Researchers explore open cluster NGC 2506 with AstroSat

Open cluster NGC 2506. Credit: StudentAstronomyGroupUoC
Open cluster NGC 2506. Credit: StudentAstronomyGroupUoC

Indian scientists explored an open cluster known as NGC 2506 using the AstroSat satellite. The study found almost 2,000 member stars of this cluster and offered new information on its features. On August 29, the findings were reported in Monthly Notices of the Royal Astronomical Society. Open clusters (OCs) are groups of stars that are gravitationally connected to one other and generated from the same massive molecular cloud. More than 1,000 of them have been identified so far in the Milky Way, and scientists are still seeking more in the hope of discovering a diversity of these star clusters. Extending the list of known galactic open clusters and researching them in depth might be critical for increasing our knowledge of our galaxy's creation and development.

NGC 2506 (also known as Caldwell 54) is a moderately elongated, intermediate-age OC located at a distance of approximately 12,700 light years. Despite the fact that this cluster has been studied extensively, nothing is known about its stellar richness. Previous observations have revealed that NGC 2506 has mass segregation, with lower mass member stars more likely to be found in the cluster's outer reaches. A team of astronomers led by Anju Panthi of the Birla Institute of Technology and Science in Pilani, India, undertook multi-wavelength studies of NGC 2506, primarily utilizing the UltraViolet Imaging Telescope (UVIT) onboard AstroSat, to throw further light on the star populations of this cluster.

We analyzed an intermediate-age open cluster NGC 2506 using AstroSat/UVIT data and other archival data, the researchers said.

Using a machine learning-based method, the researchers found 2,175 cluster members of NGC 2506. Nine blue straggler stars (BSS), three yellow straggler stars (YSS), and three red clumps (RC) stars were discovered among them. Furthermore, the researchers detected and evaluated the essential features of hot partners of three BSS, two YSS, and three RC stars. These objects were discovered to be white dwarfs with masses ranging from 0.2 to 0.8 solar masses and effective temperatures ranging from 13,250 to 31,000 K.

The effective temperatures of BSS stars in NGC 2506 range from 7,750 to 9,750 K, which is compatible with the cluster's age of around 2 billion years. YSS stars have temperatures ranging from 6,500 to 6,750 K, whereas RC stars have temperatures ranging from 5,000 to 5,250 K. According to the findings, mass transfer in a binary system mechanism is believed to be responsible for the development of at least 40% of the BSS and YSS systems in NGC 2506. They do not, however, exclude out a merger in the triple system with a near inner binary situation.

Journal Information: Anju Panthi et al, UOCS –VIII. UV Study of the open cluster NGC 2506 using ASTROSAT, Monthly Notices of the Royal Astronomical Society (2022). DOI: 10.1093/mnras/stac2421
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