Astronomers investigate chemical composition of multiple stellar populations in NGC 2808

Tomasz Nowakowski is a member of the physics.org community.

Astronomers used the Very Large Telescope and the Hubble Space Telescope to look at a cluster of stars. The results of the study were published on December 2nd on the arXiv pre-prints repository.

The GCs are collections of stars. They are thought to be natural laboratories that can be used to study the evolution of stars and galaxies. The origin of GCs seems to be related to periods of intense star formation, which could help researchers understand the formation history and evolution of early types of galaxies.

At a distance of 31,300 light years, NGC 2808 is a GC. The cluster is 10 billion years old, has a mass of 742,000 solar mass, and is metallic. There are at least three stellar populations in the area.

Marlia Gabriela Carlos is an astronomer at the University of Padua in Italy. The Wide Field Channel of the Advanced Camera and the Utraviolet andVisual Channel of the Wide Field Camera 3 were used for this purpose.

There are five different stellar populations in the cluster, which are designated from A to E. The telescopes were able to investigate 70 red giant branch and 7 asymptotic giant branch stars. The parameters and abundances of six elements were determined by them.

Light elements from one star to another are different. The maximum internal variations of carbon, nitrogen, and aluminum can be as high as 1.3 dex in oxygen. The iron peak elements show no differences between the different populations. There are many stellar populations in the sample of known clusters.

The stars from populations A and B have lower levels of aluminum and nitrogen than stars from other populations. While aluminum and nitrogen abundances are gradually higher for populations C and D, reaching their highest values in population E, the abundance of oxygen and carbon becomes systematically lower. D and E are the most helium enriched populations and they don't have any differences in light elements.

Current stellar evolution models are challenged by the fact that one AGB star, designated N2808_9_wf, depletes oxygen and is highly enhanced in aluminum.

Our discovery shows that stars with high abundances can evolve into AGB. There are distinct populations of AGB stars that are associated with population D and possibly population E according to the findings from the chMs of AGB stars.

The chemical compositions of multiple stellar populations can be found in the arXiv. There is a book titled "arxiv.2212.01319."

Journal information: arXiv

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