Astronomy and Astrophysics, volume 449, 1077-1088 (2006/4-3)
H2 active jets in the near IR as a probe of protostellar evolution.
CARATTI O GARATTI A., GIANNINI T., NISINI B. and LORENZETTI D.
Abstract (from CDS):
We present an in-depth near-IR analysis of a sample of H2 outflows from young embedded sources to compare the physical properties and cooling mechanisms of the different flows. The sample comprises 23 outflows driven by Class 0 and I sources having low-intermediate luminosity. We have obtained narrow band images in H2 2.12µm and [FeII] 1.64µm and spectroscopic observations in the range 1-2.5µm. From [FeII] images we detected spots of ionized gas in ∼74% of the outflows which in some cases indicate the presence of embedded HH-like objects. H2 line ratios have been used to estimate the visual extinction and average temperature of the molecular gas. Av values range from ∼2 to ∼15mag; average temperatures range between ∼2000 and ∼4000K. In several knots, however, a stratification of temperatures is found with maximum values up to 5000K. Such a stratification is more commonly observed in those knots which also show [FeII] emission, while a thermalized gas at a single temperature is generally found in knots emitting only in molecular lines. Combining narrow band imaging (H2, 2.12µm and [FeII], 1.64µm) with the parameters derived from the spectroscopic analysis, we are able to measure the total luminosity of the H2 and [FeII] shocked regions (LH2 and L[FeII]) in each flow. H2 is the major NIR coolant with an average LH2/L[FeII] ratio of ∼102. We find that ∼83% of the sources have a LH2/Lbol ratio ∼0.04, irrespective of the Class of the driving source, while a smaller group of sources (mostly Class I) have LH2/Lbol an order of magnitude smaller. Such a separation reveals the non-homogeneous behaviour of Class I, where sources with very different outflow activity can be found. This is consistent with other studies showing that among Class I one can find objects with different accretion properties, and it demonstrates that the H2 power in the jet can be a powerful tool to identify the most active sources among the objects of this class.
stars: circumstellar matter - ISM: jets and outflows - ISM: kinematics and dynamics - ISM: lines and bands
Fig.11, Table 7: [DE95] NGC 2264G AN (Nos I1-I5, H1-H5) added. Fig.12, Table 7: [CGN2006] VLA 1623 A (Nos A-D). Fig.12, Table 7: [GSWC2003] NNa (Nos 14h, 14i, 17b) added. Fig.17, Table 7: [NMV2001] Knot A (Nos N-R) added.
View the reference in ADS
To bookmark this query, right click on this link: simbad:2006A&A...449.1077C and select 'bookmark this link' or equivalent in the popup menu