58 Aquarii
58 Aquarii, abbreviated 58 Aqr, is a triple star system in the constellation of Aquarius. 58 Aquarii is its Flamsteed designation. It is a sixth magnitude star with an apparent visual magnitude of 6.39, which means it is a challenge to view with the naked eye. Based upon an annual parallax shift of, it is located at a distance of 243 light years.
The primary component, named 58 Aquarii Aa, has a stellar classification of A9/F0 V, matching a main sequence star with a spectrum showing mixed traits of an A/F-type. It is a chemically peculiar Am star, showing metallic lines with no magnetic field. The star has 1.7 times the mass of the Sun and 2.4 times the Sun's radius. It is radiating 12 times the Sun's luminosity from its photosphere at an effective temperature of 7,000 K.
The secondary component, named 58 Aquarii Ab, is a K-type dwarf, with around 70% of the Sun's size and an effective temperature around, separated by from Aa. It was initially uncovered via astrometry from the Hipparcos spacecraft, and later detected via interferometric observations by Idel Waisberg et al. This inner system will become a common envelope binary, when 58 Aquarii Aa expands in the red giant phase. Mass transfer between components is also expected to occur.
The tertiary component, named 58 Aquarii B, is a widely-separated white dwarf, located at from the inner pair.