Abstract
We present synthetic observations of star-forming interstellar medium structures obtained by
hydrodynamic calculations of a turbulent box under the influence of an ionizing radiation field.
The morphological appearance of the pillar-like structures in optical emission lines is found
to be very similar to observations of nearby star-forming regions. We calculate line profiles as
a function of position along the pillars for collisionally excited [O III] λ5007, [N II] λ6584 and
[S II] λ6717, which show typical full width at half-maximum of 2–4 km s−1. Spatially resolved
emission-line diagnostic diagrams are also presented which show values in general agreement
with observations of similar regions. The diagrams, however, also highlight significant spatial
variations in the line ratios, including values that would be classically interpreted as shocked
regions based on 1D photoionization calculations. These values tend to be instead the result
of lines of sight intersecting which intersect for large portions of their lengths the ionized-toneutral
transition regions in the gas. We caution therefore against a straightforward application
of classical diagnostic diagrams and 1D photoionization calculations to spatially resolved
observations of complex 3D star-forming regions.
hydrodynamic calculations of a turbulent box under the influence of an ionizing radiation field.
The morphological appearance of the pillar-like structures in optical emission lines is found
to be very similar to observations of nearby star-forming regions. We calculate line profiles as
a function of position along the pillars for collisionally excited [O III] λ5007, [N II] λ6584 and
[S II] λ6717, which show typical full width at half-maximum of 2–4 km s−1. Spatially resolved
emission-line diagnostic diagrams are also presented which show values in general agreement
with observations of similar regions. The diagrams, however, also highlight significant spatial
variations in the line ratios, including values that would be classically interpreted as shocked
regions based on 1D photoionization calculations. These values tend to be instead the result
of lines of sight intersecting which intersect for large portions of their lengths the ionized-toneutral
transition regions in the gas. We caution therefore against a straightforward application
of classical diagnostic diagrams and 1D photoionization calculations to spatially resolved
observations of complex 3D star-forming regions.
Original language | English |
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Pages (from-to) | 141-146 |
Number of pages | 6 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 420 |
Issue number | 1 |
Early online date | 23 Jan 2012 |
DOIs | |
Publication status | Published - 11 Feb 2012 |
Keywords
- stars: formation, H II regions