The outline of our Galaxy, the Milky Way / ESA/Gaia
The life of galaxies The emission of energy from the region around black holes at the centre of galaxies disrupts the inflows from the external universe of gas which is the fuel for the next generations of stars. Supernova explosions and high velocity winds from young hot stars also drive out the interstellar gas from the galaxy, and these effects combine to choke off the formation of new stars. By examining the stellar populations, using, for example, spectroscopic surveys, and by fitting population models, we recreate the potential evolutionary paths of galaxies of different types and in different environments, to understand more about the general principles governing galaxy evolution. In particular we are interested in the relative importance of black holes and supernovae in this process. As much of the star formation occurs in dusty environments from previous generations of stars, this investigation requires data in the far infrared or submillimetre band where dust is most transparent, and for this we use instruments we’ve built for ESA’s Herschel satellite. Our own Milky Way is particularly important for understanding how galaxies evolve, because we can observe individual stars and their motions within it. By building dynamical and stellar evolution models in our computers, we can model in detail the mix of different generations of stars, and make predictions about the Milky Way’s structure. We compare these predictions with data from ESA’s Gaia satellite, and especially from the spectroscopy instrument in which we’ve had a significant role. This is how we explore the predicted observational signatures from spiral arms, to discover how these beautiful features are formed, and whether they are long-lived or transient.
What is the structure of our Milky Way? How do spiral arms form? What do stellar populations tell us about a galaxy’s past? How do black holes and star formation affect the way galaxies evolve?
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