Many cool stars possess complex magnetic fields1 that are considered to undertake a central role in the structuring and energizing of their atmospheres2. Alfvénic waves are thought to make a critical contribution to energy transfer along these magnetic fields, with the potential to heat plasma and accelerate stellar winds3,4,5. Despite Alfvénic waves having been identified in the Sun’s atmosphere, the nature of the basal wave energy flux is poorly understood. It is generally assumed that the associated Poynting flux is generated solely in the photosphere and propagates into the corona, typically through the continuous buffeting of magnetic fields by turbulent convective cells4,6,7. Here, we provide evidence that the Sun’s internal acoustic modes also contribute to the basal flux of Alfvénic waves, delivering a spatially ubiquitous input to the coronal energy balance that is sustained over the solar cycle. Alfvénic waves are thus a fundamental feature of the Sun’s corona. Acknowledging that internal acoustic modes have a key role in injecting additional Poynting flux into the upper atmospheres of Sun-like stars has potentially significant consequences for the modelling of stellar coronae and winds.
This is a preview of subscription content, access via your institution
Open Access articles citing this article.
Solar Physics Open Access 25 May 2021
Solar Physics Open Access 19 April 2021
Subscribe to Nature+
Get immediate online access to the entire Nature family of 50+ journals
Subscribe to Journal
Get full journal access for 1 year
only $9.92 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
The data that support the findings of this study are available from the corresponding author upon reasonable request. The SDO data are available from the Joint Science Operations Center (http://jsoc.stanford.edu). The CoMP data are available from the High Altitude Observatory data repository (https://www2.hao.ucar.edu/mlso/mlso-home-page).
Reiners, A. Observations of cool-star magnetic fields. Living Rev. Sol. Phys. 9, 1 (2012).
Testa, P., Saar, S. H. & Drake, J. J. Stellar activity and coronal heating: an overview of recent results. Phil. Trans. R. Soc. A 373, 20140259 (2015).
Narain, U. & Ulmschneider, P. Chromospheric and coronal heating mechanisms II. Space Sci. Rev. 75, 453–509 (1996).
Suzuki, T. K. & Inutsuka, S. Making the corona and the fast solar wind: a self-consistent simulation for the low-frequency Alfvén waves from the photosphere to 0.3au. Astrophys. J. 632, L49–L52 (2005).
Verdini, A. & Velli, M. Alfvén waves and turbulence in the solar atmosphere and solar wind. Astrophys. J. 662, 669–676 (2007).
Cranmer, S. R. & van Ballegooijen, A. A. On the generation, propagation, and reflection of Alfvén waves from the solar photosphere to the distant heliosphere. Astrophys. J. Suppl. Ser. 156, 265–293 (2005).
Van Ballegooijen, A. A., Asgari-Targhi, M., Cranmer, S. R. & DeLuca, E. E. Heating of the solar chromosphere and corona by Alfvén wave turbulence. Astrophys. J. 736, 3 (2011).
Belcher, J. W. & Davis, L. J. Large-amplitude Alfvén waves in the interplanetary medium 2. J. Geophys. Res. 76, 3534–3563 (1971).
Bruno, R. & Carbone, V. The solar wind as a turbulence laboratory. Living Rev. Sol. Phys. 2, 4 (2005).
Banerjee, D., Teriaca, L., Doyle, J. G. & Wilhelm, K. Broadening of SI VIII lines observed in the solar polar coronal holes. Astron. Astrophys. 339, 208–214 (1998).
Tomczyk, S. et al. Alfvén waves in the solar corona. Science 317, 1192–1196 (2007).
De Pontieu, B. et al. Chromospheric Alfvénic waves strong enough to power the solar wind. Science 318, 1574–1577 (2007).
Morton, R. J., Tomczyk, S. & Pinto, R. F. Investigating Alfvénic wave propagation in coronal open-field regions. Nat. Commun. 6, 7813 (2015).
Morton, R. J., Tomczyk, S. & Pinto, R. F. A global view of velocity fluctuations in the corona below 1.3 R ⊙ with CoMP. Astrophys. J. 828, 89 (2016).
Van Doorsselaere, T., Nakariakov, V. M. & Verwichte, E. Detection of waves in the solar corona: kink or Alfvén? Astrophys. J. Lett. 676, L73 (2008).
McIntosh, S. W. et al. Alfvénic waves with sufficient energy to power the quiet solar corona and fast solar wind. Nature 475, 447–480 (2011).
Thurgood, J. O., Morton, R. J. & McLaughlin, J. A. First direct measurements of transverse waves in solar polar plumes using SDO/AIA. Astrophys. J. 790, L2 (2014).
