Chemical spots on the surface of the strongly magnetic Herbig Ae star HD 101412
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Due to the knowledge of the rotation period and the presence of a rather
strong surface magnetic field, the sharp-lined young Herbig Ae star HD
101412 with a rotation period of 42 d has become one of the most
well-studied targets among the Herbig Ae stars. High-resolution HARPS
polarimetric spectra of HD 101412 were recently obtained on seven
different epochs. Our study of the spectral variability over the part of
the rotation cycle covered by HARPS observations reveals that the line
profiles of the elements Mg, Si, Ca, Ti, Cr, Mn, Fe, and Sr are clearly
variable while He exhibits variability that is opposite to the behaviour
of the other elements studied. Since classical Ap stars usually show a
relationship between the magnetic field geometry and the distribution of
element spots, we used in our magnetic field measurements different line
samples belonging to the three elements with the most numerous spectral
lines, Ti, Cr, and Fe. Over the time interval covered by the available
spectra, the longitudinal magnetic field changes sign from negative to
positive polarity. The distribution of field values obtained using Ti,
Cr, and Fe lines is, however, completely different compared to the
magnetic field values determined in previous low-resolution FORS 2
measurements, where hydrogen Balmer lines are the main contributors to
the magnetic field measurements, indicating the presence of
concentration of the studied iron-peak elements in the region of the
magnetic equator. Further, we discuss the potential role of
contamination by the surrounding warm circumstellar matter in the
appearance of Zeeman features obtained using Ti lines.
Based on data obtained from the ESO Science Archive Facility under
request MSCHOELLER 101895 (ESO programme Nos. 081.C-0410(A),
085.C-0137(A), and 187.D-0917(D)).
Originalsprog | Engelsk |
---|---|
Tidsskrift | Astronomische Nachrichten |
Vol/bind | 337 |
Udgave nummer | 3 |
Sider (fra-til) | 329-338 |
ISSN | 0004-6337 |
DOI | |
Status | Udgivet - 1 mar. 2016 |
ID: 170454890