Thiago Junqueira (AIP)

Disk resonances and a new method for estimating the pattern speed of the MW spiral arms
When Jan 16, 2015 from 10:30 AM to 12:00 PM
  • Colloquium
Where SH Lecture Hall
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The resonances play an important role in the evolution of the disks of spiral galaxies, and in particular, of our Galaxy. Its effect on the chemical abundance gradients is even a tool to estimate the age of the present spiral arm structure, which we find to be long-lived, contrary to a recent common belief. One expected effect of corotation resonance is a minimum of star formation associated with the minimum velocity at which the interstellar gas feeds the spiral arms (seen as potential wells and star-formation machines). The 4:1 resonance also plays an import role in our Galaxy and it might be responsible for some bifurcations that appear as short arms, as we'll show. However, one of the fundamental parameters of the spiral structure, which determines the location of all resonances in the disk, is its angular velocity or pattern speed. In here we propose a new method based on the interaction between the spiral arms and the stars in the disk. Using a sample of around 600 open clusters and 500 giant stars observed by APOGEE DR10, we found Ωp = 23.0 ± 0.5 km s −1 kpc −1. This is in close agreement with a number of studies which suggest values in the range 20-25 km s −1 kpc −1.