Supersonic motions in giant H II regions: Handling 3D data with MATADOR

Bidimensional spectroscopy with good spatial and spectral resolution, sampling a particular emission line over the whole emitting area, is shown here to be the most suitable observational technique for understanding the kinematics of giant extragalactic H II regions (GEHRs). The TAURUS II Fabry-Perot spectrograph is an excellent instrument for this purpose, providing simultaneous sampling, at seeing limited resolution, of the whole nebula. The data analysis, however, given the large number of spectra provided in each run could be a huge task. The practical difficulty in handling 3D data sets led us to develop a specific software with this purpose. Some of the facilities provided by MATADOR¹ are specifically described in this paper together with other capabilities that should become evident from the data analysis presented for a few examples. There are regions, like NGC 5471 in M101, which display Gaussian profiles with roughly constant emission linewidth over the whole region. Other GEHRs, such as NGC 604, display split and asymmetric lines emanating from shells, loops, and filaments most likely produced by the mechanical action of massive stars. One also finds in NGC 604 that the bulk of the emission comes from smaller but much brighter areas where line profiles are well fitted by Gaussian profiles. MATADOR can evaluate and compare the emission according to line quality. In this way we have found the kinematic core, the area displaying "well-behaved" Gaussian emission with a constant velocity width, in NGC 5471, NGC 5461, and NGC 604. We conclude that, at least for these three regions it is valid to assign a single value of emission linewidth (σ) and size, the kinematic core (R_kc) as representative of the whole region.