All Figures

$\begin{figure} \par\includegraphics[angle=-90,width=15cm,clip]{4646fig1.eps} \end{figure}$ Figure 1: Overview of the S235A-B star forming complex Left: overlay of the single-dish HCN map (contours) from Cesaroni et al. (1999) with the K-band image of the S235A-B region from Felli et al. (1997). Right: overlay of the interferometric maps of the 3.3 mm continuum emission (thick contours and grey scale) with the HCO⁺(1-0) outflows (thin solid line: V < -20.9 km s^-1, dashed line: V> -15.5 km s^-1) from Felli et al. (2004). In both, a cross marks the location of the H₂O maser at -61.2 km s^-1 from Tofani et al. (1995). The infrared source with the largest near-IR excess detected in previous works, M 1, is also indicated. The offsets between M 1, the water maser, the HCN peak, and the mm continuum peak are all larger than the position uncertainties.
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In the text

$\begin{figure} \par\includegraphics[angle=90,width=9cm,clip]{4646fig2.eps} \end{figure}$ Figure 2: Three colour (4.5 blue, 5.8 green, and 8.0 $\mu$ m red) image of the S235A-B region. The labels indicate the position of M 1, S235AB-MIR, and the other stars of the cluster for which we performed photometry. (A colour version of this figure is available in the on-line edition.)
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=7.4cm,clip]{4646fig3.eps} \end{figure}$ Figure 3: The 1.2 mm core (contours) from Felli et al. (2004) overlaid on the 5.8 $\mu$ m Spitzer-IRAC image (grey scale, S235A and S235B have been saturated to show the weak emission from S235AB-MIR). The positions of the mm core, S235AB-MIR, and M 1 are indicated.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=7cm]{4646fig4.eps} \end{figure}$ Figure 4: Colour-colour plots of the most relevant sources in the area of the S235A-B cluster. The identifying numbers and symbols are the same as those used in Table 2 and Fig. 2. In the bottom box, the regions occupied by Class I and Class II sources are enclosed with dotted and dashed lines, respectively. When only an upper limit to the flux density could be estimated in one of the bands, the corresponding point in the plot is marked by an arrow.
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In the text

$\begin{figure} \par\includegraphics[width=7cm,clip]{4646fig5.eps} \end{figure}$ Figure 5: Maps of the continuum radio emission from S235A at 6, 3.6, and 1.3 cm (contours). Levels are from 2 to 14 mJy/beam by 2 mJy/beam for 6 cm, from 1 to 5 mJy/beam by 0.5 mJy/beam for 3.6 cm, and 0.1 to 0.5 mJy/beam by 0.1 mJy/beam for 1.3 cm. The 1.3 cm map has been smoothed to a lower resolution to increase the S/N ratio. The 3.6 cm map is overlaid with the 5.8 $\mu$ m Spitzer-IRAC image (grey scale).
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=7cm,clip]{4646fig6.eps} \end{figure}$ Figure 6: Map of the continuum radio emission at 1.3 cm of the area around the water masers (contours) overlaid with the map of the continuum 1.2 mm emission (grey scale) from Felli et al. (2004). Levels are from 0.12 ( $\sim$ $4\sigma$ ) to 0.48 mJy/beam in steps of 0.12 mJy/beam. The locations of the three H₂O maser spots detected in this work are indicated by "+''. M 1 and the centre of S235B (asterisk) are also indicated. The dashed lines define the directions of the two outflows. The dotted circle is the primary beam at 1.2 mm. The synthesized beam at 1.3 cm is drawn in the bottom left-hand corner.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=7cm,clip]{4646fig7.eps} \end{figure}$ Figure 7: H₂O VLA spectra averaged on a circle 1 $\hbox {$^{\prime \prime }$ }$ in radius and centred on the locations of each of the 3 maser spots. The name of the spot is indicated above the corresponding spectrum. The intensity scale is offset by 2 and 4 Jy for clearness of the display. The vertical line defines the velocity of the molecular cloud.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=7.5cm,clip]{4646fig8.eps} \end{figure}$ Figure 8: Upper envelope of all water maser spectra observed with the Medicina radio telescope towards S235A-B, until July 2005. The three corresponding maser spots detected with the VLA observations are indicated. The vertical line defines the velocity of the molecular cloud.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8.5cm,clip]{4646fig9.eps} \end{figure}$ Figure 9: Time-velocity-intensity plot of the water maser emission from S235A-B observed with the Medicina radio telescope. The starting date is March 31, 1987. The dates of the first VLA observation by Tofani et al. (1995) and of the present observations are indicated (month/year) with an arrow and their velocity ranges are enclosed within a long rectangle. The three maser spots are indicated by bracketing the velocity ranges with vertical dashed lines. The vertical solid line defines the velocity of the molecular cloud. The black areas are time-velocity regions with no observations.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8cm,clip]{4646fg10.eps} \end{figure}$ Figure 10: Time-velocity-intensity plot of the water maser emission from S235A-B observed with the Medicina radio telescope over the velocity range from -10 to +10 km s^-1, which corresponds to the maser spot S235AB-H2O/1.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=7.5cm,clip]{4646fg11.eps} \end{figure}$ Figure 11: The HCO⁺ cloud at -17 km s^-1 (contours) overlaid on the 5.8 $\mu$ m Spitzer-IRAC image (grey scale). Note that the lower contours of the molecular emission closely follow the boundary of the IR emission, suggesting that the S235A HII region is interacting with the molecular cloud.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=7.5cm,clip]{4646fg12.eps} \end{figure}$ Figure 12: Overlay of the 1.3 cm VLA map (full contours) with the Spitzer-IRAC 3.6 $\mu$ m image (grey scale) and the 1.2 mm continuum (dashed contours).
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8cm]{4646fg13.eps} \end{figure}$ Figure 13: Position of the three water masers (H20/1-3 +) and of the six methanol masers (CH3OH/1-6 $\times$ ) detected by Kurtz et al. (2004). The 1.2 mm core (triangle), VLA-1 (square), and M 1 are also indicated. Note that the symbol used to mark the location of the 1.2 mm core is smaller than the errorbars.
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In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{4646fg14.eps} \end{figure}$ Figure 14: HCO⁺(1-0) emission from the NE-SW outflow (thin contours) overlaid with the blue- and red-shifted emission of C³⁴S(5-4) (thick contours) from Felli et al. (2004). The "+'' symbols mark the location of the water maser spots H2O/1 ( $\sim$ 7 km s^-1) and H2O/3 ( $\sim$ -60 km s^-1). The background is the 8.0 $\mu$ m Spitzer-IRAC image (grey scale) and shows the position of S235AB-MIR, coincident with the southern water maser (H2O/3).
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8cm,clip]{4646fg15.eps} \end{figure}$ Figure 15: Velocities of the peaks of S235AB-H2O/1 from Gaussian fits to the data from the Medicina radio telescope. We have tentatively outlined, with dashed lines, two components (labelled as 1 and 2) whose velocities might be drifting during the period of our observations.
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In the text

