Hostname: page-component-586b7cd67f-dsjbd Total loading time: 0 Render date: 2024-11-22T10:01:32.947Z Has data issue: false hasContentIssue false

Comparing convection in the Sun with Procyon A

Published online by Cambridge University Press:  01 August 2006

Frank Robinson
Affiliation:
Department of Astronomy, Yale University, New Haven, CT 12345, USA email: [email protected]
Pierre Demarque
Affiliation:
Department of Astronomy, Yale University, New Haven, CT 12345, USA email: [email protected]
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

As well as reproducing observable features like solar granulation, 3D simulations can provide useful information for local or non-local stellar modeling. Examples include testing out the mixing length theory in the surface layers, providing the turbulent correction for stellar models of p-mode frequencies, testing eddy viscocity prescriptions used in tidal dissipation models and comparing different closures of higher order moments. Having validated the 3D code with the sun we applied it to other stars. For Procyon A the turbulence is about twice as strong as it is in the Sun (estimated by the peak root mean square vertical velocity which is about 6.5 km/s) and the granules are nearly an order of magnitude larger, with plumes regularly extending down 2-3 pressure scale heights below the surface of Procyon A. An interesting feature of the Procyon simulation is that the horizontal layers in the vicinity of the granules appear to radially pulsate in a quasi-periodic manner. This makes the superadiabatic layer move in and out over a distance of about half a pressure scale height in a time of about 20-30 minutes. This motion appears to be tied to the granulation but there may be other phenomena involved such as some kind of local kappa-mechanism confined to the granulation surface layers. We find similar behaviour in a simulation of an 11 Gyr subgiant sun. As the velocities are more like the sun (about 3km/s), the time period of the pulsation in the subgiant is 2-3 times longer than in Procyon A.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2007

References

Canuto, V.M. & Mazzitelli, I., 1991, ApJ 370, 275CrossRefGoogle Scholar
Chan, K.L. & Sofia, S. 1989, ApJ 336, 1022CrossRefGoogle Scholar
Goldreich, P. & Keeley, D.A. 1989, ApJ 211, 934CrossRefGoogle Scholar
Goodman, J. & Oh, S.P. 1997, ApJ 486, 403CrossRefGoogle Scholar
Gryanik, V.M. & Hartmann, J. 2002, J. Atmos. Sci. 59, 27292.0.CO;2>CrossRefGoogle Scholar
Guenther, D.B. & Demarque, P. 1997, ApJ 484, 937CrossRefGoogle Scholar
Kim, Y.-C. and Chan, K.L. 1998, ApJ 496, L121CrossRefGoogle Scholar
Kupka, F. 2005, in Element Stratification in Stars: 40 Years of Atomic Diffusion, edts. Alecian, G., Richard, O. and Vauclair, S., EAS Publications Series, Vol. 17, opp. 177Google Scholar
Kupka, F. & Robinson, F.J. 2007a, MNRAS 374, 305CrossRefGoogle Scholar
Kupka, F. & Robinson, F.J. 2007b, this volume p. 74CrossRefGoogle Scholar
Li, L.H., Robinson, F.J., Demarque, P., Sofia, S. and Guenther, D.B. 2002, ApJ 567, 1192CrossRefGoogle Scholar
Penev, K., Sasselov, D., Robinson, F.J. & Demarque, P. 2006, ApJ, in pressGoogle Scholar
Robinson, F.J. & Chan, K.L. 2004, Phys. of Fluids 15, 5, 1321CrossRefGoogle Scholar
Robinson, F.J., Demarque, P., Li, L.H., Sofia, S., Kim, Y.-C., Chan, K.L. & Guenther, D.B. 2003, MNRAS 340, 923CrossRefGoogle Scholar
Robinson, F.J., Demarque, P., Li, L.H., Sofia, S., Kim, Y.-C., Chan, K.L. & Guenther, D.B. 2004, MNRAS 347, 1208CrossRefGoogle Scholar
Robinson, F.J. & Sherwood, S.C. 2006, J. Atmos. Sci. 63, 1013CrossRefGoogle Scholar
Stein, R.F. and Nordlund, Å. 1998, ApJ 499, 914CrossRefGoogle Scholar
Stein, R.F. and Nordlund, Å. 2000, Solar Phys. 192, 91Google Scholar
Straka, C.W., Demarque, P., Guenther, D.B., Li, L.H. & Robinson, F.J. 2006, ApJ 636, 1078CrossRefGoogle Scholar
Unno, W., & Spiegel, E.A. 1966, PASJ 18, 85Google Scholar
Zahn, J.P., 1966, Ann. d'Ap 29, 489Google Scholar