Gas infall in the massive star formation core G192.16-3.84

Abstract

Previous observations have revealed an accretion disk and outflow motion in high-mass star-forming region G192.16-3.84. While collapse have not been reported before. We present here molecular line and continuum observations toward massive core G192.16-3.84 with the Submillimeter Array. C${}^{18}$O(2-1) and HCO${}^{+}$(3-2) lines show pronounced blue profiles, indicating gas infalling in this region. This is the first time that the infall motion has been reported in G192.16-3.84 core. Two-layer model fitting gave infall velocities of 2.0$\pm$0.2 and 2.8$\pm$0.1 km s${}^{-1}$. Assuming that the cloud core follows a power-law density profile ($\ddot{I}$$\propto$$r^{1.5}$), the corresponding mass infall rates are (4.7$\pm$1.7)$\times 10^{-3}$ and (6.6$\pm$2.1)$\times 10^{-3}$ M$_{\sun}$ yr${}^{-1}$ for C${}^{18}$O(2-1) and HCO${}^{+}$(3-2), respectively. The derived infall rates are in agreement with the turbulent core model and those in other high-mass star-forming regions, suggesting that high accretion rate is a general requirement to form a massive star.