The Delvi Star System

The Delvi System consists of one star (Fevaultar), four rocky inner planets (Tula, Collena, Sephar, Senon), and five gaseous outer planets. Rather typical of any star system of this type. The system is unique for having 3 planets that are within the habitable zone, that can also fully support life, and for having a double planet with stable orbits. All three planets have developed life independently of each other. There is a fourth world, a moon of Baultar, that has developed a fourth form of life independently. Only Collena developed Sentient life. The Regalti Species lives here, and they have created an interplanetary civilization with over a hundred billion people. They live almost entirely in space, and have mostly abandoned their original homeworld of Collena.

Author's Note

_☉ is a symbol indicating the measurement is in reference to the Sun. 1M_☉ for example means 1 solar Mass, meaning it is equal to the mass of the Sun. In this respect, I have several other symbols to indicate other measurements. _E Indicates the measurement is in reference to the Earth. _C indicates the measurement is in reference to the planent Collena. _J indicates the measurement is in reference to Jupiter. This is to make the numbers easier to understand instead of using very large numbers or an excessive number of exponents.

Location
In the Cairn Sector , 400 light-years from the center.

Population

115 Billion Regalti

1.2 Billion Vusinor

354 million Maorians

1 Billion from other sentient species

Fevaultar

Mass: 1.05 M_☉
Radius: 1.11 R_☉
Rotational Period: 26 _Edays
Surface Temperature: 5914K
Composition: 72.9% Hydrogen, 25.72% Helium, 1.38% Other

Fevaultar is the largest object in the Delvi system, comprising over 99% of the system's mass. It is a high metallicity white-yellow dwarf star, and is 4.75 billion _Eyears old. It is expected to live another 4.5 billion years before it swells into a red giant, swallowing Tula and Collena-Sephar, before it ultimately collapses into a White dwarf.

Fevaultar is a unique star in that it has three planets within its habitable zone, and all three planets around Fevaultar (Collena, Sephar, Senon) are planets that can support life. Usually all these planets would have been sterilized by a large asteroid impact or gamma ray burst, or their atmospheres would be just a little too thick or thin, or the planets would have been just a little too large or small, or their parent star itself would have had an outburst of radiation that would have fried the atmospheres. There are too many factors to count. The Devli System in this regard, has managed to stay incredibly stable.

For comparison, the Sun is a very similar star in terms of size, composition, and age to Fevaultar. The Vusinor Venjint system also has a similar star. The only difference is that Fevaultar is slightly brighter, larger, and more massive. These three systems share many similarities, such as habitable worlds, an asteroid belt separating inner, rocky planets, from outer, gaseous ones, and having a shell of comets surrounding it in a giant cloud stretching a trillion kilometers away.

The Sun by NASA/SDO (AIA)

Fevaultar looks very similar to this image of the sun, and if there was any difference at all, it would be slightly whiter and brighter, otherwise an image of the sun wouldn't be that distinguishable from an image of Fevaultar, or any other yellow dwarf star.

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Tula

Mass: 0.155 M_E
Radius: 3365 km
Density: 5.81 g/cm^3
Surface Temperature: 147*C
Surface Gravity: 0.55 earth
Escape Velocity: 6.07 km/s
Speed: 44 km/s
Distance: 0.48au (71,962,000km)
Rotational Period: 36 _Edays
Orbital Period: 119_E
Obliquity: 7.3 degrees
Composition: 52% Iron, 48% Silicates

Tula is an extremely dense, extremely hot planet. It is the closest orbiting body to Fevaultar and is one of the densest objects in the star system.

The Planet has been continuously mined for raw materials for building in space for almost four centuries, and is expected to last another few hundred thousand years before the mass of the planet is completed converted for ships and space habitats. Most of the materials are being used to construct a sort of Dyson Swarm where the vast majority of the Regalti in this system live.

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First Asteroid Belt

The remains of the second planet from Fevaultar, blasted apart in some ancient impact. The total mass in this area is roughly equal to that of Tula. Most of the asteroids here are rather small, with only three larger than 100km in diameter. Every few years, a particularly dense area of this asteroid belt aligns between the star and the planet Collena, making the skies dimmer but otherwise doing nothing.