$\begin{figure} \par\includegraphics[width=6cm,clip]{4646fg16.eps} %\end{figure}$ Figure 16: Sketch (not to scale) of the star-forming region S235A-B in light of the new data presented in this paper. New and already-known sources are labelled, and their relationships are discussed in the text.
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In the text

$\begin{figure} \par\includegraphics[angle=90,width=9cm,clip]{4646fig2.eps} \end{figure}$	Figure 2: Three colour (4.5 blue, 5.8 green, and 8.0 $\mu$ m red) image of the S235A-B region. The labels indicate the position of M 1, S235AB-MIR, and the other stars of the cluster for which we performed photometry. (A colour version of this figure is available in the on-line edition.)
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$\begin{figure} \par\includegraphics[angle=-90,width=7.4cm,clip]{4646fig3.eps} \end{figure}$	Figure 3: The 1.2 mm core (contours) from Felli et al. (2004) overlaid on the 5.8 $\mu$ m Spitzer-IRAC image (grey scale, S235A and S235B have been saturated to show the weak emission from S235AB-MIR). The positions of the mm core, S235AB-MIR, and M 1 are indicated.
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$\begin{figure} \par\includegraphics[angle=-90,width=7cm,clip]{4646fig7.eps} \end{figure}$	Figure 7: H₂O VLA spectra averaged on a circle 1 $\hbox {$^{\prime \prime }$ }$ in radius and centred on the locations of each of the 3 maser spots. The name of the spot is indicated above the corresponding spectrum. The intensity scale is offset by 2 and 4 Jy for clearness of the display. The vertical line defines the velocity of the molecular cloud.
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$\begin{figure} \par\includegraphics[angle=-90,width=7.5cm,clip]{4646fig8.eps} \end{figure}$	Figure 8: Upper envelope of all water maser spectra observed with the Medicina radio telescope towards S235A-B, until July 2005. The three corresponding maser spots detected with the VLA observations are indicated. The vertical line defines the velocity of the molecular cloud.
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$\begin{figure} \par\includegraphics[angle=-90,width=8cm,clip]{4646fg10.eps} \end{figure}$	Figure 10: Time-velocity-intensity plot of the water maser emission from S235A-B observed with the Medicina radio telescope over the velocity range from -10 to +10 km s^-1, which corresponds to the maser spot S235AB-H2O/1.
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$\begin{figure} \par\includegraphics[angle=-90,width=7.5cm,clip]{4646fg11.eps} \end{figure}$	Figure 11: The HCO⁺ cloud at -17 km s^-1 (contours) overlaid on the 5.8 $\mu$ m Spitzer-IRAC image (grey scale). Note that the lower contours of the molecular emission closely follow the boundary of the IR emission, suggesting that the S235A HII region is interacting with the molecular cloud.
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$\begin{figure} \par\includegraphics[angle=-90,width=7.5cm,clip]{4646fg12.eps} \end{figure}$	Figure 12: Overlay of the 1.3 cm VLA map (full contours) with the Spitzer-IRAC 3.6 $\mu$ m image (grey scale) and the 1.2 mm continuum (dashed contours).
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$\begin{figure} \par\includegraphics[angle=-90,width=8cm]{4646fg13.eps} \end{figure}$	Figure 13: Position of the three water masers (H20/1-3 +) and of the six methanol masers (CH3OH/1-6 $\times$ ) detected by Kurtz et al. (2004). The 1.2 mm core (triangle), VLA-1 (square), and M 1 are also indicated. Note that the symbol used to mark the location of the 1.2 mm core is smaller than the errorbars.
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$\begin{figure} \par\includegraphics[angle=-90,width=8cm,clip]{4646fg15.eps} \end{figure}$	Figure 15: Velocities of the peaks of S235AB-H2O/1 from Gaussian fits to the data from the Medicina radio telescope. We have tentatively outlined, with dashed lines, two components (labelled as 1 and 2) whose velocities might be drifting during the period of our observations.
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$\begin{figure} \par\includegraphics[width=6cm,clip]{4646fg16.eps} %\end{figure}$	Figure 16: Sketch (not to scale) of the star-forming region S235A-B in light of the new data presented in this paper. New and already-known sources are labelled, and their relationships are discussed in the text.
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