arXiv subjects

Naomi Hirano

Publications and source records attributed to Naomi Hirano.

At least 109 records · Page 6Linked to original sources

arXiv2013

Molecular Jet of IRAS 04166+2706

The molecular outflow from IRAS 04166+2706 was mapped with the Submillimeter Array (SMA) at 350 GHz continuum and CO J = 3$-$2 at an angular resolution of ~1 arcsec. The field of view covers the central arc-minute, which contains the inner four pairs of knots of the molecular jet. On the channel map, conical structures are clearly present in the low velocity range (|V$-$V$_0$|$<$10 km s$^{-1}$), and the highly collimated knots appear in the Extremely High Velocity range (EHV, 50$>$|V$-$V$_0$|$>$30 km s$^{-1}$). The higher angular resolution of ~1 arcsec reveals the first blue-shifted knot (B1) that was missing in previous PdBI observation of Santíago-García et al. (2009) at an offset of ~6 arcsec to the North-East of the central source. This identification completes the symmetric sequence of knots in both the blue- and red-shifted lobes of the outflow. The innermost knots R1 and B1 have the highest velocities within the sequence. Although the general features appear to be similar to previous CO J = 2$-$1 images in Santíago-García et al. (2009), the emission in CO J = 3$-$2 almost always peaks further away from the central source than that of CO J = 2$-$1 in the red-shifted lobe of the channel maps. This gives rise to a gradient in the line-ratio map of CO J = 3$-$2/J = 2$-$1 from head to tail within a knot. A large velocity gradient (LVG) analysis suggests that the differences may reflect a higher gas kinetic temperature at the head. We also explore possible constraints imposed by the non-detection of SiO J = 8$-$7.

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arXiv2013

Probing the Earliest Stage of Protostellar Evolution -- Barnard 1-bN and Barnard 1-bS

Two submm/mm sources in the Barnard 1b (B1-b) core, B1-bN and B1-bS, have been observed with the Submillimeter Array (SMA) and the Submillimeter Telescope (SMT). The 1.1 mm continuum map obtained with the SMA reveals that the two sources contain spatially compact components, suggesting that they harbor protostars. The N2D+ and N2H+ J=3-2 maps were obtained by combining the SMA and SMT data. The N2D+ map clearly shows two peaks at the continuum positions. The N2H+ map also peaks at the continuum positions, but is more dominated by the spatially extended component. The N2D+/N2H+ ratio was estimated to be ~ 0.2 at the positions of both B1-bN and B1-bS. The derived N2D+/N2H+ ratio is comparable to those of the prestellar cores in the late evolutionary stage and the class 0 protostars in the early evolutionary stage. Although B1-bN is bright in N2H+ and N2D+, this source was barely seen in H13CO+. This implies that the depletion of carbon-bearing molecules is significant in B1-bN. The chemical property suggests that B1-bN is in the earlier evolutionary stage as compared to B1-bS with the H13CO+ counterpart. The N2H+ and N2D+ lines show that the radial velocities of the two sources are different by ~ 0.9 km s-1. However, the velocity pattern along the line through B1-bN and B1-bS suggests that these two sources were not formed out of a single rotating cloud. It is likely that the B1-b core consists of two velocity components, each of which harbors a very young source.

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arXiv2010

Extreme Active Molecular Jets in L1448C

The protostellar jet driven by L1448C was observed in the SiO J=8-7 and CO J=3-2 lines and 350 GHz dust continuum at ~1" resolution with the Submillimeter Array (SMA). A narrow jet from the northern source L1448C(N) was observed in the SiO and the high-velocity CO. The jet consists of a chain of emission knots with an inter-knot spacing of ~2" (500 AU) and a semi-periodic velocity variation. The innermost pair of knots, which are significant in the SiO map but barely seen in the CO, are located at ~1" (250 AU) from the central source, L1448C(N). Since the dynamical time scale for the innermost pair is only ~10 yr, SiO may have been formed in the protostellar wind through the gas-phase reaction, or been formed on the dust grain and directly released into the gas phase by means of shocks. It is found that the jet is extremely active with a mechanical luminosity of ~7 L_sun, which is comparable to the bolometric luminosity of the central source (7.5 L_sun). The mass accretion rate onto the protostar derived from the mass-loss rate is ~10^{-5} M_sun/yr. Such a high mass accretion rate suggests that the mass and the age of the central star are 0.03-0.09 M_sun and (4-12)x10^3 yr, respectively, implying that the central star is in the very early stage of protostellar evolution. The low-velocity CO emission delineates two V-shaped shells with a common apex at L1448C(N). The kinematics of these shells are reproduced by the model of a wide opening angle wind. The co-existence of the highly-collimated jets and the wide-opening angle shells can be explained by the unified X-wind model" in which highly-collimated jet components correspond to the on-axis density enhancement of the wide-opening angle wind. The CO $J$=3--2 map also revealed the second outflow driven by the southern source L1448C(S) located at ~8.3" (2000 AU) from L1448C(N).

