Edasich (Iota (ι) Draconis) is a mag. +3.3 star in the curving tail of Draco, the Dragon.
Located 31.8° from Polaris (Alpha (α) Ursae Minoris), Edasich is circumpolar from the UK and never sets.
The name is a corruption of the Arabic term for ‘the male hyena’.
The Chinese name for Edasich is Zĭ Wēi Zuŏ Yuán yī, which means ‘First Star of Left Wall of Purple Forbidden Enclosure’, the enclosure asterism being formed by Iota, Theta (θ), Eta (η), Zeta (ζ), Upsilon (υ), 73, Gamma (γ) and Beta (β) Draconis.
Edasich is 1.8 times more massive, 12 times larger and 55 times more luminous than our own Sun.
It has a spectral classification of K2 III, indicating that it’s an orange giant star.
Edasich is estimated to be about 1.2 billion years old and, like our own Sun, rotates slowly with a speed of 1.5km/s.
Edasich gave rise to the first exoplanet discovered to orbit a giant star.
The discovery, made in 2002, was interesting because the habitable zone for a giant is large, giving a reasonable chance that a planet would sit within it.
Edasich’s habitable zone extends 6.8–13.5 AU and the exoplanet (Edasich-b, named Hypatia) orbits with a semi-major axis of 1.45 AU, placing it too close to the parent star.
Edasich-c, discovered in 2021, lies outside the habitable range, with an orbital semi-major axis distance of 19.4 AU.
Infrared excess from the system suggests the presence of a circumstellar debris disc in orbit around the star.
This guide originally appeared in the June 2023 issue of BBC Sky at Night Magazine.
