Â鶹ÒùÔº

Using ESA's Gaia satellite and NASA's Transiting Exoplanet Survey Satellite (TESS), astronomers from the Ege University in Turkey and elsewhere have observed a galactic open cluster known as NGC 2506. , published October 7 on the arXiv pre-print server, put more constraints on the properties of this cluster.

In general, groups of stars formed from the same giant molecular cloud and loosely gravitationally bound to each other are known as open clusters (OCs). Inspecting galactic OCs in detail could be crucial for improving our understanding of the formation and evolution of our Milky Way galaxy.

NGC 2506 is a mildly-elongated OC estimated to be located some 12,700 light years away, near the galactic anti-center. It is a well-populated, metal-poor, intermediate-age cluster with a radius of about 18.5 light years.

Although many observations of NGC 2506 have been conducted to date, there are still many discrepancies regarding some of its fundamental parameters, like metallicity, age, reddening or distance. For instance, one study suggests that NGC 2506 is 1.5 billion years old, while other studies point to an age of about 3.4 billion years.

That is why a team of astronomers led by Ege University's Kadri Yakut decided to take a closer look to better constrain its properties. To achieve this goal, they inspected binary systems in the cluster.

"Binary stars have long been recognized as fundamental astrophysical laboratories for deriving precise stellar parameters, particularly when they are double-lined and eclipsing," the researchers explained.

Yakut's team investigated five well-characterized double-lined binary systems in NGC 2506, two of which are eclipsing. They selected these binaries, with masses between 1 and 1.5 solar masses, based on their spectroscopic completeness, photometric quality, and astrometric membership probability.

The study found that NGC 2506 has a metallicity at a level of -0.3 and its age was derived to be 1.94 billion years. The distance to the cluster was measured to be approximately 10,400 light years.

Therefore, the study conducted by Yakut and colleagues makes NGC 2506 a well-characterized intermediate-age OC suitable for testing stellar evolution models at subsolar metallicities. They added that their results demonstrate the power of binary systems in tightly constraining cluster-wide age and distance at this evolutionary stage, noting that the method can bring promising results when implemented in the studies of other clusters.

"The methodology is scalable and readily applicable to other clusters with suitable spectroscopic binaries, offering a viable path toward precision stellar population studies in the Gaia era," the authors of the paper conclude.

© 2025 Science X Network