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