Eta Scorpii [SEP] constellation
Eta Scorpii
Eta Scorpii (η Sco, η Scorpii) is a star in the southern zodiac constellation of Scorpius. With an apparent visual magnitude of 3.33, this is one of the brighter members of the Scorpius and is the furthest south of the constellation stars with a Bayer designation. The distance to this star can be estimated using parallax measurements, yielding a value of with a 0.4% margin of error.
The stellar classification of this star has undergone some revision over time, with the star being classified anywhere from
upsilon Orionis (B0 V), eta Aurigae (B3 V), eta Ursae Majoris (B3 V).
Besides these anchor standards, the seminal review of MK classification by Morgan & Keenan (1973) listed "dagger standards" of Tau Scorpii (B0 V), Omega Scorpii (B1 V), 42 Orionis (B1 V), 22 Scorpii (B2 V), Rho Aurigae (B5 V), and 18 Tauri (B8 V). The Revised MK Spectra Atlas of Morgan, Abt,