Kinematics of the Scorpius-Centaurus OB association

Abstract

A fine structure related to the kinematic peculiarities of three components of the ScorpiusCentaurus association (LCC, UCL, and US) has been revealed in the UVvelocity distribution of Gould Belt stars. We have been able to identify the most likely members of these groups by applying the method of analyzing the two-dimensional probability density function of stellar UV velocities that we developed. A kinematic analysis of the identified structural components has shown that, in general, the center-of-mass motion of the LCC, UCL, and US groups follows the motion characteristic of the Gould Belt, notably its expansion. The entire Scorpius-Centaurus complex is shown to possess a proper expansion with an angular velocity parameter of 46 ± 8 km s −1 kpc −1 for the kinematic center with l 0 = −40• and R 0 = 110 pc found. Based on this velocity, we have estimated the characteristic expansion time of the complex to be 21 ± 4 Myr. The proper rotation velocity of the ScorpiusCentaurus complex is lower in magnitude, is determined less reliably, and depends markedly on the data quality.

New Expansion Rate Estimate of the Scorpius–Centaurus Association Based on T Tauri Stars from the Gaia DR2 Catalog

“…Now, we obtain a significantly smaller error in determining this coefficient, ±2 km/s/kpc. The value K = 41 ± 2 km/s/kpc from the second column of Table 1 is in close agreement with the analysis of massive stars that was also obtained in [18] without considering the spiral density wave.…”

“…1), the sample is kinematically very homogeneous. Earlier, an estimate of the linear expansion coefficient K = 46 ± 8 km/s/kpc was obtained from a sample of approximately 200 massive OB stars from the HIPPARCOS catalog [18]. Now, we obtain a significantly smaller error in determining this coefficient, ±2 km/s/kpc.…”

“…In [18], Due to the fact that 33 stars with velocities V > 10 km/s were discarded (Fig. 1), the sample is kinematically very homogeneous.…”

A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood

“…The membership status of AS Col (HD 35114) is ambiguous primarily as a result of a poorly constrained radial velocity (see e.g. Bobylev, Goncharov, &Bajkova 2006 andBajkova 2007 who derive values of 15.2 ± 1.6 km s −1 and 23.9 ± 2.2 km s −1 respectively). The analysis of Malo et al (2013) finds that AS Col belongs to either Columba or Tuc-Hor (Pv+π = 99 per cent in both cases) depending on which radial velocity is adopted.…”

Polarization of seven MBM clouds at high Galactic latitude

“…The ionized region is primarily distributed around the ζ Ophiuchus (Sh2-27, Sharpless, 1959) and the Sco OB2 (Sh2-7, Sharpless, 1959) association which are identified and labeled. Some of the members of the Scorpius-Centaurus association (LCC = Lower Centaurus-Crux, UCL = Upper Centaurus-Lupus, and US = Upper Scorpius) obtained from Bobylev & Bajkova (2007) are identified using black-yellow circles. Distribution of O-type stars towards displayed region obtained from Maíz-Apellániz et al (2004) is also shown using filled black circles.…”