The kinematics of molecular clumps surrounding hot cores in G29.96-0.02 and G31.41+0.31


C. Maxia (1,2), L. Testi (3), R. Cesaroni (3), C.M. Walmsley (3)

(1) Osservatorio Astronomico di Cagliari, Str. 54, Loc. Poggio dei Pini, I-09012 Capoterra (CA), Italy

(2) Dipartimento di Scienze Fisiche, Universit\`a di Cagliari, Cittadella Universitaria, I-09042 Monserrato (CA), Italy

(3) Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze, Italy


We present high angular resolution interferometric observations of the 3 and 1.3~mm continuum emission, and HCO$^+$(1--0) and SiO(2--1)~v=0 lines, obtained with the Owens Valley Radio Observatory millimeter-wave array, toward two hot cores (HCs) associated with two well known ultracompact (UC) \HII\ regions: \gv\ and \gt. These HCs are believed to host young forming massive stars which have been suggested to be surrounded by massive rotating accretion disks. The aim of these new observations is to study the structure and kinematics of the molecular clumps surrounding the HCs and nearby UC~\HII\ regions at moderately high angular resolution. Our observations reveal that the clumps within which the HCs and UC~\HII\ regions are embedded have a complex kinematical structure. The total mass of the clumps is estimated to be in the range 1000--3000~$M_\odot$, consistent with previous findings. Our observations also show compelling evidence that the clump in \gv\ is contracting onto the HC position, suggesting that the accretion process onto the massive young stellar object embedded in the HC is still ongoing. In these objects the kinematical structure that we observe is also compatible with the presence of a massive rotating disk within the HC, even though we cannot prove this suggestion with our data. The case of \gt\ is more complicated, and our data, although consistent with the presence of an inner disk and an infalling envelope around it, do not have the required spatial resolution to resolve the different structu res.

Mantained by: Leonardo Testi