We present a study of the kinematic properties of the ionized gas in the dominant giant H ii region of the well known H ii galaxy : II Zw 40 .
High spatial and spectral resolution spectroscopy has been obtained using IFU mode on the GMOS instrument at Gemini-North Based on observations obtained at the Gemini Observatory , which is operated by the Association of Universities for Research in Astronomy , Inc. , under a cooperative agreement with the NSF on behalf of the Gemini partnership : the National Science Foundation ( United States ) , the Science and Technology Facilities Council ( United Kingdom ) , the National Research Council ( Canada ) , CONICYT ( Chile ) , the Australian Research Council ( Australia ) , CNPq ( Brazil ) and CONICET ( Argentina ) telescope .
The observations allow us to obtain the H \alpha intensity map , the radial velocity and velocity dispersion maps as well as estimate some physical conditions in the inner region of the starburst , such as oxygen abundance ( O/H ) and electron density .
We have used a set of kinematics diagnostic diagrams , such as the intensity versus velocity dispersion ( I - \sigma ) , intensity versus radial velocity ( I - V ) and V - \sigma , for global and individual analysis in sub-regions of the nebula .
We aim to separate the main line broadening mechanisms responsible for producing a smooth supersonic integrated line profile for the giant H ii region .
Bubbles and shells driven by stellar winds and possibly supernovae , covering a large fraction on the face of the nebula , are identified on scales larger than 50 pc .
We found that unperturbed or “ free from shells ” regions showing the lowest \sigma values ( \sim 20 km s ^ { -1 } ) should be good indicators for the \sigma _ { grav } component in II Zw 40 .
The brightest central region ( R \sim 50 pc ) is responsible for \sigma derived from a single fit to the integrated line profile .
The dominant action of gravity , and possibly unresolved winds of young ( < 10 Myr ) massive stars , in this small region should be responsible for the characteristic H \alpha velocity profile of the starburst region as a whole ( \sigma = 32-35 \hbox { km } \thinspace \hbox { s } ^ { -1 } ) .
Our observations show that the complex structure of the interstellar medium of this galactic scale star-forming region is very similar to that of nearby extragalactic giant H ii regions in the Local Group galaxies .