Aims. We present a new method for reproducing high spatial resolution observations of bow shocks by using 1D plane parallel shock models. As an example we analyse one bow shock located in the Orion Molecular Cloud (OMC1). Methods. We use high spatial resolution near-infrared observations of H 2 rovibrational emission to constrain shock models. These observations have been made at the ESO-VLT using a combination of the NACO adaptive optics system and infrared camera array and the Fabry-Perot interferometer. Three rovibrational H 2 lines have been observed: v = 1−0 S(1) at 2.12 µm, v = 1−0 S(0) at 2.23 µm and v = 2−1 S(1) at 2.25 µm. The spatial resolution is 0. 15 ∼ 70 AU. We analyse a single bow shock located in our field, featuring a very well defined morphology and high brightness. Results. One dimensional shock models are combined to estimate the physical properties of pre-shock density, shock velocity and transverse magnetic field strength along the bow shock. We find that the pre-shock density is constant at ∼5 × 10 5 cm −3 and shock velocities lie between ∼35 km s −1 in the wings of the shock and ∼50 km s −1 at the apex. We also find that the transverse magnetic field is stronger at the apex and weaker further down the wings varying between ∼2 and 4 mGauss. Predictions of shock velocity and magnetic field strength agree with previous independent observations.

We present high-resolution near-infrared imaging of the compact HII region N159-5 and its immediate environment in the giantstar forming region N159 in the LMC. N159-5 was observed at high spatial resolution ∼0. 11−0. 25 in the K-band using the ESO Very Large Telescope UT4 (VLT), equipped with the NAOS adaptive optics system. Our data reveal that N159-5 has a complex morphology formed mainly by two wings and probably a single central bright star, embedded in diffuse emission of ∼4. 5 diameter. A remarkable embedded tight cluster of approximatively the same size, containing at least 38 faint stars coinciding with N159-5, is also detected. Such clusters can be found in galactic HII regions like the star-forming regions SH2 269 or M42. At the location of the radio peak, especially in the bright western wing, this cluster is rich in stars. Spectroscopic observations reveal that the diffuse region is constituted mainly of dust continuum and that the bright star #2-55 could be of type O8 V. A comparison with the radio observation flux of N159-5 published in the literature seems to show that the bright star #2-55 is not the only ionization source of N159-5. Towards N159-5 molecular H 2 emission is detected. A model of the region is proposed.

We present near-infrared imaging and spectrocopic observations of the HII region N159A (∼10 pc) in the giant star-forming region N159 (50 pc) in the LMC. N159A was observed in the J and Ks bands at high spatial resolution ∼0.2 using the ESO Very Large Telescope UT4 (VLT), equipped with the NAOS adaptative optics system. Our data reveal the morphology of this region in unprecedented detail. The protostar P2, one of the first YSOs of Class I identified in the LMC is now resolved in two YSO candidates. The ultracompact HII region LI-LMC 1501W is found to be a tight cluster embedded in a compact HII region ionised by a late O source. A new multiple system composed of a tight star cluster and an YSO candidate, all embedded in a compact nebular region (0.4 pc) is also detected at the north-east edge of N159A. The stellar population of the whole N159A region appears composed of two main stellar populations, one with an age ≤3 Myr and the other one with a large range of age (300 Myr-10 Gyr). Using spectroscopy, one of the two exciting O stars in the HII region N159A is classified O5-O6.

Aims. We present near-infrared imaging and spectroscopic high spatial resolution observations of the SMC region N88 containing the bright, excited, extincted and compact H II region N88A of the size of about 1 pc. Methods. To investigate its stellar content and reddening, N88 was observed using spectroscopy and imagery in the JHKs-and L -band at a spatial resolution of ∼0.1−0.3 , using the VLT UT4 equipped with the NAOS adaptive optics system. In an attempt to establish if the origin of the infra-red (IR) excess is due to bright nebulosity, circumstellar material and/or local dust, we used Ks vs. J − K color−magnitude (CM) and JHK color−color (CC) diagrams, as well as L imagery. Results. Our IR-data reveal in the N88 area an IR-excess fraction of ≥30 per cent of the detected stars as well as an unprecedently detailed morphology of N88A. It consists of an embedded cluster of ∼3.5 (∼1 pc) in diameter of at least thirteen resolved stars superposed with an unusual bright continuum centered on a very bright star. The four brightest stars in this cluster lie red-ward of H − K ≥ 0.45 mag and could be classified as young stellar object (YSO) candidates. Four other probable YSO candidates are also detected in N88 along a north-south bow-shaped thin H 2 filament at ∼7 east of the young central bright star. This star, which we assume to be the main exciting source, could also be complex. At 0.2 east of this star, a heavily embedded core is detected in the L -band. This core with L ∼ 14 mag and L − K ≥ 4.5 mag could be a massive class I protostar candidate. The 2.12 μm H 2 image of N88A resembles a shell of a diameter of ∼3 (∼0.9 pc) centered on the bright star. This shell consists of three bright components, of which the brightest one superposes the ionization front. The line ratios of H 2 2−1 S(1) and 1−0 S(0) relative to 1−0 S(1), as well as the presence of high v lines, are indicative of photodissociation regions, rather than shocks.