Astrophysics

Giants in the outer halo of the Milky Way

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Science  22 Aug 2014:
Vol. 345, Issue 6199, pp. 887-888
DOI: 10.1126/science.345.6199.887-g

Most stars in the Milky Way reside in the familiar spiral disk structure and probably formed in place. Stars in the galaxy's much larger and far sparser spherical halo, on the other hand, are unlikely to have formed where the gas density is so low. Too few halo stars are known, however, for scientists to model their origins. Bochanski et al. examined the motion and brightness of some candidate stars, and identified two that are the most distant members of our galaxy yet found, more than 30 times farther from the galactic center than the Sun. These observations should help tell whether these stars were captured from dwarf galaxies or ejected from the Milky Way disk.

Astrophys. J. Lett. 10.1088/2041-8205/790/1/L5 (2014).

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