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| Format: | Preprint |
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2024
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| Online Access: | https://arxiv.org/abs/2410.20557 |
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| _version_ | 1866909469087105024 |
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| author | Rui, Nicholas Z. Fuller, Jim Hermes, J. J. |
| author_facet | Rui, Nicholas Z. Fuller, Jim Hermes, J. J. |
| contents | The origin of magnetic fields in white dwarfs (WDs) remains mysterious. Magnetic WDs are traditionally associated with field strengths $\gtrsim1\,\mathrm{MG}$, set by the sensitivity of typical spectroscopic magnetic field measurements. Informed by recent developments in red giant magnetoasteroseismology, we revisit the use of WD pulsations as a seismic magnetometer. WD pulsations primarily probe near-surface magnetic fields, whose effect on oscillation mode frequencies is to asymmetrize rotational multiplets and, if strong enough, suppress gravity-mode propagation altogether. The sensitivity of seismology to magnetic fields increases strongly with mode period and decreases quickly with the depth of the partial ionization-driven surface convective zone. We place upper limits for magnetic fields in $24$ pulsating WDs: $20$ hydrogen-atmosphere (DAV) and three helium-atmosphere (DBV) carbon-oxygen WDs, and one extremely low-mass (helium-core) pulsator. These bounds are typically $\sim1$-$10\,\mathrm{kG}$, although they can reach down to $\sim10$-$100\,\mathrm{G}$ for DAVs and helium-core WDs in which lower-frequency modes are excited. Seismic magnetometry may enable new insights into the formation and evolution of WD magnetism. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2410_20557 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Supersensitive seismic magnetometry of white dwarfs Rui, Nicholas Z. Fuller, Jim Hermes, J. J. Solar and Stellar Astrophysics The origin of magnetic fields in white dwarfs (WDs) remains mysterious. Magnetic WDs are traditionally associated with field strengths $\gtrsim1\,\mathrm{MG}$, set by the sensitivity of typical spectroscopic magnetic field measurements. Informed by recent developments in red giant magnetoasteroseismology, we revisit the use of WD pulsations as a seismic magnetometer. WD pulsations primarily probe near-surface magnetic fields, whose effect on oscillation mode frequencies is to asymmetrize rotational multiplets and, if strong enough, suppress gravity-mode propagation altogether. The sensitivity of seismology to magnetic fields increases strongly with mode period and decreases quickly with the depth of the partial ionization-driven surface convective zone. We place upper limits for magnetic fields in $24$ pulsating WDs: $20$ hydrogen-atmosphere (DAV) and three helium-atmosphere (DBV) carbon-oxygen WDs, and one extremely low-mass (helium-core) pulsator. These bounds are typically $\sim1$-$10\,\mathrm{kG}$, although they can reach down to $\sim10$-$100\,\mathrm{G}$ for DAVs and helium-core WDs in which lower-frequency modes are excited. Seismic magnetometry may enable new insights into the formation and evolution of WD magnetism. |
| title | Supersensitive seismic magnetometry of white dwarfs |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2410.20557 |