Study investigates chemical composition of the young massive cluster NGC 1569-B

Utilizing the Keck Observatory, astronomers from the Radboud College within the Netherlands and elsewhere have carried out spectroscopic observations of a younger large cluster often called NGC 1569-B. Outcomes of the observational marketing campaign, printed September 23 on the arXiv pre-print server, yield necessary insights into the chemical composition of this cluster.

Basically, younger large clusters (YMCs) are dense aggregates of younger stars that type the elemental constructing blocks of galaxies. Finding out their chemical composition may present important info concerning stellar populations.

Estimated to be 15–25 million years outdated, NGC 1569-B is a YMC within the dwarf irregular galaxy NGC 1569, situated some 6,000 light years away from the Earth. With a mass of about 440,000 solar masses, NGC 1569-B is extra large than any of the younger clusters within the Milky Way or Massive Magellanic Cloud (LMC). Such large clusters are uncommon in our galaxy and even within the Native Group.

A bunch of astronomers led by Anastasia Gvozdenko investigated NGC 1569-B with the high-resolution echelle spectrometer (HIRES) on the Keck I 10-m telescope on Mauna Kea in Hawaii. The principle intention of their research was to carry out an in depth chemical abundance evaluation of this cluster.

“We carried out a high-resolution IL [integrated-light] spectrum evaluation of the YMC NGC 1569-B. That is the primary detailed abundance research of this YMC utilizing the complete optical wavelength vary,” the researchers wrote within the paper.

The observations discovered that NGC 1569-B is barely metal-poor as its metallicity was measured to be about −0.77. It showcases alpha and nearly all of the iron-peak aspect abundance ratios typical for Milky Way thick disk or LMC bar stars. What’s noteworthy is that the cluster has a very excessive titanium abundance of roughly 0.49.

Moreover, the outcomes point out that NGC 1569-B has a comparatively excessive barium-to-iron abundance ratio. This may very well be brought on by the contribution from massive stars, nevertheless no proof supporting this idea has been discovered.

One other unexpectedly excessive abundance ratio was discovered to be scandium to iron. The authors of the paper are unable to elucidate this outcome in the mean time, due to this fact additional research of the chemical composition of NGC 1569-B are required to discover a believable speculation.

Summing up the findings, the researchers famous that the chemical abundances of NGC 1569-B typically resemble these of one other YMC that was the topic of lately printed research—NGC 1705-1.

“The composition of NGC 1569-B resembles the stellar populations of the YMC NGC 1705-1, situated in a blue compact dwarf galaxy. The 2 YMCs agree with regard to alpha-elements and nearly all of the iron-peak components, aside from Sc and Ba, that are extraordinarily super-solar in NGC 1569-B—and better than in any YMC studied thus far,” the astronomers concluded.

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