An observational correlation between stellar brightness variations and surface gravity



Surface gravity is a basic stellar property, but it is difficult to measure accurately, with typical uncertainties of 25 to 50 per cent if measured spectroscopically1,2 and 90 to 150 per cent if measured photometrically3. Asteroseismology measures gravity with an uncertainty of about 2 per cent but is restricted to relatively small samples of bright stars, most of which are giants4,5,6. The availability of high-precision measurements of brightness variations for more than 150,000 stars7,8 provides an opportunity to investigate whether the variations can be used to determine surface gravities. The Fourier power of granulation on a star’s surface correlates physically with surface gravity9,10: if brightness variations on timescales of hours arise from granulation11, then such variations should correlate with surface gravity. Here we report an analysis of archival data that reveals an observational correlation between surface gravity and root mean squared brightness variations on timescales of less than eight hours for stars with temperatures of 4,500 to 6,750 kelvin, log surface gravities of 2.5 to 4.5 (cgs units) and overall brightness variations of less than three parts per thousand. A straightforward observation of optical brightness variations therefore allows a determination of the surface gravity with a precision of better than 25 per cent for inactive Sun-like stars at main-sequence to giant stages of evolution.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Simple measures of brightness variations reveal a fundamental ‘flicker sequence’ of stellar evolution.
Figure 2: Stellar surface gravity manifests in a simple measure of brightness variations.
Figure 3: An integrative view of stellar evolution in a new diagram of brightness variations.


  1. 1

    Valenti, J. & Fischer, D. A. Spectroscopic properties of cool stars (SPOCS). I. 1040 F, G, and K dwarfs from Keck, Lick, and AAT planet search programs. Astrophys. J. 159, 141–166 (2005)

    ADS  CAS  Article  Google Scholar 

  2. 2

    Ghezzi, L. et al. Stellar parameters and metallicities of stars hosting Jovian and Neptunian mass planets: a possible dependence of planetary mass on metallicity. Astrophys. J. 720, 1290–1302 (2010)

    ADS  CAS  Article  Google Scholar 

  3. 3

    Brown, T. M., Latham, D. W., Everett, M. E. & Esquerto, G. A. Kepler Input Catalog: photometric calibration and stellar classification. Astron. J. 142, 112–129 (2011)

    ADS  Article  Google Scholar 

  4. 4

    Chaplin, W. J. et al. Ensemble asteroseismology of solar-type stars with the NASA Kepler mission. Science 332, 213–216 (2011)

    ADS  CAS  Article  Google Scholar 

  5. 5

    Huber, D. et al. Testing scaling relations for solar-like oscillations from the main sequence to red giants using Kepler data. Astrophys. J. 743, 143–152 (2011)

    ADS  Article  Google Scholar 

  6. 6

    Stello, D. et al. Asteroseismic classification of stellar populations among 13,000 red giants observed by Kepler. Astrophys. J. 765, L41–L45 (2013)

    ADS  Article  Google Scholar 

  7. 7

    Basri, G. et al. Photometric variability in Kepler target stars: the Sun among stars – a first look. Astrophys. J. 713, L155–L159 (2010)

    ADS  CAS  Article  Google Scholar 

  8. 8

    Basri, G. et al. Photometric variability in Kepler target stars. II. An overview of amplitude, periodicity, and rotation in the First Quarter data. Astron. J. 141, 20–27 (2011)

    ADS  Article  Google Scholar 

  9. 9

    Mathur, S. et al. Granulation in red giants: observations by the Kepler mission and three-dimensional convection simulations. Astrophys. J. 741, 119–130 (2011)

    ADS  Article  Google Scholar 

  10. 10

    Kjeldsen, H. & Bedding, T. R. Amplitudes of solar-like oscillations: a new scaling relation. Astron. Astrophys. 529, L8–L11 (2011)

    ADS  Article  Google Scholar 

  11. 11

    Brown, T. M., Gilliland, R. L., Noyes, R. W. & Ramsey, L. W. Detection of possible p-mode oscillations on Procyon. Astrophys. J. 368, 599–609 (1991)

    ADS  Article  Google Scholar 

  12. 12

    Gilliland, R. L. et al. Kepler mission stellar and instrument noise properties. Astrophys. J. 197 (suppl.). 6–24 (2011)

    Article  Google Scholar 

  13. 13

    Strassmeier, K. G. Starspots. Astron. Astrophys. Rev. 17, 251–308 (2009)

    ADS  Article  Google Scholar 

  14. 14

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

    ADS  CAS  Article  Google Scholar 

  15. 15

    Burger, D. et al. An interactive web application for visualization of astronomy datasets. Astron. Comput. (in the press); preprint at (2013)

