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The nature of solar brightness variations

Nature Astronomy volume 1, pages 612–616 (2017)Cite this article

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Abstract

Determining the sources of solar brightness variations1,2, often referred to as solar noise3, is important because solar noise limits the detection of solar oscillations3, is one of the drivers of the Earth’s climate system4,5 and is a prototype of stellar variability6,7—an important limiting factor for the detection of extrasolar planets. Here, we model the magnetic contribution to solar brightness variability using high-cadence8,9 observations from the Solar Dynamics Observatory (SDO) and the Spectral And Total Irradiance REconstruction (SATIRE)10,11 model. The brightness variations caused by the constantly evolving cellular granulation pattern on the solar surface were computed with the Max Planck Institute for Solar System Research (MPS)/University of Chicago Radiative Magnetohydrodynamics (MURaM)12 code. We found that the surface magnetic field and granulation can together precisely explain solar noise (that is, solar variability excluding oscillations) on timescales from minutes to decades, accounting for all timescales that have so far been resolved or covered by irradiance measurements. We demonstrate that no other sources of variability are required to explain the data. Recent measurements of Sun-like stars by the COnvection ROtation and planetary Transits (CoRoT)13 and Kepler14 missions uncovered brightness variations similar to that of the Sun, but with a much wider variety of patterns15. Our finding that solar brightness variations can be replicated in detail with just two well-known sources will greatly simplify future modelling of existing CoRoT and Kepler as well as anticipated Transiting Exoplanet Survey Satellite16 and PLAnetary Transits and Oscillations of stars (PLATO)17 data.

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Fig. 1: Short-term TSI variability at three intervals of very different activity level and variability of the Sun.
Fig. 2: TSI variability on timescales from 4 min to 19 years.

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References

  1. Fröhlich, C. Total solar irradiance: what have we learned from the last three cycles and the recent minimum? Space Sci. Rev. 176, 237–252 (2013).

    Article  ADS  Google Scholar 

  2. Kopp, G. Magnitudes and timescales of total solar irradiance variability. J. Space Weather Spac. 6, A30 (2016).

    Article  ADS  Google Scholar 

  3. Rabello-Soares, M. C., Roca Cortes, T., Jimenez, A., Andersen, B. N. & Appourchaux, T. An estimate of the solar background irradiance power spectrum. Astron. Astrophys. 318, 970–974 (1997).

    ADS  Google Scholar 

  4. Ermolli, I. et al. Recent variability of the solar spectral irradiance and its impact on climate modelling. Atmosph. Chem. Phys. 13, 3945–3977 (2013).

    Article  ADS  Google Scholar 

  5. Solanki, S. K., Krivova, N. A. & Haigh, J. D. Solar irradiance variability and climate. Ann. Rev. Astron. Astrophys. 51, 311–351 (2013).

    Article  ADS  Google Scholar 

  6. Shapiro, A. I. et al. Variability of Sun-like stars: reproducing observed photometric trends. Astron. Astrophys. 569, A38 (2014).

    Article  Google Scholar 

  7. Meunier, N., Lagrange, A.-M., Borgniet, S. & Rieutord, M. Using the Sun to estimate Earth-like planet detection capabilities. VI. Simulation of granulation and supergranulation radial velocity and photometric time series. Astron. Astrophys. 583, A118 (2015).

    Article  Google Scholar 

  8. Hoeksema, J. T. et al. The Helioseismic and Magnetic Imager (HMI) vector magnetic field pipeline: overview and performance. Sol. Phys. 289, 3483–3530 (2014).

    Article  ADS  Google Scholar 

  9. Yeo, K. L., Krivova, N. A., Solanki, S. K. & Glassmeier, K. H. Reconstruction of total and spectral solar irradiance from 1974 to 2013 based on KPVT, SoHO/MDI, and SDO/HMI observations. Astron. Astrophys. 570, A85 (2014).

    Article  ADS  Google Scholar 

  10. Krivova, N. A., Solanki, S. K., Fligge, M. & Unruh, Y. C. Reconstruction of solar irradiance variations in cycle 23: is solar surface magnetism the cause? Astron. Astrophys. 399, L1–L4 (2003).

    Article  ADS  Google Scholar 

  11. Krivova, N. A., Solanki, S. K. & Unruh, Y. C. Towards a long-term record of solar total and spectral irradiance. J. Atmos. Sol.-Terr. Phys. 73, 223–234 (2011).

