Beat Cepheids

Definition

Beat Cepheids are classical Cepheid variable stars pulsating in two radial modes simultaneously. They are sometimes refered to as double-mode Cepheids.

Milky Way

There are 22 beat Cepheids known in the Milky Way. One candidate (V371 Per) is uncertain. All but two of the remainder are pulsating in the fundamental and first overtone modes. Among the beat Cepheids in our galaxy, only CO Aur and HD 304373 are known to pulsate in the first and second overtone modes. Many more probably exist, but surveys to date have not been especially well-suited to the detection of these stars.

The following table contains information on galactic beat Cepheids. The links are to available on-line photometry and radial velocities. The positions are for equinox J2000.0.

Star RA Dec V_min V_max P0 P1 P0/P1 Mode
CO Aur 06:00:28 +35:18:42 7.46 8.08 1.7841 1.4255 0.80 1H/2H
DZ CMa 07:16:53.00 -15:19:41.9 11.8 12.3 2.362896 1.700131 0.7195 F/1H
Y Car 10:33:11 -58:29:54 7.53 8.48 3.6398 2.5595 0.7032 F/1H
EY Car 10:42:23.03 -61:09:57.2 9.90 10.45 2.876(3) 2.036(2) 0.7077(8) F/1H
GZ Car 10:20:21 -59:22:36 9.98 10.47 4.1589 2.9337 0.7054 F/1H
TU Cas 00:26:20 +51:16:48 6.88 8.18 2.1393 1.5183 0.7097 F/1H
AS Cas 00:25:37 +64:13:48 11.81 12.55 3.0247 2.1556 0.7127 F/1H
GSC 4015.0972 00:25:18.2 +60:45:54 14.10 14.95 3.73425 2.65262 0.7103 F/1H
UZ Cen 11:40:58 -62:41:30 8.30 9.12 3.3344 2.3553 0.7064 F/1H
BK Cen 11:49:16 -63:04:42 9.60 10.38 3.1739 2.2230 0.7004 F/1H
V371 Per 02:55:31 +42:35:19            
VX Pup 07:32:37 -21:55:48 7.73 8.59 3.0109 2.1390 0.7104 F/1H
BE Pup 07:33:35 -25:50:35.9 13.0 13.9 2.870(3) 2.048(2) 0.7136(8) F/1H
EW Sct 18:37:51 -06:47:54 7.77 8.24 5.8232 4.0673 0.6985 F/1H
V367 Sct 18:33:36 -10:25:30 11.21 11.91 6.2931 4.3847 0.6967 F/1H
BQ Ser 18:36:16 +04:23:42 9.21 9.93 4.2707 3.0121 0.7053 F/1H
U TrA 16:07:19 -62:54:36 7.30 8.29 2.5684 1.8249 0.7105 F/1H
AP Vel 08:39:45 -43:51:42 9.49 10.48 3.1278 2.1998 0.7033 F/1H
AX Vel 08:10:49 -47:41:54 7.93 8.48 3.6732 2.5929 0.7059 F/1H
BD -10 4669 18:22:27.1 -10:07:29 10.5 11.5 4.84125 3.3853 0.6993 F/1H
GSC 8607-0608 10:09:13.62 -57:14:33.3 10.70 11.40 4.089(3) 2.869(4) 0.7017(11) F/1H
HD 304373 11:28:42.67 -59:25:43.2     0.922405 0.743241 0.8058 1H/2H
NSV 6728 14:36:55.58 -58:15:41.1 9.75 10.35 4.317(7) 3.037(3) 0.7035(14) F/1H

LMC

A total of 45 LMC beat Cepheids have been reported by the MACHO Project. These have been described in the Alcock et al. (1995).

SMC

The EROS Project has discovered 11 beat Cepheids in the SMC. Four of these are F/1H pulsators and the remainder are 1H/2H pulsators. The period ratios of the F/1H pulsators are greater than their LMC counterparts. Click here for down-loadable version of the paper "EROS Variable Stars : Discovery of Beat Cepheids in the Small Magellanic Cloud and the effect of metallicity on pulsation" by Beaulieu, J.P. et al., 1997, A&A, 321, L5.

Last updated: 2004 Mar 26
Doug Welch