Alaknanda: What Is the Newly Discovered Massive Galaxy Challenging Our Understanding of the Early Universe?
- TPP
- 2 days ago
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Named After the Sister River of Mandakini, the Milky Way’s Hindi Namesake — Alaknanda Galaxy Emerges as the Distant Cosmic Sister of Our Own Galaxy
Indian researchers have made a groundbreaking discovery — a massive, well-defined spiral galaxy that existed when the universe was just 1.5 billion years old. Named Alaknanda, this galaxy challenges long-held scientific assumptions about how early galaxies formed and evolved.
Published in the prestigious journal Astronomy and Astrophysics, this discovery is one of the earliest spiral galaxies ever observed and has been made possible with data from the James Webb Space Telescope (JWST).
Why Is the Discovery of Alaknanda Galaxy So Remarkable?
Scientists have always believed that galaxies formed in the early universe were:
Chaotic
Clumpy
Turbulent
Lacking well-defined structures
But Alaknanda defies all expectations.
Key features that make Alaknanda extraordinary:
It is a well-formed spiral galaxy, similar to our own Milky Way.
It showcases two distinctly defined spiral arms wrapping around a bright central bulge.
It spans nearly 30,000 light-years in diameter.
It existed when the universe was only 10% of its current age (~1.5 billion years after the Big Bang).
This level of complexity was thought to appear much later in cosmic history, making the discovery highly unexpected and scientifically significant.
Who Discovered the Alaknanda Galaxy and Why Is It Named So?
The discovery was made by researchers from the:
National Centre for Radio Astrophysics (NCRA-TIFR), Pune, led byProf. Yogesh Wadadekar,
Along with PhD researcher Rashi Jain, who led the study.
Meaning behind the name "Alaknanda"
The galaxy’s structure resembles the Milky Way, which is called Mandakini in Hindi.
Alaknanda is a sister river to Mandakini in the Himalayas.
Since the galaxy is a “distant sister” to our Milky Way, the researchers found this name fitting.
What Makes the Structure of Alaknanda Galaxy So Unique?
Alaknanda is described as having a textbook spiral structure.
Characteristics include:
Two clear spiral arms
Bright, central bulge
Diameter of ~30,000 light-years
Highly organized formation
Such orderly structure contradicts the conventional belief that early galaxies were:
Extremely hot
Gas-rich
Dynamically unstable
Irregular and poorly shaped
The presence of such a mature spiral galaxy so early in cosmic history suggests that galaxy evolution may have started much earlier than previously understood.
How Was the Alaknanda Galaxy Discovered?
The discovery was made using the James Webb Space Telescope (JWST) — the world’s most powerful space observatory.
Why JWST was crucial:
Its infrared imaging allows astronomers to detect extremely distant galaxies.
It can see light that has traveled 12 billion light years from early cosmic epochs.
JWST has already helped find some of the oldest known galaxies, formed just 150–300 million years after the Big Bang.
What Is the James Webb Space Telescope and What Are Its Science Goals?
The JWST, launched on December 25, 2021, is a joint mission of:
NASA,
European Space Agency (ESA), and
Canadian Space Agency (CSA).
JWST examines all phases of cosmic history, from the Big Bang to modern galaxies.
Its science goals fall under four main themes:
Look back 13.5 billion years to observe the first stars and galaxies.
Compare early faint galaxies with today’s spirals to understand galaxy assembly.
Locate regions where stars and planetary systems are forming.
Study the atmospheres of exoplanets to detect potential chemical signs of life.
The telescope continues to deliver data that is redefining modern astronomy.
What Are Galaxies and How Do They Normally Form?
Galaxies are the fundamental building blocks of the universe, each containing billions of stars, gas, dust, and dark matter.
Types of galaxies:
Spiral galaxies – containing a central bulge and rotating disk (e.g., Milky Way)
Elliptical galaxies – more rounded and less structured
Understanding galaxy evolution:
Over 13.7 billion years, smaller protogalaxies merged to form larger ones.
Studies show that more than half of modern galaxy mass was accumulated in the last 8 billion years.
Early galaxies were expected to be unsophisticated and disorganized.
Alaknanda’s presence at such an early epoch contradicts this standard view.
What Does This Discovery Mean for Our Understanding of Early Universe?
The existence of a well-formed spiral galaxy so early suggests:
Galaxy evolution may have been faster and more efficient than previously believed.
Early universe conditions might have been more conducive to spiral formation.
Some galaxies may have followed different evolutionary pathways.
This discovery adds weight to other recent JWST findings showing that the early universe was more mature than expected.
What Are the Next Steps in the Study of Alaknanda Galaxy?
Researchers plan to investigate:
1. Kinematics of gas and stars
Determine whether motions are regular (ordered) or chaotic
Understand how spiral arms formed
2. Disk stability
Whether the disk is cold or hot
This will reveal which physical mechanisms shaped its spiral arms
3. Additional observations
Using JWST’s future data
Using ALMA Telescope (Chile) to analyze cold gas distribution
These studies may confirm whether Alaknanda follows a unique evolutionary path or represents a hidden population of early spiral galaxies.
The discovery of Alaknanda is a cosmic milestone that challenges long-held theories of galaxy formation. Its mature spiral structure, observed from a time when the universe was only 10% of its current age, opens new questions about how quickly complex systems emerged after the Big Bang.
As JWST continues to peer deeper into the universe, Alaknanda may be just the beginning of many more discoveries redefining the story of our cosmic origins.