Astronomy and Astrophysics – Astrophysics
Scientific paper
2001-01-22
Astrophysical Journal, Vol. 555, p. 961-966
Astronomy and Astrophysics
Astrophysics
6 pages, 7 figures, submitted to ApJ
Scientific paper
10.1086/321497
Strange modes can occur in radiative classical Cepheids and RR Lyrae models. These are vibrational modes that are trapped near the surface as a result of a 'potential barrier' caused by the sharp hydrogen partial ionization region. Typically the modal number of the strange mode falls between the 7th and 12th overtone, depending on the astrophysical parameters of the equilibrium stellar models (L, M, \Teff, X, Z). Interestingly these modes can be linearly unstable outside the usual instability strip, in which case they should be observable as new kinds of variable stars, 'strange Cepheids' or 'strange RR Lyrae' stars. The present paper reexamines the linear stability properties of the strange modes by taking into account the effects of an isothermal atmosphere, and of turbulent convection. It is found that the linear vibrational instability of the strange modes is resistant to both of these effects. Nonlinear hydrodynamic calculations indicate that the pulsation amplitude of these modes is likely to saturate at the millimagnitude level. These modes should therefore be detectable albeit not without effort.
Buchler Jean-Robert
Kolláth Zoltan
No associations
LandOfFree
Strange Cepheids and RR Lyrae does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Strange Cepheids and RR Lyrae, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Strange Cepheids and RR Lyrae will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-11489