Acharan

Acharan (Coeric ['ˈɑxəran]) is a planet in the Riėl system, where it is the third closest planet to the star, at about the one third mark on the distance between Riėl and Seldh.

Name
Acharan is the Coeric name of the planet, but it is known by many different names across the cultures on Seldh. Acharan shares its name with a legendary figure / demigod from Coeric mythology.

The Bantazi name for the planet, Scertśe /ˈskɛɾtʃə/, comes from an earlier Classical Arazi compound Scernatiye, meaning Scerna's Star. The names Scerna and Acharam are widely believed to be cognates, and the respective heroes might have evolved from the same character in Proto-Asatic mythology.

Geography and climate
The people on Seldh know next to knowing about the physical realities of Acharan.

Acharan is tidally locked to Riėl, meaning that one half of the planet is permanently facing the sun (and the other half is permanently in the dark). Consequently, the day side is a scorching desert, while the night side is a freezing wasteland. Both hemispheres exhibit both high mountains and flatlands - evidence of extensive geological activity (definitely in the past, perhaps concurrently) and probably a history of water oceans that has since evaporated (on the dayside) or frozen solid (on the nightside).

Habitability
Acharan orbits to close to its star to fall within its habitable zone. However, the twilight zone between the dark and light side could potentially allow for reasonable temperatures and liquid water to exist. Potentially, high but gradually-sloped mountains could extend this twilight ring vertically.

Acharan also has a considerable atmosphere that works to distribute and mediate the temperatures on the planet, particularly around the terminator.