Strange Galaxies in the Early Universe Were Shaped by Weird Stars

A team of researchers at the University of Utah surveyed certain stars in nearby galaxies as analogs of those that existed when the Universe was still in its infancy. The survey, called the "Treasury of Extremely Metal-Poor O Stars (TEMPOS), used the ultraviolet (UV) light streaming from those relatively close-by stars as detected by the Hubble Space Telescope's Cosmic Origins Spectrograph. The resulting study could give astronomers much better models of the monster "Population III" stars that first formed a few hundred million years after the Big Bang. The team's dataset is identifying those stars for deep astrophysical studies. Massive ones like those in the survey (and that mimic what stars were like in the early Universe) have a huge influence on the evolution of their galaxies. "They burn very hot, bright and fast and they end their short lives as supernova explosions that deposit a lot of energy and material into the surrounding gas," said Telford. "They govern the evolution of their host galaxies by heating and essentially regulating the gas that’s then available to cool and form into new stars."

• "TEMPOS catalog comprises a look at nearby low-mass dwarf galaxies that are more like ancient galaxies than the Milky Way."
• "The Milky Way (and the Sun) are definitely not metal-poor, so that's why the team looked outside our galaxy for answers."
• "The TEMPOS research focused on 29 massive, metal-poor stars in galaxies that have metallicities far less than the Sun."

The survey found that massive stars in high-metallicity galaxies have stronger iron signals than stars in the metal-poor galaxies. If this result plays out in more distant early galaxies, it's possible that metal-poor stars at early epochs still can have a range of iron abundances. This will tell astronomers how massive-star physics work and how it changes with the amount of iron, even in very low metallicity regions of the infant Universe. The TEMPOS work has immediate application to observations of the early cosmos being done by JWST. It's currently extending our view to some of the earliest epochs of the observable Universe and may be on the verge of actually gaining good views of the earliest stars to be born. The data from the survey is made publicly available via the Space Telescope Science Institute's Mikulski Archive for Space Telescopes.

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