Utilizing the Magellan Inamori Kyocera Echelle (MIKE) spectrograph, astronomers have carried out a chemical abundance research of a galactic globular cluster often called NGC 1261. Outcomes of the analysis, revealed April 22 on arXiv.org, present insights into chemical composition of this cluster.
Globular clusters (GCs) are collections of tightly certain stars orbiting galaxies. Astronomers understand them as pure laboratories enabling research on the evolution of stars and galaxies. Specifically, globular clusters may assist researchers higher perceive the formation historical past and evolution of early kind galaxies, because the origin of GCs appears to be intently linked to intervals of intense star formation.
At a distance of some 53,000 mild years, NGC 1261 is a GC within the Milky Manner’s outer halo. The cluster is 10.Three billion years previous, has a mass of about 341,000 photo voltaic lots, and metallicity at a degree of -1.38. The chemical composition of NGC 1261 continues to be poorly understood, nevertheless some research managed to find out abundance ratios for over 20 components and instructed that a number of stellar populations could also be current on this GC.
A group of astronomers led by Andreas J. Koc-Hansen of the Heidelberg College, Germany, determined to take a more in-depth take a look at NGC 1261, specializing in its chemical properties. By using the MIKE spectrograph mounted on the 6.5 m Magellan2/Clay Telescope on the Las Campanas Observatory, Chile, they carried out a chemical abundance evaluation of this cluster.
MIKE allowed the researchers to measure 31 species of 29 components in two stars of NGC 1261, by conducting a normal evaluation based mostly on equal width (EW) measurements and spectral synthesis. The outcomes counsel that the cluster is reasonably metallic poor—with a metallicity of roughly -1.26. Nevertheless, regardless of its comparatively low metallicity, it showcases heavy factor abundances which can be in step with r-process nucleosynthesis.
“Specifically the Eu-overabundance quantitatively means that one single r-process occasion, comparable to a neutron-star neutron-star merger or a uncommon sort of supernova, will be liable for the stellar enhancement and even the cluster’s enrichment with the surplus r-material,” the scientists famous.
Furthermore, the research discovered that the sunshine components like sodium (Na), oxygen (O), magnesium (Mg), and aluminum (Al) differ considerably between the 2 investigated stars, in distinction to nearly all of different components with smaller scatter. This helps the state of affairs that a number of generations of stars coexis in NGC 1261.
All in all, the outcomes of the research present some hints relating to the origin of NGC 1261. Based on the authors of the paper, this GC was born within the Gaia-Enceladus galaxy and has been subsequently accreted into the galactic halo. It’s assumed that Gaia-Enceladus merged with the Milky Manner between eight and 11 billion years in the past. The researchers added that usually NGC 1261 seems chemically similar to Gaia-Enceladus in that it occupies the identical imply metallicity and alpha-enhancement.
“So far, the merger-GC ties are probably, however to additional sculpt this image, the addition of a chemical abundance house is crucial,” they concluded.
Chilean researchers examine chemical composition of globular cluster NGC 6553
NGC 1261: an r-process enhanced globular cluster from the Gaia-Enceladus occasion, arXiv:2104.11243 [astro-ph.GA] arxiv.org/abs/2104.11243
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Research investigates chemical properties of globular cluster NGC 1261 (2021, Could 3)
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