CRIRES User Manual
Doc. Number: ESO-254264
Doc. Version: P109.4
Issued on:
2021-12-01
Page:
11 of 99
Document Classification: ESO Internal Use [Confidential for Non-ESO Staff]
measure with greater accuracy magnetic fields in M-dwarfs and brown dwarfs for several
reasons:
1) The Zeeman splitting of a spectral line is proportional to λ
2
, so there is a huge leverage
in going to the IR;; 2) For cool objects most of the flux is in the IR so there is also a gain due
to the increased signal-to-noise ratio. 3) In order to disentangle Zeeman broadening from
other broadening effects one must compare the broadening of Zeeman sensitive lines to
magnetically insensitive lines. The large wavelength coverage of CRIRES will include many
more lines of different magnetic sensitivities needed for an accurate determination of the
field strength. 4) The capability of CRIRES to take circular and linear polarized spectra will
support these measurements.