Using the High Dispersion Spectrograph mounted on the 8.2-m Subaru Telescope on Mauna Kea, astronomers led by Dr Wako Aoki of the National Astronomical Observatory of Japan have discovered the chemical signature of what they say is one of the earliest stars in the Universe.
This is an optical image of the low-mass, second-generation star SDSS J0018-0939 (center), obtained by the Sloan Digital Sky Survey. Image credit: NAOJ / SDSS.
Dr Aoki and his co-authors analyzed a large sample of low-mass metal-poor stars and discovered a unique star – SDSS J0018-093939 – that exhibits the peculiar chemical abundance ratios associated with the process of creating new atomic nuclei (nucleosynthesis) in a first-generation very-massive star.
According to their paper published in the journal Science, SDSS J0018-093939 is a low-mass, second-generation star with a mass about half that of the Sun.
Located in the constellation Cetus, about 1,000 light-years away, the star possesses elemental-abundance ratios that differ significantly from any previously known star.
Whereas SDSS J0018-093939 contains an amount of iron about 300 times lower than the Sun’s, it is significantly deficient in lighter elements such as carbon and magnesium.
This artistic impression shows a cluster of first-generation stars. Image credit: NAOJ.
The extremely low abundances of elements other than iron indicates that this star formed directly from a hydrogen gas cloud that contained elements dispersed by a first-generation very-massive star.
Dr Aoki’s team hopes to discover more stars similar to SDSS J0018-093939, and refine their analysis in order to confirm the existence of very-massive stars in the first generation.
“Such stars could have contributed to the development of super-massive black holes like the one at the center of the Milky Way.”
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W. Aoki et al. 2014. A chemical signature of first-generation very massive stars. Science, vol. 345, no. 6199, pp. 912-915; doi: 10.1126/science.1252633
