The radius and mass of the subgiant star β Hyi from interferometry and asteroseismology

J. R. North*, J. Davis, T. R. Bedding, M. J. Ireland, A. P. Jacob, J. O'Byrne, S. M. Owens, J. G. Robertson, W. J. Tango, P. G. Tuthill

*Corresponding author for this work

Research output: Contribution to journalLetterpeer-review

40 Citations (Scopus)


We have used the Sydney University Stellar Interferometer to measure the angular diameter of β Hydri. This star is a nearby G2 subgiant the mean density of which was recently measured with high precision using asteroseismology. We determine the radius and effective temperature of the star to be 1.814 ± 0.017R⊙ (0.9 per cent) and 5872 ± 44 K (0.7 per cent) respectively. By combining the radius with the mean density, as estimated from asteroseismology, we make a direct estimate of the stellar mass. We find a value of 1.07 ± 0.03 M⊙ (2.8 per cent), which agrees with published estimates based on fitting in the Hertzsprung-Russell diagram, but has much higher precision. These results place valuable constraints on theoretical models of β Hyi and its oscillation frequencies.

Original languageEnglish
Pages (from-to)1-4
Number of pages4
JournalMonthly Notices of the Royal Astronomical Society: Letters
Issue number1
Publication statusPublished - Sep 2007
Externally publishedYes


  • Stars: fundamental parameters
  • Stars: individual: β hyi
  • Techniques: interferometric


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