Rho Aquilae

Rho Aquilae (ρ Aql, ρ Aquilae) is the Bayer designation for a star in the northern constellation of Delphinus – it moved across the border from Aquila into Delphinus in 1992. It has an apparent visual magnitude of 4.94 and is bright enough to be seen with the naked eye in good conditions. The annual parallax shift of this star is 21.75 milliarcseconds, which corresponds to a physical distance of around 150 light-years (46 parsecs) from Earth.

This star has the traditional name Tso Ke, from the Cantonese 左旗 jo keih meaning "the left flag". In Chinese, 左旗 (Zuǒ Qí in Mandarin), meaning Left Flag, refers to an asterism consisting of ρ Aquilae, α Sagittae, β Sagittae, δ Sagittae, ζ Sagittae, γ Sagittae, 13 Sagittae, 11 Sagittae and 14 Sagittae. Consequently, ρ Aquilae itself is known as 左旗九 (Zuǒ Qí jiǔ, English: the Ninth Star of Left Flag.)

Rho Aquilae is an A-type main sequence star with a stellar classification of A2 V. This star is about 50 to 120 million years old and it displays an excess emission of infrared radiation that may be explained by a circumstellar disk of dust.