A team of University of California Irvine (UCI) scientists has uncovered the cosmic equivalent of an elephant smaller than a mouse: a dwarf galaxy so small it only contains around 1,000 stars.
The scientists hope the galaxy, Segue 2, can illuminate how important elements to human life such as iron and carbon formed. Scientists had previously expected to find such a dwarf galaxy around our larger Milky Way, but the elusive nature "has been a major puzzle, suggesting that perhaps our theoretical understanding of structure formation in the universe was flawed in a serious way," co-author of the study and UCI cosmologist James Bullock said.
"Finding a galaxy as tiny as Segue 2 is like discovering an elephant smaller than a mouse," Bullock explained.
Segue 2's paltry star content of 1,000 means it only gives out a light output of 900 times our sun. The Milky Way, on the other hand, is around 20 billion times brighter. Segue 2 has been classified as a galaxy because despite its small size, it is held together by a halo of dark matter.
"It's definitely a galaxy, not a star cluster," said lead author on the study Evan Kirby.
Segue 2 lies in the Aries constellation and was discovered as part of the Sloan Digital Sky Survey a few years ago, but to obtain the precise measurements needed to determine that the galaxy was in fact much less dense than originally thought, the team had to utilize the powerful telescopes from the W. M. Keck Observatory in Mauna Kea in Hawaii.
You can read the full published study in The Astrophysical Journal.
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