The complex magnetic field topology of the cool Ap star 49 Cam

Silvester, J.; Kochukhov, Oleg; Rusomarov, N.; Wade, G. A.

doi:10.1093/mnras/stx1606

Cited by 19 publications

(17 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our assessment shows that these deviations are statistically significant. The distorted dipolar field topologies of θ Aur and ε UMa are qualitatively similar to the surface field structures found by ZDI studies of MCP stars with stronger fields Oksala et al 2015;Silvester et al 2015Silvester et al , 2017. This result suggests that there is no obvious trend of the degree of field complexity with its mean intensity.…”

Section: Conclusion and Discussionsupporting

confidence: 78%

“…These results contribute to the tension between empirical findings and the current diffusion theory predictions noted by several other recent ZDI studies of MCP stars (e.g. Silvester et al 2015Silvester et al , 2017Kochukhov et al 2017). In the light of this systematic disagreement it would be prudent to revisit the central assumption of atomic diffusion calculations that the local element accumulation is uniquely determined by the local magnetic field parameters.…”

Section: Conclusion and Discussionmentioning

confidence: 47%

“…The vast majority of recent ZDI studies of MCP stars also tend to be biased towards narrow-line stars with stronger than average magnetic fields (e.g. Kochukhov et al 2015;Rusomarov et al 2016Rusomarov et al , 2018Silvester et al 2014Silvester et al , 2015Silvester et al , 2017Yakunin et al 2015). Relatively little information is available about the structure of the weak magnetic fields of fast-rotating MCP stars, in spite of the fact that these objects include some of the brightest MCP stars with the most complete constraints on fundamental parameters, rotational variability, and surface chemistry.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Magnetic field topologies of the bright, weak-field Ap stars θ Aurigae andεUrsae Majoris

Kochukhov

Shultz

Neiner

2019

A&A

Self Cite

View full text Add to dashboard Cite

Context. The brightest magnetic chemically peculiar stars θ Aur and ε UMa were targeted by numerous studies of their photometric and spectroscopic variability. Detailed maps of chemical abundance spots were repeatedly derived for both stars. However, owing to the weakness of their surface magnetic fields, very little information on the magnetic field geometries of these stars is available. Aims. In this study we aim to determine detailed magnetic field topologies of θ Aur and ε UMa based on modern, high-resolution spectropolarimetric observations. Methods. Both targets were observed in all four Stokes parameters using the Narval and ESPaDOnS spectropolarimeters. A multiline technique of least-squares deconvolution was employed to detect polarisation signatures in spectral lines. These signatures were modelled with a Zeeman-Doppler imaging code. Results. We succeed in detecting variable circular and linear polarisation signatures for θ Aur. Only circular polarisation was detected for ε UMa. We obtain new sets of high-precision longitudinal magnetic field measurements using mean circular polarisation metal line profiles as well as hydrogen line cores, which are consistent with historical data. Magnetic inversions revealed distorted dipolar geometries in both stars. The Fe and Cr abundance distributions, reconstructed simultaneously with magnetic mapping, do not show a clear correlation with the local magnetic field properties, with the exception of a relative element underabundance in the horizontal field regions along the magnetic equators. Conclusions. Our study provides the first ever detailed surface magnetic field maps for broad-line, weak-field chemically peculiar stars, showing that their field topologies are qualitatively similar to those found in stronger field stars. The Fe and Cr chemical abundance maps reconstructed for θ Aur and ε UMa are at odds with the predictions of current theoretical atomic diffusion calculations.

show abstract

Section: Conclusion and Discussionsupporting

confidence: 78%

Section: Conclusion and Discussionmentioning

confidence: 47%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Magnetic field topologies of the bright, weak-field Ap stars θ Aurigae andεUrsae Majoris

Kochukhov

Shultz

Neiner

2019

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…Instead, fossil fields are known to affect diffusive processes in their radiative envelope (Michaud 1970;Alecian & Stift 2007), often leading to chemical abundance patches on their surface and, as a result, rotational modulation of spectral lines of various chemical elements in their spectra (e.g. Kochukhov et al 2015;Yakunin et al 2015;Silvester et al 2017). The energy distributions associated with magnetic intermediate-mass stars are also known to exhibit abnormal flux depressions in the UV (Kodaira 1969;Adelman 1975;Maitzen 1976b).…”

Section: Introductionmentioning

confidence: 99%

Magnetic OB[A] Stars with TESS: probing their Evolutionary and Rotational properties (MOBSTER) – I. First-light observations of known magnetic B and A stars

David-Uraz

Neiner

Sikora

et al. 2019

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

In this paper we introduce the MOBSTER collaboration and lay out its scientific goals. We present first results based on the analysis of nineteen previously known magnetic O, B and A stars observed in 2-minute cadence in sectors 1 and 2 of the Transiting Exoplanet Survey Satellite (TESS ) mission. We derive precise rotational periods from the newly obtained light curves and compare them to previously published values. We also discuss the overall photometric phenomenology of the known magnetic massive and intermediate-mass stars and propose an observational strategy to augment this population by taking advantage of the high-quality observations produced by TESS.

show abstract

“…Babcock 1956; Kochukhov et al 2015), although a few obvious examples of more complex fields have been discovered (e.g. Kochukhov et al 2011;Silvester et al 2017). Furthermore, both young and evolved MS mCP stars are known to exist (e.g.…”

Section: Introductionmentioning

confidence: 99%

A Volume Limited Survey of mCP Stars Within 100pc II: Rotational and Magnetic Properties

Sikora,

Wade,

Power

et al. 2018

Preprint

Self Cite

View full text Add to dashboard Cite

Various surveys focusing on the magnetic properties of intermediate-mass main sequence (MS) stars have been previously carried out. One particularly puzzling outcome of these surveys is the identification of a dichotomy between the strong ( 100 G), organized fields hosted by magnetic chemically peculiar (mCP) stars and the ultra-weak ( 1 G) fields associated with a small number of non-mCP MS stars. Despite attempts to detect intermediate strength fields (i.e. those with strengths 10 G and 100 G), remarkably few examples have been found. Whether this so-called "magnetic desert", separating the stars hosting ultra-weak fields from the mCP stars truly exists has not been definitively answered. In 2007, a volume-limited spectropolarimetric survey of mCP stars using the MuSiCoS spectropolarimeter was initiated to test the existence of the magnetic desert by attempting to reduce the biases inherent in previous surveys. Since then, we have obtained a large number of ESPaDOnS and NARVAL Stokes V measurements allowing this survey to be completed. Here we present the results of our homogeneous analysis of the rotational periods (inferred from photometric and magnetic variability) and magnetic properties (dipole field strengths and obliquity angles) of the 52 confirmed mCP stars located within a heliocentric distance of 100 pc. No mCP stars exhibiting field strengths 300 G are found within the sample, which is consistent with the notion that the magnetic desert is a real property and not the result of an observational bias. Additionally, we find evidence of magnetic field decay, which confirms the results of previous studies.

show abstract

The complex magnetic field topology of the cool Ap star 49 Cam

Cited by 19 publications

References 36 publications

Magnetic field topologies of the bright, weak-field Ap stars θ Aurigae andεUrsae Majoris

Magnetic field topologies of the bright, weak-field Ap stars θ Aurigae andεUrsae Majoris

Magnetic OB[A] Stars with TESS: probing their Evolutionary and Rotational properties (MOBSTER) – I. First-light observations of known magnetic B and A stars

A Volume Limited Survey of mCP Stars Within 100pc II: Rotational and Magnetic Properties

Contact Info

Product

Resources

About