The H ii Region Sharpless 269. I. Morphological Study of the Radial Velocity, Velocity Dispersion, and Density Fields
S. Godbout, G. Joncas, D. Durand, R. Arsenault;
ApJ, 1997, 478, 271
ABSTRACT:We present [S II] lambda lambda 6716.5, 6730.8 radial velocity, velocity
dispersion, and density field maps of the H II region Sharpless 269 obtained using a
scanning Fabry-Perot interferometer.
The radial velocity field shows a clear
bipolar morphology probably related to the dust/molecular lane bisecting the
H II region.
The mean LSR velocity (VLSR) extracted from the data is
16.45 +/- 0.03 km s-1 (1 sigma = 2.77 +/- 0.02 km s-1), blueshifted by 1.3 km s-1
from the associated molecular cloud.
The mean velocity dispersion given
by subtraction of the instrumental and thermal Doppler broadenings from
the FWHM of the line profiles is 16.43 +/- 0.10 km s-1 (1 sigma = 10.40 +/- 0.07
km s-1).
Line width analysis yields an east-west gradient caused by the
proximity of molecular material and the outflow from a young stellar object in the
western part of the nebula.
The electron density field has a mainly uniform
distribution but for a localized increase positionally associated with the young
stellar object mentioned above.
The mean density is found to be 290 +/- 2 cm-3,
while the maximum of the density distribution is centered near 200
cm-3.
Overall, the results are in good agreement with an expansion scenario for the
ionized gas except for the density field which fails to exhibit the predicted
exponential drop from the exciting star to the edge of the H II region.
KEYWORDS: ism: h ii regions, ism: individual name: sharpless 269, ism: kinematics and dynamics, ism: structure
PERSOKEY:region hii, ,
CODE: godbout97