They are many cases where adaptive optics (AO) improvements in ground-based infrared astronomy are paramount. First of all AO allows competition with space borne instruments, without the expenses and with the ease of access. This will be illustrated with the recent advances and discoveries obtained in two examples of star forming regions. The first one is the Orion Molecular Cloud (OMC1), a very crowded and complex region in our neighbourhood (450 pc). The second ones are extragalactic objects in the Magellanic clouds(MCs) located at 50 to 70 kpc.
In OMC1, where two main excitation mechanisms are coexisting,
namely i) the strong UV field emanating from nearby OB stars creating
the so called photon dominated regions (PDRs) and the different kind of
shocks associated with the star formation process itself, the actions of
multiple sources have to be disentangled. This is obtained, among many
others means, through detailed studies of the morphology, the preferred
scale sizes of the turbulent interstellar medium, the analysis of the
velocity field and of the ratio of ortho- to para-lines of molecular
hydrogen. Use is made of spectral imaging and slit spectroscopy at high
spatial and spectral resolutions in the numerous emission lines of
H
available in several infrared bands.
The use of IR wavefront
sensors has opened the access to new regions as it is the case for the
MCs. Due to their distances, extragalactic objects equivalent to OMC1
in the MCs require the full power of the AO. We present observations of
HEBs (High-Excitation Blobs) in the MCs. HEBs are compact HII regions
that constitute a rare class of ionized nebulae in the MCs. They are
considered to be the final stage of ultra compact (UC) HII regions.
Their main characteristics are: high excitation, small size (
2
pc), high density, and large extinction compared to typical MCs HII
regions. These objects are tightly linked to the early stages of
massive star formation, when the stars disrupt their natal molecular
clouds. Such studies yield important informations for a better
understanding of massive stars formation. We are now able to resolve
clumps of stars inside highly obscured UC and UHC HII regions and
detect the excitation sources.
Soon the Laser Guide star (LGA) will open the whole sky to the power of the AO.