1. Submillimeter Array CH3OH 16 1-16 -15 2-13 A Cluster of Highly Collimated and Young Bipolar Outflows Emanating from OMC1 South. Luis A. Zapata 1,2, Luis F. Rodríguez 1 and Paul Ho 2 1 Centro de Radioastronomía y Astrofísica (CRyA), UNAM. 2 Harvard-Smithsonian Center for Astrophysics (CfA) Abstract Sensitive and high angular resolution (~ 1.5’’) CO(2-1), SiO(5-4) and CH3OH (16-15) observations were obtained with the Submillimeter Array (SMA). They reveal six highly collimated (opening angle less than a few degrees) and young molecular outflows emanating from OMC1 South in the Orion Nebula. In the CO(2-1) observations we detected only a single high velocity (80 km s -1 ) bipolar outflow, while in the SiO(5-4) and CH3OH (16-15) observations we found five low and high velocity bipolar outflows. We also found that the exciting sources the strongest outflows are associated with the infrared sources B and C (Gaume et al. 1998), and those two outflow may be driving the powerful Herbig-Haro objects HH625 and HH269-HH529. Finally, in our 1.3mm continuum observations we detected nine compact sources and some of them could be identified as the exciting sources of rest of the outflows. Submillimeter Array (SMA) OMC1 South Region Introduction The OMC1-S (Orion Molecular Cloud 1 South) region is a young, compact (40” x 40”) and highly active star formation zone located about 100” south of the Orion-KL region (see figure 1). At least three powerful molecular outflows have been suggested to emanate from here (Ziurys, Wilson & Mauersberger 1990, Schmid-Burgk et al. 1990 and Rodriguez-Franco et al. 1999a, 1999b). Numerous H 2 O masers are also known to be present in OMC1S (Gaume et al. 1998). The survey of proper-motions in the Orion Nebula made by Bally et al. (2000) and O'Dell & Doi (2003) revealed that at least six relatively large Herbig-Haro outflows (HH~202, HH 269, HH 529, HH~203/204, HH~530, and possibly HH~528) originate from a region only a few arcseconds across in OMC-1S. O'Dell & Doi (2003) referred to this region as the Optical Outflow Region (OOS). Recently, Zapata et al. (2004a, 2004b), Smith et al. (2004) and Lada et al. (2004) observing at radio and infrared wavelengths, found a cluster of very young stars associated with OMC1S. While not associated with the OOS region, some of these sources may be the exciting sources of the powerful molecular outflows and Herbig- Haro flows that are emanating from the OMC1S region. Discussion 1. CO(2-1) Molecular Outflow High resolution (~1”) and sensitive 12 CO(2-1) line observations with the Submillimeter Array (SMA) towards the OMC1S region (Zapata et al. 2005a), resolved a highly collimated (~3 o ), high velocity (±80 km s -1 ) and young (600 yr) bipolar molecular outflow first detected by Rodríguez-Franco et al. (1999a). This molecular bipolar outflow seems to be emanating from the source 136-359 (or source C, Gaume et al. 1998, see figure 4), a millimeter and centimeter wavelength continuum source with a dust mass of 0.16 Msun, that is associated with a class I protostar. However, the bolometric luminosity (8 Lsun) of this source appears to be far too low to account for the powerful CO molecular outflow. Figure 1. HST image of the Orion Nebula (Odell and Wong 1996). The arrows indicates the proper motions observed in Hα+[NII]+[OII], Hα+[NII], Hα, and Hα+[OIII]. VLA 7mm Continuum 40 AU Figure 3. SMA 12 CO(2-1) (upper panel), and SiO(5-4) (lower panel) moment zero maps, and 1.3mm continuum emission (in both figures) towards the OMC1 South region at the Orion Nebula. In the upper panel the black contours and the yellow scale show the continuum emission, while the blue and red contours show the line emission. In the lower panel the yellow scale and the grey contours show the line emission, while the black contours show the continuum emission. In both images the continuum contours are 3, 6, 9, 12, 15, 18, 20, and 30 times 11 mJy beam -1, the rms noise of the continuum image. The 3- sigma continuum objects 139-409, 141-357 and 144-351 are likely real 1.3 mm continuum sources because they have 7 mm counterparts (Zapata et al. 2005c). The blue and red contours are 3, 6, 9, 12, 15, 18, 20 and 30 times 145 mJy beam -1 km s -1, the rms noise of the moment zero map. The integration is over the velocity ranges: -80 to -26 km s -1 (blueshifted emission) and 22 to 82 km s -1 (redshifted emission). The emission at ambient velocities (-25 to 21 km s -1 ) was clearly extended and poorly sampled with the SMA, and is suppressed in