Researchers study the properties of four galactic open clusters

(ORDO NEWS) — Using data from ESA’s Gaia space observatory, astronomers from the University of Istanbul in Turkey examined four open galaxy clusters. The results of this research, presented in an article published on April 16 in the arXiv preprint repository, provide important insights into the properties of these objects.

Open clusters (OS), formed from one giant molecular cloud, are groups of stars that are weakly gravitationally bound to each other.

To date, more than 1,000 such clusters have been discovered in the Milky Way, and scientists continue to search, hoping to find a wide variety of stellar groupings.

Expanding the list of known galactic open clusters and studying them in detail could be critical to improving our understanding of the formation and evolution of our galaxy.

Therefore, Turkish astronomers Hikmet Çakmaka and Yuksel Karataşa studied four OCs in the Milky Way, namely: Berkeley 10 (or Be 10), Berkeley 81 (Be 81), Berkeley 89 (Be 89) and Ruprecht 135 (Ru 135).

They analyzed photometric and astrometric data from Gaia Early Data Release 3 (EDR3) to determine the astrophysical, structural and dynamic parameters of these clusters.

“In this paper, we study the dynamical evolution of Be 81, Ru 135, Be 10 and Be 89 from Gaia EDR3 photometric/astrometric data,” they write in their study.

The study showed that the largest and most massive OC of the studied quartet is Be 89. Its radius is about 37.1 light years, and the total mass is 154.7 solar masses. The cluster is 3.2 billion years old, has a metallicity of 0.0152, and is located about 7,900 light-years from Earth. Be 89 is estimated to have at least 221 stars.

With a radius of about 5.5 light-years and a total mass of about 98.5 solar masses, Ru 135 is the smallest and least massive cluster of the four described in the paper. At only 2,900 light-years away, Ru 135 is about 1 billion years old, has a similar metallicity to Be 89, and is estimated to contain 119 stars.

Be 81 is the most distant OC in this sample, being about 8,600 light-years away. Its radius and mass are estimated at 9.84 light years and 134.5 solar masses, respectively. This cluster, known to contain at least 171 stars, is estimated to be 1.6 billion years old and has a metallicity of 0.024.

As for the 1.35 billion year old Be 10, its radius is about 21.2 light years and its total mass is 109.6 solar masses. Located 6,223 light-years away, this OC is estimated to have 197 member stars and has a metallicity of approximately 0.008.

In summary, the researchers noted that the Be 89 cluster expands over time, unlike Be 10 and Be 81, as these two clusters show relatively decreasing cluster radii due to dynamic evolution.

In the case of Ru 135, it was found that instead of decreasing in size and mass with time, this cluster may have a primordial origin, associated, as expected, with a high density of molecular gas in galactic directions.


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