Astronomy & Astrophysics

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$\begin{figure} \par\includegraphics[width=8.5cm,clip]{1914fig1.eps}\end{figure}$ Figure 1: Map of the 1.3 mm continuum flux toward NGC 7129. Levels are 22.3, 44.6, 89.2, 178.4 to 713.6 mJy/beam in steps of 178.4 mJy/beam. Crosses indicate the millimeter sources and stars the infrared sources. The contours represent the redshifted and blueshifted high-velocity gas of the nebula as traced by the ¹²CO $J=2\rightarrow$ 1 line. Velocity intervals are [-30, -13] km s^-1for the blue lobe (dark contours) and [-7, 11] km s^-1for the red-lobe (grey contours). Contours are 10 to 60 K km s^-1 in steps of 10 K km s^-1 for the blue lobe and 10 to 100 K km s^-1 in steps of 15 K km s^-1 for the red lobe.
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In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{1914fig2.eps}\end{figure}$ Figure 2: Spectra of the NH₃ (1, 1), (2, 2), (3, 3) and (4, 4) inversion lines towards NGC 7129 - FIRS 2 ( left) and LkH $\alpha$ 234 ( right).
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In the text

$\begin{figure} \par\includegraphics[width=8.7cm,clip]{1914fig3.eps}\end{figure}$ Figure 3: Rotational diagram of NH₃ in NGC 7129-FIRS 2 and LkH $\alpha$ 234. The long-dashed line corresponds to the fit assuming a single rotation temperature for all the transitions. The solid and dotted lines are the warm and cold component respectively of the two-component model. An empty inverted triangle indicates an upper limit.
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In the text

$\begin{figure} \par\includegraphics[width=7.9cm,clip]{1914fig4.eps}\end{figure}$ Figure 4: Continuum map at 1.3 mm and integrated intensity maps of the observed lines in NGC 7129 - FIRS 2. The box size is $100'' \times 100 ''$ and is centered at the star position. Contour levels are: a) 39.2 mJy/beam, and from 78.5 to 706.2 mJy/beam by 78.5 mJy /beam; b) 0.19 to 1.7 by 0.19 K km s^-1; c) 0.2 to 8.2 by 0.8 K km s^-1; d) 0.25 to 4 by 0.5 K km s^-1; e) 1.5 to 4 by 0.5 K km s^-1; f) 1.5 to 13.5 by 1.0 K km s^-1; g) 2 to 20 by 2 K km s^-1; h) 0.1 to 0.5 by 0.1 K km s^-1; i) 1 to 14 by 1 K km s^-1; j) 1 to 21 by 2 K km s^-1; k) 2 to 7 by 1 K km s^-1; l) 0.2 to 1.9 by 0.2 K km s^-1; m) 0.8 to 3.4 by 0.4 K km s^-1; n) 0.2 to 3 by 0.4 K km s^-1.
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In the text

$\begin{figure} \par\includegraphics[width=7.9cm,clip]{1914fig5.eps}\end{figure}$ Figure 5: Same as Fig. 1 for LkH $\alpha$ 234. Contour levels are: a) 39.2 mJy/beam, 78.5 to 706.2 mJy/beam by steps of 78.5 mJy/beam; b) 0.19 to 1.7 by 0.19 K km s^-1; c) 0.2 to 8.2 by 0.4 K km s^-1; d) 1.5 to 15 by 1.5 K km s^-1; e) 1 to 11 by 1 K km s^-1; f) 1.5 to 16.5 by 1.5 K km s^-1; g) 2 to 11 by 1 K km s^-1; h) 0.5 to 5 by 0.5 K km s^-1; i) 1 to 6 by 1 K km s^-1.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1914fig6.eps}\end{figure}$ Figure 6: Plots of the $r_1=I(\rm N_2H^+)/{\it I}(H^{13}CO^+)$ ratio and opacity of the main N₂H⁺ hyperfine component (solid contours), and $\tau _{\rm m}$ (dashed contours), as a function of the H¹³CO⁺ column density, $N(\rm H^{13}CO^+)$ , and hydrogen density, n, for a kinetic temperature of T_k=15 K and an N₂H⁺/H¹³CO⁺ abundance ratio, X=3, 7, 15. We have shaded with dark grey the region with $r_1 = 1.5 \pm 0.3$ ( ratio measured at the 32'' offset from the star position) and with a clear color $r_1 = 2.7 \pm 0.6$ (ratio measured at the star position). We need a depletion of at least a factor of 2 towards the center to fit both $\tau _{\rm m}$ and r₁ in both positions. Contour levels are: a) r₁ = 0.8, 1, 1.2 and $\tau _{\rm m}$ = 0.1, 0.5, 1.0, 2, 5, 10; b) r₁ = 1.8, 2.2, 2.7, 3.2 and $\tau _{\rm m}$ = 0.1, 0.5, 1.0, 2, 5, 10; c) r₁ = 3.2, 5, 7 and $\tau _{\rm m} = 0.1$ , 0.5, 1.0, 2, 5, 10.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1914fig7.eps}\end{figure}$ Figure 7: High-velocity CO emission in FIRS 2. The blue-shifted velocities are shown in the top panels, and the red-shifted velocities in the bottom panels. Straight lines indicate the outflow axis. In the case of FIRS 2-out 2 we have drawn two axis because of outflow precession. Black squares show the positions shown in Table 3. Contour levels are: a) 1 to 6 by 1 K km s^-1; b) 2 to 22 by 2 K km s^-1; c) lev 7 to 70 by 7 K km s^-1; d) 7 to 80 by 7 K km s^-1; e) 4 to 50 by 4 K km s^-1; f) 3 to 8 by 1 K km s^-1.
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In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{1914fig8.eps}\end{figure}$ Figure 8: In the central panel we show the integrated line intensity map of the SiO $J=2\rightarrow 1$ line toward FIRS 2. Contour levels are from 0.25 K km s^-1 to 4 K km s^-1 in steps of 0.5 K km s^-1. Surrounding the central panel, we show the observed spectra of the ¹³CO $1\rightarrow 0$ , SiO $2\rightarrow 1$ and H¹³CO⁺ $1\rightarrow 0$ lines towards selected positions of outflows FIRS 2-out 1 ( top panels) and FIRS 2-out 2 ( bottom panels).
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In the text

