Lithium in Cool Magnetic CP Stars: Some New Results of Observations, Using CAT (ESO) 2.6m (CrAO), (NOT) La Palma Telescopes

Polosukhina, N. S.; Kurtz, D. W.; Hack, M.; North, P.; Ilyin, I.; Zverko, J.

doi:10.1017/s0074180900167130

Cited by 10 publications

(19 citation statements)

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“…in HD 83368, Sp. A8, Polosukhina et al (1999) found a phase shift between the photometric and magnetic maxima of −0.062 P , and between the central wavelength of the Li 6708Å line and the photometric maximum of +0.029 P . In some cases the light curves in different colors are quite dissimilar, e.g.…”

Section: Introductionmentioning

confidence: 90%

On‐line database of photometric observations of magnetic chemically peculiar stars

Mikulášek¹,

Janík

Zverko

et al. 2007

Astron Nachr

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We present our extensive project of the On-line database of photometric observations of magnetic chemically peculiar stars to collect published data of photometric observations of magnetic chemically peculiar (mCP) stars in the optical and near IR regions. Now the nascent database contains more than 107 000 photometric measurements of 102 mCP stars and will be continually supplemented with published or new photometric data on these and about 150 additional mCP stars. This report describes the structure and organization of the database. Moreover, for the all included data we estimated the error of measurements and the effective amplitudes of the light curves.

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Section: Introductionmentioning

confidence: 90%

On‐line database of photometric observations of magnetic chemically peculiar stars

Mikulášek¹,

Janík

Zverko

et al. 2007

Astron Nachr

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“…Model of the oblique rotator explaining the behaviour of the Li i line is shown in Fig. 2 (Polosukhina et al 1999).…”

Section: Main Stages Of the Project Realizationmentioning

confidence: 99%

The enigma of lithium in roAp stars

et al. 2004

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Abstract. An internacional project "Lithium in magnetic Ap stars" has been run since 1996 with the purpose of creating an observational database allowing systematic studies of the abnormal occurence of lithium on the surface of cool Ap stars. The 2.6 m telescope at the Crimean Astrophysical Observatory, the ESO CAT, ESO 1.52 m telescope with FEROS, the Nordic Optical Telescope, and the 74" telescope at Mount Stromlo were employed to collect observations at the regions of the lithium resonance lines λ 6103 and λ 6708Å.Observations of the roAp-stars HD 83368, HD 60435 and HD 3980 revealed considerable periodical Doppler shifts of the line of lithium λ 6708Å which can be explained by the presence of lithium spots on their surfaces. Conjunction with structures of the magnetic field is apparent.A detailed study of the blend at λ 6708Å in HD 101065 confirmed the anomalous overabundance of lithium amounting to 3.1 dex, as well as unusual isotopic ratio 6 Li/ 7 Li∼ 0.3.

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“…A simple test (Fig. 2) indicates a possible correlation between "Li-deficiency" and Ce abundance, i.e., a star classified by Polosukhina et al (1999) as Li-deficient show no significant overabundance of Ce in its spectrum. Element abundances derived from the whole available spectral region will be used for further, more detailed modelling of the λ 6708 feature in question.…”

Section: Abundance Analysis Of Blend Componentsmentioning

confidence: 99%

“…Moreover, the central wavelength showed a redward shift 0.2Å , varying from star to star. Polosukhina et al (1999) presented the results of the study of the behavior of the Li feature with rotational phase in 8 Ap stars. For four stars in the sample, HD 83368, HD 60435, β CrB and HD 188041, wavelength variations with the rotational period have been discovered and the conclusion has been made that the Li feature can be identified as the resonant Li i doublet and the variability of the feature is explained by the existence of Li rich spots on the stellar surfaces.…”

Section: Introductionmentioning

confidence: 99%

Testing the presence of lithium on the surfaces of cool Ap stars

Nesvacil

Hubrig²,

Mathys³

2004

Proc. IAU

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Abstract. The possibility of a quite high Li abundance in the Ap stars was first raised by Wallerstein & Merchant (1965). Since then many studies investigated the problem of Li. The more recent observations in the lithium region indicate that in some Ap stars the λ6708 feature is variable and this variability can be explained by the existence of Li rich spots on the stellar surface. Atomic data for the Ce ii λ6708.099 were released by the D.R.E.A.M. database in 2002. The line was used to identify the prominent suspected Li-feature in post AGB stars and might as well be responsible for the absorption feature in Ap stars. Recent studies have mentioned this possibility, but it has yet to be investigated in more detail. Other physical phenomena, such as the occurrence of a partial Paschen-Back effect in the presence of magnetic fields, as well as possible hyperfine structure splitting of some Rare Earth transitions, must be taken into account to provide correct line identifications in the wavelength region around the Li-doublet at λ6708. We discuss a possible strategy to clarify the presence of Li in Ap stars.

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Lithium in Cool Magnetic CP Stars: Some New Results of Observations, Using CAT (ESO) 2.6m (CrAO), (NOT) La Palma Telescopes

Cited by 10 publications

References 1 publication

On‐line database of photometric observations of magnetic chemically peculiar stars

On‐line database of photometric observations of magnetic chemically peculiar stars

The enigma of lithium in roAp stars

Testing the presence of lithium on the surfaces of cool Ap stars

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