Magnetic field geometry and chemical abundance distribution of the He-strong star CPD -57 3509
| Autor: | Stefan Kimeswenger, R.-D. Scholz, M. Ramolla, Swetlana Hubrig, A. F. Kholtygin, Silva P. Järvinen, Ilya Ilyin, Norbert Przybilla, Maryline Briquet, Markus Schöller, Heidi Korhonen, M.-F. Nieva |
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| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
Physics
010308 nuclear & particles physics FOS: Physical sciences Magnetic dip chemistry.chemical_element Astronomy and Astrophysics Geometry 01 natural sciences Magnetic field Stars Dipole chemistry Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science Position (vector) Beta (plasma physics) 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) Helium Line (formation) |
| Popis: | The magnetic field of CPD -57 3509 was recently detected in the framework of the BOB (B fields in OB stars) collaboration. We acquired low-resolution spectropolarimetric observations of CPD -57 3509 with FORS2 and high-resolution UVES observations randomly distributed over a few months to search for periodicity, to study the magnetic field geometry, and to determine the surface distribution of silicon and helium. We also obtained supplementary photometric observations at a timeline similar to the spectroscopic and spectropolarimetric observations. A period of 6.36d was detected in the measurements of the mean longitudinal magnetic field. A sinusoidal fit to our measurements allowed us to constrain the magnetic field geometry and estimate the dipole strength in the range of 3.9-4.5kG. Our application of the Doppler imaging technique revealed the presence of He I spots located around the magnetic poles, with a strong concentration at the positive pole and a weaker one around the negative pole. In contrast, high concentration Si III spots are located close to the magnetic equator. Further, our analysis of the spectral variability of CPD -57 3509 on short time scales indicates distinct changes in shape and position of line profiles possibly caused by the presence of beta Cep-like pulsations. A small periodic variability in line with the changes of the magnetic field strength is clearly seen in the photometric data. 11 pages, 5 tables, 7 figures, accepted for publication in MNRAS |
| Databáze: | OpenAIRE |
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