The complex picture of HD 24712: First magnetic Doppler images of a roAp star
- Autor(en)
- Theresa Lüftinger, Oleg Kochukhov, T. Ryabchikova, Werner Wolfgang Weiss, I. Ilyin
- Abstrakt
We present the first analysis of the structure of the surface magnetic field of a rapidly oscillating Ap (roAp) star. We deduce information about magnetic field geometry and abundance distributions of a number of chemical elements on the surface of the hitherto best studied roAp star, HD 24712, using an elaborate magnetic Doppler Imaging (MDI) code, INVERS10, which allows to reconstruct simultaneously and consistently the magnetic field geometry and elemental abundance distributions on a stellar surface without any a priory assumptions. For this purpose we analysed time series spectra obtained in Stokes I and V parameters with the SOFIN polarimeter and recover surface abundance structures of sixteen different chemical elements, respectively ions, including Mg, Ca, Sc, Ti, Cr, Fe, Co, Ni, Y, La, Ce, Pr, Nd, Gd, Tb, and Dy. We find and confirm a clear dipolar structure of the surface magnetic field and unexpected correlation of elemental abundance to this field: one group of elements accumulates solely at the phase of maximum magnetic field strength, whereas the other group avoids this region and is enhanced around minimum magnetic field. We also observe relative shifts of abundance enhancement or depletion regions between the various elements exhibiting otherwise similar behaviour. We compare our results to detailed pulsational analysis of high quality spectroscopic data and to photometry from space. Recent theoretical investigations give rise to the possibility of relating the shifts mentioned above to the influence of the magnetic geometry on pulsational phase shifts.
- Organisation(en)
- Institut für Astrophysik
- Externe Organisation(en)
- Uppsala University, Russian Academy of Sciences, Universität Wien, Leibniz-Institut für Astrophysik Potsdam
- Seiten
- 119-134
- Anzahl der Seiten
- 16
- Publikationsdatum
- 2007
- ÖFOS 2012
- 1030 Physik, Astronomie
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/de670c77-e81a-4acd-831a-505451389722