Cally, P. S. & Goossens, M. Three-dimensional MHD wave propagation and conversion to Alfvén waves near the solar surface. I. Direct numerical solution. Sol. Phys. 251, 251–265 (2008).
Cally, P. S. & Hansen, S. C. Benchmarking fast-to-Alfvén mode conversion in a cold magnetohydrodynamic plasma. Astrophys. J. 738, 119 (2011).
Cally, P. S. Alfvén waves in the structured solar corona. Mon. Not. R. Astron. Soc. 466, 413–424 (2017).
Jefferies, S. M. et al. Magnetoacoustic portals and the basal heating of the solar chromosphere. Astrophys. J. 648, L151–L155 (2006).
Matthaeus, W. H., Zank, G. P., Oughton, S., Mullan, D. J. & Dmitruk, P. Coronal heating by magnetohydrodynamic turbulence driven by reflected low-frequency waves. Astrophys. J. 523, L93–L96 (1999).
Bavassano, B., Dobrowolny, M., Mariani, F. & Ness, N. F. Radial evolution of power spectra of interplanetary Alfvénic turbulence. J. Geophys. Res. 87, 3617–3622 (1982).
Pandey, B. P., Vranjes, J. & Krishan, V. Waves in the solar photosphere. Mon. Not. R. Astron. Soc. 386, 1635–1643 (2008).
Soler, R., Ballester, J. L. & Zaqarashvili, T. V. Overdamped Alfvén waves due to ion-neutral collisions in the solar chromosphere. Astron. Astrophys. 573, 79 (2015).
Arber, T. D., Brady, C. S. & Shelyag, S. Alfvén wave heating of the solar chromosphere: 1.5D models. Astrophys. J. 817, 94 (2016).
Morgan, H. & Taroyan, Y. Global conditions in the solar corona from 2010 to 2017. Sci. Adv. 3, e1602056 (2017).
McIntosh, S. W. & De Pontieu, B. Estimating the “dark” energy content of the solar corona. Astrophys. J. 761, 138 (2012).
Chaplin, W. J. & Miglio, A. Asteroseismology of solar-type and red-giant stars. Annu. Rev. Astron. Astrophys. 51, 353–392 (2013).
Tomczyk, S. et al. An instrument to measure coronal emission line polarization. Sol. Phys. 247, 411–428 (2008).
Lemen, J. R. et al. The Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO). Sol. Phys. 275, 17–40 (2012).
Goossens, M., Terradas, J., Andries, J., Arregui, I. & Ballester, J. L. On the nature of kink MHD waves in magnetic flux tubes. Astron. Astrophys. 503, 213–223 (2009).
Goossens, M. et al. Surface Alfvén waves in solar flux tubes. Astrophys. J. 753, 111 (2012).
Weberg, M., Morton, R. J. & McLaughlin, J. A. An automated algorithm for identifying and tracking transverse waves in solar images. Astrophys. J. 852, 57 (2018).
Vaughan, S. A simple test for periodic signals in red noise. Astron. Astrophys. 431, 391–403 (2005).
Ireland, J., McAteer, R. T. J. & Inglis, A. R. Coronal Fourier power spectra: implications for coronal seismology and coronal heating. Astrophys. J. 798, 12 (2015).
Feigelson, E. & Babu, G. J. Modern Statistical Methods for Astronomy (Cambridge Univ. Press, Cambridge, 2012).
De Pontieu, B. et al. The origins of hot plasma in the solar corona. Science 331, 55–58 (2011).
All authors acknowledge that this material is based on work supported by the Air Force Office of Scientific Research, Air Force Material Command, USAF under award number FA9550-16-1-0032, and the Science and Technology Facilities Council via grant number ST/L006243/1. R.J.M. is grateful to the Leverhulme Trust for the award of an Early Career Fellowship, and the High Altitude Observatory for financial assistance. M.J.W. acknowledges additional support from NASA grant NNH16AC39I and basic research funds from the Chief of Naval Research. R.J.M. is also grateful for discussions at ISSI, Bern (Towards Dynamic Solar Atmospheric Magneto-Seismology with New Generation Instrumentation) and with G. Li and S. Tomczyk. The authors acknowledge the work of the NASA/SDO and AIA science teams, and National Center for Atmospheric Research/High Altitude Observatory CoMP instrument team.
The authors declare no competing interests.
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Morton, R.J., Weberg, M.J. & McLaughlin, J.A. A basal contribution from p-modes to the Alfvénic wave flux in the Sun’s corona. Nat Astron 3, 223–229 (2019). https://doi.org/10.1038/s41550-018-0668-9
Space Science Reviews (2022)
Solar Physics (2021)
Space Science Reviews (2021)
Solar Physics (2021)
Nature Astronomy (2020)