Surface structure of the CoRoT CP2 target star HD 50773

Lüftinger, T.; Fröhlich, H.‐E.; Weiß, W. W.; Petit, P.; Aurière, M.; Nesvacil, N.; Gruberbauer, M.; Shulyak, D.; Alécian, E.; Baglin, A.; Baudin, F.; Catala, C.; Donati, J.‐F.; Kochukhov, Oleg; Michel, E.; Piskunov, Nikolai; Roudier, Th.; Samadi, R.

doi:10.1051/0004-6361/200912239

Cited by 49 publications

(52 citation statements)

References 24 publications

(38 reference statements)

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“…Furthermore, in spite of the weakness of the observed Zeeman signatures, we find repeated hints that the field structure of Vega is more complex than the large-scale fields of chemically peculiar stars (e.g. Lüftinger et al 2010), with about half of the poloidal magnetic energy reconstructed in spherical harmonics terms with > 3 (except when using the rotation period of Hill et al 2010). The complexity of this geometry is at odds with a fossil field hypothesis, since only low-order field geometries are expected to survive on long timescales.…”

Section: Discussionmentioning

confidence: 53%

The rapid rotation and complex magnetic field geometry of Vega

Petit

Lignières

Wade

et al. 2010

A&A

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106

144

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Context. The recent discovery of a weak surface magnetic field on the normal intermediate-mass star Vega raises the question of the origin of this magnetism in a class of stars that was not previously known to host detectable magnetic fields. Aims. We aim to confirm the field detection reported by Lignières et al. (2009, A&A, 500, L41) and provide additional observational constraints about the field characteristics, by modelling the large-scale magnetic geometry of the star and by investigating a possible seasonal variability of the reconstructed field topology. Methods. We analyse a total of 799 high-resolution circularly-polarized spectra collected with the NARVAL and ESPaDOnS spectropolarimeters during 2008 and 2009. Using about 1100 spectral lines, we employ a cross-correlation procedure to compute, from each spectrum, a mean polarized line profile with a signal-to-noise ratio of about 20 000. The technique of Zeeman-Doppler Imaging is then used to determine the rotation period of the star and reconstruct the large-scale magnetic geometry of Vega at two different epochs. Results. We confirm the detection of circularly polarized signatures in the mean line profiles. The signal shows up in four independent data sets acquired with both NARVAL and ESPaDOnS. The amplitude of the polarized signatures is larger when spectral lines of higher magnetic sensitivity are selected for the analysis, as expected for a signal of magnetic origin. The short-term evolution of polarized signatures is consistent with a rotational period of 0.732 ± 0.008 d. The reconstruction of the magnetic topology unveils a magnetic region of radial field orientation, closely concentrated around the rotation pole. This polar feature is accompanied by a small number of magnetic patches at lower latitudes. No significant variability in the field structure is observed over a time span of one year. Conclusions. The repeated observational evidence that Vega possesses a weak photospheric magnetic field strongly suggests that a previously unknown type of magnetic stars exists in the intermediate-mass domain. Vega may well be the first confirmed member of a much larger, as yet unexplored, class of weakly-magnetic stars now investigatable with the current generation of stellar spectropolarimeters.

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Section: Discussionmentioning

confidence: 53%

The rapid rotation and complex magnetic field geometry of Vega

Petit

Lignières

Wade

et al. 2010

A&A

Self Cite

106

144

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“…Lüftinger et al 2010). Following the fossil field hypothesis further, we can derive a rough estimate of the surface field strength of the main sequence progenitor of β Ceti.…”

