NGC 3081 a barred spiral with resonance ring
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by Budgieye moderator
The resonance ring is the smaller ring, at to the ends of the bar.
http://www.nasa.gov/sites/default/files/styles/full_width_feature/public/hubble_3.jpg?itok=IYvOSGMV
http://www.nasa.gov/content/goddard/hubble-eyes-golden-rings-of-star-formation
Taking center stage in this new NASA/ESA Hubble Space Telescope image
is a galaxy known as NGC 3081, set against an assortment of glittering
galaxies in the distance. Located in the constellation of Hydra (The
Sea Serpent), NGC 3081 is located over 86 million light-years from us.
It is known as a type II Seyfert galaxy, characterized by its dazzling
nucleus.NGC 3081 is seen here nearly face-on. Compared to other spiral
galaxies, it looks a little different. The galaxy's barred spiral
center 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 hungrily gobbles up in-falling
material.These rings form in particular locations known as resonances, where
gravitational effects throughout a galaxy cause gas to pile up and
accumulate in certain positions. These can be caused by the presence
of a "bar" within the galaxy, as with NGC 3081, or by interactions
with other nearby objects. It is not unusual for rings like this to be
seen in barred galaxies, as the bars are very effective at gathering
gas into these resonance regions, causing pile-ups which lead to
active and very well-organized star formation.Hubble snapped this magnificent face-on image of the galaxy using the
Wide Field Planetary Camera 2. This image is made up of a combination
of ultraviolet, optical, and infrared observations, allowing
distinctive features of the galaxy to be observed across a wide range
of wavelengths.Image credit: ESA/Hubble & NASA; acknowledgement: R. Buta (University
of Alabama) Text credit: European Space AgencyLast Updated: May 22, 2015 Editor: Rob Garner
http://iopscience.iop.org/1538-3881/127/4/1982/fulltext/
Forum The Kinematics and Dynamics of Galactic Rings The Physics of Resonance http://www.galaxyzooforum.org/index.php?topic=10635.msg125230#msg125230
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by Budgieye moderator
Outside the SDSS footprint ? so we aren't likely to come across it right now.
FIG. 1 CITED IN TEXT | HIGH-RESOLUTION IMAGE (211 kB) | Next
Schematic showing the relative shapes, sizes, and major-axis orientations of all of the bar and ring features of NGC 3081, including the "dimples" in the outer R1 ring feature. Here "nr" refers to the nuclear ring, and "nb" to the nuclear (secondary) bar. Axes are labeled in arcsecond offsets relative to the nucleus. North is at the top, and east is to the left.http://iopscience.iop.org/1538-3881/127/4/1982/fulltext/
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