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arXiv2010

The reflection-symmetric wiggle of the young protostellar jet HH 211

HH 211 is a highly collimated jet originating from a nearby young Class 0 protostar. Here is a follow-up study of the jet with our previous observations at unprecedented resolution up to ~ 0.3" in SiO (J=8-7), CO (J=3-2), and SO (N_J=8_9-7_8). SiO, CO, and SO can all be a good tracer of the HH 211 jet, tracing the internal shocks in the jet. Although the emissions of these molecules show roughly the same morphology of the jet, there are detailed differences. In particular, the CO emission traces the jet closer to the source than the SiO and SO emissions. In addition, in the better resolved internal shocks, both the CO and SO emission are seen slightly ahead of the SiO emission. The jet is clearly seen on both sides of the source with more than one cycle of wiggle. The wiggle is reflection-symmetric about the source and can be reasonably fitted by an orbiting source jet model. The best-fit parameters suggest that the source itself could be a very low-mass protobinary with a total mass of ~ 60 M_Jup and a binary separation of ~ 4.6 AU. The abundances of SiO and SO in the gas phase are found to be highly enhanced in the jet as compared to the quiescent molecular clouds, even close to within 300 AU from the source where the dynamical time scale is <10 yrs. The abundance enhancements of these molecules are closely related to the internal shocks. The detected SiO is either the consequence of the release of Si-bearing material from dust grains or of its formation via gas chemistry in the shocks. The SO, on the other hand, seems to form via gas chemistry in the shocks.

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arXiv2010

Outflow - Core Interaction in Barnard 1

In order to study how outflows from protostars influence the physical and chemical conditions of the parent molecular cloud, we have observed Barnard 1 (B1) main core, which harbors four Class 0 and three Class I sources, in the CO (J=1-0), CH3OH (J_K=2_K-1_K), and the SiO (J=1-0) lines using the Nobeyama 45 m telescope. We have identified three CO outflows in this region; one is an elongated (~ 0.3 pc) bipolar outflow from a Class 0 protostar B1-c in the submillimeter clump SMM 2, another is a rather compact (~ 0.1 pc) outflow from a Class I protostar B1 IRS in the clump SMM 6, and the other is an extended outflow from a Class I protostar in SMM 11. In the western lobe of the SMM 2 outflow, both the SiO and CH3OH lines show broad redshifted wings with the terminal velocities of 25 km/s and 13 km/s, respectively. It is likely that the shocks caused by the interaction between the outflow and ambient gas enhance the abundance of SiO and CH3OH in the gas phase. The total energy input rate by the outflows (1.1x10^{-3} Lsun) is smaller than the energy loss rate (8.5x10^{-3} Lsun$) through the turbulence decay in B1 main core, which suggests that the outflows can not sustain the turbulence in this region. Since the outflows are energetic enough to compensate the dissipating turbulence energy in the neighboring, more evolved star forming region NGC 1333, we suggest that the turbulence energy balance depends on the evolutionary state of the star formation in molecular clouds.

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arXiv2009

Rotation and Outflow motions in the very low-mass Class 0 protostellar system HH 211 at subarcsecond resolution

