Researchers from the Haverford College have discovered the Milky Way galaxy's most distant stars, which will be useful in determining about how our galaxy may have been formed.
John Bochanski, lead researcher and assistant professor at the Haverford College, studied stars as far as 500,000-light years away. The team was able to locate two stars called ULAS J0744+25 and ULAS J0015+01 with an estimated distance of 775,000 and 900,000 light years away respectively. The researchers used the UKIRT Infrared Deep Sky Survey and the Sloan Digital Sky Survey in locating these stars.
These stars were classified as red giant stars – a rare type compared to the more common red dwarf stars. Red giant stars are extremely luminous, making them noticeable despite the considerable distances.
The team used a combination of filters to highlight the different kinds of lights emitted by these red giant stars. They also used the 6.5m telescope of the NMT Observatory located at the Mt. Hopkins in Arizona to confirm if these were indeed red giant stars.
"It really is like looking for a needle in a haystack," Bochanski said in a university news release. "Except our haystack is made up of millions of red dwarf stars."
The distance between the two stars and their relative distance to Earth were very far. Bochanski explained that to illustrate the great distance, the light from the ULAS J0015+01 left the planet during the time when our ancestor were just learning how to make fire.
The researchers plan to assemble a larger sample of distant red giant stars to remake the formation of the Milky Way.
"Most models don't predict many stars at these distances. If more distant red giants are discovered, the models may need to be revised," Bochanski added.
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