Astronomers have discovered a star in the Milky Way Galaxy with a chemical composition unlike any other star in our Galaxy. This chemical composition has been seen in a small number of stars in dwarf galaxies orbiting the Milky Way. This suggests that the star was part of a dwarf galaxy that merged into the Milky Way.
In the LAMOST (Large Sky Area Multi-Object Fiber Spectroscopic Telescope) survey data, researchers noticed the star J1124+4535 for its unusual chemical composition. Initial observations showed that J1124+4535, located in the constellation Ursa Major (Big Dipper), had low abundances of certain elements, such as magnesium.
Follow-up observations with the High Dispersion Spectrograph on the Subaru Telescope confirmed the low levels of magnesium but found comparatively high levels of Europium. This is the first time an element ratio like this has been observed in a star in the Milky Way.
Stars form from clouds of interstellar gas. The element ratios of the parent cloud impart an observable chemical signature on stars formed in that cloud. So stars formed close together have similar element ratios. The composition of J1124+4535 doesn’t match any other stars in the Milky Way, indicating that it must have formed elsewhere.
An international team of astronomers have discovered that the Milky Way’s disc of stars becomes increasingly ‘warped’ and twisted the further away the stars are from the galaxy’s center as shown in image at top of the page. “We usually think of spiral galaxies as being quite flat, like Andromeda which you can easily see through a telescope,” says Professor Richard de Grijs, a co-author and astronomer from Australia’s Macquarie University.
The first accurate 3D map of our galaxy reveals its true shape: warped and twisted. Astronomers from Macquarie University and the Chinese Academy of Sciences have used 1339 ‘standard’ stars to map the real shape of our home galaxy in a paper published in Nature Astronomy today. Artist’s impression above of the warped and twisted Milky Way disk. (Chen Xiaodian)
The Daily Galaxy, Sam Cabot, via National Institutes of Natural Sciences