NGC 1398 is a galaxy similar in size to our Milky Way, located about 65 million light-years away in the Fornax Cluster, a cosmic archipelago of hundreds of galaxies. It is a barred spiral, so called because of the long bar in its middle. These bars are quite common in large disk galaxies (the Milky Way also has one) and are the result of gravitational perturbations. Due to the distribution of mass in these galaxies (spread throughout the disk), in the case of gravitational perturbations (for example due to the passage of nearby galaxy) the resulting distortion eventually takes this form.
This galaxy is also peculiar because it has a double ring structure, a first one around the central bar and a second one more external. These rings are created by the resonance generated by the "right" ratio of the rotational speed of the central bar to that of the stars and gas in the spiral arms. This resonance pumps the stars and gas in a similar way we pump our legs on a playground swing at the right frequency to go higher. In fact, the rings are actually made up of pairs of tightly wound spiral arms that overlap.
In the background as usual dozen and dozen of small galaxies far away are visible as a reminder of how rich and vast our beautiful universe is.
Takahashi CCA250 (250/f5) - ZWO 6200MM - L (480m) R (90m) G (110m) B (120m) - AMT Observatory (
A.Lau/M.Lorenzi/T.Tse), Río Hurtado, Chile. Image processing M.Lorenzi.
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