Study inspects chemical composition of NGC 6544

Study inspects chemical composition of NGC 6544
Heliocentric radial velocity versus [Fe/H] for all of the APOGEE targets inside 45 arcmin from the middle of NGC 6544. Credit score: Gran et al., 2021.

A world workforce of astronomers has carried out a chemical research of 23 stars within the globular cluster NGC 6544 as a part of the APOGEE survey. The analysis, printed April 12 on the arXiv pre-print server, delivers important details about 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 might assist researchers to higher perceive the formation historical past and evolution of -type galaxies because the origin of GCs appears to be carefully linked to durations of intense star formation.

At a distance of some 8,150 gentle years, NGC 6544 is a poorly studied galactic GC of medium density. It lies about 326 gentle years from the galactic aircraft, which makes it one of many closest GCs to the galactic aircraft thus far detected. Though NGC 6544 is situated comparatively near the solar, little or no is about its inner chemical composition.

Subsequently, a bunch of astronomers led by Felipe Gran of the Pontifical Catholic College of Chile in Santiago, Chile, has carried out a high-resolution spectroscopic research of NGC 6544. By analyzing the info from the APO galactic Evolution Experiment (APOGEE), they chose 23 member stars of this cluster so as to characterize the chemical properties of NGC 6544 and to match it with different GCs.

“Cluster members had been chosen from the DR16 of the APOGEE survey, utilizing chemo-dynamical standards of particular person stars. A pattern of 23 members of the cluster was chosen. An evaluation contemplating the intra-cluster abundance variations, identified anticorrelations is given,” the researchers wrote within the paper.

The analysis that the analyzed purple big department (RGB) stars of NGC 6544 have imply metallicity of about -1.44 and alpha-element abundances at a degree of 0.2. With regards to the asymptotic big department (AGB) stars, these values had been measured to be -1.66 and 0.25, respectively.

In line with the analysis, 14 out of 23 investigated stars of NGC 6544 showcase distinct chemical patterns, which signifies that they’re so-called second-generation stars. Typically, a number of populations (MPs) inside GCs refer principally to a primary (FG) and second era (SG) of stars. Research present that the FG of stars pollutes the SG with processed materials, creating totally different sub-populations in GCs. The composition of the SG stars varies virtually at a person cluster degree.

The research additionally discovered that the member stars of NGC 6544 described within the paper present a major unfold in metallicity and aluminum to iron ratio that’s bigger than anticipated. Lastly, by analyzing the datasets from the APOGEE survey, the astronomers famous that the cluster lacked additional tidal and chemically peculiar (CP) stars. , particularly from wide-field multi-object spectroscopic surveys, are wanted so as to make detections on this area.


Chilean researchers examine chemical composition of globular cluster NGC 6553


Extra info:
APOGEE view of the globular cluster NGC 6544, arXiv:2104.05865 [astro-ph.GA] arxiv.org/abs/2104.05865

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Research inspects chemical composition of NGC 6544 (2021, April 20)
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