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An international team of astronomers, including Saskia Hekker of the University of Amsterdam (UvA), has succeeded in measuring changes in the luminosity of more than 500 Sun-like stars.

An international team of astronomers, including Saskia Hekker of the University of Amsterdam (UvA), has succeeded in measuring changes in the luminosity of more than 500 Sun-like stars. The result is described in the 8 April edition of Science. It is the third article on asteroseismological results from the Kepler space telescope which has recently appeared in an authoritative scientific journal to have been co-authored by Hekker.

Kepler has listened to a kind of 'orchestra' of stars. Stars like our Sun have natural vibrations that are comparable with the vibrations in a musical instrument. The pitch of an instrument tells us, for example, how large the instrument is: a larger instrument has a lower tone than a small instrument. The stellar oscillations can not really be heard, but can be observed as very small changes in the luminosity of the stars. These changes are smaller in the case of less luminous stars, such as light, sun-like stars. For bright stars, such as red giants (stars that have come to the end of their lives), the changes in luminosity by the natural vibrations are larger and therefore easier to observe.

Dr Bill Chaplin of the University of Birmingham in the UK, who has been leading the international team, said: ‘Before we could use the Kepler telescope, we had measured the oscillations in about 20 Sun-like stars. That we have now been able to do this with more than 500 stars, with an unprecedented precision, offers significant opportunities.’

‘We can now calculate the size and mass of 500 Sun-like stars through these asteroseismological measurements,’ says co-author Saskia Hekker of the University of Amsterdam. ‘In this way, we can test theoretical models and we also get an idea of ​​what the Sun looked like in the past and what it will look like in the future. For example, there appear to be more luminous stars than expected on the basis of theory.’

Publication details

W. J. Chaplin, H. Kjeldsen, J. Christensen-Dalsgaard, S. Basu, A. Miglio, T. Appourchaux, T. R. Bedding, Y. Elsworth, R. A. García, R. L. Gilliland, L. Girardi, G. Houdek, C. Karoff, S. D. Kawaler, T. S. Metcalfe, J. Molenda-Żakowicz, M. J. P. F. G. Monteiro, M. J. Thompson, G. A. Verner, J. Ballot, A. Bonanno, I. M. Brandão, A.-M. Broomhall, H. Bruntt, T. L. Campante, E. Corsaro, O. L. Creevey, G. Doğan, L. Esch, N. Gai, P. Gaulme, S. J. Hale, R. Handberg, S. Hekker, D. Huber, A. Jiménez, S. Mathur, A. Mazumdar, B. Mosser, R. New, M. H. Pinsonneault, D. Pricopi, P.-O. Quirion, C. Régulo, D. Salabert, A. M. Serenelli, V. Silva Aguirre, S. G. Sousa, D. Stello, I. R. Stevens, M. D. Suran, K. Uytterhoeven, T. R. White, W. J. Borucki, T. M. Brown, J. M. Jenkins, K. Kinemuchi, J. Van Cleve, and T. C. Klaus: 'Ensemble Asteroseismology of Solar-Type Stars with the NASA Kepler Mission', in: Science 8 april 2011.