HH 211 is a nearby young protostellar system with a highly collimated jet. We have mapped it in 352 GHz continuum, SiO (J=8-7), and HCO+ (J=4-3) emission at up to ~ 0.2" resolution with the Submillimeter Array (SMA). The continuum source is now resolved into two sources, SMM1 and SMM2, with a separation of ~ 84 AU. SMM1 is seen at the center of the jet, probably tracing a (inner) dusty disk around the protostar driving the jet. SMM2 is seen to the southwest of SMM1 and may trace an envelope-disk around a small binary companion. A flattened envelope-disk is seen in HCO+ around SMM1 with a radius of ~ 80 AU perpendicular to the jet axis. Its velocity structure is consistent with a rotation motion and can be fitted with a Keplerian law that yields a mass of ~ 50+-15 Jupiter mass (a mass of a brown dwarf) for the protostar. Thus, the protostar could be the lowest mass source known to have a collimated jet and a rotating flattened envelope-disk. A small-scale (~ 200 AU) low-speed (~ 2 km/s) outflow is seen in HCOP+ around the jet axis extending from the envelope-disk. It seems to rotate in the same direction as the envelope-disk and may carry away part of the angular momentum from the envelope-disk. The jet is seen in SiO close to ~ 100 AU from SMM1. It is seen with a "C-shaped" bending. It has a transverse width of <~ 40 AU and a velocity of ~ 170+-60 km/s. A possible velocity gradient is seen consistently across its innermost pair of knots, with ~ 0.5 km/s at ~ 10 AU, consistent with the sense of rotation of the envelope-disk. If this gradient is an upper limit of the true rotational gradient of the jet, then the jet carries away a very small amount of angular momentum of ~ 5 AU km/s and thus must be launched from the very inner edge of the disk near the corotation radius.

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arXiv2007

The CO Molecular Outflows of IRAS 16293-2422 Probed by the Submillimeter Array

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.

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arXiv2007

Submillimeter arcsecond-resolution mapping of the highly collimated protostellar jet HH 211

We have mapped the protostellar jet HH 211 in 342 GHz continuum, SiO ($J=8-7$), and CO ($J=3-2$) emission at $\sim$ \arcs{1} resolution with the Submillimeter Array (SMA). Thermal dust emission is seen in continuum at the center of the jet, tracing an envelope and a possible optically thick compact disk (with a size $<$ 130 AU) around the protostar. A knotty jet is seen in CO and SiO as in \H2{}, but extending closer to the protostar. It consists of a chain of knots on each side of the protostar, with an interknot spacing of $\sim$ \arcs{2}$-$\arcs{3} or 600$-$900 AU and the innermost pair of knots at only $\sim$ \arcsa{1}{7} or 535 AU from the protostar. These knots likely trace unresolved internal (bow) shocks (i.e., working surfaces) in the jet, with a velocity range up to $\sim$ 25 \vkm{}. The two-sided mass-loss rate of the jet is estimated to be $\sim (0.7-2.8)\times 10^{-6}$ \solarmass{} yr$^{-1}$. The jet is episodic, precessing, and bending. A velocity gradient is seen consistently across two bright SiO knots (BK3 and RK2) perpendicular to the jet axis, with $\sim$ 1.5$\pm$0.8 \vkm{} at $\sim$ 30$\pm$15 AU, suggesting a presence of a jet rotation. The launching radius of the jet, derived from the potential jet rotation, is $\sim$ 0.15$-$0.06 AU in the inner disk.

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arXiv2007

Submillimeter Array Observation of the Proto-Planetary Nebula CRL 618 in the CO J=6-5 Line

We report on the results of a Submillimeter Array interferometric observation of the proto-planetary nebula CRL 618 in the 12CO J=6-5 line. With the new capability of SMA enabling us to use two receivers at a time, we also observed simultaneously in the 12CO J=2-1 and 13CO J=2-1 lines. The 12CO J=6-5 and 13CO J=2-1 lines were first interferometrically observed toward CRL 618. The flux of the high velocity component of the 12CO J=6-5 line is almost fully recovered, while roughly 80% of the flux of the low velocity component is resolved out. The low recovery rate suggests that the emission region of the low velocity component of the 12CO J=6-5 line is largely extended. Continuum emission is detected both at 230 and 690 GHz. The flux of the 690 GHz continuum emission seems to be partially resolved out, suggesting dust emission partly contaminates the 690 GHz continuum flux. The cavity structure, which has been confirmed in a previous observation in the 12CO J=2-1 line, is not clearly detected in the 12CO J=6-5 line, and only the south wall of the cavity is detected. This result suggests that the physical condition of the molecular envelope of CRL 618 is not exactly axial symmetric.

