3D MHD simulations and synthetic radio emission from an oblique rotating magnetic massive star

S. Daley-Yates, I. R. Stevens, A. Ud-Doula

Research output: Contribution to journalArticle

Abstract

We have performed 3D isothermal MHD simulation of a magnetic rotating massive star with a non-zero dipole obliquity and predicted the radio/sub-mm observable light curves and continuum spectra for a frequency range compatible with ALMA. From these results we also compare the model input mass-loss to that calculated from the synthetic thermal emission. Spherical and cylindrical symmetry is broken due to the obliquity of the stellar magnetic dipole resulting in an inclination and phase dependence of both the spectral flux and inferred mass-loss rate, providing testable predictions of variability for oblique rotator. Both quantities vary by factors between 2 and 3 over a full rotational period of the star, demonstrating that the role of rotation as critical in understanding the emission. This illustrates the divergence from a symmetric wind, resulting in a two-armed spiral structure indicative of an oblique magnetic rotator. We show that a constant spectral index, α, model agrees well with our numerical prediction for a spherical wind for v <103 GHz; however it is unable to capture the behaviour of emission at v > 103 GHz. As such we caution the use of such constant α models for predicting emission from non-spherical winds such as those which form around magnetic massive stars.

Original languageEnglish (US)
Pages (from-to)3251-3268
Number of pages18
JournalMonthly Notices of the Royal Astronomical Society
Volume489
Issue number3
DOIs
StatePublished - Jan 1 2019

Fingerprint

magnetic stars
radio emission
massive stars
obliquity
radio
simulation
thermal emission
prediction
predictions
magnetic dipoles
light curve
inclination
symmetry
broken symmetry
divergence
frequency ranges
dipoles
continuums
stars
loss

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

@article{ea4e245f87844448bb2cb9bb5196d021,
title = "3D MHD simulations and synthetic radio emission from an oblique rotating magnetic massive star",
abstract = "We have performed 3D isothermal MHD simulation of a magnetic rotating massive star with a non-zero dipole obliquity and predicted the radio/sub-mm observable light curves and continuum spectra for a frequency range compatible with ALMA. From these results we also compare the model input mass-loss to that calculated from the synthetic thermal emission. Spherical and cylindrical symmetry is broken due to the obliquity of the stellar magnetic dipole resulting in an inclination and phase dependence of both the spectral flux and inferred mass-loss rate, providing testable predictions of variability for oblique rotator. Both quantities vary by factors between 2 and 3 over a full rotational period of the star, demonstrating that the role of rotation as critical in understanding the emission. This illustrates the divergence from a symmetric wind, resulting in a two-armed spiral structure indicative of an oblique magnetic rotator. We show that a constant spectral index, α, model agrees well with our numerical prediction for a spherical wind for v <103 GHz; however it is unable to capture the behaviour of emission at v > 103 GHz. As such we caution the use of such constant α models for predicting emission from non-spherical winds such as those which form around magnetic massive stars.",
author = "S. Daley-Yates and Stevens, {I. R.} and A. Ud-Doula",
year = "2019",
month = "1",
day = "1",
doi = "10.1093/mnras/stz1982",
language = "English (US)",
volume = "489",
pages = "3251--3268",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "3",

}

3D MHD simulations and synthetic radio emission from an oblique rotating magnetic massive star. / Daley-Yates, S.; Stevens, I. R.; Ud-Doula, A.

In: Monthly Notices of the Royal Astronomical Society, Vol. 489, No. 3, 01.01.2019, p. 3251-3268.

Research output: Contribution to journalArticle

TY - JOUR

T1 - 3D MHD simulations and synthetic radio emission from an oblique rotating magnetic massive star

AU - Daley-Yates, S.

AU - Stevens, I. R.

AU - Ud-Doula, A.

PY - 2019/1/1

Y1 - 2019/1/1

N2 - We have performed 3D isothermal MHD simulation of a magnetic rotating massive star with a non-zero dipole obliquity and predicted the radio/sub-mm observable light curves and continuum spectra for a frequency range compatible with ALMA. From these results we also compare the model input mass-loss to that calculated from the synthetic thermal emission. Spherical and cylindrical symmetry is broken due to the obliquity of the stellar magnetic dipole resulting in an inclination and phase dependence of both the spectral flux and inferred mass-loss rate, providing testable predictions of variability for oblique rotator. Both quantities vary by factors between 2 and 3 over a full rotational period of the star, demonstrating that the role of rotation as critical in understanding the emission. This illustrates the divergence from a symmetric wind, resulting in a two-armed spiral structure indicative of an oblique magnetic rotator. We show that a constant spectral index, α, model agrees well with our numerical prediction for a spherical wind for v <103 GHz; however it is unable to capture the behaviour of emission at v > 103 GHz. As such we caution the use of such constant α models for predicting emission from non-spherical winds such as those which form around magnetic massive stars.

AB - We have performed 3D isothermal MHD simulation of a magnetic rotating massive star with a non-zero dipole obliquity and predicted the radio/sub-mm observable light curves and continuum spectra for a frequency range compatible with ALMA. From these results we also compare the model input mass-loss to that calculated from the synthetic thermal emission. Spherical and cylindrical symmetry is broken due to the obliquity of the stellar magnetic dipole resulting in an inclination and phase dependence of both the spectral flux and inferred mass-loss rate, providing testable predictions of variability for oblique rotator. Both quantities vary by factors between 2 and 3 over a full rotational period of the star, demonstrating that the role of rotation as critical in understanding the emission. This illustrates the divergence from a symmetric wind, resulting in a two-armed spiral structure indicative of an oblique magnetic rotator. We show that a constant spectral index, α, model agrees well with our numerical prediction for a spherical wind for v <103 GHz; however it is unable to capture the behaviour of emission at v > 103 GHz. As such we caution the use of such constant α models for predicting emission from non-spherical winds such as those which form around magnetic massive stars.

UR - http://www.scopus.com/inward/record.url?scp=85075131563&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85075131563&partnerID=8YFLogxK

U2 - 10.1093/mnras/stz1982

DO - 10.1093/mnras/stz1982

M3 - Article

AN - SCOPUS:85075131563

VL - 489

SP - 3251

EP - 3268

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 3

ER -