Why Dwarf Galaxies Lack Star Power
In a study in the journal Nature, researchers show that the relative lack of star density in dwarf galaxies need not conflict with standard cosmological models if you include the blast effects of supernovae. Karen Hopkin reports
SUBSCRIBE TO Science Quickly
For astronomers who study the large-scale structure of the universe, dwarf galaxies have proven quite vexing. Because the leading model of cosmology has been unable to account for their relative lack of substance. Now scientists writing in the journal Nature show that the current model can actually generate dwarf galaxies just fine. You just need to look at the stars.
There are two types of matter in the universe: ordinary matter, including the material that makes up stars. And dark matter: that mysterious stuff we can’t see but that clearly affects ordinary matter. It’s the presence of cold dark matter that explains how the young universe went from being smooth to being lumpy, as ordinary matter coalesced first into stars and then into galaxies. The problem is that dwarf galaxies are not as dense as the cold dark matter model says they should be.
Now an international team of astronomers says you can blame gusts of stellar wind. Because in the roiling cauldron of activity that governs galaxy formation, some stars go supernova. Those spectacular explosions literally blow matter away, and you’re left with a dwarf galaxy that’s a lot like most independent films: a bit light on stars.
—Karen Hopkin
[The above text is an exact transcript of this podcast.]
On supporting science journalism
If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
[Scientific American is part of Nature Publishing Group.]
Subscribe to Support Independent Journalism
Great science journalism requires human expertise, time, effort and creativity. And it costs money. That’s why I and the journalists here at Scientific American hope you’ll join our community.
When you subscribe, you are supporting staff and freelance journalists who are passionate about telling science stories that are true, important and compelling. Our editors and reporters are often experts in their fields, which means they understand the nuances of big discoveries and can untangle the breakthroughs from the hype. With a subscription, you are also supporting rigorous fact-checking to ensure the words we publish are precise and accurate. And you’re supporting original illustrations, graphics and photos that bring you closer to an advanced laboratory, an ice sheet in Antarctica or a space mission in orbit. You’re helping us craft other types of high-quality journalism as well: Our newsletters are carefully written, edited and curated by staffers you have or will come to know and love. Our Science Quickly podcast is based on original reporting, collaboration with editors and scientists and exacting production.
Subscriptions keep this engine running so we can continue to deliver thoughtful, rigorous and independent science journalism to you. In an era of viral misinformation, this work is crucial. If you value what we do, I hope you’ll consider joining us as a subscriber
