A Re-Examination of the Space Motions and Luminosities of the Stars of the Cassiopeia–Taurus Group Based Upon New Radial Velocities

Results are presented of an investigation of the motions of 49 stars composing the Cassiopeia–Taurus group. New radial velocities of 40 stars are given, based upon 668 spectrograms. Seven stars are found to vary in radial velocity. The new velocities are, on the average, 2 km/sec more negative than existing catalogue values. Spectroscopic absolute magnitudes of 46 stars are measured. Proper motions are used to find the convergent point of the group and radial velocities then supply the stream motion and K-term. Correcting the observed motions for differential galactic rotation, the convergent point is at A = 97°, D = – 18°; the stream motion S = 23.9 km/sec and the K-term is –1.2 km/sec. Including corrections for differential galactic rotation, the elements of the motion are A = 97°, D = – 15°, S = 20.1 km/sec, K = +0.4 km/sec. It is concluded that the stars are a sample of the general population in that they possess normal solar motion plus average random motion. This conclusion is confirmed in a general way by plots of the space motions after standard solar motion is removed. Furthermore the motions do not show an expansion of the stars from a common region. The mean parallax deduced from the assumption of standard solar motion agrees exactly with the mean of the individual spectroscopic parallaxes.