    Article  ADS  Google Scholar 

  12. Vögler, A. et al. Simulations of magneto-convection in the solar photosphere. Equations, methods, and results of the MURaM code. Astron. Astrophys. 429, 335–351 (2005).

    Article  ADS  Google Scholar 

  13. Bordé, P., Rouan, D. & Léger, A. Exoplanet detection capability of the COROT space mission. Astron. Astrophys. 405, 1137–1144 (2003).

    Article  ADS  Google Scholar 

  14. Borucki, W. J. et al. Kepler planet-detection mission: introduction and first results. Science 327, 977–980 (2010).

    Article  ADS  Google Scholar 

  15. Basri, G., Walkowicz, L. M. & Reiners, A. Comparison of Kepler photometric variability with the Sun on different timescales. Astrophys. J. 769, 37 (2013).

    Article  ADS  Google Scholar 

  16. Ricker, G. R. et al. Transiting Exoplanet Survey Satellite (TESS). J. Astron. Telesc. Instrum. Syst. 1, 014003 (2015).

    Article  ADS  Google Scholar 

  17. Rauer, H. et al. The PLATO 2.0 mission. Exper. Astron. 38, 249–330 (2014).

    Article  ADS  Google Scholar 

  18. Schou, J. et al. Design and ground calibration of the Helioseismic and Magnetic Imager (HMI) instrument on the Solar Dynamics Observatory (SDO). Sol. Phys. 275, 229–259 (2012).

    Article  ADS  Google Scholar 

  19. Beeck, B., Cameron, R. H., Reiners, A. & Schüssler, M. Three-dimensional simulations of near-surface convection in main-sequence stars. II. Properties of granulation and spectral lines. Astron. Astrophys. 558, A49 (2013).

    Article  Google Scholar 

  20. Aigrain, S., Favata, F. & Gilmore, G. Characterising stellar micro-variability for planetary transit searches. Astron. Astrophys. 414, 1139–1152 (2004).

    Article  ADS  Google Scholar 

  21. Seleznyov, A. D., Solanki, S. K. & Krivova, N. A. Modelling solar irradiance variability on time scales from minutes to months. Astron. Astrophys. 532, A108 (2011).

    Article  ADS  Google Scholar 

  22. Rast, M. P. The scales of granulation, mesogranulation, and supergranulation. Astrophys. J. 597, 1200–1210 (2003).

    Article  ADS  Google Scholar 

  23. Solanki, S. K., Inhester, B. & Schüssler, M. The solar magnetic field. Rep. Progr. Phys. 69, 563–668 (2006).

    Article  ADS  Google Scholar 

  24. Bastien, F. A., Stassun, K. G., Basri, G. & Pepper, J. An observational correlation between stellar brightness variations and surface gravity. Nature 500, 427–430 (2013).

    Article  ADS  Google Scholar 

  25. Schmutz, W., Fehlmann, A., Finsterle, W., Kopp, G. & Thuillier, G. Total solar irradiance measurements with PREMOS/PICARD. AIP Conf. Proc. 1531, 624–627 (2013).

  26. Fröhlich, C. et al. VIRGO: experiment for helioseismology and solar irradiance monitoring. Sol. Phys. 162, 101–128 (1995).

    Article  ADS  Google Scholar 

  27. Fröhlich, C. Solar irradiance variability since 1978. Revision of the PMOD composite during solar cycle 21. Space Sci. Rev. 125, 53–65 (2006).

    Article  ADS  Google Scholar 

  28. Shapiro, A. I., Solanki, S. K., Krivova, N. A., Yeo, K. L. & Schmutz, W. K. Are solar brightness variations faculae- or spot-dominated? Astron. Astrophys. 589, A46 (2016).

    Article  ADS  Google Scholar 

  29. Aigrain, S. et al. Testing the recovery of stellar rotation signals from Kepler light curves using a blind hare-and-hounds exercise. Mon. Not. R. Astron. Soc. 450, 3211–3226 (2015).

    Article  ADS  Google Scholar 

  30. Ludwig, H.-G. et al. Hydrodynamical simulations of convection-related stellar micro-variability. II. The enigmatic granulation background of the CoRoT target HD 49933. Astron. Astrophys. 506, 167–173 (2009).

    Article  ADS  Google Scholar 

  31. Fröhlich, C. et al. First results from VIRGO, the experiment for helioseismology and solar irradiance monitoring on SOHO. Sol. Phys. 170, 1–25 (1997).

