HE1327-2326 is the most metal-poor star known;
it has a metallicity of -5.6, which
means it has an iron content 300,000 times less than that of the Sun and
is composed almost purely of hydrogen and helium. On this basis, it is also
the oldest known star in the Milky Way Galaxy with an estimated age of more than 12 billion years. HE1327-2326 lies in
the constellation Hydra (RA 13h 30m 06s; Dec.
-23° 41' 54") at a distance of about 4,000 light-years in the sparsely
populated halo region of old objects that surrounds the Galaxy. It has a
visual magnitude of 13.5.
|HE1327-2326. Image: Subaru Telescope
- Frebel, A., Aoki, W., Christlieb, N., Ando, H., Asplund, M., Barklem,
P. S., Beers, T. C., Eriksson, K., Fechner, C., Fujimoto, M. Y., Honda,
S., Kajino, T., Minezaki, T., Nomoto, K., Norris, J. E., Ryan, S. G.,
Takada-Hidai, M., Tsangarides, S., and Yoshii, Y. "Nucleosynthetic signatures
of the first stars," Nature, 434, 871-873 (2005).