$\begin{figure} \par\includegraphics[width=7.1cm,clip]{1914fig9.eps}\end{figure}$ Figure 9: Observed CS and C³⁴S spectra towards the (0, 0) position in NGC 7129 - FIRS 2 and LkH $\alpha$ 234.
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In the text

$\begin{figure} \par\includegraphics[width=7.4cm,clip]{1914fig10.eps}\end{figure}$ Figure 10: Observed spectra of CH₃OH and H₂CO lines towards the (0, 0) position in NGC 7129-FIRS 2 and LkH $\alpha$ 234.
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In the text

$\begin{figure} \par\includegraphics[width=8.6cm,clip]{1914fig11.eps}\end{figure}$ Figure 11: The a) panel shows the rotational diagram for CH₃OH in the (0, 0) position of NGC 7129 - FIRS 2. We degraded the angular resolution of the 1.3 mm maps (the $5\rightarrow 4$ and $8\rightarrow 7$ methanol lines) to the angular resolution of the 3 mm maps (the $2\rightarrow 1$ and $11\rightarrow 10$ lines). Two rotation temperatures ( $T_{\rm rot}=17$ K and $T_{\rm rot} >80$ K are required to fit the data). In the b) and c) panels we plot the line velocities and linewidths, V and $\Delta V$ , of the CH₃OH lines as given by the Gaussian fits shown in Table 3 versus the upper state energy of the observed transition (E_u). Finally, the d) panel shows V versus $\Delta V$ for the CH₃OH lines. This panel clearly shows the existence of two velocity components, one at $\sim$ -10 km s^-1 and the other at $\sim$ -8 km s^-1 in this position.
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In the text

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{1914fig12.eps}\end{figure}$ Figure 12: The top panels show the rotational diagram for CH₃OH in LkH $\alpha$ 234 in the two limit cases assumed in the paper; panel a) corresponds to a beam filling factor $\sim$ 1 and panel b) corresponds to a point source. In the bottom panels we plot the linewidths, $\Delta V$ , derived from the Gaussian fits versus the upper energy state of the transition, E_u, and the central velocity, V, for all the lines. In the case of LkH $\alpha$ 234 we have only one velocity component.
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In the text

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{1914fig13.eps}\end{figure}$ Figure 13: Panels a)- d) are the integrated intensity maps of the H₂CO $2_{12} \rightarrow 1 _{11}$ line towards NGC 7129-FIRS 2 for different velocity intervals. In panel e) we show the integrated intensity map of the H₂CO lines after subtracting the Gaussian fit to the wide component from all the spectra. In panel f) we show the area of this wide component as derived from the Gaussian fit. The axes of the outflow FIRS 2-out 1 and FIRS 2-out 2 are indicated. Contour levels are: a) 0.5 to 5 by 0.5 K km s^-1; b)1.0 to 6.5 by 0.5 K km s^-1; c) 0.5 to 5 by 0.5 K km s^-1; d)1 to 14 by 1 K km s^-1; e) 0.5 to 5 by 0.5 K km s^-1; f) 1 to 11.5 by 1 K km s^-1.
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In the text

$\begin{figure} \par\includegraphics[width=8.7cm,clip]{1914fig14.eps}\end{figure}$ Figure 14: Rotational diagram of CH₃CN in the (0, 0) position of FIRS 2 and LkH $\alpha$ 234.
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In the text

