In an entirely strange phenomenon, astronomers have spotted two neutron stars being swallowed by different black holes.

What are Black Holes?

• A black hole is a region of spacetime where gravity is so strong that nothing—no particles or even electromagnetic radiation such as light—can escape from it.
• Neutron stars and black holes are among the most extreme objects in the universe. They are the fossil relics of massive dead stars.
• When a star that is more than eight times as massive as the Sun runs out of fuel, it undergoes a spectacular explosion called a supernova.
• What remains can be a neutron star or a black hole.

There is no upper limit to how massive a black hole can be, but all black holes have two things in common: a point of no return at their surface called an “event horizon”, from which not even light can escape and a point at their centre called a “singularity”, at which the laws of physics as we understand them break down.

What about Neutron stars?

• Neutron stars are typically between 1.5 and two times as massive as the Sun but are so dense that all their mass is packed into an object the size of a city.
• At this density, atoms can no longer sustain their structure and dissolve into a stream of free quarks and gluons: the building blocks of protons and neutrons.

What is the news observation?

• Gravitational waves are produced when celestial objects collide and the ensuing energy creates ripples in the fabric of space-time which carry all the way to detectors on Earth.
• The reverberations from the two celestial objects were picked up using a global network of gravitational wave detectors.

What makes this strange phenomenon?

• This is the first time scientists have seen gravitational waves from a neutron star and a black hole.
• Previous gravitational wave detections have spotted black holes colliding, and neutron stars merging but not one of each.

Why study this?

• Neutron star-black hole systems allow us to piece together the evolutionary history of stars.
• Gravitational-wave astronomers are like stellar fossil-hunters, using the relics of exploded stars to understand how massive stars form, live and die.

Answer this PYQ in the comment box:

Q.“Event Horizon” is related to (CSP 2018):

(a) Telescope

(b) Black hole

(c) Solar glares

(d) None of the above

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