Knowledge Nugget | ‘Alaknanda’ Galaxy: How is its discovery relevant to your UPSC exam?

2. The discovery has been published in the leading European astronomy journal Astronomy and Astrophysics.

3. “We have named it Alaknanda, after the Himalayan river,” Professor Yogesh Wadadekar at the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research (NCRA-TIFR) in Pune said Tuesday while announcing the discovery.

4. The striking thing about Alaknanda is its textbook spiral structure. The galaxy has two well-defined spiral arms wrapping around a bright central bulge, spanning approximately 30,000 light-years in diameter. 

5. According to the current understanding of scientists, the earliest formed galaxies did not have well-defined structures, were chaotic and clumpy, extremely hot and turbulent. But Alaknanda is nothing like that.

6. Rashi Jain, a PhD student who led this research under Wadadekar’s guidance explained the reason why the researchers decided to name it Alaknanda. “Alaknanda is a spiral galaxy located about 12 billion light years away and has a prominent grand design spiral structure just like our own galaxy, the Milky Way. Just as Alaknanda is the sister river of Mandakini river, which is also the Hindi name for our own Milky Way galaxy, we thought it fitting to name this distant sister after the Alaknanda river.”

7. The discovery was made using NASA’s James Webb Space Telescope, the most powerful piece of observation equipment put into space. 

James Webb Space Telescope (JWST)

1. JWST has been in the works for years. NASA led its development with the European Space Agency (ESA) and the Canadian Space Agency. It was launched aboard a rocket on December 25, 2021. 

2. The James Webb Space Telescope examines every phase of cosmic history: from the Big Bang to the formation of galaxies, stars, and planets to the evolution of our own Solar System. The science goals for the Webb can be grouped into four themes. 

(i) The first is to look back around 13.5 billion years to see the first stars and galaxies forming out of the darkness of the early universe. 

(ii) Second, to compare the faintest, earliest galaxies to today’s grand spirals and understand how galaxies assemble over billions of years. 

(iii) Third, to see where stars and planetary systems are being born. 

(iv) Fourth, to observe the atmospheres of extrasolar planets (beyond our solar system), and perhaps find the building blocks of life elsewhere in the universe. 

3. The JWST  has already produced data that is redefining our understanding of the universe. This includes spotting some of the oldest galaxies in the universe, those that were formed just a few hundred million years after the Big Bang.

BEYOND THE NUGGET: What are Galaxies?

1. Galaxies are the fundamental building blocks of our visible universe, each containing billions of stars, like our Sun. They can broadly be classified into two types – elliptical and spiral.

2. A typical spiral galaxy has two structural components: a central bulge in which stars move, more or less, on random orbits and a disk in which they move on approximately circular orbits like planets in our solar system. Understanding the formation and the evolution of these galaxies over the age of the universe, approximately 13.7 billion years, is at the heart of astronomical research.

3. Modern astronomy provides a fairly good understanding of how the universe has developed into its present state. Smaller galaxies are known to have merged and coalesced into more massive ones. More than half of the mass of the present day galaxies has been acquired in the last eight billion years.

Post Read Question

Consider the following phenomena: (UPSC CSE 2018)

1. Light is affected by gravity.

2. The Universe is constantly expanding.

3. Matter warps its surrounding space-time.

Which of the above is/are the prediction/predictions of Albert Einstein’s General Theory of Relativity, often discussed in media?

(a) 1 and 2 only

(b) 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

(Sources: Pune researchers find spiral galaxy like Milky Way from early universe, Explained: NASA’s Webb Telescope, From the lab: Why some spiral galaxies beat the ‘bulge’)

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