HD 15241 System

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HD 15241, a K-type orange dwarf star 15 light-years from Sol, is the star around which Artemis revolves. It was originally colloquially known as 'Peeper'. A survey done in 2174 by colonist Cameron Perez instead resulted in the name 'Riganna', courtesy of Roark McKay. (Riganna is another name for the Celtic goddess Rhiannon, who is associated with motherhood, rebirth, wisdom, and mystery.)

Planets of HD 15241 'Riganna'[edit | edit source]

HD 15241's planetary system contains five sub-stellar bodies, not including asteroids, moons and planetoids: Abel, Artemis, Freyja, Nautilus, and Forefather. Two of these five bodies sit within HD 15241's 'Goldilocks zone', having the required temperature for liquid water and to develop life - the second of which is Artemis itself. A third is a little too close to the star, being reduced to a blistering ball of silicon, and a fourth is too far - a frigid iceball. The last body is a sizable Jovian-class gas giant, sitting on the other side of an asteroid belt from the farthest terrestrial planet.

HD 15241-1, Aka 'Abel'[edit | edit source]

Sitting a bare 0.3 AU from its star, HD 15241-1 lies just within the habitable zone, close enough that the planet suffers from being tidally locked. Whilst HD 15241-1 retains an atmosphere, its searing temperatures and high-speed winds caused by the extreme temperature difference between its far and star-facing sides makes for an extreme environment. Despite this, streaks of ancient deserts can be found spotted across its surface, implying the previous existence of water.

HD 15241-1-1, Aka 'Cain'[edit | edit source]

The singular moon to HD 15241-1, HD 15241-1-1 ("Cain") sports an irregular, oval and vertical orbit around its parent planet, implying an origin from outside the system. Due to the low albedo of the material making up its surface, mapping from afar has proven difficult.

HD 15241-2, Aka 'Artemis'[edit | edit source]

Artemis sits comfortably within the habitable zone, 0.7 AU away from its star. The rich, green flora of its surface can be seen from orbit, giving proof of native life likely compatible in some way with Earth's. Along with its average temperature of 23 degrees Celsius in the northern hemisphere, HD 15241-2 was an obvious choice for the MBC's colonial efforts.

Strangely enough, the vegetation on its surface is abruptly missing in places, with no consistent pattern or due to any obvious cause. It was in one of these barer areas, Callysto Crater, that the Artemis mission was chosen to land - minimizing disruption of the existing ecosystem.

HD 15241-2 sports an atmosphere with a pressure of 0.94atm, composed of ~60% carbon dioxide, ~16% argon, ~10% oxygen, and trace amounts of nitrogen and helium. This makes for a deceptively deadly atmosphere to humans, being scentless but leading to slow, but certain asphyxiation on an average of 60 to 140 seconds.

Gravity: 0.94

Mass: 1.02 EM (Earth Masses)

HD 15241-2-1, Aka 'Diana'[edit | edit source]

Diana is Artemis's only moon. With a standard orbit around its planet, it contributes to the planet's stable hydrosphere. Its surface is a brownish-grey, made from a mixture of silicates and mottled with countless impact craters. Due to its close proximity to Artemis (approximately only 250,000km away), it appears far larger in the night sky when compared to the Terran moon.

HD 15241-3, Aka 'Freyja'[edit | edit source]

On the edge of the habitable zone sits HD 15241-3, a frosty planet with a line of floral growth along its equator. Due to a lack of exploratory expeditions, the nature of its native wildlife is unknown. From readings, its atmosphere - 40% carbon dioxide, 30% argon, 23% oxygen and with trace amounts of nitrogen, methane and neon - would be breathable if not for the frigid cold. At its hottest points near the equator, surface temperatures on Frejya linger around -10°C to -5°C.

HD 15241-4, Aka 'Nautilus'[edit | edit source]

On the edge of the terrestrial planets is a large, ice-coated world 1.8 times the size of Earth. Despite its extreme distance from its star (2.1 AUs, far from the habitable zone) its thick casing of ice is theorized to give way to a massive underground ocean of liquid water. Due to its high albedo, HD 15241-4 can be seen with the naked eye from both Freyja and Artemis.

HD 15241-5, Aka 'Forefather'[edit | edit source]

HD 15241-5 is the system's only gas giant. It's on the large size for its class, being 1.3 Jupiter masses. As a class II giant, its appearance is composed of streaks of greys, blues and whites, making for a tranquil pattern despite the raging storms inside its atmosphere. HD 15241-5 sits 4.6 AU away from its parent star, with the 'Onixian' asteroid belt separating it from the inner solar system at 3.2 AU.