While the asteroids are mostly composed of Iron and Nickel, heavier elements like Iridium, osmium, platinum, and more are found here in large quantities, and are necessary for many of the advanced machines the Regalti build. For this reason there are numerous mining stations set up throughout this region. Depleted asteroids are often sealed and turned into space habitats, creating living spaces for tens of thousands of people.

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Collena and Sephar

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Collena

Mass: 0.995 M_E
Radius: 6,948 km
Density: 4.24 g/cm^3
Surface Temperature: 13.2*C
Surface Gravity: 0.842 earth
Escape Velocity: 10.7 km/s
Speed: 27.1 km/s
Distance: 1.26au (188,000,000km)
Rotational Period: 28 _Ehours (1 _Cday)
Orbital Period: 498 _Edays (414 _CDays)
Obliquity: 22.2 degrees
Composition: 25.05% Iron, 73.5% Silicates, 1.45% other

Map: Link
Population: 1 Billion

While Sephar is often called Collena's Moon, the two are infact a double planet, orbiting each other around a barycenter well away from the surface of either world. But for the purpose of this reference, Collena will be referred to as the planet, and Sephar will be referred to as the moon as there is still a considerable size difference between the two.

Sephar has a much denser elemental composition than Collena and it is speculated that it was once much cloer to the sun, that changed its position in the early history of this star system. Collena and Sephar possibly even collided, then ended up orbiting each other. Both planets have substantial hydrospheres. and are able to easily support life. Regalti live on both worlds and both are considered their home worlds.

Sephar

Mass: 0.28 M_E
Radius: 3,507km
Density: 9.28 g/cm^3
Surface Temperature: 14.9*C
Surface Gravity: 0.92 earth, 9.09 m/s^2
Escape Velocity: 7.98 km/s
Speed: 0.953 km/s (orbiting Collena)
Distance: 512,529 km (from Collena)
Rotational Period: 19.3 _Ehours
Orbital Period: 30.33333 _Edays (26 _Cdays)
Obliquity: 22.2 degrees
Composition: 32.9% Iron, 66.1% silicates, 1% other

Population: 800 million

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Senon

Mass: 1.1 M_E
Radius: 6557km
Density: 5.55g/cm^3
Surface Temperature: 19.7*C
Surface Gravity: 1.04 earth
Escape Velocity: 11.6 km/s
Speed: 20.7 km/s
Distance: 326,811,750 km
Rotational Period: 38.4 _Ehours
Orbital Period: 3.15 _Eyears
Obliquity: 28.9 dgrees
Composition: 21.7% Iron, 78.1% silicates, 0.2% other

Population: About 500 Million

Third planet from Fevaultar, Senon is a planet with a dense, oxygen rich atmosphere. Despite being much more distant to the star than Collena, Senon is currently a warmer world, though it has had frequent stretches of ice ages. Senon has three moons, each a tenth of the mass of the planet. They orbit in a 1:1, 2:1, and 4:1 resonance with Senon, creating periodic surges of oceanic tides.

Currently the planet is at the end of its last ice age cycle, which lasted almost twenty million years. The Regalti found vast swaths of empty fertile land when they first explored the world. It was settled but because this was just as the Exodus from Collena was starting, most Regalti stayed in space instead of settling a new planet. the population never reached more than half a billion people, and today, large swaths of the planet are currently used to support the hundred billion people living in space with food and animal products. Most of the planet remains undeveloped and unexplored.

Senon's Moons

Name	Description
Liaria	Closest moon to Senon with a rotational period of 15 days. It is icy, and has a subterranean ocean. It is lifeless. The ocean water, though salty, is quite pure, and the entire moon is designated as a reservoir for the Regalti living in space. It is estimated that with proper recycling, the moon can supply over five million years worth of water to trillions of people. This moon is tidally locked with Senon.
Atar	Middle moon of Senon with a rotational period of 30 days. It is a rocky world with no atmosphere and a large iron core. Its pristine white surface is ruined in many parts by craters and still active volcanoes, which remain active due to tidal forces between Atar, Senon, and the other two moons.
Eltar	Farthest moon of Senon with a rotational period of 60 days. It is a dark, red, sandy world that is no longer volcanically active. It has no atmosphere, but possibly did in the distant past. This world was thought to be able to support life, but after centuries of searching, none was ever found.

