Spectropolarimetric measurements of the mean longitudinal magnetic field of chemically peculiar stars

Leone, F.; Catanzaro, G.

doi:10.1051/0004-6361:20000450

Cited by 37 publications

(35 citation statements)

References 52 publications

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“…HD 125248 (CS Vir) is an extremely well-studied magnetic Ap star, with many longitudinal field measurements made by authors from Babcock (1958) to Leone & Catanzaro (2001). Typical standard errors of previous longitudinal field measurements have been hundreds of gauss, while we have made two measurements, both with σ = 43 G. Our measurements are in nearly perfect agreement with the purely sinusoidal longitudinal field curve seen in Fig.…”

Section: Hd 125248supporting

confidence: 79%

A highly sensitive search for magnetic fields in B, A and F stars

Shorlin

Wade

Donati

et al. 2002

A&A

154

197

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Abstract. Circular spectropolarimetric observations of 74 stars were obtained in an attempt to detect magnetic fields via the longitudinal Zeeman effect in their spectral lines. The sample observed includes 22 normal B, A and F stars, four emission-line B and A stars, 25 Am stars, 10 HgMn stars, two λ Boo stars and 11 magnetic Ap stars. Using the Least-Squares Deconvolution multi-line analysis approach , high precision Stokes I and V mean signatures were extracted from each spectrum. We find absolutely no evidence for magnetic fields in the normal, Am and HgMn stars, with upper limits on longitudinal field measurements usually considerably smaller than any previously obtained for these objects. We conclude that if any magnetic fields exist in the photospheres of these stars, these fields are not ordered as in the magnetic Ap stars, nor do they resemble the fields of active late-type stars. We also detect for the first time a field in the A2pSr star HD 108945 and make new precise measurements of longitudinal fields in five previously known magnetic Ap stars, but do not detect fields in five other stars classified as Ap SrCrEu. We also report new results for several binary systems, including a new v sin i for the rapidly rotating secondary of the Am-δ Del SB2 HD 110951.

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Section: Hd 125248supporting

confidence: 79%

A highly sensitive search for magnetic fields in B, A and F stars

Shorlin

Wade

Donati

et al. 2002

A&A

154

197

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“…The equipment, observations and data reduction procedures are described by Leone et al (2000). A detailed log of these observations is given by Leone & Catanzaro (2001). Due to the low resolution, this data set was not used for a direct comparison of synthetic vs. observed spectra, but only for determinations of longitudinal field (see Sect.…”

Section: Observations At the Osservatorio Astrofisico DI Cataniamentioning

confidence: 99%

A study of polarized spectra of magnetic CP stars: Predicted vs. observed Stokes IQUV profiles forβCrB and 53 Cam

Bagnulo¹,

Wade

Donati³

et al. 2001

A&A

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Abstract. We present a comparison of observed and calculated Stokes IQUV spectra of two well-known magnetic chemically peculiar stars, β Coronae Borealis and 53 Camelopardalis. The observed Stokes spectra were recently described by Wade et al. (2000a), and have been complemented with additional circularly polarized spectra obtained at the Special Astrophysical Observatory. The calculated spectra represent the predictions of new and previously published magnetic field models derived from the analysis of some surface averaged field estimates (e.g., longitudinal field, magnetic field modulus, etc.). We find that these magnetic models are not sufficient to account fully for the observed Stokes profiles -particularly remarkable is the disagreement between the predicted and observed Stokes Q and U profiles of 53 Cam. We suggest that this should be interpreted in terms of magnetic morphologies which are significantly more complex than the second-order multipolar expansions assumed in the models. However, it is clear that some of our inability to reproduce the detailed shapes of the Stokes IQUV profiles is unrelated to the magnetic models. For many metallic ions, for both stars, we found it impossible to account for the strengths and shapes of the observed spectral line profiles when we adopted a unique value for the individual ion abundance. We suggest that this results from strongly non-uniform distributions of these ions as a function of optical depth (i.e., chemical stratification), a hypothesis that is supported by comparison with simple chemically stratified models.

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“…The last two decades have seen rapid progress in the measurement of the surface magnetic fields (Mathys 1988(Mathys , 1991(Mathys , 1995a(Mathys , 1995bMathys & Hubrig 1997;Leone & Catanzaro 2001). First introduced by Mathys (1988), the moment technique relates the line profile asymmetries (while measuring the Stokes V parameter) to the mean values of the longitudinal magnetic field (first moment) and the crossover effect (second moment) for a given phase of stellar rotation.…”

Section: Introductionmentioning

confidence: 99%

Modeling the crossover variability in a differentially rotating star

Khalack

2002

A&A

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Abstract. Reconstruction of phase-dependent crossover effect variations is performed for a differentially rotating star assuming that point-like magnetic charges are distrubuted under the stellar surface. Models adopting the solar differential rotation law and an exponential rotation law are considered and compared to the case of a rigidly rotating star. It is shown that neglect of differential stellar rotation leads to underestimation of the equatorial rotational velocity by ∼2-5%.

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Spectropolarimetric measurements of the mean longitudinal magnetic field of chemically peculiar stars

Cited by 37 publications

References 52 publications

A highly sensitive search for magnetic fields in B, A and F stars

A highly sensitive search for magnetic fields in B, A and F stars

A study of polarized spectra of magnetic CP stars: Predicted vs. observed Stokes IQUV profiles forβCrB and 53 Cam

Modeling the crossover variability in a differentially rotating star

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