NGC 3081  NGC 3081 is a barred lenticular ring galaxy in the constellation of Hydra. NGC 3081 is located about 85 million light-years away from Earth, which means, given its apparent dimensions, that NGC 3081 is approximately 60,000 light years across. It is a type II Seyfert galaxy, characterised by its bright nucleus. It was discovered by William Herschel on 21 December 1786. NGC 3081 is seen nearly face-on. The galaxy's barred spiral centre is surrounded by a bright loop known as a resonance ring. This ring is full of bright clusters and bursts of new star formation, and frames the supermassive black hole thought to be lurking within NGC 3081 — which glows brightly as it gobbles up infalling material. NGC 3081 is known to feature an active galaxy nucleus which is categorised as type II Seyfert galaxy. Even though NGC 3081 shows significant absorption, it is Compton thin. Also it does not show spectral variability on monthly timescales in X-rays. In the nucleus of the galaxy is thought to exist a supermassive black hole whose mass upper limit is estimated to be between 8.5 and 37 million , based on the intrinsic velocity dispersion as measured by the Hubble Space Telescope. Observations obtained with the GMOS integral field spectrograph on the Gemini North telescope show a gas flow is present in the inner ≈ 2arcsec (200pc) of the galaxy, whose appearance is consistent with a bipolar outflow oriented along the north–south direction. Its outflow rate in ionized gas is estimated to be between 1.9 ×10−3/year and 6.9 ×10−3 /year. There was also observed residual gas motion which is interpreted as gas following non-circular orbits in the barred potential, which may lead to gas inflow up to 1.3 ×10−2 /year. NGC 3081 features four well defined rings; a misaligned nuclear ring with angular radius 14", an aligned inner ring with angular radius 35", an outer ring with radius 90", and an outer pseudoring with radius 105". Each ring is a well-defined zone of active star formation, while little or no star formation is observed between the rings. The rings lie at periodic orbits, known as resonances, certain positions where gravitational effects throughout the galaxy cause gas to pile up and accumulate in. These can be caused by the presence of a bar within the galaxy, as with NGC 3081, or by interactions with other nearby objects.