CAOSP abstracts, Volume: 38, No.: 2, year: 2008

Author(s): Lüftinger, T.; Kochukhov, O.; Ryabchikova, T.; Piskunov, N.; Weiss, W.W.; Ilyin, I.
Journal: Contributions of the Astronomical Observatory Skalnaté Pleso, vol. 38, no. 2, p. 335-340.
Date: 4/2008
Title: 3D atmospheric structure of the prototypical roAp star HD 24712 (HR1217)
Keyword(s): stars: chemically peculiar, stars: magnetic fields, methods: numerical, techniques: polarimetric, stars: individual: HD 24712
Pages: 335 -- 340

Abstract: The first analysis of the structure of the surface magnetic field of a rapidly oscillating Ap (roAp) star is presented. We obtain information about abundance distributions of a number of chemical elements on the surface of the prototypical roAp star HD 24712 and about magnetic field geometry. Inverting rotationally modulated spectra in Stokes parameters I and V obtained with the SOFIN spectropolarimeter attached to the NOT, we recover surface abundance structures of sixteen different chemical elements, including Mg, Ca, Sc, Ti, Cr, Fe, Co, Ni, Y, La, Ce, Pr, Nd, Gd, Tb, and Dy. Our analysis reveal a pure dipolar structure of the stellar magnetic field and surprising and unexpected correlations of the various elemental surface abundance structures to this field geometry. Stratification analysis at phases of both magnetic extrema enable us to obtain the vertical dimension in the atmosphere of HD 24712. High time resolved spectroscopic data and observations obtained with the MOST space photometer give us the possibility to compare (Lüftinger, 2007) our results to detailed pulsational analysis.