02-26-2018, 04:10 PM
Galactic eviction
In a new study, a group of astronomers discovered that two separate groups of associated stars, one group way above the Galactic plane, and one way below, were likely moved out of the Galactic plane by interactions with passing galaxies. The stars all have identical chemical properties to stars in the plane meaning they are unlikely to have come from other galaxies, rather, they were evicted from their original area by the gravitational effects of passing galaxies. The study used the Keck Observatory on Mauna Kea to determine the stars' chemical properties.
https://phys.org/news/2018-02-stars-milk...aders.html
"Bergemann and her team, for the first time, now presented detailed chemical abundance patterns of these stars, obtained with high-resolution spectra taken with the Keck and VLT (Very Large Telescope, ESO) telescopes. "The analysis of chemical abundances is a very powerful test, which allows, in a way similar to the DNA matching, to identify the parent population of the star. Different parent populations, such as the Milky Way disc or halo, dwarf satellite galaxies or globular clusters, are known to have radically different chemical compositions. So once we know what the stars are made of, we can immediately link them to their parent populations.", explains Bergemann.
When comparing the chemical compositions of these stars with the ones found in other cosmic structures, the scientists were surprised to find that the chemical compositions are almost identical, both within and between these groups, and closely match the abundance patterns of the Milky Way disc stars. This provides compelling evidence that these stars most likely originate from the Galactic thin disc (the younger part of Milky Way, concentrated towards the Galactic plane) itself, rather being debris from invasive galaxies!"
In a new study, a group of astronomers discovered that two separate groups of associated stars, one group way above the Galactic plane, and one way below, were likely moved out of the Galactic plane by interactions with passing galaxies. The stars all have identical chemical properties to stars in the plane meaning they are unlikely to have come from other galaxies, rather, they were evicted from their original area by the gravitational effects of passing galaxies. The study used the Keck Observatory on Mauna Kea to determine the stars' chemical properties.
https://phys.org/news/2018-02-stars-milk...aders.html
"Bergemann and her team, for the first time, now presented detailed chemical abundance patterns of these stars, obtained with high-resolution spectra taken with the Keck and VLT (Very Large Telescope, ESO) telescopes. "The analysis of chemical abundances is a very powerful test, which allows, in a way similar to the DNA matching, to identify the parent population of the star. Different parent populations, such as the Milky Way disc or halo, dwarf satellite galaxies or globular clusters, are known to have radically different chemical compositions. So once we know what the stars are made of, we can immediately link them to their parent populations.", explains Bergemann.
When comparing the chemical compositions of these stars with the ones found in other cosmic structures, the scientists were surprised to find that the chemical compositions are almost identical, both within and between these groups, and closely match the abundance patterns of the Milky Way disc stars. This provides compelling evidence that these stars most likely originate from the Galactic thin disc (the younger part of Milky Way, concentrated towards the Galactic plane) itself, rather being debris from invasive galaxies!"