Neoilius System
Introduction
The Neoilius (/ˌni.oʊˈɪl.i.ʌs/) system is a planetary system that consists of all objects in orbit around and gravitationally bound to the star Neoilius. In one of many parallels to the Solar system, the Neoilius system formed over 5.2 billions years ago from the gravitational coalescences and collapse of an interstellar molecular cloud, noteworthy for being particularly metal-rich in composition; this is hypothesized to have partly underpinned the emergence of a very large and diverse planetary system favorable to the later emergence of native life.
By astronomic convention and consensus, the Neoilius system comprises 11 planets, 7 dwarf planets, and 26 planetary-mass natural satellites. Six of these planets are terrestrial, though unlike in the Solar system they exhibit
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5.229 billion years
Local Bubble, Orion–Cygnus Arm, Milky Way
Epsilon Eridani
Epsilon Eridani system
1 (Neoilius)
11
7
26
no particular pattern of arrangement. These planets, in order of their distance from Neoilius, are Gehenna, Abzu, Lyonesse, Duat and Aaru as a binary system, and Savaiki. The remaining five are larger gas planets of varying types, consisting of the planets Tirnanog, Navacasha, Xibalba, Yggdrasil, and Nocturne, also in order. Both within and between this binary designation of terrestrial and gaseous planets, all eleven of these planets are very diverse and distinct from one another in appearance and properties, defying easy categorization. Nonetheless, these planets are also categorizable on the basis of distance from Neoilius, divisible into three groupings separated by two asteroid belts, in a manner akin to the Solar system's planets being separable into two groups divided by its one asteroid belt.
Table of Contents
The Neoilius system was the third planetary system ever to be identified by humans as home to native, indigenously-evolved life, and the second in which life was found to exist on more than one of its planetary bodies. All life native to the Neoilius system was found to have originated on Novaluna, the largest moon of the gas giant Navacasha and home to by far the greatest diversity and density of wildlife in the system, all stemming from a remote universal common ancestor thought to have arisen roughly 4 billion years ago, only slightly shorter than the timescale exhibited by life on Earth. Life was then propagated to other nearby bodies in the Neoilius system via ejecta from impact events in a process known as panspemia, leading to flourishing yet comparably sparse and primitive communities of organisms establishing themselves beyond just Novaluna.
At a distance of roughly 11.74 light years (3.6 parsecs) from the Sun, Neoilius is a relatively nearby star, and is only 2.0 light years (0.61 parsecs) and 3.1 light years (0.95 parsecs) from the similarly nearby stars Epsilon Eridani and Tau Ceti, respectively. As a result of its relatively nearby location and proximity to other stars of interest, Neoilius was one of the foremost candidates for humanity's first efforts at interstellar travel, with its priority swiftly rising to number one when the first biosignatures were identified on multiple of its planetary bodies. It was also the first extrasolar system to be visited by a crewed mission and colonized by humans, when in 2200 CE the starship Ad Astra brought a crew of 2000 in biostasis to the system's most habitable body, the moon Novaluna, after a 40-year journey (from the perspective of a stationary observer) through interstellar space.
Planetary Bodies
Gehenna
Gehenna (/ɡəˈhɛnə/) is the first planet from Neoilius. It is also the largest and most massive terrestrial planet in the Neoilius system. Due in part to its strong gravitational pull and persistent emissions by its considerable tectonic activity, Gehenna possesses an extremely thick atmosphere primarily of carbon dioxide, which coupled with its high levels of incident stellar radiation results in a potent greenhouse effect and exceptionally high surface temperatures in excess of 1000 Kelvin. Additionally, its persistent and prodigious volcanism and periodic heavy bombardment by the nearby associated Hinnom system of asteroids and moonlets contribute to Gehenna's noteworthy appearance as a hellish, lifeless, lava-enswathed world to which it owes its name.