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arXiv2007

HH 212: SMA Observations of a Remarkable Protostellar Jet

HH 212 is a nearby (460 pc) protostellar jet discovered in H$_2$ powered by a Class 0 source, IRAS 05413-0104, in the L1630 cloud of Orion. It is highly collimated and symmetric with matched pairs of bow shocks on either side of the source. We have mapped it in 850 $μ$m continuum, SiO ($J=8-7$), CO ($J=3-2$), SO ($N_J=8_9-7_8$), HCO$^+$ ($J = 4-3$), and H$^{13}$CO$^+$ ($J = 4-3$) emission simultaneously at $\sim$ 1$''$ resolution with the Submillimeter Array (SMA). Thermal dust emission is seen in continuum around the source, mainly arising from an inner envelope (i.e., the inner part of a previously seen flattened envelope) and a possible disk. The inner envelope is also seen with rotation in CO, HCO$^+$, and probably SO. Like H$_2$ emission, CO and SiO emission are seen along the jet axis but extending closer to the source, tracing the bow shocks with a broad range of velocities and the continuous structures in between. SO emission is seen only around the source, forming a jetlike structure extending along the jet axis from the source, likely tracing the jet near the launching region. The jet is episodic and bending. It may also be slightly precessing as the jetlike SO structure shows a slight S-shaped symmetry about the source. A hint of jet rotation is also seen across the jet axis. Internal outflow shells are seen in CO and HCO$^+$, associated with the bow shocks in the inner part of the jet. The bases of the HCO$^+$ shells are seen with a hint of rotation similar to that seen in the inner envelope, probably consisted mainly of the material extended from the inner envelope and even the possible disk.

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arXiv2006

654 GHz Continuum and C18O (6-5) Observations of G240.31+0.07 with the Submillimeter Array

We report a dual-band observation at 223 and 654 GHz (460 micron) toward an ultracompact (UC) HII region, G240.31+0.07, with the Submillimeter Array. With a beam size of 1"5 X 0"8, the dust continuum emission is resolved into two clumps, with clump A coincident well with an H2O maser and the UC HII region. The newly discovered clump, B, about 1"3 (~8.3 X 10^3 AU) to the southwest of clump A, is also associated with H2O masers and may be a more recent star-forming site. The continuum flux densities imply an opacity spectral index of β= 1.5 +- 0.3, suggestive of a value lower than the canonical 2.0 found in the interstellar medium and in cold, massive cores. The presence of hot (~100 K) molecular gas is derived by the brightness ratio of two H2CO lines in the 223 GHz band. A radial velocity difference of 2.5 +- 0.4 km/s is found between the two clumps in C18O (6-5) emission. The total (nebular and stellar) mass of roughly 58 Msun in the central region is close to, but not by far larger than, the minimum mass required for the two clumps to be gravitationally bound for binary rotation. Our continuum data do not suggest a large amount of matter associated with the H2 knots that were previously proposed to arise from a massive disk or envelope.

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arXiv2005

SiO J=5--4 in the HH211 Protostellar Jet Imaged with the SMA

We have mapped the SiO J=5-4 line at 217GHz from the HH211 molecular outflow with the Submillimeter Array (SMA). The high resolution map (1.6''x0.9'') shows that the SiO J=5-4 emission comes from the central narrow jet along the outflow axis with a width of ~0.8'' (~250 AU) FWHM. The SiO jet consists of a chain of knots separated by 3-4'' (~1000 AU) and most of the SiO knots have counterparts in shocked H_2 emission seen in a new, deep VLT near-infrared image of the outflow. A new, innermost pair of knots are discovered at just +/-2'' from the central star. The line ratio between the SiO J=5-4 data and upper limits from the SiO J=1-0 data of Chandler & Richer (2001) suggests that these knots have a temperature in excess of 300-500 K and a density of (0.5-1) x10^7 cm^{-3}. The radial velocity measured for these knots is ~30 km/s, comparable to the maximum velocity seen in the entire jet. The high temperature, high density, and velocity structure observed in this pair of SiO knots suggest that they are closely related to the primary jet launched close to the protostar.

