セイファート銀河
The Circinus Galaxy (ESO 97-G13) is a Seyfert galaxy in the constellation of Circinus. It is located 4 degrees below the Galactic plane, and, at a distance of , is one of the closest major galaxies to the Milky Way. The galaxy is undergoing tumultuous changes, as rings of gas are likely being ejected from the galaxy. Its outermost ring is 1400 light-years across while the inner ring is 260 light-years across. Although the Circinus galaxy can be seen using a small telescope, it was not noticed until 1977 because it lies close to the plane of the Milky Way and is obscured by galactic dust. The Circinus Galaxy is a Type II Seyfert galaxy and is one of the closest known active galaxies to the Milky Way, though it is probably slightly farther away than Centaurus A.