NGC 4631 also known as the Whale Galaxy
(Photo : National Radio Astronomy Observatory via Instagram) The blue and green filaments shown in the photo are the galaxy's magnetic field. The Whale Galaxy's magnetic field is one of the largest halos seen among edge-on galaxies.

For the longest time, astronomers are aware of the presence of areas around a galaxy which is filled with hot gas and dark matter that extends beyond its visible part -- halos, as they call it. The halos have magnetic fields that affect the passage of cosmic rays that may influence the formation of a star. However, astronomers are not yet sure about the exact structure of these magnetic fields until recently.

Through NSF' Karl G. Jansky's Very Large Array, astronomers are looking at the whale galaxy -- also known as NCG 4631 -- to learn about these magnetic fields. 


In an image captured by the Very Large Array in New Mexico, the Whale Galaxy appears to have hair-like filaments sticking out. These filaments are its magnetic field, and astronomers are excited by this new finding as it is one of the largest halos found and can help astronomers understand the structures of magnetic halos.

According to the official statement, as explained by astronomer Dr. Marita Krause of the Max Planck Institute for Radio Astronomy, this is the first time that large-scale coherent magnetic fields that were situated far in the halo of a spiral galaxy were detected by astronomers. 

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In able for astronomers to detect the magnetic fields of the Whale Galaxy, they used the antenna array to be able to locate naturally emitted radio waves. Using the array's different configurations, astronomers were finally able to detect both the larger structures in the Whale Galaxy as well as its finer details, including the hair-like filaments.


Since the Whale Galaxy is thousands of lightyears away from our planet, does identify its magnetic fields will affect our galaxy? Are the findings useful? Astronomers would answer: yes. According to them, these findings can help to explain the relationship between the formation of galaxies and their magnetic fields. The results can also answer important questions such as how do galaxies acquire their magnetic fields and whether these magnetic fields were produced by what they call the dynamo effect.

The Whale Galaxy has been discovered to exhibit one of the largest gaseous halos among edge-on galaxies. Astronomers would like to examine the synchrotron and polarization properties of its disk and halo emissions with the new radio continuum data. 


NGC 4631 is dubbed as the Whale Galaxy because of its angle and its shape that reminded astronomers of the large ocean-dwelling mammal. It was first discovered in 1787 by British astronomer William Herschel and found that this edge-on galaxy is 80,000 lightyears away from the Milky Way. The new findings regarding the galaxy's magnetic field indicate that these large-scale fields were created the same way the Earth's magnetic field was created and spirals outward in the form of giant magnetic ropes perpendicular to the disk. Dr. Richard Henriksen from Queen's University said, "we are like the blind men and the elephant, since each time we look at the galaxy in a different way we reach a different conclusion about its nature. He also explains that sometimes, there is this rare occasion where the dynamo effect can be predicted in the Whale Galaxy quite well. The observations about the Whale Galaxy's magnetic field are published in Astronomy and Astrophysics.

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