Hinnom System
The Hinnom (/ˈhɪnɔm/) system is an extensive and complex array of asteroids, planetoids, and moonlets in gravitational association with the massive planet Gehenna as well as Neoilius, comprising a dense belt of astronomic debris forming a persistent field in and near Gehenna's orbit. The densest agglomerations of asteroids and related objects are in a large, granular planetary ring around Gehenna itself, as well as clusters of trojans in its L4 and L5 Lagrange points, but enough asteroids persist outside of these zones to classify it as an asteroid belt. In spite of the Neoilius system's age and Gehenna's considerable mass as an indubitable planet, orbital effects have continued to maintain a quasistable state for the Hinnom system, and though Gehenna continues to accrete Hinnom objects, it is estimated that several billion more years will be required before Gehenna fully clears its orbital neighborhood.
Ba'al, Dagon, and Moloch
Gehenna possesses three gravitationally rounded moons of planetary mass, all of which trace their origins to the accumulation of Hinnom asteroids into planetary objects. These three moons, in order of size, are Ba'al (/ˈbeɪ.əl/), Dagon (/ˈdeɪɡɒn/), and Moloch (/ˈmoʊlɑk/). They are all of similar composition due to their shared origins and, like Gehenna, continue to experience periodic impact events from other objects in the Hinnom system.
Gehenna
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4.64E+10 km / 0.31 AU
6.43E+10 km / 0.43 AU
81 d / 0.22 yr
3 planetary moons (Ba'al, Dagon, Moloch); innumerable Hinnom asteroids
11295 km / 1.77 Earths
70966 km / 1.77 Earths
1.60E+09 sq km / 3.14 Earths
6.04E+12 cu km / 5.57 Earths
3.32E+25 kg / 5.54 Earths
5.501 g/cm^3
17.37 m/s^2 / 1.77 g
1.47 d / 35.3 hr
1106K / 833°C
11679 kPa / 115.3 atm
Tirnanog
Tirnanog (/tirnəˈnɑg/) is the second planet from Neoilius. Categorized as a "warm Mini-Neptune", it is a relatively small and rarified ice giant planet generally noteworthy for its complex atmospheric composition and dynamics, resulting in a vibrantly colorful and variegated cloud deck consisting of swirling bands of pink, green, blue, and orange depending on the season. Although beneath its thick atmosphere lies a surface of liquid water and other substances, average surface temperatures in excess of 450K and pressures over ten times that of Earth's atmosphere have precluded the presence of any natural life.
Atmosphere and Climate
Tirnanog exhibits one of the most complicated and dynamical climactic systems of any gas planet in the Neoilius system, the result in part of its highly varied composition; in addition to the light elements of hydrogen and helium, as well as an abundance of the reduced forms of common heavier elements such as methane, ammonia, and water, traces of heavier hydrides such as hydrogen sulfide, phosphine, and heavier hydrocarbons as well as numerous more oxidized forms of these common elements have been observed in varying quantities depending on the time and place. This is the result of complex abiotic chemical processes that lead to an unusual equilibrium in the atmospheric chemistry of Tirnanog, as well as large anisometries in the distribution of these compounds in both the gaseous and liquid phases, both of which drive weather systems in a manner akin to the influence on climate by landmasses in terrestrial planets.
Avalon and Annwn
Tirnanog has 2 planetary moons as well as a handful of smaller, irregular moonlets. These planetary moons are known, in order of their mass, as Avalon (/ˈævəlɒn/) and Annwn (/ˈanʊn/). Both moons are barren and rocky and lack substantial atmospheres. However, both moons have eccentric orbits stabilized by orbital resonances with each other, producing tidal heating effects that result in both moons nonetheless having active and varied geologies as well as diverse mineral compositions.
