Astronomy Colloquium for 2020-09-16

Series: Astronomy Colloquium
Date: Wednesday 16-Sep-2020
Time: 16:00-17:00 (4:00-5:00 pm)
Location: Online Zoom Only: Contact Stuart Vogel for URL
Speaker: Dr. Mark Reid (Harvard-Smithsonian Center for Astrophysics)
Title: "The Spiral Structure of the Milky Way"

The Bar and Spiral Structure Legacy (BeSSeL) Survey uses the Very Long Baseline Array to observe masers associated with massive young stars and provide trigonometric parallaxes across the Milky Way. The Survey is named for Friedrich Bessel, who in 1838 measured the first stellar parallax. I will show Bessel's original data and comment on its accuracy.

There are now about 200 maser parallaxes and these are accurately tracing spiral structure of the Milky Way, the distance to its center, its rotation curve, and the location of the Sun. We have developed a Bayesian approach to leverage these results to estimate distances to large numbers of sources from surveys based only on Galactic coordinates and velocities. Using this program we can make a realistic visualization of the Milky Way.

Additionally, our results make strong predictions for the distance of the Hulse-Taylor binary pulsar, assuming its orbital decay from gravitational radiation follows General Relativity, and for the proper motion of Sgr A*, if indeed it is a supermassive black hole.

Colloquia for the Fall 2020 semester will be held on zoom. Contact Prof. Alberto Bolatto for details.

Colloquium Organizer: Prof. Alberto Bolatto


Special accommodations for individuals with disabilities can be made by calling (301) 405-3001. It would be appreciated if we are notified at least one week in advance.


Directions and information about parking can be found here.

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