A Messier Milky Way

Thursday, March 12, 2020 - 4:00pm
Phillips Auditorium
Center for Astrophysics | Harvard & Smithsonian

In 1771, Charles Messier published his first catalog of “not comets,” which are today favorites of deep-sky amateur astronomers. Many of the Messier objects are beautiful spiral galaxies. They are beautiful, but if one looks at them closely, they are not such perfect spirals. Why, then, have we imagined our Milky Way to be a well-behaved “spiral” for so long? In this talk, I will show new data, simulations, and visualizations that suggest that our Milky Way is much “messier” than we may have anticipated. In particular, I will focus on the recent discovery of “The Radcliffe Wave,” which is a 2.7-kpc long collection of gas that undulates sinusoidally 160 pc above and below the mid-plane of our Galaxy near the Sun. The gas in the wave seems to be the so-called “Local Arm” of the Milky Way, which suggests the possibility that we live in a ripply galactic neighborhood. The cause of the Radcliffe Wave remains unknown, so I will discuss several possibilities currently being explored. I will also highlight the new data (primarily Gaia, data science (3D dust mapping) and visualization (glue, WorldWide Telescope) techniques that allowed for the discovery of The Radcliffe Wave.

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