Polarimetric detection of non-radial oscillation modes in the β Cephei star β Crucis

Cotton, Daniel V.; Buzasi, Derek L.; Aerts, C.; Bailey, Jeremy; Burssens, S.; Pedersen, May G.; Stello, Dennis; Kedziora-Chudczer, Lucyna; Horta, A. Y. De; Cat, P. De; Lewis, F; Malla, Sai Prathyusha; Wright, D. E.; Bott, Kimberly

doi:10.1038/s41550-021-01531-9

Cited by 13 publications

(9 citation statements)

References 47 publications

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“…This is quite common in slowly rotating β Cep stars. 9,98,99 Finally, we also searched for single frequencies that can be explained as radial modes, e.g. the high amplitude single frequencies f 8 = 8.96669(1) d −1 and f 20 = 9.19716(4) d −1 (cf.…”

Section: Forward Asteroseismic Modellingmentioning

confidence: 99%

A calibration point for stellar evolution from massive star asteroseismology

et al. 2023

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Massive stars are progenitors of supernovae, neutron stars and black holes. During the hydrogen-core burning phase their convective cores are the prime drivers of their evolution, but inferences of core masses are subject to unconstrained boundary mixing processes.Moreover, uncalibrated transport mechanisms can lead to strong envelope mixing and differential radial rotation. Ascertaining the efficiency of the transport mechanisms is challenging because of a lack of observational constraints. Here we deduce the convective core mass and robustly demonstrate non-rigid radial rotation in a supernova progenitor, the 12.0 +1.5 −1.5 solar-mass hydrogen-burning star HD 192575, using asteroseismology, TESS photometry, high-resolution spectroscopy, and Gaia astrometry. We infer a convective

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Section: Forward Asteroseismic Modellingmentioning

confidence: 99%

A calibration point for stellar evolution from massive star asteroseismology

et al. 2023

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“…Watson (1983)ʼs analytical model enables polarimetric pulsation amplitudes to be determined by multiplying the photometric amplitude by the ratio of scaling factors, z ℓ λ /b ℓ λ , and a term derived from the mode geometry we label G ℓmi . The terms b ℓ λ and z ℓ λ are calculated from the intensity and polarization dependence on viewing angle, determined from stellar atmosphere models as described by Cotton et al (2022b), for a given mode degree, ℓ, and wavelength, λ. G ℓmi -which is independent of stellar type-is a function of ℓ; azimuthal order, m; and inclination, i (see Cotton et al 2022b, Figure 4).…”

Section: Nonradial Pulsationsmentioning

confidence: 99%

“…Linear polarimetry provides spatial information, either in the form of normalized Stokes vectors q and u, or in total linear polarization, p, and position angle, θ. It can be used in asteroseismology to break degeneracies and enable mode determination (Cotton et al 2022b). However, large polarization variability has been observed in other α Cygni stars and explained as arising from scattering in a clumpy wind (e.g., Hayes 1984Hayes , 1986; see also Clarke 2010, Ch.…”

Section: Introductionmentioning

confidence: 99%

Deneb Is a Large-amplitude Polarimetric Variable

Cotton,

Bailey,

Perkins

et al. 2024

ApJL

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We write to report the discovery that Deneb is a large-amplitude polarization variable. Over a ∼400 days time span from 2022 August Deneb’s polarization was typically around 3900 parts per million (ppm) in the SDSS g ′ band. Yet, it varied by several hundred parts per million in an irregular way on a timescale of weeks. The largest polarization change, amounting to 2500 ppm, occurred shortly after the last pulsation “resumption” event identified by Abt et al. in TESS photometry. The relationship between the observed polarization—particularly corresponding to the resumption event—and its brightness and H α spectra suggests a mechanism involving density changes in its wind and/or extended atmosphere. Smaller effects due to pulsations are not ruled out, and further study is recommended.

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“…Recent results using a new generation of high-precision polarimeters have shown that intrinsic polarization among bright stars is much more common than was previously thought (Cotton et al 2016), and have revealed a range of previously unobserved polarization mechanisms. These include the detection of polarization due to rotational distortion in hot stars (Cotton et al 2017a;Bailey et al 2020b;Lewis et al 2022), the detection of broad-band linear polarization due to magnetic fields in active dwarfs (Cotton et al 2017b(Cotton et al , 2019 and the observation of polarization due to non-radial pulsation modes in a 𝛽 Cephei star (Cotton et al 2022a). In addition polarization due to photospheric reflection has been confirmed to be an important contributor to the polarization of binary systems (Bailey et al 2019;Cotton et al 2020).…”

Section: Introductionmentioning

confidence: 99%

PICSARR: high-precision polarimetry using CMOS image sensors

Bailey¹,

Cotton²,

Horta³

et al. 2023

Preprint

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We have built and tested a compact, low-cost, but very-high-performance astronomical polarimeter based on a continuously rotating half-wave plate and a high-speed imaging detector. The polarimeter is suitable for small telescopes up to ∼1 m in aperture.The optical system provides very high transmission over a wide wavelength range from the atmospheric UV cutoff to ∼1000 nm. The high-quantum-efficiency, low-noise and high-speed of the detectors enable bright stars to be observed with high-precision as well as polarization imaging of extended sources. We have measured the performance of the instrument on 20 cm and 60 cm aperture telescopes. We show some examples of the type of science possible with this instrument. The polarimeter is particularly suited to studies of the wavelength dependence and time variability of the polarization of stars and planets.

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Polarimetric detection of non-radial oscillation modes in the β Cephei star β Crucis

Cited by 13 publications

References 47 publications

A calibration point for stellar evolution from massive star asteroseismology

A calibration point for stellar evolution from massive star asteroseismology

Deneb Is a Large-amplitude Polarimetric Variable

PICSARR: high-precision polarimetry using CMOS image sensors

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