The Zeeman Effect in the Interstellar Medium

lines

neutral Hydrogen 21-cm

line-of-sight magnetic field (μG)

0

temperature (K)

3

Y axis bounds for Stokes V

1

turbulent velocity (km/s)

0

signal-to-noise ratio

1000

Module{ΔνD$,ΔνZ$,νval$,ϕ$,ϕpts$,SI$,StokesI$,Ipts$,StokesV$,Vpts$,ϕplot$,Bplot$,Iplot$,Vplot$},ΔνD$=

FE`Lines$$6990550247868761661368102809126627966704〚2〛

2kFE`T$$6990550247868761661368102809126627966704

FE`Lines$$6990550247868761661368102809126627966704〚1〛

+

FE`vturb$$6990550247868761661368102809126627966704100000

10

9



2

c

This Demonstration discusses the effects of a magnetic field on observations of certain emission lines. Strong magnetic fields can split emission and absorption lines, an effect discovered by Pieter Zeeman in 1896. This is one of the very few ways scientists can measure magnetic field strength in the interstellar medium. By matching the observed Stokes V profile with a scaled derivative of the Stokes I (details below), the line-of-sight strength of the magnetic field can be determined.