    Article  ADS  Google Scholar 

  32. Fröhlich, C. & Lean, J. Solar radiative output and its variability: evidence and mechanisms. Astron. Astrophys. Rev. 12, 273–320 (2004).

    Article  ADS  Google Scholar 

  33. Unruh, Y. C., Solanki, S. K. & Fligge, M. The spectral dependence of facular contrast and solar irradiance variations. Astron. Astrophys. 345, 635–642 (1999).

    ADS  Google Scholar 

  34. Kurucz, R. L. “Finding” the “missing” solar ultraviolet opacity. Rev. Mex. Astron. Astrof. 23, 181–186 (1992).

    ADS  Google Scholar 

  35. Castelli, F. & Kurucz, R. L. Model atmospheres for VEGA. Astron. Astrophys. 281, 817–832 (1994).

    ADS  Google Scholar 

  36. Ball, W. T., Krivova, N. A., Unruh, Y. C., Haigh, J. D. & Solanki, S. K. A new SATIRE-S spectral solar irradiance reconstruction for solar cycles 21–23 and its implications for stratospheric ozone. J. Atmos. Sci. 71, 4086–4101 (2014).

    Article  ADS  Google Scholar 

  37. Ortiz, A., Solanki, S. K., Domingo, V., Fligge, M. & Sanahuja, B. On the intensity contrast of solar photospheric faculae and network elements. Astron. Astrophys. 388, 1036–1047 (2002).

    Article  ADS  Google Scholar 

  38. Beeck, B., Cameron, R. H., Reiners, A. & Schüssler, M. Three-dimensional simulations of near-surface convection in main-sequence stars. I. Overall structure. Astron. Astrophys. 558, A48 (2013).

    Article  Google Scholar 

  39. Willson, R. C. & Mordvinov, A. V. Secular total solar irradiance trend during solar cycles 21–23. Geophys. Res. Lett. 30, 3–1 (2003).

    Article  ADS  Google Scholar 

  40. Dewitte, S., Crommelynck, D., Mekaoui, S. & Joukoff, A. Measurement and uncertainty of the long-term total solar irradiance trend. Sol. Phys. 224, 209–216 (2004).

    Article  ADS  Google Scholar 

  41. Dudok de Wit, T., Kopp, G., Fröhlich, C. & Schöll, M. Methodology to create a new total solar irradiance record: making a composite out of multiple data records. Geophys. Res. Lett. 44, 1196–1203 (2017).

    Article  ADS  Google Scholar 

  42. Kopp, G., Lawrence, G. & Rottman, G. The Total Irradiance Monitor (TIM): science results. Sol. Phys. 230, 129–139 (2005).

    Article  ADS  Google Scholar 

Download references

Acknowledgements

The authors received funding from the People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme (FP7/2007-2013) under grant agreement No. 624817 and the European Research Council under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 715947). Financial support was also provided by the Brain Korea 21 plus program through the National Research Foundation funded by the Ministry of Education of Korea and by the German Federal Ministry of Education and Research under project 01LG1209A. We would like to thank the International Space Science Institute, Bern, for their support of science team 373 and the resulting helpful discussions.

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Authors and Affiliations

  1. Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077, Göttingen, Germany

    A. I. Shapiro, S. K. Solanki, N. A. Krivova, R. H. Cameron & K. L. Yeo

  2. School of Space Research, Kyung Hee University, Yongin, Gyeonggi, 446-701, Korea

    S. K. Solanki

  3. Physikalisch-Meteorologishes Observatorium Davos, World Radiation Centre, 7260, Davos Dorf, Switzerland

    W. K. Schmutz

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Contributions

A.I.S., S.K.S. and N.A.K. designed the study. A.I.S. performed the calculations with contributions from R.H.C., who provided the MURaM time series, and K.L.Y., who prepared the HMI/SDO magnetograms and corrected them for noise. N.A.K. and S.K.S. led the development of the SATIRE code. R.H.C. actively contributed to the development of the MURaM code. W.K.S. provided the PREMOS data and expertise on the TSI data. A.I.S., S.K.S., N.A.K. and R.H.C. wrote the paper.

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Correspondence to A. I. Shapiro.

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Shapiro, A.I., Solanki, S.K., Krivova, N.A. et al. The nature of solar brightness variations. Nat Astron 1, 612–616 (2017). https://doi.org/10.1038/s41550-017-0217-y

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