Exploring southern star forming regions : H 2 jets driven by very young protostars

1. GD3 – A parsec scale jet emerges from a young near-infrared cluster centred on IRAS08476-4306. The proposed exciting source, detected in the NIR bands (IRS20,#98, [3] ), is indicated. GD3 IRS20, #98 70µm 0.30pc 0.68 pc 24µm 24µm GD1 70µm 70µm 70µm 0.18pc GD2 GD5 24µm 24µm 0.13pc 70µm 24µm GD4 0.08pc Exploring southern star forming regions : H2 jets driven by very young protostars T.Giannini1, M. De Luca1, D. Lorenzetti1, G.Fazio2, M. Marengo2, F.Massi3,B. Nisini1, H.A. Smith2 1- Osservatorio Astronomico di Roma, Italy (giannini@mporzio.astro.it); 2- Harvard-Smithsonian Center for Astrophysics, MA-USA; 3- Osservatorio Astrofisico di Arcetri, Italy In the framework of a multi-frequency/multi-mode study we are conducting since many years on the star forming region Vela Molecular Ridge (VMR, e.g.[1,2]), we present a preliminary study on the association between dust cores and protostellar jets/outflows in the D-cloud. This work is also aimed to find the Class 0 population in the region, which would provide suitable targets to be observed with ALMA. Starting from a 1 deg2 map of the dust emission (obtained at 1.2mm with SIMBA/SEST, see also De Luca et al., this conference) we have performed a systematic search for H2 jets (H2 2.12 µm - SofI/NTT) associated with the detected dust peaks. Dust and H2 maps have been also correlated with very recent Spitzer MIPS maps, aiming to identiy the sources that drive the discovered jets. Evidence of shocked emission has been recognized in 16 out of 20 imaged fields in the H2 (1-0)S(1) line (2.12 µm), five of them showing a clear jet-like morphology.Quite recently, Spitzer has observed this region with MIPS at 24 and 70µm, allowing to discover the driving source for three jets (GD2, GD4, GD5), sofar undetected in both NIR (K) and FIR (N, IRAS, MSX). Here MIPS 24 µm and 70 µm images are shown, with overlaied the H2 2.12 µm (green) and dust (yellow) contours (in steps of 3σ) . GD2-GD4 – Two small jets have been detected in correspondence of faint dust peaks. The exciting sources, not detected in the infrared (NIR bands, IRAS, MSX), are clearly recognizable in the MIPS images. The compactness of these jets suggests a very short dynamical age, if reasonable conditions for both shock velocity (50 km s-1) and inclination angle (i=45º) are assumed (see table below). GD1 – A millimeter peak (MMS2) is found at the jet center, where no infrared source is detected up to K=17 mag. In the Spitzer 24 µm band, an emission peak is found (A), not aligned with the jet axis. The lack of an aligned source suggests two alternative scenarios: (i) we are observing just one jet lobe or (ii), more reasonably, the exciting source is too faint to be detected even by MIPS (F(24) < 0.6 mJy). Scheduled APEX observations will answer this question. GD5 – A point-like 24/70µm source aligned with the jet and corresponding to a dust peak (umms19) is found about 2 arcmin apart toward the NE direction. Assuming that this source is driving the jet, implies we are observing just one jet lobe, being the counter-jet located outside the SofI field. A NIR cluster is also found in the MIPS source position. A H2 luminosity vs. bolometric luminosity (adapted from [4]). H2 luminosity has been evaluated by assuming L(H2)=10 x L(2.12µm) and an extinction of Av=10 mag. Following the prescriptions by [4], these assumptions would imply an uncertainty on L(H2) up to ~30% , which has been assumed in the plot. All the Vela sources follow the black dotted line, which identifies young protostars (Class 0/I). Spectral Energy Distribution’s (SED’s) of the jets driving sources. Continuous lines connect MIPS and 1.2 mm data, while the dashed line refers to IRAS points. Upper limits (3) are derived from [3] or from the 2MASS catalogue. SED’s of GD2, GD4, GD5 resemble those of Class 0 protostars with Tbol ~30-35K, while the most luminous source (GD3), detected in the NIR, is more probably a Class I . References [1] – Elia, D. et al. 2006, ApJ, in press [2] – Massi et al. 2007, A&A, submitted [3] – Massi et al. 1999, AASS, 138, 471) [4] – Caratti o Garatti et al., 2006, A&A , 449,1077