Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Superflares on solar-type stars



Solar flares are caused by the sudden release of magnetic energy stored near sunspots. They release 1029 to 1032 ergs of energy on a timescale of hours1. Similar flares have been observed on many stars, with larger ‘superflares’ seen on a variety of stars2,3, some of which are rapidly rotating4,5 and some of which are of ordinary solar type3,6. The small number of superflares observed on solar-type stars has hitherto precluded a detailed study of them. Here we report observations of 365 superflares, including some from slowly rotating solar-type stars, from about 83,000 stars observed over 120 days. Quasi-periodic brightness modulations observed in the solar-type stars suggest that they have much larger starspots than does the Sun. The maximum energy of the flare is not correlated with the stellar rotation period, but the data suggest that superflares occur more frequently on rapidly rotating stars. It has been proposed that hot Jupiters may be important in the generation of superflares on solar-type stars7, but none have been discovered around the stars that we have studied, indicating that hot Jupiters associated with superflares are rare.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Get just this article for as long as you need it


Prices may be subject to local taxes which are calculated during checkout

Figure 1: Light curve of typical superflares.
Figure 2: Frequency distribution of superflares on G-type main-sequence stars.
Figure 3: Relations between the brightness variation period and the properties of flares on G-type main-sequence stars.


  1. Baker, D. N. in Space Weather: The Physics Behind a Slogan (eds Scherer, K., Fichtner, H., Heber, B. & Mall, U. ) 3–20 (Lect. Notes Phys. 656, Springer, 2004)

    Book  Google Scholar 

  2. Schaefer, B. E. Flashes from normal stars. Astrophys. J. 337, 927–933 (1989)

    Article  ADS  Google Scholar 

  3. Schaefer, B. E., King, J. R. & Deliyannis, C. P. Superflares on ordinary solar-type stars. Astrophys. J. 529, 1026–1030 (2000)

    Article  ADS  Google Scholar 

  4. Gershberg, R. E. Solar-Type Activity in Main-Sequence Stars 191–380 (Springer, 2005)

    Google Scholar 

  5. Shibata, K. & Yokoyama, T. A Hertzsprung-Russell-like diagram for solar/stellar flares and corona: emission measure versus temperature diagram. Astrophys. J. 577, 422–432 (2002)

    Article  ADS  Google Scholar 

  6. Landini, M., Fossi, B. C., Pallavicini, R. & Piro, L. EXOSAT detection of an X-ray flare from the solar type star π1 UMa. Astron. Astrophys. 157, 217–222 (1986)

    CAS  ADS  Google Scholar 

  7. Rubenstein, E. P. & Schaefer, B. E. Are superflares on solar analogues caused by extrasolar planets? Astrophys. J. 529, 1031–1033 (2000)

    Article  ADS  Google Scholar 

  8. Koch, D. G. et al. Kepler mission design, realized photometric performance, and early science. Astrophys. J. 713, L79–L86 (2010)

    Article  CAS  ADS  Google Scholar 

  9. Brown, T. M., Latham, D. W., Everett, M. E. & Esquerdo, G. A. Kepler input catalog: photometric calibration and stellar classification. Astron. J. 142, 112 (2011)

    Article  ADS  Google Scholar 

  10. Kretzschmar, M. The Sun as a star: observations of white-light flares. Astron. Astrophys. 530, A84 (2011)

    Article  ADS  Google Scholar 

  11. Rodono, M. et al. Rotational modulation and flares on RS CVn and BY Dra-type stars. I - Photometry and SPOT models for BY Dra, AU Mic, AR Lac, II Peg and V 711 Tau ( = HR 1099). Astron. Astrophys. 165, 135–156 (1986)

    ADS  Google Scholar 

  12. Kopal, Z. Close Binary Systems 147–261 (Chapman & Hall, 1959)

    Google Scholar 

  13. Unno, W., Osaki, Y., Ando, H., Saio, H. & Shibahashi, H. Nonradial Oscillations of Stars 237–255 (Univ. Tokyo Press, 1989)

    Google Scholar 

  14. Debosscher, J., Blomme, J., Aerts, C. & De Ridder, J. Global stellar variability study in the field-of-view of the Kepler satellite. Astron. Astrophys. 529, A89 (2011)

    Article  ADS  Google Scholar 

  15. Crosby, N. B., Aschwanden, M. J. & Dennis, B. R. Frequency distributions and correlations of solar X-ray flare parameters. Sol. Phys. 143, 275–299 (1993)