Section: Discussionmentioning

confidence: 99%

Magnetic field structure in single late-type giants:βCeti in 2010–2012

Tsvetkova

Petit

Aurière

et al. 2013

A&A

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Aims. We study the behavior of the magnetic field and the line activity indicators of the single late-type giant β Ceti. Using spectropolarimetric data, we aim to reconstruct the magnetic field structure on the star's surface and to present the first magnetic maps for β Ceti. Methods. The data were obtained using two spectropolarimeters -Narval at the Bernard Lyot Télescope, Pic du Midi, France, and ESPaDOnS at CFHT, Hawaii. Thirty-eight circularly-polarized spectra have been collected in the period June 2010-January 2012. The least square deconvolution method was applied for extracting high signal-to-noise ratio line profiles, from which we measured the surface-averaged longitudinal magnetic field B l . Chromospheric activity indicators CaII K, Hα, CaII IR (854.2 nm), and radial velocity were simultaneously measured, and their variability was analyzed along with the behavior of B l . The Zeeman Doppler imaging (ZDI) inversion technique was employed for reconstructing the large-scale magnetic field and two magnetic maps of β Ceti are presented for two periods (June 2010-December 2010 and June 2011-January 2012). Results. The B l stays with a same positive polarity for the whole observational period and shows significant variations in the interval 0.1-8.2 G. The behavior of the line activity indicators is in good agreement with the B l variations. Searching for periodic signals in the Stokes V time series, we found a possible rotation period of 215 days. The two ZDI maps show a mainly axisymmetric and poloidal magnetic topology and a simple surface magnetic field configuration dominated by a dipole. Little evolution is observed between the two maps, in spite of a 1 yr interval between both subsets. We also use state-of-the-art stellar evolution models to constrain the evolutionary status of β Ceti. We derive a mass of 3.5 M and propose that this star is already in the central helium-burning phase. Conclusions. Considering all our results and the evolutionary status of the star, we suggest that dynamo action alone may not be efficient enough to account for the high magnetic activity of β Ceti. As an alternate option, we propose that it is a descendant of an Ap star presently undergoing central helium-burning and still exhibiting a remnant of the Ap star magnetic field.

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“…The code uses a regularized minimization algorithm and can treat many individual lines and their blends simultaneously. A detailed description of the software and some practical applications are given by, e.g., Piskunov & Rice (1993), Lüftinger et al (2010), and Kochukhov et al (2004).…”

Section: Basic Methodsmentioning

confidence: 99%

Multi-element Doppler imaging of the CP2 star HD 3980

Nesvacil

Lüftinger

Shulyak

et al. 2012

A&A

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Context. In atmospheres of magnetic main-sequence stars, the diffusion of chemical elements leads to a number of observed anomalies, such as abundance spots across the stellar surface. Aims. The aim of this study was to derive a detailed picture of the surface abundance distribution of the magnetic chemically peculiar star HD 3980. Methods. Based on high-resolution, phase-resolved spectroscopic observations of the magnetic A-type star HD 3980, the inhomogeneous surface distribution of 13 chemical elements (Li, O, Si, Ca, Cr, Mn, Fe, La, Ce, Pr, Nd, Eu, and Gd) has been reconstructed. The INVERS12 code was used to invert the rotational variability in line profiles to elemental surface distributions. Results. Assuming a centered, dominantly dipolar magnetic field configuration, we find that Li, O, Mg, Pr, and Nd are mainly concentrated in the area of the magnetic poles and depleted in the regions around the magnetic equator. The high abundance spots of Si, La, Ce, Eu, and Gd are located between the magnetic poles and the magnetic equator. Except for La, which is clearly depleted in the area of the magnetic poles, no obvious correlation with the magnetic field has been found for these elements otherwise. Ca, Cr, and Fe appear enhanced along the rotational equator and the area around the magnetic poles. The intersection between the magnetic and the rotational equator constitutes an exception, especially for Ca and Cr, which are depleted in that region. Conclusions. No obvious correlation between the theoretically predicted abundance patterns and those determined in this study could be found. This can be attributed to a lack of up-to-date theoretical models, especially for rare earth elements.

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Surface structure of the CoRoT CP2 target star HD 50773

Cited by 49 publications

References 24 publications

The rapid rotation and complex magnetic field geometry of Vega

The rapid rotation and complex magnetic field geometry of Vega

Magnetic field structure in single late-type giants:βCeti in 2010–2012

Multi-element Doppler imaging of the CP2 star HD 3980

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