Radius = 2795 km, 0.364 Bajor
• Density = 5.5 g/cm³
• Gravity = 0.438 Eg
• Mass = 0.0843 M-earth
• Semi Major Axis = 0.2529 AU

Bajor V

• Space Engine Class = Warm Selena
• Star Trek Class = D
• Radius = 2443 km, 0.318 Bajor
• Density = 5.3 g/cm³
• Gravity = 0.369 Eg
• Mass = 0.054 M-earth
• Semi Major Axis = 0.3108 AU

Bajor VI

• Space Engine Class = Warm Selena
• Star Trek Class = D
• Radius = 2304 km, 0.3 Bajor
• Density = 5.3 g/cm³
• Gravity = 0.348 Eg
• Mass = 0.0455 M-earth
• Semi Major Axis = 0.3345 AU

Bajor VII

• Space Engine Class = Temperate Selena
• Star Trek Class = D
• Radius = 2304 km, 0.3 Bajor
• Density = 5.3 g/cm³
• Gravity = 0.348 Eg
• Mass = 0.0455 M-earth
• Semi Major Axis = 0.4813 AU (Note: it's possible that Bajor VII is meant to represent a trojan companion to Bajor VIII, and would actually orbit at the same distance but 60 degrees ahead in its orbit)

Bajor VIII

• Space Engine Class = Temperate Terra Somehow with Life
• Star Trek Class = L
• Radius = 3840 km, 0.5 Bajor
• Density = 4.3 g/cm³
• Gravity = 0.4704 Eg
• Mass = 0.1709 M-earth
• Semi Major Axis = 0.4936 AU

Bajor IX

• Space Engine Class = Selena
• Star Trek Class = D
• Radius = 1745 km, 0.227 Bajor
• Density = 3.2 g/cm³
• Gravity = 0.159 Eg
• Mass = 0.0119 M-earth
• Semi Major Axis = 0.5384 AU

The Wormhole and the Denorios Belt.

• Semi Major Axis = 0.571 AU

Bajor X

• Space Engine Class = Desert
• Star Trek Class = H
• Radius = 3490 km, 0.455 Bajor
• Density = 3.4 g/cm³
• Gravity = 0.338 Eg
• Mass = 0.1014 M-earth
• Semi Major Axis = 0.734 AU

Bajor XI (BajorWorld)

• Space Engine Class = Temperate Terra with Life
• Star Trek Class = M
• Radius = 7679 km, 1.205 Earth radii
• Density = 4.8 g/cm³
• Gravity = 0.915 Eg
• Mass = 1.3286 M-earth
• Semi Major Axis = 0.93 AU

Bajor XII

• Space Engine Class = Cool Desert
• Star Trek Class = H
• Radius = 3840 km, 0.5 Bajor
• Density = 3.2 g/cm³
• Gravity = 0.35 Eg
• Mass = 0.1272 M-Earth
• Semi Major Axis = 1.0279 AU

Bajor XIII

• Space Engine Class = Cold Desert
• Star Trek Class = K
• Radius = 4884 km, 0.636 Bajor
• Density = 3.4 g/cm³
• Gravity = 0.473 Eg
• Mass = 0.2779 M-Earth
• Semi Major Axis = 1.085 AU

Bajor XIV

• Space Engine Class = Cold Ice World
• Star Trek Class = D
• Radius = 3490 km, 0.455 Bajor
• Density = 2.9 g/cm³
• Gravity = 0.288 Eg
• Mass = 0.0865 M-Earth
• Semi Major Axis = 1.2033 AU

[Nibb31]

What has this got to do with science or KSP? 

[Zeiss Ikon]

I'd say you have a bad case of assuming the DS9 writers knew, or cared, about actual astrophysics when they made up this system.  Star Trek is not and never has been hard SF -- it's space opera with an agenda, and enough science added to give the required level of technobabble.

[Whirligig Girl]

Just now, Zeiss Ikon said:

I'd say you have a bad case of assuming the DS9 writers knew, or cared, about actual astrophysics when they made up this system.  Star Trek is not and never has been hard SF -- it's space opera with an agenda, and enough science added to give the required level of technobabble.

I know full well that Star Trek is soft science fiction. No one in their right mind should be under the impression that Star Trek is fundamentally realistic. Most of the astronomy is bullgarbage. Ship design, while visually impressive, belongs no where near rocket science. The Denorios Belt and the Wormhole being a good example in this system of unnatural astronomy. But it's still fun to work out parts of it. That's why the Daystrom Institute subreddit exists. That's what Star Trek nerds have been doing for decades. All I've done with this post is taken a relatively unassuming LCARS display and extrapolated from it using astronomy and planetary science what a realistic system would look like.