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Second Asteroid Belt

The asteroids contained here are much more numerous and larger than those found around the first asteroid belt. Two are larger than 500km in size, with numerous smaller ones trailing off in size. the largest Asteroids, Gintamor and Wrethalmor, have vast interconnecting networks of tunnels and mining stations housing so many Regalti that the two have multiple independent nations with their own beliefs and political issues.

This second Asteroid Belt did house some violent creatures known as Void Wasps that prevented the Regalti from expanding their civilization into the outer system. these creatures are common in every star system but are usually found well beyond the last planet in the system's Oort Cloud. A military attachment from visiting Vusinor and Maorian empires eradicated them, allowing the Regalti to expand across their system unimpeded.

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Baultar

Mass: 3.56 M_J
Radius: 84,361 km
Density: 2.7 g/cm^3
Surface Temperature: -170*C
Surface Gravity: 6.49 earth
Escape Velocity: 104 km/s
Speed: 11.7 km/s
Distance: 6.75au
Rotational Period: 14 _Ehours
Orbital Period: 17 _Eyears
Obliquity: 10 degrees
Composition: 86% hydrogen, 6% Helium, 6% Chlorine, 2% other

Fourth planet from Fevaultar, and comprising a large chunk of the mass that isn't part of Felvater, Baultar is the largest planet in the system and is large enough to have an influence on every other object in the system, including the star. It has thick bands of chlorine gas, hydrogen and helium. It has an extremely powerful magnetic field that reaches past the orbit of the 5th planet from Fevaultar, Kinta, and the 6th planet Mintar. Its position in the star system is quite important as far as life on Collena, Sephar, and Senon are concerned, as well as the numerous space habitats, because Baultar tends to alter the orbits of asteroids and comets away from these worlds.

Baultar

This planet has over 30 moons, including one that is nearly as large as Collena, three that are larger than Sephar, and three more that are larger than Tula. These moons are almost entirely icy water worlds, too far from Fevaultar to recieve any warmth, or are smaller, rockier, captured asteroids. Two are volcanic hellscapes, being torn apart by tidal forces between Baultar and the moons. There is one more moon, where an alternate form of biochemistry was discovered that uses a number of exotic elements. It is entirely single celled, and is not studied due to the extremely corrosive aspects of the world.

Baultar's Major Moons

Name	Description
Ikon	Largest moon of Baultar, it is nearly the size of Collena. This world is mainly composed of rock, though it does have a significant amount of ice. Around half of this ice is water, and the other half is various forms of frozen acids. Water isn't harvested from this world generally, but the amount of frozen acids that can safely be extracted has contributed greatly to the Regalti's industrial developements in space.
Arkon	Second largest moon of Baultar, it is 50% the size of Collena. This moon has a thick atmosphere made of Hydrochloric Acid. Its oceans are made of Florine, water, and Nitric Acid. It's main crust composition is various compounds of sulphur. The world is all around acidic and highly reactive, even explosive, with itself. Tidal forces, combined with the thick atmosphere keep the world warm enough for all these elements to remain in liquid and gaseous states. How anything can form life here without dissolving isn't beyond Regalti science, but they make no attempt to study it. Most attempts to land a probe results in the probe melting into a torrent of liquid before it ever reaches the surface, so studies are done from orbit with imaging systems.
Cevaultar	Third largest moon of Baultar. It is one of the closer moons to the planet. As a result, this planet is one of the volcanic hellscapes, being ripped apart by tidal forces. It has by far the most active volcanism in the Delvi system. Huge pieces of crust regularly shatter off the world and break apart, turning into a temporary ring around Baultar as it eventually burns the planet's atmosphere. Cevaultar is rapidly shrinking as a result, and it is estimated the moon will no longer exist in about another hundred thousand years.

