Kinematics and dynamics of the H II region sharpless 142. I - The velocity field of the ionized hydrogen
G. Joncas, J. R. Roy;
ApJ, 1984, 283, 640
ABSTRACT:Nearly 41,000 radial velocity points across the H II region S142 have been measured using an efficient Fabry-Perot interferometer camera and
image processing techniques.
The locus of the most negative H-alpha
velocities coincides with the position of the 'hot' component of the CO molecular
cloud to the east of the nebula.
The observed velocity field is explained as a
systematic expansion of the ionized gas away from the molecular cloud and from the
observer.
There is a striking match between the most negative velocities and the shape
of the CO emission contours.
Some neutral material acts as a wall across
the face of the H II region, inhibiting the flow of ionized gas in the earth's
direction.
The resulting flow configuration explains the radial velocity gradient
across the nebula and the fact that the mean V(LSR) for the whole nebula is
redshifted by +5 km/s with respect to the -41 km/s of the molecular cloud.
KEYWORDS: h ii regions, interferometry, interstellar gas, ionized gases, nebulae, radial velocity, h alpha line, image processing
PERSOKEY:region hii, optical, halpha, ,
CODE: joncas84