Magnetic field of the Ap star 52 Her

Бычков, В. Д.; Bychkova, L. B.; Madej, J.; Panferov, A. A.

doi:10.1134/s199034131202006x

Cited by 5 publications

(7 citation statements)

References 25 publications

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“…e.g. Bychkov et al 2012), it seems secure that the oblique rotator model is applicable throughout the whole period range of mCP stars and that the period of the observed variations, regardless of the involved time-scales, is the rotation period. This leads to a spread in rotational velocities of about 5−6 orders of magnitude among the A-type stars, which is unique among non-degenerate stars (Mathys 2015).…”

Section: Rotation Of Magnetic Cp Starsmentioning

confidence: 95%

An investigation of the rotational properties of magnetic chemically peculiar stars

Netopil

Paunzen

Hümmerich

et al. 2017

Monthly Notices of the Royal Astronomical Society

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The magnetic chemically peculiar (mCP) stars of the upper main sequence exhibit strong, globally organized magnetic fields that are inclined to the rotational axis and facilitate the development of surface abundance inhomogeneities resulting in photometric and spectroscopic variability. Therefore, mCP stars are perfectly suited for a direct measurement of the rotational period without the need for any additional calibrations. We have investigated the rotational properties of mCP stars based on an unprecedentedly large sample consisting of more than 500 objects with known rotational periods. Using precise parallaxes from the Hipparcos and Gaia satellite missions, wellestablished photometric calibrations and state-of-the-art evolutionary models, we have determined the location of our sample stars in the Hertzsprung-Russell diagram and derived astrophysical parameters such as stellar masses, effective temperature, radii, inclinations and critical rotational velocities. We have confirmed the conservation of angular momentum during the main sequence evolution; no signs of additional magnetic braking were found. The inclination angles of the rotational axes are randomly distributed, although an apparent excess of fast rotators with comparable inclination angles has been observed. We have found a rotation rate of υ/υ crit ≥ 0.5 for several stars, whose characteristics cannot be explained by current models. For the first time, we have derived the relationship between mass and rotation rate of mCP stars, and provide an analysis that links mass and rotation with magnetic field strength. Our sample is unique and offers crucial input for forthcoming evolutionary models that include the effects of magnetic fields for upper main sequence stars.

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Section: Rotation Of Magnetic Cp Starsmentioning

confidence: 95%

An investigation of the rotational properties of magnetic chemically peculiar stars

Netopil

Paunzen

Hümmerich

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…The magnetic measurements of Gamma Equ were derived from the Zeeman spectra, obtained in the coudé focus of the 1-m telescope of SAO RAS. The instrumentation and data reduction procedures were described in Bychkov (2008). In our case, we analysed high-quality spectral data (R = 45000, CCD, S/N ≈ 100) and processed them using the MIDAS software.…”

Section: Details Of Our Observationsmentioning

confidence: 99%

“…Assuming that the scatter of Be values due to inaccurate measurements and other reasons is described by a normal law of distribution, the probable error σ(Be) was computed. Instrumental effects are taken into account according to Bychkov et al (2000). During observations, we regularly registered the magnetic standards, α 2 CVn and 53 Cam, and the standards of the null field α CMi, α Boo, the Moon, etc., as described in Bychkov et al (2006).…”

Section: Details Of Our Observationsmentioning

confidence: 99%

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Periods of magnetic field variations in the Ap star γ Equulei (HD 201601)

Бычков

Бычкова

Madej

2015

Mon. Not. R. Astron. Soc.

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This paper presents a series of 95 new measurements of the longitudinal (effective) magnetic field B e of the Ap star γ Equ (HD 201601). Observations were obtained at the coudé focus of the 1-m reflector at the Special Astrophysical Observatory (SAO RAS) in Russia over a time period of 4190 days (more than 11 years). We compiled a long record of B e points, adding our measurements to all published data. The time series of magnetic data consists of 395 B e points extending for 24488 days, i.e. over 67 years. Various methods of period determination were examined for the case in which the length of the observed time series is rather short and amounts only to 69 percent of the period. We argue that the fitting of a sine wave to the observed B e points by least squares yields the most reliable period in the case of γ Equ. Therefore, the best period for long-term magnetic variations of γ Equ, and hence the rotational period, is P rot = 35462.5 ± 1149 days = 97.16 ± 3.15 years.

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“…In the y/V plot, filled stars, pluses, and filled triangles are the V values of Abt & Golson (1962), Stepien (1968) and Winzer (1974), respectively. In the H e plot, open triangles, open diamonds and filled diamonds are the average values of Babcock (1958), Scholz (1978Scholz ( , 1983 and Bychkov et al 2012, respectively. The Eu and Cr plots represent estimated line strengths; the filled inverted triangles are the values of Rice (1988).…”

Section: Hd 8441=hn Andmentioning

confidence: 99%

On the Photometric Variability of Very Sharp-lined Cool mCP Stars

Pyper

Adelman

2017

PASP

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We investigate the photometric variability of very sharp-lined cool mCP stars from a list published in 1970 by Dr. George W. Preston who suggested that some belonged to the long-period tail of the period distribution. In this study, we discuss our Strömgren uvby observations obtained with the Four College Automated Photometric Telescope (FCAPT) at the Fairborn Observatory for 22 of the stars in Preston's list. We improved the periods of 11 stars. Further, we discuss results from the literature concerning the light, magnetic, and spectrum variability of these stars. Eleven of the stars are found to have periods longer than 20 days, and all but one of these stars display variations in the u and v filters that cannot be explained by the simple oblique rotator theory. We discuss some possible causes of this behavior.

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Magnetic field of the Ap star 52 Her

Cited by 5 publications

References 25 publications

An investigation of the rotational properties of magnetic chemically peculiar stars

An investigation of the rotational properties of magnetic chemically peculiar stars

Periods of magnetic field variations in the Ap star γ Equulei (HD 201601)

On the Photometric Variability of Very Sharp-lined Cool mCP Stars

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