CAAUL Seminar - Runaway stars as tracers of the spiral arms - 3 março 2014



Runaway stars as tracers of the spiral arms

Manuel Silva



Abstract / Resumo

The spiral arms are readily visible in photographic images of face-on spiral galaxies. They are usually traced, in visible light, by young hot stars and respective ionised Hydrogen regions. They are the preferred sites of star formation. Our position within the Galactic disc is an obstacle to a direct observation of the spiral arms of the Milky Way, as they appear superimposed along our line of sight and are heavily obscured by dust. The obscuration is more severe in the direction of the Galactic centre, such that the region of the disc behind the centre is particularly poorly known. We propose a new method based on the analysis of the birthplaces of high Galactic latitude runaway stars to map the spiral arms and determine their dynamics. These stars provide the means to reach the poorly known regions of the disc, as they are less obscured by dust and thus visible at greater distances. We show how the method performs with data obtained by the Hipparcos satellite mission, and how data by the upcoming Gaia mission will improve upon it.


3 de março de 2014 | 15:30

OAL - Observatório Astronómico de Lisboa

Seminar room at 15:30 with coffee, tea and biscuits from 15:15

CAAUL Seminars webpage