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.

Gravity modes as a way to distinguish between hydrogen- and helium-burning red giant stars



Red giants are evolved stars that have exhausted the supply of hydrogen in their cores and instead burn hydrogen in a surrounding shell1,2. Once a red giant is sufficiently evolved, the helium in the core also undergoes fusion3. Outstanding issues in our understanding of red giants include uncertainties in the amount of mass lost at the surface before helium ignition and the amount of internal mixing from rotation and other processes4. Progress is hampered by our inability to distinguish between red giants burning helium in the core and those still only burning hydrogen in a shell. Asteroseismology offers a way forward, being a powerful tool for probing the internal structures of stars using their natural oscillation frequencies5. Here we report observations of gravity-mode period spacings in red giants6 that permit a distinction between evolutionary stages to be made. We use high-precision photometry obtained by the Kepler spacecraft over more than a year to measure oscillations in several hundred red giants. We find many stars whose dipole modes show sequences with approximately regular period spacings. These stars fall into two clear groups, allowing us to distinguish unambiguously between hydrogen-shell-burning stars (period spacing mostly 50 seconds) and those that are also burning helium (period spacing 100 to 300 seconds).

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: Mixed modes and avoided crossings in red giant stars.
Figure 2: Oscillation power spectra and échelle diagrams of two red giant stars observed with Kepler.
Figure 3: Asteroseismic diagrams for red giants observed with Kepler.


  1. Schwarzschild, M. & Härm, R. Red giants of population II. II. Astrophys. J. 136, 158–165 (1962)

    Article  CAS  ADS  Google Scholar 

  2. Iben, I., Jr Low-mass red giants. Astrophys. J. 154, 581–595 (1968)

    Article  ADS  Google Scholar 

  3. Sweigart, A. V. & Gross, P. G. Evolutionary sequences for red giant stars. Astrophys. J. Suppl. Ser. 36, 405–437 (1978)

    Article  CAS  ADS  Google Scholar 

  4. Charbonnel, C. in Cosmic Abundances as Records of Stellar Evolution and Nucleosynthesis (eds Barnes, T. G. & Bash, F. N. ) 119–130 (Vol. 336, Astronomical Society of the Pacific Conference Series, 2005)

    Google Scholar 

  5. Aerts, C., Christensen-Dalsgaard, J. & Kurtz, D. W. Asteroseismology (Springer, 2010)

    Book  Google Scholar 

  6. Beck, P. G. et al. Detection of gravity-mode period spacings in red giant stars by the Kepler Mission. Science (in the press)

  7. De Ridder, J. et al. Non-radial oscillation modes with long lifetimes in giant stars. Nature 459, 398–400 (2009)

    Article  CAS  ADS  Google Scholar 

  8. Kallinger, T. et al. Oscillating red giants in the CoRoT exo-field: asteroseismic radius and mass determination. Astron. Astrophys. 509, A77 (2010)

    Article  Google Scholar 

  9. Bedding, T. R. et al. Solar-like oscillations in low-luminosity red giants: first results from Kepler. Astrophys. J. 713, L176–L181 (2010)

    Article  ADS  Google Scholar 

  10. Huber, D. et al. Asteroseismology of red giants from the first four months of Kepler data: global oscillation parameters for 800 stars. Astrophys. J. 723, 1607–1617 (2010)

    Article  CAS  ADS  Google Scholar 

  11. Mosser, B. et al. The universal red-giant oscillation pattern. An automated determination with CoRoT data. Astron. Astrophys. 525, L9 (2011)

    Article  ADS  Google Scholar 

  12. Dziembowski, W. A., Gough, D. O., Houdek, G. & Sienkiewicz, R. Oscillations of α UMa and other red giants. Mon. Not. R. Astron. Soc. 328, 601–610 (2001)

    Article  ADS  Google Scholar 

  13. Christensen-Dalsgaard, J. Physics of solar-like oscillations. Sol. Phys. 220, 137–168 (2004)

    Article  ADS  Google Scholar 

  14. Dupret, M. et al. Theoretical amplitudes and lifetimes of non-radial solar-like oscillations in red giants. Astron. Astrophys. 506, 57–67 (2009)

    Article  ADS  Google Scholar 

  15. Montalbán, J., Miglio, A., Noels, A., Scuflaire, R. & Ventura, P. Seismic diagnostics of red giants: first comparison with stellar models. Astrophys. J. 721, L182–L188 (2010)

    Article  ADS  Google Scholar 

  16. Di Mauro, M. P. et al. Solar-like oscillations from the depths of the red-giant star KIC 4351319 observed with Kepler. Mon. Not. R. Astron. Soc. (submitted)

