Journal
ASTRONOMY & ASTROPHYSICS
Volume 509, Issue -, Pages -Publisher
EDP SCIENCES S A
DOI: 10.1051/0004-6361/200811545
Keywords
stars: imaging; stars: atmospheres; stars: abundances; stars: chemically peculiar; stars: magnetic field; stars: individual: HD 24712
Categories
Funding
- Austrian Science Fund [FWF-PP17890]
- Royal Swedish Academy of Sciences [11630102]
- RFBR [08-02-00469a]
- RAS Presidium
- Knut and Alice Wallenberg Foundation
Ask authors/readers for more resources
Aims. We present the first magnetic Doppler images of a rapidly oscillating Ap (roAp) star. Methods. 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, HD24712, using the magnetic Doppler imaging (MDI) code, INVERS10, which allows us to reconstruct simultaneously and consistently the magnetic field geometry and elemental abundance distributions on a stellar surface. For this purpose we analyse time series spectra obtained in Stokes I and V parameters with the SOFIN polarimeter at the Nordic Optical Telescope 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. For the rare earth elements (REE) Pr and Nd separate maps were obtained using lines of the first and the second ionization stage. Results. We find and confirm a clear dipolar structure of the surface magnetic field and an unexpected correlation of elemental abundance with respect to this field: one group of elements accumulates solely where the positive magnetic pole is visible, whereas the other group avoids this region and is enhanced where the magnetic equatorial region dominates the visible stellar surface. We also observe relative shifts of abundance enhancement- or depletion regions between the various elements exhibiting otherwise similar behaviour.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available