Scientists at Nainital-based ARIES shed new light on evolution of stars

Vijay Mohan

Tribune News Service

Chandigarh, June 21

Astronomers at the Aryabhatta Research Institute of Observational Sciences (ARIES), Nanital, have found that stars of varied ages can co-exist in open clusters.

This challenges earlier understanding that all stars in an open cluster have the same age.

Open star clusters are a system of stars bound by gravity in which stars are born from the same molecular clouds. All the stars in a cluster follow the evolutionary sequence as per their initial masses at the time of formation of these stars. Open clusters are also important in probing the formation and evolution of the Milky Way galaxy as they are distributed throughout the galactic disk.

Scientists at ARIES measured the light emitted from three poorly studied open clusters, NGC-381, NGC-2360 and Berkeley-68 using the 1.3-m telescope situated in the Himalayas for studying the evolution of stars in these clusters. They found two different stellar evolutionary sequences in the cluster NGC-2360, which has been observed in very few open clusters in the Milky Way until now.

The team at ARIES, an autonomous institute under the Department of Science and Technology, observed thousands of stars in the three aforementioned clusters. The clusters are found to be relatively older, having ages between 446 Million years to 1,778 million years.

Other than the stellar evolution, the researchers also studied the dynamical evolution of these clusters for the first time. The mass distribution of stars belonging to the clusters has shown the preferential distribution of massive stars in the inner part of the clusters while low mass stars are found towards outer region of the clusters.

Scientists believe that some of the very low mass stars have in fact, left their parent clusters and may be roaming as a free star like our own Sun.

The study, recently published in the Monthly Notices of the Royal Astronomical Society, a leading journal in the field of astronomy and astrophysics published by Oxford University Press, United Kingdom, has lent important insight about the stellar and dynamical evolution of these clusters.

According to a statement issued by the Ministry of Science and Technology today, the scientists are further aiming to do an in-depth analysis of many more open star clusters in the near future using observational facilities available at ARIES along with the supplementary data provided by other space missions.

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