Infernum

Currently unofficial lore, and in progress.

Infernum

Orbital characteristics
Semi-major axis	0.025 AU (3,739,900 km)
Eccentricity	0
Orbital period (sidereal)	1.041053241 days (24.9852778 h)
Inclination	76.3°
Star	Solakku
Physical characteristics
Mean radius	1.497 RJ
Mass	3.1 MJ
Albedo	0.5
Temperature	3,187 K (2,910 °C; 5,280 °F)

Infernum (natively Valotolave, lit. "burning land") is a hot jupiter planet orbiting close to Solakku. It orbits with a short period of about 25 hours, making it observable as transiting Solakku several times per Avalon day. Its close proximity to Solakku is responsible for tidal effects on the surface of the star, which trigger observable stellar activity.

Physical Characteristics

Composition

The upper atmosphere for Infernum is observed to contain 96% Hydrogen, with almost 4% Helium and traces of various molecules such as titanium monoxide and carbon monoxide. However, the overall ratio of gases within the planet is estimated to be closer to 80% Hydrogen and 20% Helium. A significant amount of silicates and iron are observable in Infernum’s spectrum, dredged up by the high temperatures.

Size and mass

Infernum measures about 16 Earth radii, or 50 times the size of Avalon. However, this figure is only a rough average. In reality, Infernum is prolate as it is being stretched by the gravity of Solakku. Its radius is additionally being inflated by the high temperatures puffing it up even before being stretched.

Infernum’s mass sits at 985 Earths or 36,000 Avalons, making it the heaviest planet in the Solakku system, only eclipsed by the star Crest. This mass is still by far not enough to have it be considered a brown dwarf, despite the fact that Infernum visibly radiates light on its far side. This mass is also slowly dropping as Infernum undergoes mass loss from Solakku’s gravity slowly stripping material from Infernum’s atmosphere. The high temperatures also aid in allowing atoms to be accelerated away from the planet. However, this process is very slow and is expected to take much longer to completely strip the planet of its atmosphere than it will take for its orbit to drop past the roche limit.

Atmosphere

Infernum’s atmosphere consist primarily of hydrogen and helium, with smaller amounts of other compounds such as iron, titanium monoxide, carbon monoxide and even water and ammonia vapors.

A thick cloud layer of silicate and iron vapors is constantly maintained everywhere on the planet. As these are highly opaque, they make direct observation of deeper layers of the planet difficult. They are also highly reflective, raising Infernum’s albedo to 0.5. It is assumed that, just like clouds on other planets, these are capable of precipitation, in this case in the form of droplets of molten iron, which re-evaporate in the hotter deeper layers of the planet.

The atmosphere of Infernum is also characterized by intense winds circulating heat between the near and far side at speeds of up to 12 km/s. The temperature of the day side is about 3,187 K (2,910 °C; 5,280 °F), which drops to 1,853 K (1,580 °C; 2,880 °F) on the night side. The day side temperature is actually high enough to ionize hydrogen. These hydrogen ions flow to the far side and recombine into neutral atoms, before cycling back towards the near side.

Internal structure

Due to difficulty of observation, Infernum’s internal structure is hard to discern, but it most likely contains a mantle of metallic hydrogen with a layer of liquid hydrogen coating it before the puffy atmosphere. At the very center should be a rocky core, from which the planet originally grew.

The temperature of Infernum’s interior is estimated to be even more extreme below the cloud layers than the visible layers of atmosphere, probably growing to 10,000s of Kelvins.

Formation

It is highly improbably that Infernum formed in its present location. Gas giants generally form past the frost line, which is where temperatures allow volatile chemicals to freeze solid, and contribute to the mass of growing terrestrial planetoids. This eventually pushes them pass a mass where they are able to start accreting a thick hydrogen and helium envelope, eventually developing into a gas giant.

However, this close to Solakku, there would have been neither enough rocky nor gassy material available to form a gas giant directly. Instead, Infernum is likely to have formed as just described, and then migrated inwards to its current orbit. The mechanics by which this could have occurred are numerous, but the amount of distance Infernum would have had to cross means it was potentially extreme.

Most likely, Infernum formed together with Valaya in relatively close orbits, before an encounter with a heavy object from interstellar space pushed both planets into closer orbits, though Infernum was affected more strongly. This theory also explains why there are only two terrestrial bodies in-between the orbits of Valaya and Infernum, as the latter’s migration would have disrupted the orbits of every object within this space.

Orbit and rotation

Infernum has an incredibly close orbit to Solakku, only 0.025 AU, which is 21 times closed than even Magnus. It completes this orbit once every 25 hours, meaning it is seen transiting Solakku several times per day from Avalon. Its orbital eccentricity is negligible and can be assumed to be zero, the result of its orbit having long since circularized under the gravitational pull of Solakku. Its inclination is incredibly high, on an almost polar orbit around Solakku, further indicating that it migrated to its current orbit after a major disruption to the Solakku system.

Infernum is tidally locked to Solakku due to its proximity. However, Infernum is not a solid body, meaning the atmosphere is free to rotate at a different speed at different latitudes. The rotation of its magnetosphere is instead used as a reference point for measuring Infernum’s rotation.