Magnetic field of a spiral galaxy
Field lines extend far beyond galaxy's disk

Date:
July 21, 2020
Source:
National Radio Astronomy Observatory
Summary:
A new image from the VLA dramatically reveals the extended magnetic
field of a spiral galaxy seen edge-on from Earth.



FULL STORY ==========================================================================
This image shows the huge extent of a spiral galaxy's magnetic field. The galaxy NGC 4217 is a star-forming, spiral galaxy, similar to our own
Milky Way, 67 million light-years from Earth in the constellation Ursa
Major. The galaxy is seen edge-on in a visible-light image from the
Sloan Digital Sky Survey and Kitt Peak National Observatory, and the
magnetic field lines, shown as green, are revealed by the National Science Foundation's Karl G. Jansky Very Large Array (VLA) radio telescope.


==========================================================================
The magnetic field lines extend as much as 22,500 light-years beyond the galaxy's disk. Scientists know that magnetic fields play an important role
in many processes, such as star formation, within galaxies. However, it
is not fully understood how such huge magnetic fields are generated and maintained. A leading explanation, called the dynamo theory, suggests
that magnetic fields are generated by the motion of plasma within the
galaxy's disk. Ideas about the cause of the kinds of large vertical
extensions seen in this image are more speculative, and astronomers
hope that further observations and more analysis will answer some of
the outstanding questions.

"This image clearly shows that when we think of galaxies like the Milky
Way, we should not forget that they have galaxy-wide magnetic fields,"
said Yelena Stein, of the Centre de Donne'es astronomiques de Strasbourg, leader of the study.

The scientists who produced the image are reporting their results in
the journal Astronomy & Astrophysics.


========================================================================== Story Source: Materials provided by
National_Radio_Astronomy_Observatory. Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. Y. Stein, R.-J. Dettmar, R. Beck, J. Irwin, T. Wiegert,
A. Miskolczi, Q.

D. Wang, J. English, R. Henriksen, M. Radica, J.-T. Li. CHANG-ES.

Astronomy & Astrophysics, 2020; 639: A111 DOI: 10.1051/0004-6361/
202037675 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200721160739.htm

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