Beta Cephei stars and slowly pulsating B stars

Variability is common among B stars. The Beta Cephei stars and the slowly pulsating B stars are two classes of well established B-type pulsators amongst them and are found in the upper part of the main-sequence (Fig. 1). Their pulsations are driven by the opacity mechanism acting on the Z-bump.

HR diagram with all classes of pulsating stars Position of the beta Cephei stars and the Slowly Pulsating B stars in the HR diagram

Fig. 1. Left: Location of the main classes of variable stars in a theoretical Hertzsprung-Russell diagram. The beta Cephei stars and the Slowly Pulsating B stars are respectively given in turquoise and green (figure taken from ESA, 2000, "Eddington - A mission to map stellar evolution and to find habitable planets, Results of the Assessment Study")
Right: The positions of the confirmed (full symbols) and candidate (open symbols) beta Cephei stars (circles) and Slowly Pulsating B stars (squares) in the main-sequence. We also show the ZAMS (lower dotted lines), the TAMS (upper dotted lines) and the theoretical instability strips for Z = 0.020 for modes with pulsation degree l < 2, computed using the OPAL opacities for stellar models with X= 0.70 for which effects of rotation and convective overshooting were not taken into account (Pamyatnykh A.A., 1999, Acta Astronomica, 49, 119).

Slowly pulsating B stars are:

high radial order g-mode pulsators (pulsation periods: 0.5-5 days)
mid to late B-type stars (spectral type: B2-B9)
massive (M: 3-8 solar masses)
hot (T_eff: 10000-20000 K)

list of confirmed slowly pulsating B stars and their pulsational properties (last update: 28/01/2004)*

list of candidate slowly pulsating B stars and their pulsational properties (last update: 28/01/2004)*

Beta Cephei stars are:

low radial order p/g-mode pulsators (pulsation periods: 2-12 hours)
early B-type stars (spectral type: B0.5-B3)
massive (M: 7-20 solar masses)
hot (T_eff : 18000-35000 K)

list of confirmed field beta Cephei stars and their pulsational properties (last update: 18/01/2005)*

list of candidate field beta Cephei stars (photometric variables) (last update: 24/10/2001)*
list of candidate field beta Cephei stars (line-profile variables) (last update: 24/10/2001)*

All the references used in the different tables can be found here.

* Note that we list only stars for which Geneva photometry is available to enable a homogeneous determination of
the stellar parameters!

Any additions, corrections or suggestions are always welcome!
Anyone interested in the asteroseismology of beta Cephei stars and/or slowly pulsating B stars is encouraged to contact us.

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Last update: 28/01/2004