Volume 549, January 2013
|Number of page(s)||15|
|Section||Interstellar and circumstellar matter|
|Published online||06 December 2012|
Figure A.1 shows an enlargement of the 179 μm emission in the region around L1448-C. Both the continuum and the H2O emission are displayed, with superimposed contours of the CO(3–2) and different H2 lines (near-IR, from Davis & Smith 1996, and Spitzer from Giannini et al. 2011). The 179 μm line peaks toward the C(N) source but is elongated along the direction of the molecular jet, as discussed in Sect. 4.1, which in the figure is traced by the H2 0–0 S(0) and S(1) lines and comprises the inner peaks in the CO(3–2) emission. The H2 S(0) line is observed on source and along the SE (redshifted) jet, while the S(1) line is detected only toward the NW blueshifted jet and toward the B1 region. Extinction is the likely reason why the S(1) line is not detected on-source. Assuming a temperature of about 300 K, the ratio between the S(0) flux and the S(1) upper limit implies a lower limit of Av ~ 65 mag toward the source and 45 mag in the redshifted jet.
Finally, Fig. A.1 shows the overlay with the H2 2.12 μm line. At the central source position the line is almost totally extincted and thus no NIR emission is associated with the jet. The 2.12 μm line emission traces instead a bow shock in the blue lobe originated in the interaction of the jet with the ambient medium, which also shows up also as a clump of H2O emission.
Maps of the 179 μm line and continuum emission in the region around L1448-C sources, compared with CO(3–2) and H2 lines at different excitation, namely the 0–0 S(0)(28 μm), 0–0 S(1)(17 μm), and 1–0 S(1)(2.12 μm). White contours, shown in the bottom right and upper left panels, for the line and continuum emission respectively, are drawn at the following values: 1.5, 2.0, 3.0, 4.0, 6.0 8.0 × 10-5 erg s-1 cm-2 sr-1 for the line emission, and 0.6, 0.8, 1.2, 1.6 × 10-3 erg s-1 cm-2 sr-1 for the continuum emission.
|Open with DEXTER|
The 179 μm continuum image, displayed in Fig. A.2, shows unresolved emission from the three sources of the L1448-N cluster, whose peak coincides with the N(A) source. The H2 S(0) emission, overlaid on the continuum image, also peaks toward N(A), indicating large columns of cold gas. As described in Sect. 3.1, only two of the three sources power outflows, resolved through interferometric observations by Girart et al. (2001) and Kwon et al. (2006). The outflow from N(A) is very compact and is seen almost perpendicular to the line of sight. By contrast, the outflow from N(B) is more elongated and extends to about 100′′ from the driving source (at PA = 110°) both in the blue- and redshifted lobes. In our CO map we cannot distinguish the blueshifted gas of these two outflows from the large-scale L1448-C main outflow; however, we identify redshifted emission at velocity between ~+1 and +20 km s-1 mainly originating from the N(B) flow (see also Fig. 3, left).
Same as Fig. A.1 for a region around L1448-N. In this case, white contours are drawn for the line and continuum emission with the following values: 0.6, 1.2, 1.8, 2.4, 4.0 × 10-5 erg s-1 cm-2 sr-1 (line) and 0.6, 0.8, 1.2, 1.6 × 10-3 erg s-1 cm-2 sr-1 (continuum). A contour of black broken line delineates the absorption region.
|Open with DEXTER|
In contrast with L1448-C, the 179 μm line emission does not peak toward the sources of this region, but is associated only with the outflow: bright emission is, in particular, observed close to the H2 S(1) and to the CO(3–2) redshifted peaks. The bulk of the water emission, however, does not follow the curving H2 large-scale jet driven by L1448-C, but seems to be associated with the 2.12 μm H2 emission (knots Y/Z in Davis & Smith 1996), excited in the L1448-N(A/B) outflows. This could be a density effect, if one assumes that the density at the base of the N(A/B) flows is higher than the gas along the large-scale jet.
North of the N(A/B) sources the water emission decreases abruptly, while an absorption line of water appears, that follows the 179 μm continuum. The water absorption region lies along the line of sight of the L1448-N reflection nebula, visible in the IR images at both 2.12 μm and in the Spitzer IRAC maps (Davis & Smith 1996; Tobin et al. 2007). This evidence suggests that the cold water in the blueshifted outflow is seen in absorption against the nebula, which therefore lies in the background.
HIFI map of the H2O 110 − 101 557 GHz line. The data have been regridded onto a regular grid of 18″ of spacing (i.e. half of the instrumental HPBW, which is displayed in the figure as reference) and binned at 1 km s-1 resolution. The map is centered on the L1448-C source at α2000 = 03h25m38.4s, δJ2000 = +30o44′06″.
|Open with DEXTER|
Contours of integrated H2O 557 GHz intensities in velocity intervals of ΔV = 5 km s-1 superimposed on gray-scale maps of the CO(3–2) intensity integrated in the same bins. The center velocity of the bins is indicated in each panel. H2O contours are in steps of 0.03 K km s-1 and the first contour is at 0.03 K km s-1 (equivalent to 3σ), while CO gray levels are in steps of 1.2 K km s-1 and the first contour is at 0.2 K km s-1. The starred symbols represent the positions of the L1448-C and L1448-N sources.
|Open with DEXTER|
© ESO, 2012
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.