N88: The physical properties of a compact star-forming region and its neighbourhood in the SMC

This paper, the second in a series of papers on the conspicuous compact HII region N88A in the Small Magellanic Cloud, emphasizes the properties of the H2 emission as well as of the surrounding stellar content of the entire Henize region N88. Using VJK photometry and stellar evolutionary models our analysis of N88 reveals a miscellaneous population of evolved stars of low and intermediate masses (1.2–8 $M_\odot$) in an age range of 40 Myr to 6 Gyr. The majority of these stars are found in the cluster HW 82 which also contains several main sequence stars. AV in N88A is revisited using near-IR Pδ, Pγ and Pβ Paschen emission lines. Spectroscopic measurements of the H2 emission in Z, J, H and K bands allow, in conjunction with measurements in the visible, a full spectral coverage from 0.37 μm to 2.45 μm. Long slit spectroscopy through N88 and the nebulosity to the east clearly distinguishes the ionization zone in N88 characterized by H I and He I emission with pure H2 emission clearly delineated in the cloud nearby. The principal excitation mechanism for H2 is through fluorescent excitation in a photodissociation region associated with N88A