Astrosat satellite spots old globular clusters known as dinosaurs of the universe


The Department of Science and Technology said on Thursday, astronomers, with the help of India's first multi-wavelength space satellite Astrosat, have spotted a massive intriguing globular cluster in the Milky Way galaxy with rare hot UV-bright stars in it.


These stars whose inner core is almost exposed, making them very hot, exist in the late stages of evolution of a Sun like star. It is not clear how these stars end their lives as not many of them are detected in these fast evolving phases, making their study crucial.


The old globular clusters referred to as dinosaurs of the universe, present excellent laboratories where astronomers can understand how stars evolve through various phases between their birth and death with spectacular ultraviolet images of the cluster from Ultraviolet Imaging Telescope (UVIT) on board.


The properties of these stars were then used to place them on what astronomers call the Hertzsprung-Russel (HR) diagram along with theoretical models to throw light on the characteristics of their parent stars and to predict their future evolution.


Most of the stars were found to have evolved from a solar stage called the horizontal branch stars with hardly any outer envelope.


Thus they were bound to skip the last major phase of life called the asymptotic giant phase and directly become dead remnants or white dwarfs.


According to the Department of Science and Technology, Such UV-bright stars are speculated to be the reason for the ultraviolet radiation coming from old stellar systems such as elliptical galaxies which are devoid of young blue stars. So, it is all the more important to observe more such stars to understand their properties.

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