I. I. Romanyuk

Magnetic fields of chemically peculiar stars. I. The catalog of magnetic CP stars

This is the first paper of the series dedicated to the analysis of the magnetism of chemically peculiar (CP) stars of the upper Main Sequence. We use our own measurements and published data to compile a catalog of magnetic CP stars containing a total of 326 objects with confidently detected magnetic fields and 29 stars which are very likely to possess magnetic field. We obtained the data on the magnetism of the overwhelming majority of the stars solely based on the analysis of longitudinal field component Be. The surface magnetic field, Bs, has been measured for 49 objects. Our analysis shows that the number of magnetic CP stars decreases with increasing field strength in accordance with exponential law, and stars with Be exceeding 5kG occur rarely (about 3% objects of our list).

Results of magnetic field measurements of CP stars carried out with the Russian 6-m telescope. I. Observations in 2007

This paper presents the results of magnetic field measurements for 39 chemically peculiar and 3 normal main sequence stars used as standard stars. Observations were carried out with the Main Stellar Spectrograph of the Russian 6-m telescope during 2007. Zeeman measurements for 8 stars were performed for the first time. The accuracy analysis for the longitudinal magnetic field measurements of the stars confirms that the systematic errors do not exceed 10–20 G and are within the quoted limits. The absence of significant instrumental deviations follows from the measurements of the CP stars with well-known Be variation curves.

Speckle interferometry of magnetic stars with the BTA. I. First results

We present the results of speckle interferometry of a sample of 117 chemically peculiar stars with global magnetic fields. The observations were made in December 2009 at the BTA with a spatial resolution of about 0.02″ in the visual spectral region. Twenty-nine stars were resolved into individual components, 14 of them for the first time (HD965, HD5797, HD8855, HD10783, HD16605, HD21699, HD35502, HD51418, HD64486, HD79158, HD103498, HD108651, HD213918, HD293764). In twelve cases a companion turned out to be 2–4m fainter than the main component—a magnetic star. Young hot Bp stars HD35502 and HD213918 are exceptions, since their companions are fainter by about 1m. In all cases, the linear distance from a star to its companion at the epoch of observations in the picture plane exceeded 109 km. Eighty-eight magnetic CP stars revealed no secondary components within our study. Thus, the fraction of speckle interferometric binaries in our sample amounts to 25%.

Magnetic field monitoring of the very slowly rotating CP star HD 965

With the 6-m telescope we performed the magnetic field Be measurements for the chemically peculiar star HD 965. During 2000–2015 we obtained over 30 spectra with a Zeeman circular polarization analyzer. The longitudinal field reaches +600 G at the positive extremum and goes below −1300 G at the negative one. The magnetic monitoring of the star shows that the period of Be variability, i.e., the rotation period, exceeds 15 years. Thus, HD 965 belongs to the five slowest rotators among magnetic stars.

Chemically peculiar stars in the orion OB1 association. I. occurrence frequency, spatial distribution, and kinematics

A total of 85 CP stars of various types are identified among 814 members of the OriOB1 association. The fraction of CP stars decreases with age for different cluster subgroups: from 15.1% in the youngest subgroup (b) to 7.7% in the oldest one (a). Individual comments are provided for each of the 85 stars, where we analyze the physical parameters and distance of the objects. All the 23 Am stars identified as a result of this study are found to have heliocentric distances between 100 and 300 pc and appear not to be members of the OrionOB1 association, but foreground objects. We identified 59 Bp stars, which account for 13.4% of the total number of B-type stars in the association. The fraction of peculiar B-type stars in the OriOB1 association is found to be twice higher than that of peculiar A-type stars. The same is true for field stars. The association contains 22 magnetic stars, out of which 21 are Bp stars and only one is an Ap star. Seventeen of these stars are objects with anomalous helium lines. Magnetic stars show a well-defined tendency to concentrate in the central region of the association (in Orion’s Belt), which contains most of these objects. No significant differences are found between the field strengths in the B-type stars of the association and Bp-type field stars, although there is a noticeable trend for He-rich stars to have stronger fields compared to He-weak stars. We identified 17 binaries, which make up 20% of the total number of peculiar stars studied, which is the standard ratio for CP stars. Except for one HgMn star (HD35548), the radial velocities and proper motions of our identified objects are consistent with the corresponding parameters of normal B-type stars.

On discovery of strong magnetic field in the binary system HD34736

We present the results of a study of the star HD34736. The spectropolarimetric observations carried out at the 6-m telescope showed the presence of a strong variable longitudinal magnetic field, exceeding −4500 G. The analysis of the Hipparcos photometry gives a set of possible periods of the brightness variability of the star, of which

Magnetic B-type stars of the main sequence. I. Problem formulation and selection of objects for observations

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Magnetic fields of chemically peculiar and related stars. I. Main results of 2014 and near-future prospects

is preferred. The variable radial velocity of spectral lines of the star and some signatures of lines of at least one other component show that HD34736 is a binary short-period system. Modeling of the spectra allowed us to estimate the effective temperature Teff of the stars (13 700 and 11 500 K) and their projected rotational velocities υ sin i (73 and ≥ 90 km s−1). The analysis of all the available information about the star allows us to hypothesize that the object of study is a close, possibly interacting binary system.