NRAO: Image release: Giant magnetic ropes in a galaxy’s halo

VLA observations reveal details of magnetic structure

NOVEMBER 26, 2019 — An astronomy composite image produced by professor Jayanne English, physics and astronomy, using radio data was released by the National Radio Astronomy Observatory (NRAO), on November 26, 2019

As the NRAO reports:

This image of the “Whale Galaxy” (NGC 4631), made with the National Science Foundation’s Karl G. Jansky Very Large Array (VLA), reveals hair-like filaments of the galaxy’s magnetic field protruding above and below the galaxy’s disk.

The spiral galaxy is seen edge-on, with its disk of stars shown in pink. The filaments, shown in green and blue, extend beyond the disk into the galaxy’s extended halo. Green indicates filaments with their magnetic field pointing roughly toward us and blue with the field pointing away. This phenomenon, with the field alternating in direction, has never before been seen in the halo of a galaxy. …

An international team of astronomers who are part of a project called the Continuum HAlos in Nearby Galaxies — an EVLA Survey (CHANG-ES), led by Judith Irwin of Queen’s University in Ontario, said the image indicates a large-scale, coherent magnetic field that is generated by dynamo action within the galaxy and spirals far outward in the form of giant magnetic ropes perpendicular to the disk. …

The image was made by combining data from multiple observations with the VLA’s giant dish antennas arranged in different configurations to show both large structures and finer details within the galaxy. The naturally-emitted radio waves from the galaxy were analyzed to reveal the magnetic fields, including their directions.

The scientists said the techniques used to determine the direction of the magnetic field lines, illustrated by this image, now can be used on this and other galaxies to answer important questions about whether coherent magnetic fields are common in galactic halos and what their shapes are.


Interested in astronomy image making?

Register for this course offered Winter 2020.

SCI 4000 – The Art of Scientific Visualization,
Winter 2020 Term
Instructor: Jayanne English
Time: Tuesday – Thursday – 2:30 – 3:45 pm