Companion AG Draconis B | Magnitude 9.8 Apparent magnitude (V) 9.8 | |
Similar T Coronae Borealis, CM Draconis, R Aquarii, Struve 2398, RS Ophiuchi | ||
AG Draconis is a binary system consisting of an orange-red giant star and a white dwarf star that revolve around each other every 550 days. It has a baseline apparent magnitude of around 9.8 and flares up to around magnitude 7.3 and is one of the most-studied of symbiotic star systems and its variations in brightness have been observed for 124 years. The outbursts occur every 15 years and last for 3–6 years.
The larger star is thought to be an orange giant around 1.5 times as massive as the Sun that has swollen to around 35 times the diameter of the Sun with a spectral type measured at K3IIIep. The smaller star is a compact hot white dwarf around 0.4 times as massive as the Sun, with a surface temperature of around 80,000 K.
The star is located in a spherical halo around the Milky Way, and is a nova variable, erupting every 10–15 years.