PPAK integral field spectroscopy survey of the Orion nebula

Abstract

We present a low-resolution spectroscopic survey of the Orion nebula. The data are released for public use. We show the possible applications of this dataset analyzing some of the main properties of the nebula. Methods. We perform an integral field spectroscopy mosaic of an area of similar to 5' x 6' centered on the Trapezium region of the nebula, including the ionization front to the south-east. Analysis of the line fluxes and line ratios of both the individual and integrated spectra allowed us to determine the main characteristics of the ionization throughtout the nebula. Results. The final dataset comprises 8182 individual spectra, sampled in a circular area of similar to 2.7" diameter. The data can be downloaded as a single row-stacked spectra fit file plus a position table or as an interpolated datacube with a final sampling of 1.5"/pixel. The integrated spectrum across the field-of-view was used to obtain the main integrated properties of the nebula, including the electron density and temperature, the dust extinction, the Ha integrated flux (after correcting for dust reddening), and the main diagnostic line ratios. The individual spectra were used to obtain line intensity maps of the different detected lines. These maps were used to study the distribution of the ionized hydrogen, the dust extinction, the electron density and temperature, and the helium and oxygen abundance. All of them show a considerable degree of structure as already shown in previous studies. In particular, there is a tight relation between the helium and oxygen abundances and the ionization structure that cannot be explained by case B recombination theory. Simple arguments like partial ionization and dust mixed with the emitting gas may explain these relations. However a more detailed modeling is required, for which we provide the dataset.