$\begin{figure} \par\includegraphics[width=7.3cm,clip]{1914fig15.eps}\end{figure}$ Figure 15: Observed spectra towards the (0, 0) position in LkH $\alpha$ 234 and NGC 7129 - FIRS 2. The warming of the gas during the protostellar evolution produces significant chemical changes, especially in the cold component.
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In the text

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{1914fig16.eps}\end{figure}$ Figure 16: CN $1\rightarrow 0$ /HCN $1\rightarrow 0$ integrated intensity ratio in NGC 7129 - FIRS 2 ( left) and LkH $\alpha$ 234 ( right). Contour levels are 0.10 to 0.35 by 0.05 in NGC 7129 - FIRS 2 and 0.35 to 1.1 by 0.05 in LkH $\alpha$ 234.
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In the text

$\begin{figure} \par\includegraphics[width=8.6cm,clip]{1914fig17.eps}\end{figure}$ Figure 17: Histogram with the total beam-averaged molecular column densities estimated in the IM Class 0 YSO NGC 7129 - FIRS 2 and the HBe star LkH $\alpha$ 234. The column densities of the molecules tracing the cold envelope decrease by at least a factor of 5 between NGC 7129 - FIRS 2 and LkH $\alpha$ 234. An exception is H¹³CO⁺, which is depleted in the Class 0 protostar (see text). The column densities of the molecules tracing the warm envelope and the PDR remain quite constant, and in some cases increase, from the Class 0 protostar to the HBe star. The SiO column density is lower by almost 2 orders of magnitude in LkH $\alpha$ 234 than in NGC 7129 - FIRS 2. This is very likely related to the absence of an energetic bipolar outflow in the HBe star.
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In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{1914fig2.eps}\end{figure}$	Figure 2: Spectra of the NH₃ (1, 1), (2, 2), (3, 3) and (4, 4) inversion lines towards NGC 7129 - FIRS 2 ( left) and LkH $\alpha$ 234 ( right).
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$\begin{figure} \par\includegraphics[width=8.7cm,clip]{1914fig3.eps}\end{figure}$	Figure 3: Rotational diagram of NH₃ in NGC 7129-FIRS 2 and LkH $\alpha$ 234. The long-dashed line corresponds to the fit assuming a single rotation temperature for all the transitions. The solid and dotted lines are the warm and cold component respectively of the two-component model. An empty inverted triangle indicates an upper limit.
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$\begin{figure} \par\includegraphics[width=7.9cm,clip]{1914fig5.eps}\end{figure}$	Figure 5: Same as Fig. 1 for LkH $\alpha$ 234. Contour levels are: a) 39.2 mJy/beam, 78.5 to 706.2 mJy/beam by steps of 78.5 mJy/beam; b) 0.19 to 1.7 by 0.19 K km s^-1; c) 0.2 to 8.2 by 0.4 K km s^-1; d) 1.5 to 15 by 1.5 K km s^-1; e) 1 to 11 by 1 K km s^-1; f) 1.5 to 16.5 by 1.5 K km s^-1; g) 2 to 11 by 1 K km s^-1; h) 0.5 to 5 by 0.5 K km s^-1; i) 1 to 6 by 1 K km s^-1.
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$\begin{figure} \par\includegraphics[width=7.1cm,clip]{1914fig9.eps}\end{figure}$	Figure 9: Observed CS and C³⁴S spectra towards the (0, 0) position in NGC 7129 - FIRS 2 and LkH $\alpha$ 234.
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$\begin{figure} \par\includegraphics[width=7.4cm,clip]{1914fig10.eps}\end{figure}$	Figure 10: Observed spectra of CH₃OH and H₂CO lines towards the (0, 0) position in NGC 7129-FIRS 2 and LkH $\alpha$ 234.
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$\begin{figure} \par\includegraphics[width=8.7cm,clip]{1914fig14.eps}\end{figure}$	Figure 14: Rotational diagram of CH₃CN in the (0, 0) position of FIRS 2 and LkH $\alpha$ 234.
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$\begin{figure} \par\includegraphics[width=7.3cm,clip]{1914fig15.eps}\end{figure}$	Figure 15: Observed spectra towards the (0, 0) position in LkH $\alpha$ 234 and NGC 7129 - FIRS 2. The warming of the gas during the protostellar evolution produces significant chemical changes, especially in the cold component.
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$\begin{figure} \par\includegraphics[width=7.7cm,clip]{1914fig16.eps}\end{figure}$	Figure 16: CN $1\rightarrow 0$ /HCN $1\rightarrow 0$ integrated intensity ratio in NGC 7129 - FIRS 2 ( left) and LkH $\alpha$ 234 ( right). Contour levels are 0.10 to 0.35 by 0.05 in NGC 7129 - FIRS 2 and 0.35 to 1.1 by 0.05 in LkH $\alpha$ 234.
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