Rho Aquilae [SEP] constellation
Rho Aquilae
Rho Aquilae, ρ Aquilae, is the Bayer designation for a star in the northern constellation of Delphinus. It has an apparent visual magnitude of 4.94 and is bright enough to be seen with the naked eye in good conditions.
Distance, proper motion and constellation.
Parallax shift (measured at any interval of half of a year) is 21.75 milliarcseconds, which corresponds to a distance of the star of around from Earth. Relatively high proper motion resulted in the star crossing the border from Aquila into
Scorpius to Libra and given the new names Sigma and Upsilon Librae. (To add to the confusion, the star now known as Omicron Scorpii was not named by Bayer but was assigned the designation o Scorpii (Latin lower case 'o') by Lacaille – which later astronomers misinterpreted as omicron once Bayer's omicron had been reassigned to Libra.)
A few stars no longer lie (according to the modern constellation boundaries) within the constellation for which they are named. The proper motion of Rho Aquilae, for example