High-resolution spectroscopy of low-mass stars

by Ulf Seemann
Doctoral thesis
Date of Examination:2014-04-02
Date of issue:2015-03-23
Advisor:Prof. Dr. Ansgar Reiners
Referee:Prof. Dr. Stefan Dreizler
Referee:Prof. Dr. Artie Hatzes
Referee:Prof. Dr. Jürgen Schmitt
Persistent Address: http://dx.doi.org/10.53846/goediss-4979

 

 

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Abstract

English

High-resolution spectroscopy is employed to investigate a large sample of open cluster low-mass stars. The stellar rotation and magnetic activity of these stars are measured and their correlation is studied. I find in this sample that the same relation between these parameters holds on either side around the mass where stellar structure changes from partially to fully convective. These results promote a rotation driven magnetic dynamo mechanism in this whole mass regime for stars of intermediate ages (∼ 625Myr), and advocate against a correlation between rapid rotation prevalence and the transition to full convection. In this work, also a new wavelength calibration device is developed for the technique of highresolution spectroscopy. This device enables unprecedented long pathlengths in transmission spectroscopy of absorption gases for wavelength referencing. The concept and design are presented and a detailed implementation of this design for a high-resolution near-infrared spectrograph (VLT/CRIRES) is modelled and characterized. The novel approach allows for higher precision wavelength calibration than existing techniques of similar kind.
Keywords: high-resolution spectroscopy; low-mass stars; M-dwarfs; stellar rotation; stellar activity; magnetic fields; open clusters: Hyades; astronomical instrumentation; infrared spectrographs; VLT/CRIRES; wavelength calibration; gas absorption cell; high-precision radial velocities; optical design
 
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