Indian astronomers explore open cluster NGC 6940 with AstroSat

Utilizing the AstroSat spacecraft, astronomers from the Birla Institute of Know-how and Science in Pilani, India, have investigated a close-by open cluster NGC 6940. Outcomes of the observational marketing campaign, published December 21 on the pre-print server arXiv, shed extra mild on the properties and stellar populations of this cluster.

Open clusters (OCs), fashioned from the identical big molecular cloud, are teams of some tens to a couple hundred stars loosely gravitationally certain to 1 one other. Thus far, greater than 1,000 OCs have been recognized within the Milky Way. Finding out these stellar groupings intimately might be important for enhancing our understanding of the formation and evolution of our galaxy.

Found in 1784, NGC 6940 (also called Melotte 232) is an open cluster within the constellation Vulpecula, at a distance of about 2,500 light years. The cluster is estimated to be 720 million years outdated and has a near-solar metallicity.

Earlier observations of NGC 6940 have discovered that it harbors a number of unique stellar populations, aside from regular single and binary stars, comparable to blue straggler stars (BSS), blue lurkers (BLs), yellow straggler stars (YSS), and pink clump (RC) stars. Nonetheless, though many research of this OC have been carried out, these unique stars haven’t been comprehensively investigated but.

Lately, astronomers Anju Panthi and Kaushar Vaidya employed AstroSat’s Ultraviolet Imaging Telescope (UVIT) to take a more in-depth take a look at NGC 6940, with the primary purpose of gathering extra data relating to its unique stellar content material. In addition they used information from ESA’s Gaia satellite to establish cluster members.

“This cluster has been noticed with the Ultraviolet Imaging Telescope (UVIT) on board the AstroSat, which has the flexibility to detect unique objects and their sizzling companions when mixed with different multi-wavelength information,” the researchers defined.

All in all, the astronomers recognized 492 members of NGC 6940, and 16 of them turned out to be unique stars. Specifically, they discovered 11 blue lurker star candidates, two yellow straggler stars, two pink clump stars, and one blue straggler star.

Moreover, it was discovered that three BL candidates most probably have white dwarfs as a sizzling companion. The 2 YSS stars have sdB stars as probably sizzling companions and one of many recognized RC stars has a white dwarf companion.

In response to the examine, NGC 6940 reveals proof of mass segregation, what means that dynamic evolution has occurred inside the cluster. The large single stars showcase the very best diploma of segregation adopted by the equal-mass binary principal sequence (MS) populations after which the low-mass single stars.

Furthermore, the observations discovered the presence of an prolonged main-sequence turn-off (eMSTO) function in NGC 6940. The astronomers suppose that the age unfold of stars is among the elements contributing to the noticed eMSTO. Nonetheless, they don’t exclude the chance that the impact of stellar rotation and the dust absorption contribute to this.

The authors of the paper additionally estimated the core radius of NGC 6940, which was calculated to be 9.8 arcminutes and its tidal radius was measured to be 37.5 arcminutes.

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