Detalles de publicación
PP 06021
High spatial resolution mid-infrared spectroscopy of the starburst galaxies NGC3256, IIZw40 and Henize2-10
(1) IAC, (2) Observatoire de Geneve, (3) Laboratoire Astrophysique de Toulouse-Tarbes, (4) NASA Ames Research Center, (5) SRON National Institute for Space Research and Kapteyn Institute, (6) CEA/DSM/DAPNIA/SAp
In order to show the importance of high spatial resolution observations of
extra-galactic sources when compared to observations obtained with larger
apertures such as ISO, we present N-band spectra (8-13 um) of some locations in
three starburst galaxies. In particular, the two galactic nuclei of the spiral
galaxy NGC3256, the compact IR supernebula in the dwarf galaxy IIZw40 and the
two brightest IR knots in the central starburst of the WR galaxy He2-10. The
spectra have been obtained with TIMMI2 on the ESO 3.6m telescope. An inventory
of the spectra in terms of atomic fine-structure lines and molecular bands is
presented. We show the great value of these high spatial resolution data at
constraining properties such as the extinction in the mid-IR, metallicity or
stellar content (age, IMF, etc.). Regarding this, we have constrained the
stellar content of the IR compact knot in IIZw40 by using the mid-IR
fine-structure lines and setting restrictions on the nebular geometry.
Considering the PAH bands, we have constructed a new mid-/far-IR diagnostic
diagram based on the 11.2 um PAH and continuum, accessible to ground-based
observations. Finally, we find a dependence between the presence or
non-presence of PAHs and the hardness of the radiation field as measured by the
[SIV]/[NeII] ratio. In particular, sources with PAH emission have in general a
[SIV]/[NeII] ratio < 0.35. We investigate possible origins for this relation
and conclude that it does not necessarily imply PAH destruction, but could also
be explained by the PAH-dust competition for FUV photons.
extra-galactic sources when compared to observations obtained with larger
apertures such as ISO, we present N-band spectra (8-13 um) of some locations in
three starburst galaxies. In particular, the two galactic nuclei of the spiral
galaxy NGC3256, the compact IR supernebula in the dwarf galaxy IIZw40 and the
two brightest IR knots in the central starburst of the WR galaxy He2-10. The
spectra have been obtained with TIMMI2 on the ESO 3.6m telescope. An inventory
of the spectra in terms of atomic fine-structure lines and molecular bands is
presented. We show the great value of these high spatial resolution data at
constraining properties such as the extinction in the mid-IR, metallicity or
stellar content (age, IMF, etc.). Regarding this, we have constrained the
stellar content of the IR compact knot in IIZw40 by using the mid-IR
fine-structure lines and setting restrictions on the nebular geometry.
Considering the PAH bands, we have constructed a new mid-/far-IR diagnostic
diagram based on the 11.2 um PAH and continuum, accessible to ground-based
observations. Finally, we find a dependence between the presence or
non-presence of PAHs and the hardness of the radiation field as measured by the
[SIV]/[NeII] ratio. In particular, sources with PAH emission have in general a
[SIV]/[NeII] ratio < 0.35. We investigate possible origins for this relation
and conclude that it does not necessarily imply PAH destruction, but could also
be explained by the PAH-dust competition for FUV photons.