view Abstract Citations (1) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The radial velocity variations of the shell star ζ Tauri. Underhill, Anne B. Abstract Radial-velocity measurements of the hydrogen lines covering the period 1930 to 1952 are presented. It is shown that from 1930 to 1946 the observed variations in radial velocity were regular and can be described as binary motion. A least-squares solution was performed for this data and the following orbital elements were derived: P = 132.91 days (assumed), T = 17.78 + 4.08 days, = 318?51 + 12?32, e = 0.162 + 0.041, K = 8.92 + 0.57 km%ec, V0 = $21.75 + 0.30 km/sec, a3 sin i = 1.608 X I0 km, f(m) = 0.009400. The published radial velocities at other epochs are compared with this basic binary motion, and it is shown that there were significant deviations from simple binary motion in 1902-05, 1914, 1921, and in 1923-27. Pronounced random fluctuations in the radial velocity from the hydrogen lines took place during the observing season 1951-52. Also the hydrogen cores have changed in appearance, the lines being rather shallow and diffuse in 1950, but becoming sharper and deeper in 1951 and 1952. They now appear as they were in 1939. However, there has been no appreciable change in the metallic line spectrum since its enhancement in 1949. The changes in the shell spectrum are secular in nature and do not vary with the radial- velocity period of 132.91 days. It is suggested that the outer shell in which the sharp hydrogen cores originate is rather a field of changing clouds `or prominences than a quiescent body of gas, and that the sporadic radial-velocity fluctuations observed arise because from time to time different elements with differing radial velocities are in the line of sight. Dominion A strophysical Observatory, Victoria, B. C. Publication: The Astronomical Journal Pub Date: October 1952 DOI: 10.1086/106743 Bibcode: 1952AJ.....57..168U full text sources ADS | data products SIMBAD (1)