TY - JOUR

T1 - Magnetic field geometry and chemical abundance distribution of the He-strong star CPD-57 degrees 3509

AU - Hubrig, S.

AU - Przybilla, N.

AU - Korhonen, H.

AU - Ilyin, I.

AU - Schoeller, M.

AU - Jaervinen, S. P.

AU - Nieva, M. -F.

AU - Scholz, R. -D.

AU - Kimeswenger, S.

AU - Ramolla, M.

AU - Kholtygin, A. F.

AU - Briquet, M.

PY - 2017/10

Y1 - 2017/10

N2 - 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 the FOcal Reducer low-dispersion Spectrograph 2 and high-resolution UV-Visual Echelle Spectrograph 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 6.36 d 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 3.9-4.5 kG. 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. Furthermore, 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 β Cep like pulsations. A small periodic variability in line with the changes of the magnetic field strength is clearly seen in the photometric data.

AB - 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 the FOcal Reducer low-dispersion Spectrograph 2 and high-resolution UV-Visual Echelle Spectrograph 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 6.36 d 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 3.9-4.5 kG. 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. Furthermore, 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 β Cep like pulsations. A small periodic variability in line with the changes of the magnetic field strength is clearly seen in the photometric data.

KW - stars: abundances

KW - stars: evolution

KW - stars: individual: CPD-57 degrees 3509

KW - stars: magnetic field

KW - stars: massive

KW - stars: oscillations

KW - LINE-DATA-BASE

KW - AP-STARS

KW - OPEN CLUSTERS

KW - ROAP STARS

KW - SURFACE

KW - VLT

KW - MAGNETOSPHERE

KW - TELESCOPE

KW - EVOLUTION

KW - CATALOG

U2 - 10.1093/mnras/stx1654

DO - 10.1093/mnras/stx1654

M3 - статья

VL - 471

SP - 1543

EP - 1552

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 2

ER -