Collision of neutron stars gives a new measure to one of the fundamental cosmic constants

explosive merger of neutron stars helps in measuring hubble constant
Faint afterglow of the explosive merger of two neutron stars in the galaxy NGC 4993. (Credits - NASA/JPL-Caltech)

It’s been almost two years since the collision of two neutron stars which took place in a galaxy which was 130 million light years away from our universe. The fact which made this collision unique was that it helped in improving pre-existing knowledge about the universe and related features to it.
Basically, neutron stars are condensed, burnt out debris of humongous stars which are out of fuel. Such stars finally blow up and die. So, this collision has contributed in understanding of the concept of Hubble constant but on the other hand, the results have created more confusion also. Hubble constant is the rate at which the universe is expanding and to calculate this crucial constant, astronomers have more than 3 options. The study has been published in the Nature Astronomy journal.
The first method used for calculating Hubble constant uses data from Planck satellite which is used for measuring cosmic microwave background condition. The results obtained from this method has given Hubble constant as 67.4 kilometres per second per megaparsec.
Apart from this, another method used is through studying Nebulae which is left behind by Type La Supernovae which is a kind of supernova. Through this way, Hubble constant was calculated as 72.78 kilometres per second per megaparsec.
Adding to the dilemma, there was a third method which is through standard candles like Cepheid stars known for its luminosity which helps in accurate calculations. Most recently, a measurement based on the motions of 70 Cepheid variables returned a result of 74.03 kilometres per second per megaparsec. So, you see the dilemma. The measurement from this third method is way faster than the previous two methods.
All of this chaos due to various methods has forced the scientific community to think about the validity of the methods and even the models are suspected to underpin the processes.

Furthermore, the reason why we are discussing this collision is because even through this merging of stars the team of scientists have calculated a value for the Hubble Constant. The process was to find the orientation of this collision through recognizing the minor changes in the location and shape, which further aided in knowing the precise distance of collision. Subsequently, resulting in a different value for Hubble Constant which was 70.3 kilometres per second per megaparsec.
Summarizing the aforementioned points, it will surely take some time to understand the results of different methods and then finally consolidating those deductions about the Hubble constant. These kinds of discoveries have contributed to the understanding of our universe to a large extent and thus it is mandatory to look for precise conclusions to remove any kind of errors.


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