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Irus, captured by the VOD-1 (Verge of Death-1) probe
Creation dateFebruary 11th, 2021
Release number15
Orbital characteristics
~79.65 AU
~234 years
Known satellites0 known
Physical characteristics
Mean radius
~8821.433 km (1.385 ER)
Mass~3.567 Earth Masses
5.142662375 days
Temperature659.174°C (934.324 K)

Irus, also known as WI 43500 b or CelWP T58 b is a relatively hot super-Earth orbiting the Wolf-Rayet star Muuren, 5728 light years from Arnar. It is quite small for a super-Earth, mostly because its growth was quickly stalled by Muuren's harsh stellar winds. Irus may even be a chthonian planet.

Irus is also the only world orbiting a Wolf-Rayet star to have been photographed or visited by a probe, so this world offers many insights into the lives of planets orbiting Wolf-Rayet stars.

Properties[edit | edit source]

Irus is relatively small as far as super-Earths go, being just around 3.57 Earth Masses in mass and 38.5% bigger than Earth. What you may have already noticed is that its mass is disproportionally high compared to its size. If we had an object that size with Earth-esque density, it would be nearly one Earth mass less massive. This means that Irus's density is very high for its size, at nearly 7.41 g/cm^3, which holds many clues into the exact nature of this veritable world. We will discuss this later.

Irus is very carbon-rich, mostly because it formed in an initially carbon-rich system, and there is not much tectonic activity going on. Some carbon has also been collected from its star, Muuren, which produces profuse amounts of carbon-rich dust every year. This carbon shows itself as massive flats of carbon-rich minerals, coating the planet. These have a low albedo and so absorb a large amount of heat, making them glow a deep red colour in the dark.

Atmosphere[edit | edit source]

Irus has a stupendously thick atmosphere (around 4400 bar), likely the remnant of an even thicker one. It is blue, but due to the high temperature it becomes slightly redder and takes on a purplish hue. It is mostly made of water vapour, methane, ammonia and carbon dioxide, with a small amount of halogens in the atmosphere and an unusually large amount of iodine, adding to the purplish hue. Large clouds of carbon dioxide and ammonia help trap even more heat.

History[edit | edit source]

Irus formed around 8 million years ago, around a million years after Muuren, back then an O7.5V star, formed in a large molecular cloud. It started out as a massive gas giant core, quickly accumulating gaseous mass around a 5 earth mass ball. In 400,000 years, Irus grew to about Saturn-size. Another 300,000 years passed and Irus was already at two Jupiters in mass. Sadly, this was when Muuren's powerful stellar winds started to rapidly interfere with Irus's unprecedented growth.

Around 2 million years into Muuren's life, it was already starting to move off the main sequence. Increasingly strong solar winds started to really gnaw at what was left of its protoplanetary disk, shutting off any more growth for Irus. And it too would suffer from Muuren's searing, ferocious, unrelenting stellar winds. 4 million years of painful whittling passed, and Irus was small enough that its core weighed more than half its total mass. Another two million years later, Irus's atmosphere was so thin the surface was finally visible, and became subject to Muuren's stellar winds as well. They quickly started to strip mass off the core as well as the atmosphere, and a million years later, this is where it is, a mere skeleton of its former self.

In just a million years, Muuren is projected to collapse in a type Ic supernova, destroying itself, Irus and any other material in its orbit. A black hole will be left behind and Irus will likely be completely gone, as it is now so light and small.

Missions[edit | edit source]

An expedition known as Verge Of Death (referring to Muuren's evolved status) was sent to Irus just a few years after its discovery. It consisted of around 5,000 solar sails which would fly past Irus and collect data about this strange world and its surroundings. The mission was very successful and collected much useful data about Irus's parameters, history and its interaction with its parent star.

Trivia[edit | edit source]

  • Irus was the first planet Trolligi made in 3 months.