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<strong>Barred</strong> <strong>Spiral</strong> <strong>Galaxies</strong><br />
Bar<br />
Type Sbc<br />
- Loosely bound arms<br />
- Visible bar<br />
- <strong>Barred</strong> spiral<br />
NGC 7479<br />
Presented by:<br />
Gary Li<br />
Astro 122<br />
Fall ‘11
<strong>Spiral</strong> Arm<br />
Gas is forced toward<br />
galactic center resulting<br />
in massive star formation,<br />
feeding black hole, and<br />
developing central bulge.<br />
Stellar orbits perturbed until<br />
locked in a bar shape.<br />
“Orbital resonance”<br />
BAM!<br />
STELLAR<br />
FORMATION<br />
Galactic<br />
Center<br />
<strong>Spiral</strong> Arm
Other Information<br />
- Gas channeled to center, fueling Active<br />
Galactic Nuclei (AGN)<br />
- Bar creation theory: density wave emanates<br />
outward, reshaping the orbits of stars<br />
- Bar signify “mature” spirals<br />
- Less barred spirals in the past<br />
- 20% of spirals in distant past had bars, 70% of<br />
modern day counterparts (from Kartik Sheth<br />
of CalTech)<br />
Sources:<br />
http://en.wikipedia.org/wiki/<strong>Barred</strong>_spiral_galaxy<br />
http://www.astronomy.com/en/sitecore/content/Home/News-Observing/News/<br />
2008/07/<strong>Barred</strong>%20spiral%20galaxies%20are%20latecomers.aspx
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