Tirnanog
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8.68E+10 km / 0.58 AU
8.98E+10 km / 0.60 AU
179 d / 0.49 yr
2 planetary moons (Avalon, Annwn)
18496 km / 2.90 Earths
116212 km / 2.90 Earths
4.30E+09 sq km / 8.43 Earths
2.65E+13 cu km / 24.47 Earths
2.21E+25 kg / 3.70 Earths
0.834 g/cm^3
4.31 m/s^2 / 0.44 g
1.88 d / 45.1 hr
454K / 181°C
1063.9 kPa / 10.5 atm
Abzu
Abzu (/ˈɑbzu/) is the third planet from Neoilius. Orbiting near the inner boundary for Neoilius' habitable zone, Abzu is a "super-Earth", a terrestrial planet greater in mass and radius than Earth, that is most noteworthy for being completely covered in a deep layer of liquid fresh water. Additionally, Abzu was the first body in the Neoilius system on which biosignatures were detected, before even Novaluna, and thus the foremost point of interest in the early years of humanity's exploration of the Neoilius system. Indeed, Abzu does play host to a flourishing ecosystem of primitive unicellular and multicellular marine organisms. However, high irradiation, low concentrations of dissolved mineral nutrients, paucity of accessible carbon, and tectonic moribundity have precluded the emergence of indigenous life forms, and the life that exists upon it now are entirely of relatively recent panspermic origin from Novaluna.
Life on Abzu
Abzu's ecosystem of living organisms are entirely of Novalunar panspermic organisms, deriving from a handful of separate microorganism lineages that were propagated by impact events on Novaluna. These panspermic events occurred relatively recently in geological terms, dating to no earlier than 750 million years before the present, and given that all but the hardiest (and thus, in many cases, simplest) organisms survived the ejection and journey from Novaluna to Abzu, this resulted in something of an evolutionary bottleneck. Coupled with the adverse but not completely inimical conditions of Abzu, its panspermic life remained highly reduced and reclusive for a long span of its history before beginning to radiate and proliferate. To this day such life remains primitive and basal compared to Novaluna's yet is at this point well-established and vibrant.
Tiamat
Tiamat (/ˈtiəˌmæt/) is Abzu's sole natural satellite. Formed from the same protoplanetary primordium that gave rise to Abzu, Tiamat has a rather similar composition and even appearance; as it too it fully covered in an ocean of liquid water, it somewhat resembles a much smaller version of Abzu, even harboring life of its own dating back to the same event that seeded Abzu. However, unlike Abzu's fresh waters, the global sea of Tiamat is highly saline and contains many dissolved minerals, affording new challenges and opportunities alike for its own native life.
Abzu
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1.33E+11 km / 0.89 AU
1.39E+11 km / 0.93 AU
293 d / 0.80 yr
1 planetary moon (Tiamat)
7929 km / 1.24 Earths
49819 km / 1.24 Earths
7.90E+08 sq km / 1.55 Earths
2.09E+12 cu km / 193 Earths
1.14E+25 kg / 1.91 Earths
5.463 g/cm^3
12.11 m/s^2 / 1.23 g
2.95 d / 70.8 hr
323K / 50°C
218.86 kPa / 2.16 atm
Navacasha
Navacasha (/ˌnɑvəˈkɑʃə/) is the fourth planet from Neoilius. A large yet highly rarified Type II-III gas giant with a vibrant blue atmospheric envelope and extensive ring system, Navacasha is one of the brightest and most visually prominent objects in the Neoilius system. It is furthermore remarkable for its six planetary moons, three of which are among the five planetary bodies in the Neoilius system known to host extant communities of living organisms–the other two being Abzu and its moon Tiamat–one of which, Novaluna, is both the origin of all life in the Neoilius system and the first extrasolar body visited, colonized, and inhabited by humans.
Nyrsjor
Nyrsjor (/ˈnɪəɹsjɔɹ/) is the first major moon from Navacasha. A prototypical water-ice moon in a vein similar to Europa or Enceladus of the Solar system, Nyrsjor possesses a massive subsurface ocean upon a tectonically active seafloor beneath a thin layer of ice, in places less than a kilometer thick, as a result of tidal heating via its orbit around Navacasha and resonance with nearby moons. Although its surface experiences high levels of incident radiation due to its orbit lying within Navacasha's Van Allen belt, its subsurface ocean is known to be very favorable to life; it is one of the five bodies in the Neoilius system known to harbor life. Nyrsjor's endemic life, like all other life native to the Neoilius system, ultimately originated on Novaluna and was distributed via impact events dating to roughly 2 billion years before the present. Such life, though not remotely approaching Novaluna's in density or diversity, is nonetheless noteworthy for its unique adaptations to Nyrsjor's lightless marines environs.