    Article  ADS  Google Scholar 

  16. Shakhovskaia, N. I. Stellar flare statistics - Physical consequences. Sol. Phys. 121, 375–386 (1989)

    ADS  Google Scholar 

  17. Noyes, R. W., Hartmann, L. W., Baliunas, S. L., Duncan, D. K. & Vaughan, A. H. Rotation, convection, and magnetic activity in lower main-sequence stars. Astrophys. J. 279, 763–777 (1984)

    Article  CAS  ADS  Google Scholar 

  18. Pallavicini, R. et al. Relations among stellar X-ray emission observed from Einstein, stellar rotation and bolometric luminosity. Astrophys. J. 248, 279–290 (1981)

    Article  ADS  Google Scholar 

  19. Parker, E. N. Cosmical Magnetic Fields: Their Origin and Their Activity 532–749 (Oxford Univ. Press, 1979)

    Google Scholar 

  20. Randich, S. Coronal activity among open cluster stars. ASP Conf. Ser. 198, 401–410 (2000)

    ADS  Google Scholar 

  21. Skumanich, A. Time scales for CaII emission decay, rotational braking, and lithium depletion. Astrophys. J. 171, 565–567 (1972)

    Article  CAS  ADS  Google Scholar 

  22. Barnes, S. A. On the rotational evolution of solar- and late-type stars, its magnetic origins, and the possibility of stellar gyrochronology. Astrophys. J. 586, 464–479 (2003)

    Article  ADS  Google Scholar 

  23. Shea, M. A., Smart, D. F., McCracken, K. G., Dreschhoff, G. A. M. & Spence, H. E. Solar proton events for 450 years: the Carrington event in perspective. Adv. Space Res. 38, 232–238 (2006)

    Article  CAS  ADS  Google Scholar 

  24. Carrington, R. C. Description of a singular appearance seen in the Sun on September 1, 1859. Mon. Not. R. Astron. Soc. 20, 13–15 (1859)

    Article  ADS  Google Scholar 

  25. Tsurutani, B. T., Gonzalez, W. D., Lakhina, G. S. & Alex, S. The extreme magnetic storm of 1–2 September 1859. J. Geophys. Res. 108, 1268–1275 (2003)

    Article  Google Scholar 

  26. Cuntz, M., Saar, S. H. & Musielak, Z. E. On stellar activity enhancement due to interaction with extrasolar giant planets. Astrophys. J. 533, L151–L154 (2000)

    Article  CAS  ADS  Google Scholar 

  27. Ip, W.-H., Kopp, A. & Hu, J.-H. On the star-magnetosphere interaction of close-in exoplanets. Astrophys. J. 602, L53–L56 (2004)

    Article  ADS  Google Scholar 

  28. Borucki, W. J. et al. Characteristics of planetary candidates observed by Kepler. II. Analysis of the first four months of data. Astrophys. J. 736, 19 (2011)

    Article  ADS  Google Scholar 

  29. Howard, A. W. et al. Planet occurrence within 0.25 AU of solar-type stars from Kepler. Preprint at 〈〉 (2011)

Download references


Kepler was selected as NASA’s tenth Discovery mission. Funding for the mission is provided by the NASA Science Mission Directorate. The data presented in this paper were obtained from the Multimission Archive at STScI. This work was supported by the Grant-in-Aid for the Global COE Program ‘The Next Generation of Physics, Spun from Universality and Emergence’ and the Grant-in-Aid for Young Scientists (B) from the Ministry of Education, Culture, Sports, Science and Technology of Japan. We are grateful to K. Sekiguchi and A. Hillier for suggestions.

Author information

Authors and Affiliations



H.M. was responsible for planning, coordination and data analysis. He also wrote the majority of the text. T.S. performed the data analysis for many stellar flares observed by Kepler, and S.N. and Y.N. analysed the rotation of stars observed by Kepler. T.N. and S.K. helped with data analysis and interpretation. S.H. and D.N. contributed to the interpretation of the stellar brightness variation and helped with the data analysis from a general stellar astronomical point of view. K.S. provided theoretical interpretation of the observations and gave advice on the paper’s content.

Corresponding author

Correspondence to Hiroyuki Maehara.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Discussion and Data, Supplementary Figures 1-8, Supplementary Table 1 and additional references. (PDF 2603 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Maehara, H., Shibayama, T., Notsu, S. et al. Superflares on solar-type stars. Nature 485, 478–481 (2012).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing