All Figures

$\begin{figure} \par\mbox{\includegraphics[height=4.2cm,width=5.9cm,clip]{Hh151_f... ...\includegraphics[height=4.2cm,width=5.8cm,clip]{Hh151_fig02.ps} } \end{figure}$ Figure 1: Left: Spitzer IRS observations of IRAS 19156+1906 (L723-VLA2) in the 14-27 $\mu$ m range (see text for details). The deep absorption centered at 15.2 $\mu$ m arises from the bending mode absorption of CO₂ ice present in the grain mantles. The dashed line represents the expected continuum in the absence of the ice feature. Right: extracted optical depth profile of the CO₂ ice bending mode, using the local continuum shown in the left panel, heavily saturated.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{Hh151_fig03.ps} \end{figure}$ Figure 2: Absorption and scattering cross-section of the grains. The real ( upper panel) and imaginary ( lower panel) part of the complex refractive index of the core interstellar silicates (dot-dashed line) and ice mantle (full line) are displayed. The silicates constants are the Draine & Lee (1984) ones. The H₂O:CO₂ refractive index from 2 to 25 $\mu$ m was measured at IAS at 10 K. The set was extended using the water dominating mantle absorption measured by Trotta (1996) at wavelengths above 25 $\mu$ m, and UV-optical data ( $\lambda<2~\mu$ m) were adopted from Warren (1984).
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8.4cm,clip]{Hh151_fig04.ps} \end{figure}$ Figure 3: Mass absorption cross-sections adopted in the radiative transfer model. The dashed line is the absorption, thin one the scattering, and thick line the extinction cross-section. Upper panel: silicates ellipsoids with a MRN grain size distribution. Lower panel: silicates core/ ice mantle grains with a MRN grain size distribution.
Open with DEXTER

In the text

$\begin{figure} \includegraphics[width=18cm,clip]{f4.eps} \end{figure}$ Figure 4: Model of the spectral energy distribution (SED) of L723. In addition to the Spitzer Long-Low spectrum, fluxes originating from different observatories are plotted (Table 1). The emergent SED calculated with the 1D transfer model using the parameters given in Table 2 is overplotted. The right panels are the $\chi ^2$ minimization surfaces for p indexes of 1., 1.5 and 1.9. The contours correspond to 1, 2 and 3 $\sigma$ with respect to the best fit. The 2MASS points have been excluded from the fit. n₁₀₀ is well constrained by the mid-infrared points. The additional constraint on the outer radius ( $r_{\rm out}\approx 1{-}3$ $\times$ $10^4~{\rm AU}$ , see Fig. 8) measured by Shirley et al. (2002) also excludes the p=1. and also the p=1.9 cases, although less firmly for the later.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=8.4cm,clip]{Hh151_fig04.ps} \end{figure}$	Figure 3: Mass absorption cross-sections adopted in the radiative transfer model. The dashed line is the absorption, thin one the scattering, and thick line the extinction cross-section. Upper panel: silicates ellipsoids with a MRN grain size distribution. Lower panel: silicates core/ ice mantle grains with a MRN grain size distribution.
Open with DEXTER