Galaxy Evolution

Heavy elements are intergalactic travelers

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Science  18 Aug 2017:
Vol. 357, Issue 6352, pp. 657-658
DOI: 10.1126/science.357.6352.657-c

The Crab Nebula, a remnant of a supernova

PHOTO: STOCKTREK IMAGES/ALAMY STOCK PHOTO

All elements heavier than helium are made in stars, which can eject them in a supernova explosion. In small dwarf galaxies, a single supernova has enough energy to completely expel enriched gas out of the galaxy and into the intergalactic medium. Anglés-Alcázar et al. have used hydrodynamic simulations to quantify how much of that gas later falls into another galaxy. This process preferentially transfers gas to larger galaxies, owing to their stronger gravity. For a galaxy such as our Milky Way at the present day, around half of its stars were formed from gas enriched in other galaxies. Given that Earth is made of these heavy elements, we are all part intergalactic travelers.

Mon. Not. R. Astron. Soc. 470, 4698 (2017).

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