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Register a new userOn the origin of the molecular outflows in IRAS 16293-2422
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Added by
Josep Miquel Girart
Publication date
2013
fields
Physics
and research's language is
English
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We present CO 3-2, SiO 8-7, C34S 7-6, and 878 mum dust continuum subarcsecond angular resolution observations with the SMA toward IRAS 16293-2422 (I16293). The C34S emission traces the 878 mum dust continuum well, and clearly shows a smooth velocity gradient along the major axis of component I16293A. The CO shows emission at moderate high velocities arising from two bipolar outflows, which appear to be perpendicular with respect to each other. The high sensitivity and higher angular resolution of these observations allows us to pinpoint well the origin of these two outflows at the center of component I16293A. Interestingly, the most compact outflow appears to point toward I16293B. Our data show that the previously reported monopolar blueshifted CO outflow associated with component I16293B seems to be part of the compact outflow arising from component I16293A. In addition, the SiO emission is also tracing this compact outflow: on one hand, the SiO emission appears to have a jet-like morphology along the southern redshifted lobe; on the other hand, the SiO emission associated with the blueshifted northern lobe traces a well defined arc on the border of component I16293B facing I16293A. The blueshifted CO lobe of the compact outflow splits into two lobes around the position of this SiO arc. All these results lead us to propose that the compact outflow from component I16293A is impacting on the circumstellar gas around component I16293B, possibly being diverged as a consequence of the interaction.
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We have mapped the proto-binary source IRAS 16293-2422 in CO 2-1, 13CO 2-1, and CO 3-2 with the Submillimeter Array (SMA). The maps with resolution of 1.5-5 reveal a single small scale (~3000 AU) bipolar molecular outflow along the east-west direction. We found that the blueshifted emission of this small scale outflow mainly extends to the east and the redshifted emission to the west from the position of IRAS 16293A. A comparison with the morphology of the large scale outflows previously observed by single-dish telescopes at millimeter wavelengths suggests that the small scale outflow may be the inner part of the large scale (~15000 AU) E-W outflow. On the other hand, there is no clear counterpart of the large scale NE-SW outflow in our SMA maps. Comparing analytical models to the data suggests that the morphology and kinematics of the small scale outflow can be explained by a wide-angle wind with an inclination angle of ~30-40 degrees with respect to the plane of the sky. The high resolution CO maps show that there are two compact, bright spots in the blueshifted velocity range. An LVG analysis shows that the one located 1 to the east of source A is extremely dense, n(H_2)~10^7 cm^-3, and warm, T_kin >55 K. The other one located 1 southeast of source B has a higher temperature of T_kin >65 K but slightly lower density of n(H_2)~10^6 cm^-3. It is likely that these bright spots are associated with the hot core-like emission observed toward IRAS 16293. Since both two bright spots are blueshifted from the systemic velocity and are offset from the protostellar positions, they are likely formed by shocks.
We present ALMA and VLA observations of the molecular and ionized gas at 0.1-0.3 arcsec resolution in the Class 0 protostellar system IRAS 16293-2422. These data clarify the origins of the protostellar outflows from the deeply embedded sources in this complex region. Source A2 is confirmed to be at the origin of the well known large scale north-east--south-west flow. The most recent VLA observations reveal a new ejection from that protostar, demonstrating that it drives an episodic jet. The central compact part of the other known large scale flow in the system, oriented roughly east-west, is well delineated by the CO(6-5) emission imaged with ALMA and is confirmed to be driven from within component A. Finally, a one-sided blueshifted bubble-like outflow structure is detected here for the first time from source B to the north-west of the system. Its very short dynamical timescale (~ 200 yr), low velocity, and moderate collimation support the idea that source B is the youngest object in the system, and possibly one of the youngest protostars known.
The protonated form of CO2, HOCO+, is assumed to be an indirect tracer of CO2 in the millimeter/submillimeter regime since CO2 lacks a permanent dipole moment. Here, we report the detection of two rotational emission lines (4 0,4-3 0,3) and (5 0,5-4 0,4) of HOCO+ in IRAS 16293-2422. For our observations, we have used EMIR heterodyne 3 mm receiver of the IRAM 30m telescope. The observed abundance of HOCO+ is compared with the simulations using the 3-phase NAUTILUS chemical model. Implications of the measured abundances of HOCO+ to study the chemistry of CO2 ices using JWST-MIRI and NIRSpec are discussed as well.
The Class 0 protostar IRAS 16293$-$2422 Source A is known to be a binary system (A1 and A2) or even a multiple system, which processes a complex outflow structure. We have observed this source in the C$^{34}$S, SO, and OCS lines at 3.1 mm with the Atacama Large Millimeter/submillimeter Array (ALMA). A substructure of this source is traced by our high angular-resolution observation (0farcs12; 20 au) of the continuum emission. The northwest-southeast (NW-SE) outflow on a 2arcsec scale is detected in the SO ($J_N$ = $2_2$--$1_1$) line. Based on the morphology of the SO distribution, this bipolar outflow structure seems to originate from the protostar A1 and its circumstellar disk, or the circummultiple structure of Source A. The rotation motion of the NW-SE outflow is detected in the SO and OCS emissions. We evaluate the specific angular momentum of the outflowing gas to be $(8.6 - 14.3) times 10^{-4}$ km s$^{-1}$ pc. If the driving source of this outflow is the protostar A1 and its circumstellar disk, it can be a potential mechanism to extract the specific angular momentum of the disk structure. These results can be a hint for the outflow launching mechanism in this source. Furthermore, they provide us with an important clue to resolve the complicated structure of IRAS 16293$-$2422 Source A.
The low mass protostar IRAS 16293$-$2422 is a well-known young stellar system that is observed in the L1689N molecular cloud in the constellation of Ophiuchus. In the interstellar medium and solar system bodies, water is a necessary species for the formation of life. We present the spectroscopic detection of the rotational emission line of water (H$_{2}$O) vapour from the low mass protostar IRAS 16293$-$2422 using the Atacama Large Millimeter/submillimeter Array (ALMA) band 5 observation. The emission line of H$_{2}$O is detected at frequency $ u$ = 183.310 GHz with transition J=3$_{1,3}$$-$2$_{2,2}$. The statistical column density of the emission line of water vapour is $N$(H$_{2}$O) = 4.2$times$10$^{16}$ cm$^{-2}$ with excitation temperature ($T_{ex}$) = 124$pm$10 K. The fractional abundance of H$_{2}$O with respect to H$_{2}$ is 1.44$times$10$^{-7}$ where $N$(H$_{2}$) = 2.9$times$10$^{23}$ cm$^{-2}$.
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