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

Daniel V. Cotton; Derek L. Buzasi; Conny Aerts; Jeremy Bailey; Siemen Burssens; May G. Pedersen; Dennis Stello; Lucyna Kedziora-Chudczer; Ain De Horta; Peter De Cat; Fiona Lewis; Sai Prathyusha Malla; Duncan J. Wright; Kimberly Bott

doi:10.1038/s41550-021-01531-9

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

Daniel V. Cotton, Derek L. Buzasi, Conny Aerts, Jeremy Bailey, Siemen Burssens, May G. Pedersen, Dennis Stello, Lucyna Kedziora-Chudczer, Ain De Horta, Peter De Cat, Fiona Lewis, Sai Prathyusha Malla, Duncan J. Wright, Kimberly Bott

Research output: Contribution to journal › Article › peer-review

11 Citations (Scopus)

Abstract

Here we report the detection of polarization variations due to non-radial modes in the β Cephei star β Crucis. In so doing we confirm 40-year-old predictions of pulsation-induced polarization variability and its utility in asteroseismology for mode identification. In an approach suited to other β Cephei stars, we combine polarimetry with space-based photometry and archival spectroscopy to identify the dominant non-radial mode in polarimetry, f₂, as mode degree ℓ = 3, azimuthal order m = −3 (in the m-convention of Dziembowski) and determine the stellar axis position angle as 25 (or 205) ± 8°. The rotation axis inclination to the line of sight was derived as ~46° from combined polarimetry and spectroscopy, facilitating identification of additional modes and allowing for asteroseismic modelling. This reveals a star of 14.5 ± 0.5 M_⊙ and a convective core containing ~28% of its mass—making β Crucis the most massive star with an asteroseismic age.

Original language	English
Pages (from-to)	154-164
Number of pages	11
Journal	Nature Astronomy
Volume	6
Issue number	1
DOIs	https://doi.org/10.1038/s41550-021-01531-9
Publication status	Published - Jan 2022

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© 2021, The Author(s), under exclusive licence to Springer Nature Limited.

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@article{057ca6d978e245ce9341bb4145c2c09f,

title = "Polarimetric detection of non-radial oscillation modes in the β Cephei star β Crucis",

abstract = "Here we report the detection of polarization variations due to non-radial modes in the β Cephei star β Crucis. In so doing we confirm 40-year-old predictions of pulsation-induced polarization variability and its utility in asteroseismology for mode identification. In an approach suited to other β Cephei stars, we combine polarimetry with space-based photometry and archival spectroscopy to identify the dominant non-radial mode in polarimetry, f2, as mode degree ℓ = 3, azimuthal order m = −3 (in the m-convention of Dziembowski) and determine the stellar axis position angle as 25 (or 205) ± 8°. The rotation axis inclination to the line of sight was derived as ~46° from combined polarimetry and spectroscopy, facilitating identification of additional modes and allowing for asteroseismic modelling. This reveals a star of 14.5 ± 0.5 M⊙ and a convective core containing ~28% of its mass—making β Crucis the most massive star with an asteroseismic age.",

author = "Cotton, {Daniel V.} and Buzasi, {Derek L.} and Conny Aerts and Jeremy Bailey and Siemen Burssens and Pedersen, {May G.} and Dennis Stello and Lucyna Kedziora-Chudczer and {De Horta}, Ain and {De Cat}, Peter and Fiona Lewis and Malla, {Sai Prathyusha} and Wright, {Duncan J.} and Kimberly Bott",

note = "Publisher Copyright: {\textcopyright} 2021, The Author(s), under exclusive licence to Springer Nature Limited.",

year = "2022",

month = jan,

doi = "10.1038/s41550-021-01531-9",

language = "English",

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T1 - Polarimetric detection of non-radial oscillation modes in the β Cephei star β Crucis

AU - Cotton, Daniel V.

AU - Buzasi, Derek L.

AU - Aerts, Conny

AU - Bailey, Jeremy

AU - Burssens, Siemen

AU - Pedersen, May G.

AU - Stello, Dennis

AU - Kedziora-Chudczer, Lucyna

AU - De Horta, Ain

AU - De Cat, Peter

AU - Lewis, Fiona

AU - Malla, Sai Prathyusha

AU - Wright, Duncan J.

AU - Bott, Kimberly

PY - 2022/1

Y1 - 2022/1

N2 - Here we report the detection of polarization variations due to non-radial modes in the β Cephei star β Crucis. In so doing we confirm 40-year-old predictions of pulsation-induced polarization variability and its utility in asteroseismology for mode identification. In an approach suited to other β Cephei stars, we combine polarimetry with space-based photometry and archival spectroscopy to identify the dominant non-radial mode in polarimetry, f2, as mode degree ℓ = 3, azimuthal order m = −3 (in the m-convention of Dziembowski) and determine the stellar axis position angle as 25 (or 205) ± 8°. The rotation axis inclination to the line of sight was derived as ~46° from combined polarimetry and spectroscopy, facilitating identification of additional modes and allowing for asteroseismic modelling. This reveals a star of 14.5 ± 0.5 M⊙ and a convective core containing ~28% of its mass—making β Crucis the most massive star with an asteroseismic age.

AB - Here we report the detection of polarization variations due to non-radial modes in the β Cephei star β Crucis. In so doing we confirm 40-year-old predictions of pulsation-induced polarization variability and its utility in asteroseismology for mode identification. In an approach suited to other β Cephei stars, we combine polarimetry with space-based photometry and archival spectroscopy to identify the dominant non-radial mode in polarimetry, f2, as mode degree ℓ = 3, azimuthal order m = −3 (in the m-convention of Dziembowski) and determine the stellar axis position angle as 25 (or 205) ± 8°. The rotation axis inclination to the line of sight was derived as ~46° from combined polarimetry and spectroscopy, facilitating identification of additional modes and allowing for asteroseismic modelling. This reveals a star of 14.5 ± 0.5 M⊙ and a convective core containing ~28% of its mass—making β Crucis the most massive star with an asteroseismic age.

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VL - 6

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EP - 164

JO - Nature Astronomy

JF - Nature Astronomy

IS - 1

ER -

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

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