Early stars identified

Scientists at Osaka Sangyo University have identified some of the first stars to form in the universe, just 250 million years after the Big Bang, according to a study published in Nature magazine this week.

Using the Alma telescope in Chile, they were able to observe the distant galaxy MACS1149JD1 (inset, above) as it existed roughly 550 million years after the Big Bang.

The galaxy’s ‘‘red shift’’ was determined to be 9.1096, a measurement arrived at using the spectral lines of ionised oxygen instead of the ionised carbon usually used in examining distant objects.

The detection of oxygen (distribution shown above in green) in the galaxy was instructive. The universe initially was devoid of elements such as oxygen, carbon and nitrogen, which were first created in the fusion furnaces of the earliest stars and then spewed into interstellar space when these stars died.

The presence of oxygen showed that an even earlier generation of stars had formed and died in MACS1149JD1 and that star formation in that galaxy began about 250 million years after the Big Bang, when the universe was only about 2% of its current age, the researchers said.

The researchers confirmed the distance of the galaxy with observations from groundbased telescopes in Chile and reconstructed its earlier history using infrared data from orbiting telescopes.