Utilizing the Very Giant Telescope (VLT), astronomers from Chile have carried out a chemical evaluation of a pattern of stars within the globular cluster NGC 6553. Outcomes of this examine, obtainable in a paper revealed March 12 on the arXiv pre-print server, shed extra mild on the 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 sort galaxies, because the origin of GCs appears to be carefully linked to durations of intense star formation.
Positioned some 19,500 light years away, NGC 6553 is a metal-rich GC within the bulge of the Milky Method galaxy. The cluster is about 13 billion years outdated and has a mass of roughly 235,000 photo voltaic lots. Though a number of research of NGC 6553 have been performed, nonetheless little is thought about its chemical composition.
A staff of astronomers, led by Carolina Montecinos of the College of Concepción, Chile, has now carried out a chemical evaluation of NGC 6553 to a pattern of over 100 big stars, investigating the information primarily from the FLAMES/GIRAFFE spectrograph on VLT. The examine was complemented by outcomes from VISTA Variables within the Vía Láctea (VVV) survey Information Launch 2 (DR2) of ESA’s Gaia satellite tv for pc.
“On this work, we have now realized a chemical evaluation of the bulge globular cluster NGC 6553 to a pattern of 116 giant stars each within the horizontal department as big department, utilizing the FLAMES/GIRAFFE spectrograph. (…) Then, we have now realized a comparability between NGC 6553 and different close by bulge globular clusters, in addition to with different galaxy globular clusters and ﬁeld stars from the bulge, the disk and halo of the Milky Method,” the researchers wrote within the paper.
The examine discovered that the investigated stars in NGC 6553 showcase overabundance of 5 alpha parts—oxygen, magnesium, silicon, calcium and titanium. That is in settlement with all GCs within the Milky Method’s bulge, as in addition they have comparable overabundance of alpha parts.
Furthermore, a vertical anticolerration of sodium-oxygen was recognized, as there’s a unfold in sodium, however the variation in oxygen is minimal. Such anticolerration happens in different clusters of the galactic bulge.
Moreover, the analysis didn’t discover an intrinsic variation within the content material of alpha and iron-peak parts. The astronomers famous that that is in settlement with the pattern of the galactic bulge ﬁeld stars, what suggests the same origin and evolution.
The imply iron content material of the pattern of stars in NGC 6553 was discovered to be at a degree of -0.1. Nonetheless, no signiﬁcant unfold within the iron content material was detected by the examine.
Chemical evaluation of the Bulge Globular Cluster NGC 6553, arXiv:2103.07014 [astro-ph.GA] arxiv.org/abs/2103.07014
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Chilean researchers examine chemical composition of globular cluster NGC 6553 (2021, March 22)
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