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Kinta

Mass: 24 M_E
Radius: 26,642 km
Density: 1.81 g/cm^3
Surface Temperature: -194*C
Surface Gravity: 1.37 earth
Escape Velocity: 26.8 km/s
Speed: 9.17 km/s
Distance: 11.1 au
Rotational Period: 12.2 _Ehours
Orbital Period: 36 _Eyears
Obliquity: 3 degree
Composition: 70% Hydrogen, 28% Iron, 2% other elements

Fifth Planet from Fevaultar, Kinta is a deceptively low mass gas giant that appears to be quite normal. Its mass isn't anything to write about, especially for a gas giant. It's almost entirely composed of hydrogen, but has an extremely massive Iron core for its size. The interactions between the iron core and the metallic hydrogen just above, combined with solar wind and its placement in Baultar's magnetic field, gives it especially powerful magnetic storms. Normally they appear to be green in color, but have been observed being every other color, sometimes disappearing only to be emitting in a different spectrum of light. Most gas giants have never ending auroras in some way, but none as intense as seen on this world.

Kinta globe

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Mintar

Mass: 1.1 M_J
Radius: 69,384 km
Density: 1.49 g/cm^3
Surface Temperature: -212*C
Surface Gravity: 2.95 earth
Escape Velocity: 63.4 km/s
Speed: 8 km/s
Distance: 14.6 au
Rotational Period: 8.8 _Ehours
Orbital Period: 54.8 years
Obliquity: 36 degree
Composition: 90% Hydrogen, 2% Methane, 2% Ammonia, 2% Water, 2% other elements

Sixth Planet from Fevaultar, Mintar would be quite the impressive planet...if it weren't in the same system as Baultar. This planet does have one of the larger ring systems among the gas giants of the system, but there are much more impressive examples elsewhere. The specific composition of this planet makes it appear violet, and its rings are very bright. Very much like Baultar, Mintar influences everything near its orbit, including the other planets. It has 23 moons, including several that are larger than Sephar and Tula.

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Halana

Mass: 18 M_E
Radius: 26,709 km
Density: 1.35 g/cm^3
Surface Temperature: -214*C
Surface Gravity: 1.03 earth
Escape Velocity: 23.2 km/s
Speed: 7.13 km/s
Distance: 18.4 au
Rotational Period: 21 _Ehours
Orbital Period: 77.6 years
Obliquity: 63 degree
Composition: 80% Hydrogen, 10% Helium, 5% Water, 3% Methane, 2% other elements

Second to last planet from Fevaultar, Halana is an "Ice Giant". It is primarily composed of Hydrogen and Helium, but also a significant amount of water and methane, giving it its blue appearance. It has 13 moons.

The Vusinor have a significant presence in the Devli system, but only specifically around Halana. They paid the Regalti for the mining rights to several of Halana's moons, and harvesting rights to Halana itself. They use the planet Halana as a Switchboard World to allow for instant communication across their empire. They gave the Regalti access to roughly 25% of the network capability of the planet, which is far, far more bandwidth than the Regalti's current population can take advantage of.

Halana (natural)

Halana (Switchboard)

Research Log

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Arta

Mass: 3 M_E
Radius: 17,703 km (3998 km not including atmosphere)
Density: 0.918 g/cm^3
Surface Temperature: -223*C
Surface Gravity: 0.4 earth
Escape Velocity: 12 km/s
Speed: 5.69 km/s
Distance: 28.8 au
Rotational Period: 8.8 _Ehours
Orbital Period: 152 years
Obliquity: 26.3 degree
Composition: 25% Helium, 25% Hydrogen, 20% Nitrogen, 15% Iron, 5% Silicates, 5% Water, 3% Methane, 2% other elements

Arta is the furthest planet from Fevaultar. It is the coldest planet, and has the longest orbital period. This planet is known to the Regalti as the Idanthi World, which the closest translation to English is "Marshmallow".

The Planet's atmosphere is 2.4 M_E in size, while the planet itself is only 0.6 M_E in size. The inner world is almost never visible, covered in a thick cloud of Nitrogen and Water, the outer radius of this layer almost three times as large as the planet. Swirling clouds of Methane float on top of that, and then there's hydrogen and helium above that.

The Helium Layer is constantly being blasted away by solar winds as the planet's gravity isn't strong enough to hold it all in place. Estimates say the planet was originally 6-10 M_E in size, but the gravitational forces were never enough to keep the mainly helium atmosphere in place, causing it to be blasted away over the billions of years. It will eventually reach a size where the planet's magnetic field will protect its atmosphere from the Solar Winds, but that's still almost a billion years away.

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