Keele

IAU Symposium 256
The Magellanic System: Stars, Gas, and Galaxies
28 July - 1 August 2008            Keele University (UK)

IAU
Outreach: Structure
The Large and Small Magellanic Clouds appear to have started out as barred spiral galaxies, with a core of new stars and short bars extending from the core into spiral arms. The gravity of our galaxy, the Milky Way, has distorted the Clouds into irregular shapes. Another effect of the Milky Way's gravity is to create streams of hydrogen and stars between the three galaxies. The Milky Way's gravity may eventually destroy the Magellanic Clouds.The Tarantula Nebula

The Magellanic StreamThe Large and Small Magellanic Clouds contain stars similar to those found in the Milky Way early in its history. They are rich in gas and dust, which means that a lot  of new stars are produced within them. The most active area for new star production in  our Local Group, the Tarantula Nebula, can be found in the Large Magellanic Cloud. The Magellanic Clouds have a higher proportion of gases such as hydrogen and helium than the Milky Way, and a lower proportion of metals.

The Magellanic System is less evolved than the Milky Way. The Large Magellanic Cloud contains a quarter of the amount of 'heavy' elements, for example carbon and oxygen, of the Milky Way, while the Small Magellanic Cloud contains a tenth of the Milky Way's heavy elements.                                                                                                                                                                                                                

The Large Magellanic Cloud contains sixty globular clusters, four hundred planetary nebulae and seven hundred open clusters. Globular clusters are collections of stars which orbit the centre of the galax. They are tightly bound in a sphere by gravity and have high densities at the centre. Planetary nebulae have nothing to do with planets; they are shells of gas and plasma which are formed by some types of stars at the end of their lives. Open clusters are groups of a few thousand stars formed at the same time, held loosely together by gravity.