Radial velocity observations of OB1d association in NGC 1977

Radial velocity observations for members of the Ori OB1d association in the nebula NGC 1977 were obtained using the MRES spectrograph with the 2.4 m telescope at Thai National Observatory. Radial velocities of 2MASS J05352174-0453118, HD 37059, HD 294264 are detectable for the first time with a value of 30.02, 32.19 and 60.27 km/s, respectively. Combining the obtained radial velocities from this research with database proper motion, it was found that all observed star are moving in a different direction. This might be a result from the fact that Ori OB1d is dynamically young with active ongoing star formation. The association is small and loose. Members are less gravitationally bound and the cluster is expanding. (paper)