[Sigma88]

1 hour ago, Nibb31 said:

What has this got to do with science or KSP? 

39 minutes ago, Zeiss Ikon said:

I'd say you have a bad case of assuming the DS9 writers knew, or cared, about actual astrophysics when they made up this system.  Star Trek is not and never has been hard SF -- it's space opera with an agenda, and enough science added to give the required level of technobabble.

I think you guys ended up on the wrong thread, what you are looking for is probably this one:

 

 

[KerbMav]

@GregroxMun 11th planet? How big/hot is the star then for Bajor being in the habitable zone?

1 hour ago, Nibb31 said:

What has this got to do with science or KSP? 

As he said, applying science to fictive places to come up with a "might be so and so".

 

Edited July 4, 2017 by KerbMav

[Whirligig Girl]

1 minute ago, KerbMav said:

@GregroxMun 11th planet? How big/hot is the star then for Bajor being in the habitable zone?

As addressed in the OP, it's actually cooler than the Sun. Bajor simply orbits a bit closer to its sun, and there are a lot of small, close-in mercuries in the inner system.

[Green Baron]

1 hour ago, Nibb31 said:

What has this got to do with science or KSP? 

Very little and marginal, with a whole lot of goodwill.

But maybe somebody can boost the thread by calculating possible stable configurations of such a system. Initial publications on Trappist-1 could serve as a base :-)

[Gordon Fecyk]

Is GregroxMun looking to remake Bajor in KSP, perhaps?

[Stevie_D]

@GregroxMun, How DARE you post the details of a fictitious set of planets owned by a fictitious alien race in a fictitious universe, of all places on the forums of a game about a fictitious alien race inhabiting fictitious alien planets in a fictitious universe!

How DARE you! How DARE you, good sir! 

Edited July 5, 2017 by Stevie_D

[Nibb31]

2 hours ago, Stevie_D said:

@GregroxMun, How DARE you post the details of a fictitious set of planets owned by a fictitious alien race in a fictitious universe, of all places on the forums of a game about a fictitious alien race inhabiting fictitious alien planets in a fictitious universe!

How DARE you! How DARE you, good sir! 

Actually this is Science & Spaceflight, which isn't supposed to be about a fictitious alien race inhabiting fictitious alien planets but real-life science.

I'm sure there are plenty of Star Trek fanfic forums where this would be on topic.

[Sigma88]

53 minutes ago, Nibb31 said:

Actually this is Science & Spaceflight, which isn't supposed to be about a fictitious alien race inhabiting fictitious alien planets but real-life science.

I'm sure there are plenty of Star Trek fanfic forums where this would be on topic.

might be worth a read

 

[Stevie_D]

4 hours ago, Nibb31 said:

Actually this is Science & Spaceflight, which isn't supposed to be about a fictitious alien race inhabiting fictitious alien planets but real-life science.

I'm sure there are plenty of Star Trek fanfic forums where this would be on topic.

And despite it being fictitional, i think you'll still find that it included Science... Go figure!

[ProtoJeb21]

@GregroxMun It seems like a system with compact Mercury-sized planets, as seen around Bajor, isn't so far fetched anymore. Why? Because just today me and one of my collaborators on Exoplanet Explorers found such a system.

https://www.zooniverse.org/projects/ianc2/exoplanet-explorers/talk/821/320198?comment=646224&page=17

The star EPIC 212343667 has three likely planet candidates. At first glance it seems rather normal, but a closer inspection reveals that this system is absolutely TINY. The host star is much smaller than Bajor at 0.149 R_Sun and 0.129 M_Sun, with a temperature of just 3,130^oK. These three planets are small as well, being just 0.20, 0.1675, and 0.213 R_E. This might actually make them dwarf planets! However, the orbital periods of 13.832, 18.7261, and 34.53 days are close to 3:4 and 2:1 mean-motion resonances, which proves that compact and resonant systems of sub-Mars-sized are not out of the real of possibility. In addition, more small planets may be present and make this seem even MORE like Bajor. The lack of Mars-sized or even Earth-sized planets is quite odd in my opinion...

[sumghai]

[MOD - The moderation team has examined this topic, and as it makes use of real science, it has been deemed appropriate for this subforum.

Carry on ]