Astronomers explore multiple stellar populations in Messier 92

Utilizing the James Webb House Telescope (JWST) and the Hubble House Telescope (HST), astronomers from the College of Padua, Italy, and elsewhere have noticed a metal-poor globular cluster generally known as Messier 92. The observations ship essential data concerning a number of stellar populations on this cluster. Outcomes had been revealed April 12 on the arXiv pre-print server.

Research present that the majority globular clusters (GCs) exhibit star-to-star abundance variations of sunshine parts equivalent to helium (He), oxygen (O), nitrogen (N), carbon (C) and calcium (Na). This means self-enrichment in GCs and means that star clusters are composed of a minimum of two stellar populations.

Situated some 26,700 light years away within the constellation of Hercules, Messier 92 (or M92 for brief) is a GC with a metallicity of simply -2.31 and a mass of about 200,000 solar masses. The cluster, estimated to be 14.2 billion years outdated, is understood to host a minimum of two stellar generations of stars—named 1G and 2G. Earlier research have discovered that Messier 92 has an prolonged 1G sequence, which hosts about 30.4% of cluster stars, and two distinct teams of 2G stars (2GA and 2GB).

A staff of astronomers led by College of Padua’s Tuila Ziliotto determined to examine these stellar populations of Messier 92, benefiting from knowledge collected by JWST and HST.

“This paper investigates a number of populations in metal-poor GCs by combining HST and JWST photometry of M 92, a metal-poor GC with [Fe/H]=−2.3, with isochrones and artificial spectra,” the researchers wrote.

The observations recognized the three beforehand reported stellar teams, specifically 1G, 2GA and 2GB. These three stellar populations had been discovered to share comparable radial distributions of the correct movement dispersion, which vary from about 0.2 mas/yr close to the cluster middle to 0.15 mas/yr round a distance of about 2.2 half-light radii. Furthermore, the 1G, 2GA, and 2GB stars turned out to exhibit isotropic motions within the studied radial interval inside about 1.5 half-light radii.

Primarily based on the comparability between the noticed colours of the cluster stars and the colours derived by artificial spectra, the astronomers discovered that helium abundances of 2GA and 2GB stars have increased mass fractions than that of the 1G stars by 0.01 and 0.04, respectively. They famous that helium distinction between 2GB and 1G MS stars is according to the utmost helium variation inferred for purple large department (RGB) stars.

Moreover, color-magnitude diagrams (CMDs) present that most important sequence (MS) stars of Messier 92 fainter than the so-called MS knee (a characteristic in CMD occurring on the low-mass finish of the MS) exhibit an intrinsic colour unfold, which is current amongst stars with plenty of about 0.1–0.4 solar plenty. These low-mass stars seem to exhibit a steady colour distribution and don’t showcase proof for distinct teams of 1G and 2G stars.

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