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Дата изменения: Wed Mar 18 12:25:11 2015
Дата индексирования: Sun Apr 10 04:11:07 2016
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Поисковые слова: ceres
A CS and NH3 Survey of Regions with H2O Maser Emission
Guillem Anglada, Robert Estalella, and Josefa Pastor,
Luis F. Rodriguez, Aubrey D. Haschick
abstract
We present CS(J=1->0) and NH3(1,1) observations towards 172 different star
forming regions (99 observed in both molecules) associated with H2O
maser emission. We make a comparative study between the physical
parameters obtained from the CS and NH3 spectra, and their relationship
with the H2O maser emission. We compare the detection rates, line
intensities, line widths and central velocities of the CS and NH3
emissions. We find a relationship between the velocity range of the H2O
maser emission and its luminosity, being the masers with high velocity
components more luminous than masers without high velocity components,
suggesting that the maser pumping mechanism is related to kinetic energy
dissipated when small maser condensations move through the molecular
cloud. We find that both the CS and the NH3 lines are significantly
wider in regions with H2O masers than in other regions. Furthermore, for
the first time, we find evidence that these line widths increase with the
H2O maser luminosity. These results suggest that the presence of H2O
maser emission is intrinsically associated with an increase of the thermal
and turbulent energy of the ambient cloud, in agreement with the current
models which propose that the H2O maser emission originates in shocked
regions, such as those associated with the outflows from young stellar
objects.