Black Holes Current Affairs - 2020

LIGO detects first merger of two unequal-mass black holes

The scientists of Laser Interferometer Gravitational Wave Laboratory (LIGO) have recently recorded the first merger of black holes that were of unequal masses.

On April 12, 2020, the LIGO-Virgo collaboration detected collision between two black holes that were 2.4 billion light years away. The scientists have now concluded from their researches and analysis that these black holes were of unequal masses.


The black holes were 20 and 40 times the mass of the sun. One of the black holes was 29.7 solar masses and the other was 8.4 solar masses. Though they are heavier and uneven, they are the lowest-mass black holes recorded so far.

The Findings

Black holes revolve around each other. When the black holes are of equal masses, they return to the same position after they complete their revolution in each of their respective orbits. Therefore, in these cases, the black holes generate gravitational wave frequency that is twice their orbital frequency. On the other hand, the black holes of uneven masses produce additional (second) weaker gravitational wave frequency.

Solar Mass

Solar Mass is the standard of mass in astronomy that is used to indicate masses of other masses. One solar mass is equal to 2×1030 Kg.

LIGO: Second Merger of Neutron Stars detected

The LIGO (Laser Inferometer Gravitational-wave Observatory) detected gravitational waves due to collision of two neutron stars. This is the second time the gravitational waves are being detected.


The mass of the neutron stars detected is expected to be 3.3 times and 3.7 times as that of the sun. The scientists believe that the neutron stars were formed separately and drifted together to form a star pair. The neutron stars were at a distance of 520 million light years from the earth. The combined mass is the heaviest of the stars known so far.

The first neutron star detection was in 2017. However, the second event that was recorded now, is not as strong as the first.


Currently LIGO operates three gravitational wave detectors at Livingston, Louisiana and Hanford. They are located 3,000 km apart in the shape of ‘L’.

Indian Contribution

LIGO India is to come up in Maharashtra. It will aim at locating gravitational waves and their new sources.

Why is the study important?

The gravitational waves are caused by exploding stars, black holes, merging neutron stars. LIGO helps to detect these waves and analyze the information that they carry. As the waves interact very weakly with matter, they help to learn about the universe and its origin.