  16. 16

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

    ADS  MathSciNet  Article  Google Scholar 

  17. 17

    Basri, G., Walkowicz, L. M. & Reiners, A. Comparison of Kepler photometric variability with the Sun on different timescales. Astrophys. J. 769, 37–49 (2013)

    ADS  Article  Google Scholar 

  18. 18

    Brown, T. M. & Gilliland, R. L. Asteroseismology. Annu. Rev. Astron. Astrophys. 32, 37–82 (1994)

    ADS  Article  Google Scholar 

  19. 19

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

    ADS  Article  Google Scholar 

  20. 20

    Chaplin, W. J. & Miglio, A. Asteroseismology of solar-type and red giant stars. Annu. Rev. Astron. Astrophys (in the press)

  21. 21

    Dumusque, X., Udry, S., Lovis, C., Santos, N. C. & Monteiro, M. J. P. F. G. Planetary detection limits taking into account stellar noise. I. Observational strategies to reduce stellar oscillation and granulation effects. Astron. Astrophys. 525, 140–151 (2011)

    ADS  Article  Google Scholar 

  22. 22

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

    ADS  Google Scholar 

  23. 23

    Henry, G. W., Fekel, F. C., Henry, S. M. & Hall, D. S. Photometric variability in a sample of 187 G and K giants. Astrophys. J. 130 (suppl.). 201–225 (2000)

    ADS  CAS  Article  Google Scholar 

  24. 24

    Gilliland, R. L. Photometric oscillations of low-luminosity red giant stars. Astron. J. 136, 566–579 (2008)

    ADS  Article  Google Scholar 

  25. 25

    Schröder, C., Reiners, A. & Schmitt, J. H. M. M. Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo. Astron. Astrophys. 493, 1099–1107 (2009)

    ADS  Article  Google Scholar 

  26. 26

    Chaplin, W. J., Elsworth, Y., Isaak, G. R., Miller, B. A. & New, R. Variations in the excitation and damping of low-l solar p modes over the solar activity cycle. Mon. Not. R. Astron. Soc. 313, 32–42 (2000)

    ADS  CAS  Article  Google Scholar 

  27. 27

    Komm, R. W., Howe, R. & Hill, F. Solar-cycle changes in GONG p-mode widths and amplitudes 1995–1998. Astrophys. J. 531, 1094–1108 (2000)

    ADS  CAS  Article  Google Scholar 

  28. 28

    Chaplin, W. J. et al. Evidence for the impact of stellar activity on the detectability of solar-like oscillations observed by Kepler. Astrophys. J. 732, L5–L10 (2011)

    ADS  Article  Google Scholar 

  29. 29

    Bastien, F. A. et al. Radial velocity variations of photometrically quiet, chromospherically inactive Kepler stars: a link between RV jitter and photometric flicker. Astron. J (submitted)

  30. 30

    Pinsonneault, M. et al. A revised effective temperature scale for the Kepler Input Catalog. Astrophys. J. 199 (suppl.). 30–51 (2012)

    Article  Google Scholar 

Download references


The research described in this paper makes use of Filtergraph (, an online data visualization tool developed at Vanderbilt University through the Vanderbilt Initiative in Data-intensive Astrophysics. We acknowledge discussions with P. Cargile, K. Carpenter, W. Chaplin, D. Huber, M. Paegert, M. Sinha and D. Weintraub. We thank D. Huber and T. Metcalfe for sharing the average asteroseismic parameters of Kepler stars with us. F.A.B. acknowledges support from a NASA Harriet Jenkins Fellowship and a Vanderbilt Provost Graduate Fellowship. F.A.B. and K.G.S. acknowledge NSF PAARE grant AST-0849736.

Author information




F.A.B. and K.G.S. contributed equally to the identification and analysis of the major correlations. F.A.B. principally wrote the first version of the manuscript. K.G.S. prepared the figures. G.B. calculated the variability statistics of the Kepler light curves and performed an independent check of the analysis. J.P. checked against biases in the datasets. All authors contributed to the interpretation of the results and to the final manuscript.

Corresponding author

Correspondence to Fabienne A. Bastien.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Text and Supplementary Figures 1-3. (PDF 1707 kb)

Supplementary Data

This file contains a machine-readable table corresponding to Supplementary Figure 2. (TXT 32 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Bastien, F., Stassun, K., Basri, G. et al. An observational correlation between stellar brightness variations and surface gravity. Nature 500, 427–430 (2013).

Download citation

Further reading


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.