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Mc Leod, A. F.; Weilbacher, P. M.; Ginsburg, A.; Dale, J. E.; Ramsay, S.; Testi, L. (2016): A nebular analysis of the central Orion nebula with MUSE. In: Monthly Notices of the Royal Astronomical Society, Vol. 455, No. 4: pp. 4057-4086
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Abstract

A nebular analysis of the central Orion nebula and its main structures is presented. We exploit observations from the integral field spectrograph Multi Unit Spectroscopic Explorer ( MUSE) in the wavelength range 4595-9366 angstrom to produce the first O, S and N ionic and total abundance maps of a region spanning 6 arcmin Chi 5 arcmin with a spatial resolution of 0.2 arcsec. We use the S-23(=([S (II)] lambda lambda 6717, 6731+[ S (III)] lambda 9068)/H beta) parameter, together with [O (II)]/[O (III)] as an indicator of the degree of ionization, to distinguish between the various small-scale structures. The only Orion bullet covered by MUSE is HH 201, which shows a double component in the [Fe (II)] lambda 8617 line throughout indicating an expansion, and we discuss a scenario in which this object is undergoing a disruptive event. We separate the proplyds located south of the Bright Bar into four categories depending on their S-23 values, propose the utility of the S-23 parameter as an indicator of the shock contribution to the excitation of line-emitting atoms, and show that the MUSE data are able to identify the proplyds associated with discs and microjets. We compute the second-order structure function for the H alpha, [O (III)] lambda 5007, [S (II)] lambda 6731 and [O (I)] lambda 6300 emission lines to analyse the turbulent velocity field of the region covered with MUSE. We find that the spectral and spatial resolution of MUSE are not able to faithfully reproduce the structure functions of previous works.