Editing Galaxy (section)

==Magnetic fields==
Galaxies have [[magnetic field]]s of their own. A galaxy's magnetic field influences its dynamics in multiple ways, including affecting the formation of spiral arms and transporting angular momentum in gas clouds. The latter effect is particularly important, as it is a necessary factor for the gravitational collapse of those clouds, and thus for star formation.<ref name="galactic_magnetic_fields">{{Cite journal|title = Galactic magnetic fields|journal = [[Scholarpedia]] |volume = 2|issue = 8|page = 2411|last = Beck|first = Rainer|doi = 10.4249/scholarpedia.2411|bibcode = 2007SchpJ...2.2411B |year = 2007|doi-access = free}}</ref>

The typical average [[Equipartition theorem|equipartition]] strength for [[Spiral galaxy|spiral galaxies]] is about 10 μG ([[Gauss (unit)|microgauss]]) or 1{{nbsp}}nT ([[Tesla (unit)|nanotesla]]). By comparison, the Earth's magnetic field has an average strength of about 0.3 G (Gauss) or 30 μT ([[Tesla (unit)|microtesla]]). Radio-faint galaxies like [[Andromeda Galaxy|M 31]] and [[Triangulum Galaxy|M33]], the [[Milky Way]]'s neighbors, have weaker fields (about 5{{nbsp}}μG), while gas-rich galaxies with high star-formation rates, like M 51, M 83 and NGC 6946, have 15 μG on average. In prominent spiral arms, the field strength can be up to 25 μG, in regions where cold gas and dust are also concentrated. The strongest total equipartition fields (50–100 μG) were found in [[Starburst galaxy|starburst galaxies]]—for example, in M 82 and the [[Antennae Galaxies|Antennae]]; and in nuclear starburst regions, such as the centers of NGC 1097 and other [[Barred spiral galaxy|barred galaxies]].<ref name="galactic_magnetic_fields"/>