Candidate Rotating Toroids around High-Mass (Proto)Stars
Furuya, R S ; Cesaroni, R ; Takahashi, S ; et al. ; - ASI Sponsor
Jan - 2008
journal : The Astrophysical Journal
type: Article Journal
Abstract
Using the OVRO, Nobeyama, and IRAM mm-arrays, we searched fo r “disk”- outflow systems in three high-mass (proto)star forming regi ons: G16.59 − 0.05, G23.01 − 0.41, and G28.87+0.07. These were selected from a sample of N H 3 cores (Codella, Testi \& Cesaroni) associated with OH and H 2 O maser emission (Foster \& Caswell) and with no or very faint continuum emissi on. Our imaging of molecular line (including rotational transitions of CH 3 CN) and 3mm dust continuum emission revealed that these are compact ( ∼ < 0.05 – 0.3 pc), massive ( ∼ 100 – 400 M ⊙ ), and hot ( ∼ 100 K) molecular cores (HMCs), that is likely sites of high-mass star formation prior to the appearance of ultraco mpact H II regions. All three sources turn out to be associated with molecular outflo ws from 12 CO and/or HCO + J =1–0 line imaging. In addition, velocity gradients of 10 – 10 0 km s − 1 pc − 1 in the innermost ( ∼ < 0.03 – 0.13 pc), densest regions of the G23.01 − 0.41 and G28.87+0.07 HMCs are identified along directions roughl y perpendicular to the axes of the corresponding outflows. All the results sug gest that these cores might be rotating about the outflow axis, although the c ontribution of rotation to gravitational equilibrium of the HMCs appears t o be negligible. Our analysis indicates that the 3 HMCs are close to virial equili brium due to turbulent pressure support. Comparison with other similar objects wh ere rotating toroids have been identified so far shows that in our case rotation app ears to be much less prominent; this can be explained by the combined effect of unf avorable projection, large distance, and limited angular resolution with the cur rent interferometers.
keywords : 0.05,0.41,G23.01,G28.87+0.07) — stars: early type — radio continuum,ISM: evolution — ISM: individual (G16.59,−