The Magnetic Field and other Parameters of the Chemically Peculiar Stars

1986 ◽  
pp. 33-36 ◽  
Author(s):  
Yu. V. Glagolevskij ◽  
I. I. Romanyuk ◽  
N. M. Chunakova
Keyword(s):  
Magnetic Field ◽  
Chemically Peculiar ◽  
Peculiar Stars ◽  
Chemically Peculiar Stars ◽  
The Magnetic Field

scholarly journals The Magnetic Field and other Parameters of the Chemically Peculiar Stars

1986 ◽  
Vol 90 ◽  
pp. 33-36
Author(s):  
Glagolevskij Yu.V. ◽  
Romanyuk I.I. ◽  
Chunakova N.M.
Keyword(s):  
Magnetic Field ◽  
Surface Field ◽  
Chemically Peculiar ◽  
Peculiar Stars ◽  
Magnetic Stars ◽  
Chemically Peculiar Stars ◽  
Working Out ◽  
The Magnetic Field ◽  
Multicolor Photometry

The surface field Bs ( but not the effective Be one ) is responsible for different processes occuring in the magnetic stars atmospheres. For this reason it is natural that different investigators are interested in working out and improving methods of determination of Bs. Especially great attention attracts the method based on using the multicolor Geneva photometry. Cramer and Maeder have found a dependence between Bs and parameter Z of multicolor photometry wich they use for the estimation of the surface field. But it is necessary to investigate this method before application. Due to this reason we have put the following two problems:A - The search for stars with a maximal predicted fieldB - Examination of calibration of Bs (Z).

scholarly journals Global properties of the light curves of magnetic, chemically peculiar stars as a testbed for the existence of dipole-like symmetry in surface structures

2019 ◽  
Vol 622 ◽  
pp. A199 ◽  
Author(s):  
M. Jagelka ◽  
Z. Mikulášek ◽  
S. Hümmerich ◽  
E. Paunzen
Keyword(s):  
Magnetic Field ◽  
Rotation Period ◽  
Principal Component ◽  
Light Curves ◽  
Surface Structures ◽  
Magnetic Field Topology ◽  
Chemically Peculiar ◽  
Peculiar Stars ◽  
Chemically Peculiar Stars ◽  
The Magnetic Field

Context. Magnetic, chemically peculiar stars are known for exhibiting surface abundance inhomogeneities (chemical spots) that lead to photometric and spectroscopic variability with the rotation period. It is commonly assumed that the surface structures are causally connected with the global magnetic field that dominates the photospheric and subphotospheric layers of these stars. As a rule, the observed magnetic fields show a simple dipole-like geometry, with the magnetic axis being noncollinear to the rotational one. Aims. The present study aims at detecting underlying patterns in the distribution of photometric spots in a sample of 650 magnetic, chemically peculiar stars and examines their link to the magnetic field topology. Methods. Photometric time-series observations from the ASAS-3 archive were employed to inspect the light-curve morphology of our sample stars and divide them into representative classes described using a principal component analysis. Theoretical light curves were derived from numerous simulations assuming different spot parameters and following the symmetry of a simple dipole magnetic field. These were subsequently compared with the observed light curves. Results. The results from our simulations are in contradiction with the observations and predict a much higher percentage of double-wave light curves than is actually observed. We thereby conclude that the distribution of the chemical spots does not follow the magnetic field topology, which indicates that the role of the magnetic field in the creation and maintenance of the surface structures may be more subsidiary than what is predicted by theoretical studies.

scholarly journals The Nonhomogeneous Distribution of Abundances and the Magnetic Field Measurements in CP Stars

1986 ◽  
Vol 90 ◽  
pp. 149-149
Author(s):  
F.A. Catalano
Keyword(s):  
Magnetic Field ◽  
Field Measurements ◽  
Homogeneous Distribution ◽  
Chemically Peculiar ◽  
Peculiar Stars ◽  
Magnetic Field Measurements ◽  
Chemically Peculiar Stars ◽  
The Magnetic Field

AbstractThe influence of the non homogeneous distribution of the abundance of elements on the magnetic field measurements in chemically peculiar stars is discussed.

scholarly journals K2 space photometry reveals rotational modulation and stellar pulsations in chemically peculiar A and B stars

2018 ◽  
Vol 616 ◽  
pp. A77 ◽  
Author(s):  
D. M. Bowman ◽  
B. Buysschaert ◽  
C. Neiner ◽  
P. I. Pápics ◽  
M. E. Oksala ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Intrinsic Variability ◽  
B Stars ◽  
Pulsating Stars ◽  
Chemically Peculiar ◽  
Large Scale Magnetic Field ◽  
Peculiar Stars ◽  
Show Evidence ◽  
Chemically Peculiar Stars

Context. The physics of magnetic hot stars and how a large-scale magnetic field affects their interior properties is largely unknown. Few studies have combined high-quality observations and modelling of magnetic pulsating stars, known as magneto-asteroseismology, primarily because of the dearth of detected pulsations in stars with a confirmed and well-characterised large-scale magnetic field. Aims. We aim to characterise observational signatures of rotation and pulsation in chemically peculiar candidate magnetic stars using photometry from the K2 space mission. Thus, we identify the best candidate targets for ground-based, optical spectropolarimetric follow-up observations to confirm the presence of a large-scale magnetic field. Methods. We employed customised reduction and detrending tools to process the K2 photometry into optimised light curves for a variability analysis. We searched for the periodic photometric signatures of rotational modulation caused by surface abundance inhomogeneities in 56 chemically peculiar A and B stars. Furthermore, we searched for intrinsic variability caused by pulsations (coherent or otherwise) in the amplitude spectra of these stars. Results. The rotation periods of 38 chemically peculiar stars are determined, 16 of which are the first determination of the rotation period in the literature. We confirm the discovery of high-overtone roAp pulsation modes in HD 177765 and find an additional 3 Ap and Bp stars that show evidence of high-overtone pressure modes found in roAp stars in the form of possible Nyquist alias frequencies in their amplitude spectra. Furthermore, we find 6 chemically peculiar stars that show evidence of intrinsic variability caused by gravity or pressure pulsation modes. Conclusions. The discovery of pulsations in a non-negligible fraction of chemically peculiar stars make these stars high-priority targets for spectropolarimetric campaigns to confirm the presence of their expected large-scale magnetic field. The ultimate goal is to perform magneto-asteroseismology and probe the interior physics of magnetic pulsating stars.

scholarly journals Surface Magnetic Field Measurements in Hot Chemically Peculiar Stars

1988 ◽  
Vol 132 ◽  
pp. 313-316
Author(s):  
Pierre. Didelon
Keyword(s):  
Magnetic Field ◽  
Field Measurements ◽  
Surface Magnetic Field ◽  
Surface Field ◽  
Chemically Peculiar ◽  
Peculiar Stars ◽  
Magnetic Field Measurements ◽  
First Results ◽  
Chemically Peculiar Stars ◽  
Good Agreement

The first results of magnetic field measurements are presented here for HD 187474, a slowly rotating Ap star. From resolved Zeeman pattern the strength of the field and its mean inclination were obtained. From differential magnetic broadening a second value of the field strength has been deduced, which is compatible with the previous one. The “Robinson” method has been tested and a good agreement is found between observed and calculated Zeeman broadening of FeII lines. This method can therefore certainly be used to measure the surface field in slow rotating chemically peculiar stars.

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