The galaxy mergers are often subtle, as seen in Centaurus A, which was studied extensively with the James Webb Space Telescope (JWST). New observations on July 7, 2026, show evidence of a past merger, highlighting how these cosmic events can remain obscured over time.
Understanding Galaxy Mergers
Galaxy mergers can take hundreds of millions of years to develop. Initially, galaxies on a collision course interact gravitationally, forming long streams of gas and stars known as tidal tails. As the galaxies pass each other, friction between their stars and dark matter reduces their orbital energy.
As a result, the galaxies loop back and collide again, repeating this process multiple times. This interaction can lead to what astronomers call violent relaxation, where the gravitational potential of dark matter changes, causing star orbits to become more random.
Evidence of Past Collisions in Centaurus A
Centaurus A, also known as NGC 5128, is approximately 11 million light-years away and is the fifth-brightest galaxy in the sky. It is classified as a starburst galaxy, indicating rapid star formation, often a result of mergers. The latest observations from JWST's Mid-Infrared Instrument (MIRI) have revealed hidden structures and dust that provide evidence of Centaurus A's past collisions.
Visual evidence of mergers can often become obscured over time. Thick dust lanes within Centaurus A hide much of the galaxy's center, although signs of mergers, such as bright young star clusters, remain visible. However, these signs are not definitive.
The Role of Advanced Telescopes
The JWST has opened new avenues for observing galaxies like Centaurus A. As Shawn Domagal-Goldman, division director of astrophysics at NASA Headquarters, stated, "No single telescope tells the whole story. Discoveries build over time, and new observatories expand on the foundations laid by earlier missions." The JWST captures wavelengths and details previously inaccessible, allowing for a deeper understanding of galaxy structures.
Images taken by the JWST show unexpected dust formations and structures in Centaurus A, including wispy filaments and an unusual parallelogram-shaped feature. The active black hole at the galaxy's center is also emitting powerful jets, further complicating the picture of its formation.
- Centaurus A is about 11 million light-years away.
- The galaxy is the fifth-brightest in the sky.
- Evidence of a merger includes young star clusters and hydrogen clouds.
- JWST's MIRI has captured significant details about the galaxy's structure.
🤖 This article was rewritten by Feed and Figures' editorial AI from a report originally published by Phys.org. Facts and quotes are preserved from the original; the rewrite focuses on clarity and structure. For the unedited original, see the source link below.