this moment zero map. The grey contours are 2, 3, 4, 5, 6, 7, 8, 10, 12, 16, 18, 20, 30 and 60 times 150 mJy beam -1 km s -1, the rms noise of the moment zero. The integration is over the velocity ranges: -88 to 0 km s -1 (blueshifted emission) and 0 to 108 km s -1 (redshifted emission). In the lower panel the diagonal arrow indicates the position the collimated CO(2-1) outflow shown in the upper figure. The blue and red arrows indicates the blueshifted and the redshifted emission, respectively. The half power contour of the synthesized beam is shown in both images at the bottom left corner. The cross denotes the position of the source FIR 4 (Mezger et al. 1990). At the upper figure, the presumed exciting source of this collimated outflow is also shown at the center of the upper left box. Figure 2. SMA CH3OH 16 1-16 -15 2-13 moment zero map of the source 139-409. The contours are 2, 4, 6, 8 and 10 times 610 mJy beam -1 km s -1, the rms noise of the moment zero. The integration is over a velocity range of 20 km s -1. The half power contour of the synthesized beam is shown at the bottom left corner. Note that this source is very elongated in the East-West direction suggesting that the CH3OH molecule emission is tracing a outflow associated with the source 139-409. Figure 5. High resolution (0.05’’) and sensitivity VLA 7mm color continuum image of the source 144-351. The peak of the flux is 3 mJy. The scale of the figure is show at the left bottom corner. Note that quite resolved NW-SE elongated structure might be a dusty edge-on disk, and the perpendicular lobes, the outflows associated with faint free-free emission. Figure 4. JKH image of the OMC1 South obtained with the FLW Observatory (Lada et al. 2000). Note that in the lower right corner are found the two strong infrared sources that are driving the strongest molecular outflows observed with the SMA. The rest of the molecular outflows are driving for very embedded sources that even at these wavelengths are “invisibles”. 2. SiO(5-4) Molecular Outflows High angular (2’’) and SiO(5-4) observations were carried out the last October 2004 at SMA towards the OMC1 South region revealing a cluster of bipolar and monopolar low and high velocity molecular outflows emanating from some millimeter sources found in the CO(2-1) observations (see Figure 3b). The strongest millimeter source (137-359) is associated with two perpendicular SiO(5-4) molecular flows, see Figure 3b. The NW-SE flow has a blueshifted and redshifted gas velocity of ±70 km s -1, and it is very collimate. The NE-SW flow is a monopolar low velocity (15 km s -1 ) molecular outflow. This outflow is well aligned with the large scale, low velocity and collimated CO monopolar outflow found by Schmid-Burgk et al. (1990), we suggest that this SiO outflow may be the “base” of the monopolar CO outflow. No strong SiO(5-4) emission was found to be associated with the CO(2-1) high velocity and collimated outflow. The infrared source B (Gaume et al. 1998) is associated a quite strong East-West SiO(5-4) collimated bipolar outflow, see Figures 3 and 4. This outflow reach up blueshifted and redshifted gas velocities of ±100 km s -1. We found the SiO outflow flow is well alginate with the powerful HH-529 and HH-269 objects suggesting that it may be driving those objects. Finally, the source 137-347 is associated with a NW-SE monopolar SiO(5-4) outflow of low velocity (10 km s -1 ). In the CO(2-1) observations we did not detect these four SiO outflows due to two possible reasons: i) Two of them are low velocity outflows (~ 10 kms -1 ) and are confused with extended CO emission at ambient velocities (-25 to 21 km s -1 ), and ii) due to different excitation conditions between the CO and SiO molecules. 2. Others Outflows Figure 2 shows the integrate CH3OH molecule emission of the source 139-409. We note that the emission is very elongated (about two beams) in the NE-SW direction. We propose that this source might be associated with a young outflow. Figure 3 shows the high angular resolution (0.05”) and sensitive 7mm continuum image of the source 144-351. This source is quite resolved showing a very interesting morphology, in the center part we found a strong and very elongated structure (possibly the disk), while that perpendicular to it, we found two lobes (jets). However, we need more high angular observations at different wavelengths to obtain the spectral indices of each component and thus know its nature. C B SiO outflow CO outflow OMC1 South JHK 139-409 144-351