Lecture18 - AstroNova Cassini probe detects organic...

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AstroNova Cassini probe detects organic molecules in geysers from Saturn’s moon Enceladus erupt from warm cracks in moon’s icy surface similar to comet material National dark-sky week March 29-April 4 Rutgers women’s basketball team expected to “shoot the lights out” on April 1 Recently-activated ISS robot Dextre requests salary and benefits of other crew members promises not to disrupt station activities insists on calling NASA mission controllers “Dave”
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Previous Lecture Disk Galaxy Rotation Curves shape: flat at large radii amplitude: 100 – 300 km/s, depending on mass of galaxy indication of dark matter Milky Way data r Sun = 8 kpc v cir, Sun = 220 km/sec P Sun = 2x10 8 yr Spiral structure possibly a long-lived density wave possibly temporary but repeating structures
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Quiz Question #1 How would you describe the rotation curve of the Milky Way? A. It doesn’t rotate. B. It increases from 0 at the center to 220 km/sec at the outermost points in a constantly rising straight line. C. It increases from 0 at the center to 220 km/sec in a short distance, and then gradually declines back to 0 at the outermost points. D. It increases from 0 at the center to 220 km/sec in a short distance, and then remains constant at that value to the outermost points. E. It is a confused mess with no discernable structure.
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The Center of the Milky Way Highly obscured by dust in optical – IR and radio provide clearer views Our views about the center of the Galaxy are still confused A trip inward to the Galaxy’s core: at R ~ 4 Kpc, ring of mostly molecular gas inside ring: less gas, non-circular motions; bar? inside R ~ 10 pc clumpy molecular gas, M ~ 10 4 M sun circular orbits of v ~ 110 km/s M interior ~ 5 x 10 6 M sun (!)
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Milky Way Center (continued) inside R ~ 2 pc, streamers of ionized gas inner 0.1 pc cluster of luminous IR sources (probably O stars)
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Lecture18 - AstroNova Cassini probe detects organic...

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