An update on the rotational period of the magnetic chemically peculiar star CU Virginis

Pyper, D. M.; Stevens, I. R.; Adelman, Saul J.

doi:10.1093/mnras/stt256

Cited by 21 publications

(25 citation statements)

References 16 publications

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“…Consequently, CU Vir is one of a few stars for which rotational period changes have been securely detected. Remarkably, this star appears to show period glitches (Pyper et al 1998(Pyper et al , 2013 or possibly a cyclic period variation (Mikulášek et al 2011) rather than a constantly increasing period, as expected from magnetic spin down models (Ud-Doula et al 2009). The origin of these period changes is currently unknown.…”

Section: Introductionmentioning

confidence: 83%

“…The sharp radio emission pulses can also be used for a very precise measurement of the stellar rotational period. However, it is not clear if the phase shifts observed in the radio are related to the intrinsic variation of the stellar rotation or to instabilities in the region where the radio emission is produced (Ravi et al 2010;Pyper et al 2013).…”

Section: Introductionmentioning

confidence: 99%

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Magnetic field topology of the unique chemically peculiar star CU Virginis

Kochukhov

Lüftinger

Neiner

et al. 2014

A&A

105

162

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Context. The late-B, magnetic, chemically peculiar star CU Vir is one of the fastest rotators among the intermediate-mass stars with strong fossil magnetic fields. It shows a prominent rotational modulation of the spectral energy distribution and absorption line profiles due to chemical spots and exhibits a unique, strongly beamed variable radio emission. Aims. Little is known about the magnetic field topology of CU Vir. In this study, we aim to derive detailed maps of the magnetic field distribution over the surface of this star for the first time. Methods. We use high-resolution spectropolarimetric observations covering the entire rotational period. These data are interpreted using a multi-line technique of least-squares deconvolution (LSD) and a new Zeeman Doppler imaging code, which is based on detailed polarised radiative transfer modelling of the Stokes I and V LSD profiles. This new magnetic inversion approach relies on the spectrum synthesis calculations over the full wavelength range that is covered by observations and does not assume that the LSD profiles behave as a single spectral line with mean parameters. Results. We present magnetic and chemical abundance maps derived from the Si and Fe lines. Mean polarisation profiles of both elements reveal a significant departure of CU Vir's magnetic field topology from the commonly assumed axisymmetric dipolar configuration. The field of CU Vir is dipolar-like but clearly non-axisymmetric, showing a large difference in the field strength between the regions of opposite polarity. The main relative abundance depletion features in both Si and Fe maps coincide with the weak-field region in the magnetic map. Conclusions. The detailed information on the distorted dipolar magnetic field topology of CU Vir provided by our study is essential for understanding chemical spot formation, radio emission, and rotational period variation of this star.

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Section: Introductionmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Magnetic field topology of the unique chemically peculiar star CU Virginis

Kochukhov

Lüftinger

Neiner

et al. 2014

A&A

105

162

View full text Add to dashboard Cite

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“…Nevertheless, there is some evidence that the ARE behavior can be variable. For CU Vir, the pulses do not exactly repeat, although they do show a regular phase arrival time (Lo et al 2012;Pyper et al 2013). Consequently, the ARE of hot stars is not necessarily stable.…”

Section: Discussionmentioning

confidence: 99%

Evidence for radio and X-ray auroral emissions from the magnetic B-type star ρ Oph A

Leto

Trigilio

Leone³

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We present new ATCA multi-wavelength radio measurements (range 2.1-21.2 GHz) of the early-type magnetic star ρ Oph A, performed in March 2019 during 3 different observing sessions. These new ATCA observations evidence a clear rotational modulation of the stellar radio emission and the detection of coherent auroral radio emission from ρ Oph A at 2.1 GHz. We collected high-resolution optical spectra of ρ Oph A acquired by several instruments over a time span of about ten years. We also report new magnetic field measurements of ρ Oph A that, together with the radio light curves and the temporal variation of the equivalent width of the He I line (λ = 5015Å), were used to constrain the rotation period and the stellar magnetic field geometry. The above results have been used to model the stellar radio emission, modelling that allowed us to constrain the physical condition of ρ Oph A's magnetosphere. Past XMM-Newton measurements showed periodic X-ray pulses from ρ Oph A. We correlate the X-ray light curve with the magnetic field geometry of ρ Oph A. The already published XMM-Newton data have been re-analyzed showing that the X-ray spectra of ρ Oph A are compatible with the presence of a non-thermal X-ray component. We discuss a scenario where the emission phenomena occurring at the extremes of the electromagnetic spectrum, radio and X-ray, are directly induced by the same plasma process. We interpret the observed X-ray and radio features of ρ Oph A as having an auroral origin.

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“…The rapidly rotating star CU Virginis ( P =0.52 days, with observations stretching back to 1949 [44]), has increased its rotation period by about 50 ppm (figure 6). The O–C data (the phase drift relative to a fixed period) can be fit by an increase in rotation period within a few years around 1984 [46,47] 3 ). This would be reminiscent of the ‘glitches’ seen in pulsars.…”

Section: Observed Properties Of Magnetic Starsmentioning

confidence: 99%

Magnetic fields in non-convective regions of stars

Braithwaite

Spruit

2017

R. Soc. open sci.

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We review the current state of knowledge of magnetic fields inside stars, concentrating on recent developments concerning magnetic fields in stably stratified (zones of) stars, leaving out convective dynamo theories and observations of convective envelopes. We include the observational properties of A, B and O-type main-sequence stars, which have radiative envelopes, and the fossil field model which is normally invoked to explain the strong fields sometimes seen in these stars. Observations seem to show that Ap-type stable fields are excluded in stars with convective envelopes. Most stars contain both radiative and convective zones, and there are potentially important effects arising from the interaction of magnetic fields at the boundaries between them; the solar cycle being one of the better known examples. Related to this, we discuss whether the Sun could harbour a magnetic field in its core. Recent developments regarding the various convective and radiative layers near the surfaces of early-type stars and their observational effects are examined. We look at possible dynamo mechanisms that run on differential rotation rather than convection. Finally, we turn to neutron stars with a discussion of the possible origins for their magnetic fields.

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An update on the rotational period of the magnetic chemically peculiar star CU Virginis

Cited by 21 publications

References 16 publications

Magnetic field topology of the unique chemically peculiar star CU Virginis

Magnetic field topology of the unique chemically peculiar star CU Virginis

Evidence for radio and X-ray auroral emissions from the magnetic B-type star ρ Oph A

Magnetic fields in non-convective regions of stars

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