Study inspects population of variable stars in the cluster NGC 7006

Utilizing the Indian Astronomical Observatory (IAO) in Hanle, India, astronomers have noticed a globular cluster generally known as NGC 7006. Outcomes of the examine, offered December 9 on the arXiv pre-print server, yield vital insights into the properties of variable star inhabitants 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. Particularly, globular clusters might assist researchers to higher perceive the formation historical past and evolution of early-type galaxies because the origin of GCs appears to be carefully linked to durations of intense star formation.

Positioned some 137,000 gentle years away within the constellation Delphinus, NGC 7006 (often known as Caldwell 42) is a Galactic GC with an estimated mass of about 300,000 solar lots. Earlier observations of NGC 7006 have discovered that it comprises not less than 76 variable stars of which 64 turned out to be RR Lyrae variables.

As a way to shed extra gentle on the inhabitants of variable stars in NGC 7006, a staff of astronomers, led by Armando Arellano Ferro of the Nationwide Autonomous College of Mexico, carried out photometric observations of the variable stars within the area of the cluster.

“The observations had been carried out with the two m telescope on the Indian Astronomical Observatory (IAO) in Hanle, India. The detector used was a SITe ST-002 2Kx4K CCD pixels with a scale of 0.296 arcsec/pix, translating to a area of view (FoV) of roughly 10.1 × 10.1 arcmin²,” the researchers wrote within the paper.

The staff managed to determine 470 stars which are seemingly members of NGC 7006. Subsequent, they carried out a routine seek for new variables on this pattern. In outcome, 10 new variables had been detected and acquired variable numbers as follows: two RR Lyrae stars of the RRc sort (V77 and V78), two RR Lyrae stars of the RRab sort (V79 and V80), one BL Hercules star (V81) and 5 semiregular (SR) variables (V82, V83, V84, V85 and V86).

The common interval of the RRab stars in NGC 7006 was calculated to be 0.577 days and the fraction of RRc stars on this cluster was discovered to be roughly 0.14. Based on the astronomers, these values point out that NGC 7006 is of Oosterhoff sort OoI.

The examine discovered that the weighted imply radius and mass of all of the recognized RRab variables in NGC 7006 are 5.61 solar radii and 0.67 solar lots. In terms of the RRc stars, these values had been measured to be 4.27 solar radii and 0.55 solar lots. The researchers suppose that the principle sequence predecessor of RR Lyrae stars in NGC 7006 had a mass of about 0.82–0.85 solar masses and misplaced between 25% and 35% of its mass through the pink large department occasions.

The collected information additionally allowed the scientists to acquire some basic parameters of NGC 7006. They discovered that the cluster is situated roughly 134,200 light years away from the Earth, has a metallicity of -1.53 and its reddening is at a degree of 0.08.

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