Context: AstroSat’s Ultraviolet Imaging Telescope spots rare ultraviolet-bright stars in a massive intriguing cosmic dinosaur in the Milky Way.

• Astronomers exploring the massive intriguing globular cluster in our Galaxy called NGC 2808 that is said to have at least five generations of stars have spotted 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.
• Motivated by the fact that 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) onboard India’s first multi-wavelength space satellite, AstroSat, they distinguished the hot UV-bright stars from the relatively cooler red giant and main-sequence stars.
• 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.
• Hence, it is all the more important to observe more such stars to understand their properties.

AstroSat MISSION

• AstroSat is the first dedicated Indian astronomy mission aimed at studying celestial sources in X-ray, optical and UV spectral bands simultaneously.
• The payloads cover the energy bands of Ultraviolet (Near and Far), limited optical and X-ray regime (0.3 keV to 100keV).
• One of the unique features of AstroSat mission is that it enables the simultaneous multi-wavelength observations of various astronomical objects with a single satellite.
• AstroSat with a lift-off mass of 1515 kg was launched on September 28, 2015 into a 650 km orbit inclined at an angle of 6 deg to the equator by PSLV-C30 from Satish Dhawan Space Centre, Sriharikota.
• The minimum useful life of the AstroSat mission is expected to be 5 years.
• The scientific objectives of AstroSat mission are:
  • To understand high energy processes in binary star systems containing neutron stars and black holes;
  • Estimate magnetic fields of neutron stars;
  • Study star birth regions and high energy processes in star systems lying beyond our galaxy;
  • Detect new briefly bright X-ray sources in the sky;
  • Perform a limited deep field survey of the Universe in the Ultraviolet region.

https://pib.gov.in/PressReleaseIframePage.aspx?PRID=1690854#:~:text=With%20spectacular%20ultraviolet%20images%20of,appear%20dim%20in%20these%20images.

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