Measurements of stellar magnetic fields using synthetic spectrum fitting

• Main Authors: Nielsen, Krister, Wahlgren, Glenn
• Format: Article in Journal/Newspaper
• Language: English
• Published: EDP Sciences 2002
• Subjects: Astronomy; Astrophysics and Cosmology; magnetic fields; line: profiles; stars: chemically peculiar; Norway; Lambda; Iceland
• Online Access: https://lup.lub.lu.se/record/130314; https://doi.org/10.1051/0004-6361:20021276; https://portal.research.lu.se/files/4496133/624134.pdf

A sample of Ap and Bp stars have been investigated with respect to theirsurface magnetic field using synthetic spectrum fitting. The advantageof this technique is the simplicity in determining the surface fieldstrength and the possibility to apply it to objects whose spectrum doesnot display resolved Zeeman components. We show the usefulness of themethod by demonstrations on stellar spectra with resolved Zeemancomponents, where the results have been compared with values based onmeasurements of the Zeeman splitting for the magnetically sensitive FeIi lambda 6149 line. The objects HD 192678 and HD 165474 have been observed over their rotationalperiod to investigate magnetic field variations. The analysis is thenextended to objects where no resolved structure is observed. The rapidlyrotating stars HD 22316 and HD10783 are used as examples where this method is useful toachieve a value of the surface field. The relative intensification ofthe Fe Ii lambda lambda 6147, 6149 lines is investigated in an attemptto understand its relation to the surface magnetic field strength forthe stars HD 22316 and HD 10783. Based on observations obtained with theNordic Optical Telescope, operated on the island of La Palma jointly byDenmark, Finland, Iceland, Norway, and Sweden, in the SpanishObservatorio del Roque de los Muchachos of the Instituto de Astrofisicade Canarias.