Delta Equulei, also named Tepennekhet, is the second brightest star in the constellation Equuleus. Delta Equulei is a binary star system about 60 light-years away, with components of class G0 and F5. Their combined magnitude is 4.47, and their absolute magnitude is 3.142. There is controversy as to the exact masses of the stars. One study puts the larger at 1.22 solar masses and the smaller at 1.17, while another pegs them at 1.66 and 1.593. The luminosity of the larger star is calculated to be 2.23 solar, and the smaller to be 2.17.

Nomenclature

Delta Equulei, Latinized from δ Equulei, is the star's Bayer designation. This star was part of the ancient Egyptian constellation Nekhet, the Giant, attested in the Ramesside star clocks; its head (Tepennekhet) was in Equuleus. The IAU Working Group on Star Names adopted the name Tepennekhet for this star on 16 July 2026.

System

William Herschel listed Delta Equulei as a wide binary. Friedrich Georg Wilhelm von Struve later showed this to be an unrelated optical double star. However his son Otto Wilhelm von Struve while making follow-up observations in 1852 found that while the separation of the optical double continued to increase, Delta Equulei itself appeared elongated. He concluded that it is a much more compact binary.

References

External links

• Delta Equulei