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| Paper: |
Investigation of Magnetically Sensitive FeH Lines |
| Volume: |
448, 16th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun |
| Page: |
1309 |
| Authors: |
Wende, S.; Reiners, A.; Seifahrt, A.; Shulyak, D.; Kochukhov, O. |
| Abstract: |
M-type stars exhibit strong magnetic fields towards decreasing effective temperatures.
The measurement of these fields is complicated due to missing
indicators. Molecular FeH lines provide an excellent means to
determine magnetic field strengths from the Zeeman broadening of
magnetically sensitive lines.
Our aim is the investigation of possible dependencies of the amount of
sensitivity to magnetic fields from rotational quantum number, branch,
and the projection of the total angular momentum onto the internuclear axis
(Ω).
We also compare results from computations with those from
observations.
We use high resolution CRIRES spectra of the two M dwarfs GJ1002
(M5.5 inactive) and GJ1224 (M4.5 active). Individual lines are
fitted by Gaussians and the obtained line depths and widths from the
active and inactive star can be compared with each other. In this
way, magnetically sensitive lines can be detected. For test purposes,
we do the same with computed spectra of FeH. One with zero magnetic
field and the other with a 2 kG magnetic field vector used
in the disc integration (i.e. pure radial at the disc center).
We found, in agreement with theory, that lines with high Ω show
strong sensitivity to magnetic fields. No obvious correlation with
branch or J was found, which was also expected for lines formed in
intermediate Hund's case. The computations agreed in general well with
the observations, but in many cases the individual splitting of
certain lines can be very different to observations. |
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