Recently, astronomers located rare hot Ultra Violet (UV)-bright stars in the massive globular cluster known as NGC 2808 within the Milky Way Galaxy. This discovery was facilitated by India’s first universal space satellite, AstroSat.
The Role of Data and Space Equipment
Scientists procured data from the Ultraviolet Imaging Telescope, integrated into AstroSat, and compared it with observations made using other space missions such as the Hubble Space Telescope and the Gaia telescope, along with ground-based optical observations. The Hubble Space Telescope, launched into Low Earth orbit in 1990, is one of the largest and most versatile space telescopes to date. On the other hand, Gaia, a space observatory launched by the European Space Agency in 2013, is designed for astrometry, facilitating the measurement of the positions, distances, and motions of stars with remarkable accuracy.
Findings from the Globular Cluster NGC 2808
The analysis led to the discovery of about 34 UV-bright stars as members of the globular cluster (NGC 2808). One of the UV-bright stars was found to be approximately 3000 times brighter than the Sun with a surface temperature of around 1,00,000 K. These scorching UV-bright stars have been differentiated from the relatively cooler red giant and main-sequence stars. Most of these stars were found to have evolved from a stage called the horizontal branch stars, which essentially possess little or no outer envelope. As such, they are likely to bypass the asymptotic giant phase, one of the last major phases in stellar life, and directly become remnants or white dwarfs.
The Significance of these Findings
These findings present potential improvements in comprehension about these stars’ properties like their surface temperatures, luminosities, and radii. They also serve as laboratories for astronomers wishing to understand the evolution of stars from birth to death. UV-bright stars are speculated to be the reason for the ultraviolet radiation emanating from old stellar systems.
About NGC 2808
NGC 2808 is a globular cluster located within the constellation Carina. It is part of the Milky Way galaxy and is one of the most massive clusters containing millions of stars. The cluster’s age is estimated to be about 12.5 billion years, and it’s home to at least five generations of stars.
Understanding Stellar Evolution
A nebula serves as a stellar nursery, comprised of gas and dust in space. Main sequence stars, constituting approximately 90% of all stars, including the Sun, fuse hydrogen atoms to form helium atoms in their cores. Towards the end of its life, a star like the Sun inflates into a red giant before shedding its outer layers as a planetary nebula and finally shrinking to become a white dwarf.
AstroSat: India’s First Multi-wavelength Space Satellite
India’s multi-wavelength astronomy mission AstroSat was launched into near-equatorial orbit in 2015. Its unique feature is that it enables simultaneous multi-wavelength observations of various astronomical objects with a single satellite. This milestone has placed India amongst the elite countries with multi-wavelength space observatories.
Last Modified: February 10, 2024