European scientists have noted unusual explosive activity in the double star of AG Dragon. New data shows that recent changes in brightness are different from previous ones.
Before you is a classic symbiotic double variable star (S-type) living in a spherical halo around our galaxy. It is presented by the cold red giant (4300 K) and the heated white dwarf (100000 K). The first one is about 30 times larger than the Sun, but only 1.5 times larger in mass. The white dwarf is 40% -60% massive. Spend 550 days on the orbital path.
Dragon AG is one of the most studied symbiotic star systems, because its brightness has been monitored for more than a century. Binary stars pass through a characteristic symbiotic activity, in which active and quiet stages alternate. The apparent magnitude is 9.8, but with a flare it can increase to 1.4 with an interval of 9-15 years.
Historical Brightness curve (LC) AG of the Dragon for 1889-2017, created on the basis of photographic and B-band observations LC is divided into active (AB) and passive (Q1-Q6) stages along vertical lines. Early data showed that the active stages include several outbreaks per year. It all starts with a major event that cools off as the pseudo-atmosphere of the dwarf expands. But the last stage (started in 2015) is different from the overall picture. It turned out that in the first half of the year the brightness began to grow with a weak initial burst. The second outbreak fell on April 2016.
In May 2015, the increase in brightness led to a value of 10.7, and the second rose to 9.9. But both events are considered insignificant, so the recent activity looks unusually strong. Usually, the starting flash starts at a brightness of 8.8, so new data raises questions about the nature of the events. Perhaps this is a new kind of outbreak, indicating a transition between hot and cool views.