Astrosat Current Affairs - 2019

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New population of Ultraviolet Stars Identified in the Globular Cluster NGC 2808

Astronomers from Thiruvananthapuram and Mumbai have identified a new population of ultraviolet stars in the globular cluster NGC 2808 using the Indian multi-wavelength space observatory AstroSat, launched in September 2015.

AstroSat

AstroSat is India’s dedicated multi-wavelength space observatory which endeavours for a more detailed understanding of our universe. ASTROSAT observes the universe in the optical, Ultraviolet, low and high energy X-ray regions of the electromagnetic spectrum. Major astronomy Institutions and some Universities in India are participating in these observations.

NGC 2808

Globular clusters are collections of thousands to millions of stars, moving as one unit. These stars are tightly held together by the gravity of the cluster itself and are believed to have formed together at roughly the same time.  The globular cluster contains stars with a variety of masses but with similar chemical composition.

NGC 2808 is one of the massive globular clusters and is located at a distance of 47,000 light years from us.

Recent studies have shown that many globular clusters may well host more than one population of stars contrary to popular belief that all stars in such clusters are of the same age. Observations suggest that NGC2808 may have at least five different populations of stars.

Astrosat, Chandra and Hubble jointly detect massive cosmic explosion on Proxima Centauri

India’s first dedicated space observatory AstroSat along with other space and earth-based observatories have detected a massive coronal explosion on Proxima Centauri, sun’s closest star neighbour.

The explosion was detected as part of joint multi-wavelength simultaneous observational campaign undertaken by three space-based observatories, Astrosat, Chandra and Hubble Space Telescope and the ground-based High Accuracy Radial velocity Planet Searcher (HARPS) observatory.

Proxima Centauri

It is group of stars which hosts an Earth-like habitable planet — Proxima Centaur b — orbiting within (Proxima Centauri) its habitable zone. It is a cool dwarf star located around 4.25 light years away from the Earth. It was discovered in 2016.

Key Facts

The massive coronal explosion has sent out powerful solar flare having energy of 10-raised-to-30 ergs, about 100 times a typical solar flare. Such powerful flaring may have produced large radiations and particles which may significantly influence the atmosphere of the Proxima Centauri b and affect its habitability.

The habitability of Proxima Centauri especially its ability to sustain its atmosphere and in particular to sustain water in liquid form may get affected due to abnormal planetary atmosphere heating due absorption of  the high-energy photons like the ultraviolet (UV) and X-ray photons released by the coronal explosion.

If such a massive flare occurs in our Sun, it might have a devastating effect on power grids, interrupt broadcasts and electricity, affect electronic instruments, and cause excess UV radiation in space.

Coronal explosion: is an unusually large release of plasma and magnetic field from the solar corona. They often follow solar flares and are normally present during a solar prominence eruption. The plasma is released into the solar wind, and can be observed in coronagraph imagery.