Novyogni
Novyogni (/nɔvˈij.ɑgni/) is the second major moon from Navacasha. A chiefly rocky moon rich in heavier elements, it possesses a relatively thick and complex atmosphere primarily comprising carbon dioxide, nitrogen, sulfur dioxide, methane, and various derivatives thereof. Its vibrant and varied orange surface is characterized by heavy volcanism, a major cause of its atmospheric dynamism, and results in surface conditions that, though not as severe as Gehenna's, are still hostile to life, with average surface temperatures hovering around 612K.
Navacasha
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1.78E+11 km / 1.19 AU
1.78E+11 km / 1.19 AU
360 d / 0.99 yr
6 planetary moons (Nyrsjor, Novyogni, Nawiyaban, Carrac Nuae, Novaluna, Norsaren); countless moonlets
62924 km / 9.87 Earths
395351 km / 9.87
4.98E+10 sq km / 97.5 Earths
1.04E+15 cu km / 963 Earths
5.23E+26 kg / 87.61 Earths
0.481 g/cm^3
8.82 m/s^2 / 0.90 g
4.53 d / 108.72 hr
301K / 28°C
79.844 kPa / 0.79 atm
Nawiyaban
Nawiyaban (/nɑˈwi.jəbɑn/) is the third major moon from Navacasha. It has a rocky, sandy surface and possesses a moderately thin atmosphere of carbon dioxide, nitrogen, oxygen, methane, ammonia, and hydrogen. Despite relatively moderate temperatures and pressures, and the presence of subsurface ice deposits, it is extremely arid; liquid water and water vapor exist almost solely in transient, ephemeral phases upon its desert surface, and only a very small proportion of its surface is covered in persistent bodies of water, many of which consist either of scattered oases or short streams near the melt boundaries of its ice caps. In spite of these harsh conditions, however, Nawiyaban is one of the few bodies in the Neoilius system that is permanently host to life alongside Nyrsjor and Novaluna, with its reception of Novalunar life dating back to roughly the same incidents that propagated life to Nyrsjor.
Carrac Nuae
Carrac Nuae (/kæɹək nu.eɪ/) is the fourth major moon from Navacasha. A large and rocky moon with only a vestigial atmosphere and moderate tectonic activity, it is uninhabitable, barren, heavily cratered, and bears no trace of natural life, despite life-harboring Novalunar ejecta having been discovered on its surface. Nonetheless, it is of scientific and commercial interest due to the accessible abundance of minerals in its crust that are comparably rare elsewhere in the Neoilius system.
Novaluna
Main Article: Novaluna
Novaluna (/noʊvəˈlunə/) is the fifth and largest major moon from Navacasha, and the first not to exhibit tidal locking to its parent planet. As the largest natural satellite in the Neoilius system, Novaluna is a terrestrial body with a radius and mass well in excess of many of the system's smaller formal planets, and comparable to that of Earth and Venus. Although it is not the only body in the Neoilius system harboring extrasolar life, it is the origin of life in the Neoilius system and bears by vast margins the highest diversity, richness, and biomass density. It is also readily habitable by human beings, with an oxygenated atmosphere, liquid water oceans, productive dry land, and temperate global climate, and as such was the first celestial body outside of the Solar system to be settled by humans.
Norsaren
Norsaren (/nɔɹˈsɑɹən/) is the sixth major moon from Navacasha. The second largest after Novaluna, Norsaren is an exemplar icy moon, though unlike Nyrsjor its cratered icy crust is vastly thicker, its subsurface oceans are sandwiched between different phases of ice, and its cool, homogenous interior exhibits little sign of present geological activity. No life has been found to survive on Norsaren, and as such it is of only passing scientific and commercial interest.