New discoveries shedding light on star formation at the beginning of the universe.
Astronomers, looking at the galaxy’s bulge, have discovered what they believe are the oldest stars in the Milky Way, according to a report on cbsnews.com.
Earlier research has suggested that about 13.6 billion years ago, the first stars were formed, beginning a period known as the cosmic dawn. The astronomers say they haven’t found the first star, but using the Australian National University’s SkyMapper telescope, they scanned about 5 million stars located in the Milky Way’s bulge, by looking at the elements of which a star is composed.
The bulge in a galaxy is the central region that is loaded with gas and debris, items from which stars are formed. The oldest stars, ones that have been defined as being poor in metals, should be located in the bulge area, according to prior studies.
SkyMapper identified more than 14,000 potential poor-metal stars, and the scientists went on to use the Australian Astronomical Observatory’s Anglo-Australian Telescope to confirm more than 500 fit the criteria. Most were located in the bulge area.
When these old stars died, they released their metals into space, an event known as a supernova. Research says every generation of stars normally contain more metals than the previous generation, allowing astronomers to decide the oldest.
Upon further examination of 23 of the oldest stars, they were found to be lacking in carbon as well, suggesting to the astronomers the early stars may have died as hypernovas, some 10 time stronger than supernovas.
The Milky Way’s bulge is extremely dense with gas and dust, which allowed for fast formation of stars in the past. The astronomers estimate the dying stars in that area enriched the surrounding area with many heavier elements during the first 1-2 billion years of the existence of the universe.
That same density, coupled with the distance from the Earth to the bulge, make it very difficult to locate stars that fit into the poor-metal category. Study lead author Louise Howes, an astronomer now at Lund University in Sweden, who carried out this research while at Australian National University in Canberra, likened the search to finding a “needle in a haystack.”
Despite the enormity of the project, the research only looked at one-third of the Milky Way’s bulge area, and the researchers hope more detailed analysis is forthcoming.
The findings of the research was published in the journal Nature.