  17. Tassoul, M. Asymptotic approximations for stellar nonradial pulsations. Astrophys. J. Suppl. Ser. 43, 469–490 (1980)

    Article  ADS  Google Scholar 

  18. Miglio, A., Montalbán, J., Eggenberger, P. & Noels, A. Gravity modes and mixed modes as probes of stellar cores in main-sequence stars: from solar-like to β Cep stars. Astron. Nachr. 329, 529–534 (2008)

    Article  CAS  ADS  Google Scholar 

  19. Aizenman, M., Smeyers, P. & Weigert, A. Avoided crossing of modes of non-radial stellar oscillations. Astron. Astrophys. 58, 41–46 (1977)

    ADS  Google Scholar 

  20. Deheuvels, S. & Michel, E. New insights on the interior of solar-like pulsators thanks to CoRoT: the case of HD 49385. Astrophys. Space Sci. 328, 259–263 (2010)

    Article  ADS  Google Scholar 

  21. Jenkins, J. M. et al. Initial characteristics of Kepler long cadence data for detecting transiting planets. Astrophys. J. 713, L120–L125 (2010)

    Article  ADS  Google Scholar 

  22. Mosser, B. & Appourchaux, T. On detecting the large separation in the autocorrelation of stellar oscillation times series. Astron. Astrophys. 508, 877–887 (2009)

    Article  ADS  Google Scholar 

  23. Gough, D. O. in Hydrodynamic and Magnetodynamic Problems in the Sun and Stars (ed. Osaki, Y. ) 117–143 (Univ. Tokyo Press, 1986)

    Google Scholar 

  24. Girardi, L. A secondary clump of red giant stars: why and where. Mon. Not. R. Astron. Soc. 308, 818–832 (1999)

    Article  ADS  Google Scholar 

  25. Miglio, A. et al. Probing populations of red giants in the galactic disk with CoRoT. Astron. Astrophys. 503, L21–L24 (2009)

    Article  CAS  ADS  Google Scholar 

  26. Kjeldsen, H. & Bedding, T. R. Amplitudes of stellar oscillations: the implications for astero-seismology. Astron. Astrophys. 293, 87–106 (1995)

    ADS  Google Scholar 

  27. Christensen-Dalsgaard, J. ASTEC – the Aarhus STellar Evolution Code. Astrophys. Space Sci. 316, 13–24 (2008)

    Article  ADS  Google Scholar 

  28. Kjeldsen, H., Bedding, T. R. & Christensen-Dalsgaard, J. Correcting stellar oscillation frequencies for near-surface effects. Astrophys. J. 683, L175–L178 (2008)

    Article  ADS  Google Scholar 

  29. Ventura, P., D'Antona, F. & Mazzitelli, I. The ATON 3.1 stellar evolutionary code. A version for asteroseismology. Astrophys. Space Sci. 316, 93–98 (2008)

    Article  ADS  Google Scholar 

  30. Pietrinferni, A., Cassisi, S., Salaris, M. & Castelli, F. A large stellar evolution database for population synthesis studies. I. Scaled solar models and isochrones. Astrophys. J. 612, 168–190 (2004)

    Article  CAS  ADS  Google Scholar 

Download references


We acknowledge the entire Kepler team, whose efforts made these results possible. We thank M. Biercuk for comments. Funding for this Discovery mission was provided by NASA's Science Mission Directorate. T.R.B and D.S. were supported by the Australian Research Council; P.B. and C.A. were supported by European Community's 7th Framework Programme (PROSPERITY); S.H. was supported by the Netherlands Organisation for Scientific Research (NWO). The National Center for Atmospheric Research is sponsored by the National Science Foundation.

Author information

Authors and Affiliations



T.R.B, B.M., P.B., Y.P.E, R.A.G., S.H., C.A., A.-M.B. and F.C. measured and interpreted period spacings; B.M., D.H., R.A.G., S.H., T.K., W.J.C., C.B., D.L.B. and S.M. calculated power spectra and measured large frequency separations; J.M., J.C.-D., A.M., D.S., T.R.W., K.B., M.P.D.M., M.-A.D., M.-J.G., S.K., A.N., V.S.A. and P.V. calculated and interpreted theoretical models; J.D.R., S.H., S.F., Y.P.E., D.S., T.M.B., H.K., J.C.-D. and R.L.G contributed to the coordination of the project, including the acquisition and distribution of the data; and J.M.J. constructed the photometric time series from the original Kepler pixel data. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Timothy R. Bedding.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Table

This file contains a Supplementary Table listing the Red Giants that are shown in Figure 3 of the main paper. (PDF 106 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Bedding, T., Mosser, B., Huber, D. et al. Gravity modes as a way to distinguish between hydrogen- and helium-burning red giant stars. Nature 471, 608–611 (2011).

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