The Solar System

Somewhere in the infinite expanse of space, in a galaxy known as The Medetran, lies a humble and isolated solar system. At the heart of the solar system sits two binary stars - Magnus and Ignis. Ignis is the smallest of the two stars and completes its orbit around Magnus every 21 Enkeian days. The Magnus system is a p-type circumbinary system, meaning all planets orbit around both parental stars. Two of the planets, Enkei and Yaima, are themselves binary planets and are the only known planets known to harbor life. Enkei is also home to the only known intelligent life form in the universe - the homonids.

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Interactive map of the star system (click to jump)

The Binary Stars

The Magnus-Ignis system formed just over 2 billion [Enkeian] years ago through the gravitational collapse of a molecular cloud. About 80.8% of the system's mass comprises the primary star, Magnus, with a further 19.1% corresponding to the binary star, Ignis. Only around 0.1% of the system's mass lies outside it's two stars. The two known planets - Enkei and Yaima are widely studied while the remaining three planets - Elysium, Aesir, and Tiimyat, remain hypothetical.

At an orbital distance of 0.2 AU, Ignis makes its home in the gravitational shadow of Magnus, tugging gently on the planets as it moves but otherwise causing little disruption. Despite being dwarfed by its sibling star, Ignis is believed to have played a pivotal role in shaping life in the solar system. The slight perturbations it creates in the orbits of the planets and the regular occlusion of Magnus as it passes creates a significant amount of instability on the surface of the planets. This instability is thought to have resulted in extreme selection pressures on early life forms, and may have sped up the arrival of complex life such as plants and animals.

 
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The solar system scaled to size (distances not to scale)

Magnus

Mass:
Luminosity:
Diameter:
Surface Temp:
Lifetime:
Habitable Zone:
Frost Line:
Gravity Line:

Peak Wavelength:

Peak Frequency:

2.1879 × 10^30 kg

5.6 x 10^26 W

1488800 km

6063 K / 5790 °C

3.59 Billion Enkei Years

1.13 - 1.98 AU

5.73 AU

0.11 - 44 AU

478 nm

356.4 THz

(1.1 Sol)

(1.464 Sol)

(1.069 Sol)

(1.049 Sol)

7.88 Billion Earth Years

(0.957 Sol)

(1.045 Sol)

Ignis

Mass:
Luminosity:
Diameter:
Surface Temp:
Lifetime:
Habitable Zone:
Frost Line:
Gravity Line:

 

Peak Wavelength:

Peak Frequency:

Semi-Major Axis:

Orbital Period:

5.1714 × 10^29 kg

6.489 x 10^25 W

542400 km

2927 K / 2654 °C

132 Billion Enkei Years

0.42 - 0.86 AU

0.459 AU

0.026 - 10.4 AU

990 nm

172 THz

29920000 km

21.0092448 Enkei Days

 

(0.26 Sol)

(0.1687 Sol)

(0.389 Sol)

(0.5065 Sol)

290 Billion Earth Years

(1.982 Sol)

(0.5 Sol)

0.2 AU

0.08636 [Earth] years

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A comparison of a sunset as seen on Enkei and Earth

Enkei

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Physical Properties

Enkei's day lasts 32 hours, being slowed over time by Yaima, which is tidally locked to Enkei. Enkei orbits its parent star every 600 local days. A year on Enkei is equivalent to 2.19 years on Earth. Days, months and years from this point on will be given in local (Enkeian) time unless otherwise stated. With a shallow axial tilt of 12.8°, seasons are not very pronounced throughout most of the planet. The southernmost continent, Polaris, exhibits the most seasonal variation. Much of Polaris can spend up to six months in near-total darkness. The greenhouse effect, axial tilt and arrangement of continents mean that the majority of landmasses only experience two seasons - wet and dry.

Enkei is home to countless diverse ecosystems from deepsea hydrothermal vents, to anoxic swamps, to dense jungles and great plains. Native organisms have adapted to life in the oceans, on land and in the skies. The mineral-rich crust disperses vast amounts of iron and phosphorus across oceans and continents whilst high levels of volcanic activity continually pump minerals up from out of the seafloor. The nutrient-rich environment, warm climate, and vast network of inland seas means the current geological era is the most productive Enkei has ever seen. Continents are dominated by animals that regularly exceed 50 tonnes whilst the largest marine organisms reach 5 times that weight. These organisms are still dwarfed by the largest plant species which reach heights in excess of 250 metres.

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With an average density of 4.25g and a diameter of 13761 km, the surface gravity on Enkei is a comfortable 0.83G. Interestingly, due to the moderately high atmospheric density of around 15 kg/m^2, the terminal velocity of a human works out at less than 12 m/s (26 mph). Consequentially, a 1000 foot fall is no more dangerous than a 10 foot fall for a person. This explains the widespread convergence of gliding membranes among land vertebrates as even a slight amount of webbing between the limbs creates enough drag to greatly increase the survivability of falls.

​Enkei's iron core is atypically small for its size. Small enough in fact that it doesn't seem like it should be able to generate a magnetosphere powerful enough to shield its atmosphere from solar winds. Yet the atmosphere persists. So what gives? Well, for the most part, luck. Orbiting at a comfortable 1.74 AU, Enkei is somewhat out of the immediate firing range of solar winds. Likewise, Enkei may also owe its survivability to Ignis, whose close proximity to Magnus may help to block or redirect harmful flares. But what about the magnetosphere itself? For that Enkei owes it's gratitude, once again, to Yaima. Zooming around Enkei in just 112 hours, Yaima provides yet another buffer from harmful winds. Yaima's iron core is slightly more conductive than Enkei's but is similarly incapable of producing a strong magnetosphere. Interestingly, however, the thick atmosphere is capable of inducing its own magnetosphere as charged particles from the stars interact with the ionosphere. The same is true for Enkei to a lesser extent. Furthermore, the close orbital distance between Enkei and Yaima results in a significant amount of gravitational stress within both planets. This is especially true for Enkei where the barycenter of the two bodies lie within it's mantle. This stress churns up the mantle and the core, driving convection forces within. These forces not only "supercharge" the internal dynamo of the core but they also manifest an enormous amount of tectonic and volcanic activity which continually replenish the atmosphere. The gravitational disturbance caused by Ignis only magnifies these forces. Enkei and Yaima are, in a sense, dependant on each other survival - neither planet would survive very long on their own.

Orbital Mechanics

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Enkei semi-major axis

The unique orbital mechanics between Enkei, Magnus and Ignis result in Enkei's eccentricity fluctuating on an annual basis. This change in eccentricity typically means that Enkei's climate alternates between low seasonal variation and moderate seasonal variation. A year with mild seasons is typically followed by a year with more pronounced seasons, over a cycle of around 50 years. The gravitational influence of Ignis also effects Enkei's semi-major axis which can vary by up to 0.03AU every 10 years. The change in insolation results in extreme summer and winter periods, each lasting around half a decade. The intensity of these periods are difficult to predict but are usually significant enough for extensive ice sheets to form and thaw on Polaris each winter and summer.

In addition to annual and decennial winters, Ignis partially eclipses Magnus (and is completely eclipsed itself) on a monthly basis, resulting in noticeable, periodic cycles of insolation each month. This exacerbates the double winters (and summers). This intense, yet rhythmic, variability is a major driving force behind Enkei's biosphere, with average temperatures varying by around 4 degrees Celsius between double summers and double winters. The complex seasonal cycles and low insolation is often cited as providing the necessary selection pressures for complex life, and complex life cycles, to evolve.

 

Insolation

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The solar constant, or solar flux, is a measure of how much energy is recieved from the star(s) at a given distance. At a distance of 1.74AU, the solar contant from Enkei's atmosphere works out at ~660 Watts, plus 75 Watts from Ignis (assuming no eclipse is taking place). For plants, this equates to around 25 calories per square meter at the surface, in ideal conditions.

Yaima

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Not much is known about Yaima. For most of human history, it was simply regarded as a large blue moon. In the 123rd century, the first manned voyage to Yaima took place as a multinational venture. Within minutes of ariving, the presence of long-theorised native macrofauna were comfirmed. After the loss of two crew members, the remaining astronaughts opted to not to return to earth due to contamination concerns. Video data was transmitted from the vessel for 6 months before a presumed power failure. Yaima was declared too high-risk and no further missions were planned until the turn of the 124th century when multiple drones were launched with the intention of documenting the ecology on the surface.

 

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A comparison of the Moon, as seen from Earth, and Yaima, as seen from Enkei