GS PAPER III: Science and Technology- developments and their applications and effects in everyday life.

Context: Scientists have discovered what may be the smallest-known black hole in the Milky Way galaxy and the closest to our solar system — an object so curious that they nicknamed it 'the Unicorn.'

• The black hole is roughly three times the mass of our sun, testing the lower limits of size for these extraordinarily dense objects that possess gravitational pulls so strong not even light can escape.
• A luminous star called a red giant orbits with the black hole in a so-called binary star system named V723 Mon.
• The black hole is located about 1,500 light years — the distance light travels in a year, 9.5 trillion km — from Earth.
• While it may be the closest one to us, it is still far away. By way of comparison, the closest star to our solar system, Proxima Centauri, is 4 light years away.

About Black holes:

• Black holes are electromagnetically dark, and so they are difficult to find
• There are three categories of black holes:
  • The smallest, like 'the Unicorn,' are so-called stellar mass black holes formed by the gravitational collapse of a single star.
  • There are gargantuan 'supermassive' black holes like the one at our galaxy's center, 26,000 light years from Earth, which is four million times the sun's mass.
  • A few intermediate-mass black holes also have been found with masses somewhere in between.

'The Unicorn'

• 'The Unicorn' falls into what the researchers called a "mass gap" between the largest-known neutron stars - objects similarly formed by a large star's collapse - at around 2.2 times the mass of our sun and what previously had been considered the smallest black holes at around five times the sun's mass.
• Black holes like this one form when massive stars die and their cores collapse.
• Its strong gravity alters the shape of its companion star in a phenomenon known as tidal distortion, making it elongated rather than spherical and causing its light to change as it moves along its orbital path.
• It was these effects on the companion star, observed using Earth-based and orbiting telescopes, that indicated the black hole's presence.

https://www.thehindu.com/sci-tech/science/a-black-hole-dubbed-the-unicorn-may-be-galaxys-smallest-one/article34412174.ece?homepage=true

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