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arXiv2005

Infall and Outflow around the HH 212 protostellar system

HH 212 is a highly collimated jet discovered in H2 powered by a young Class 0 source, IRAS 05413-0104, in the L1630 cloud of Orion. We have mapped around it in 1.33 mm continuum, 12CO ($J=2-1$), 13CO ($J=2-1$), C18O ($J=2-1$), and SO ($J_K = 6_5-5_4$) emission at $\sim$ \arcs{2.5} resolution with the Submillimeter Array. A dust core is seen in the continuum around the source. A flattened envelope is seen in C18O around the source in the equator perpendicular to the jet axis, with its inner part seen in 13CO. The structure and kinematics of the envelope can be roughly reproduced by a simple edge-on disk model with both infall and rotation. In this model, the density of the disk is assumed to have a power-law index of $p=-1.5$ or -2, as found in other low-mass envelopes. The envelope seems dynamically infalling toward the source with slow rotation because the kinematics is found to be roughly consistent with a free fall toward the source plus a rotation of a constant specific angular momentum. A 12CO outflow is seen surrounding the H2 jet, with a narrow waist around the source. Jetlike structures are also seen in 12CO near the source aligned with the H2 jet at high velocities. The morphological relationship between the H2 jet and the 12CO outflow, and the kinematics of the 12CO outflow along the jet axis are both consistent with those seen in a jet-driven bow shock model. SO emission is seen around the source and the H2 knotty shocks in the south, tracing shocked emission around them.

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arXiv2004

High velocity bipolar outflow and disk-like envelope in the carbon star V Hya

Using the partially completed Submillimeter Array with five antennas, we have observed the CO J=2-1 and 3-2 emission from the envelope surrounding the carbon star V Hya. The high-angular resolution (2"-4") maps show that V Hya is powering a bipolar molecular jet having an extreme velocity of 70-185 km/s. The axis of this high velocity jet is perpendicular to the major axis of the flattened disk-like envelope, which is expanding with a velocity of ~16 km/s.There is a third kinematic component, a medium-velocity wind having a deprojected velocity of 40-120 km/s moving along the disk plane. Both the high velocity jet and the medium velocity wind have a dynamical time scale of a few hundred years. The flattened structure and the collimated jet observed in V Hya suggests that the formation of asymmetrical structure proceeds while the central star is still in the AGB phase

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arXiv2004

Submillimeter Array Observations of L1551 IRS 5 in CS (J=7-6)

We have imaged the circumstellar envelope around the binary protostar L1551 IRS 5 in CS (J=7-6) and 343 GHz continuum emission at ~ 3 arcsec resolution using the Submillimeter Array. The continuum emission shows an elongated structure (~ 220 x 100 AU) around the binary perpendicular to the axis of the associated radio jet. The CS emission extends over ~ 400 AU, appears approximately circularly symmetric, and shows a velocity gradient from southeast (blueshifted) to northwest (redshifted). The direction of the velocity gradient is different from that observed in C18O (J=1-0). This may be because rotation is more dominant in the CS envelope than the C18O envelope, in which both infall and rotation exist. The CS emission may be divided into two velocity components: (1) a "high" velocity disk-like structure surrounding the protostar, +-1.0 - 1.5 km s-1 from the systemic velocity, and (2) a "low" velocity structure, located southwest of the protostar, < 1.0 km s -1 from the systemic velocity. The high-velocity component traces warm and dense gas with kinematics consistent with rotation around the protostar. The low-velocity component may arise from dense gas entrained in the outflow. Alternatively, this component may trace infalling and rotating gas in an envelope with a vertical structure.

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arXiv2003

Interaction between the Outflow and the Core in IRAM 04191+1522

We have carried out mapping observations of the molecular core associated with the young Class 0 protostar, IRAM 04191+1522, in the CH3OH (JK=2K-1K) and C34S (J=2-1) lines using the 45 m telescope at Nobeyama Radio Observatory. As well as an elongated envelope associated with the protostellar formation (size \~0.07 pc x 0.04 pc, mass ~ 2.3 Mo), two compact (~ 0.03 pc) condensations were found in the CH3OH line at the southern edge of the elongated envelope, where the blueshifted CO outflow emerging from the protostar is located. In contrast to the elongated envelope, those compact CH3OH condensations show much larger line width (up to 2.0 km s-1) with centroid velocities blueshifted by ~ 0.8 km s-1. The compact condensations have momenta (~ 0.06 Mo km s-1) comparable to that of the blueshifted molecular outflow. These results suggest that the compact condensations are probably formed in the course of interaction between the outflow and the ambient gas surrounding the protostar, and that such interaction may cause dissipation of a part of the ambient gas. No drastic, localized enhancement of the CH3OH abundance is, however, observed toward the compact condensations, implying that there seems to be no significant shock heating at the compact condensations. This may be because the CO outflow velocity (< 10 km s-1) is too low to cause effective heating to release CH3OH on dust grains into gas phase.

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arXiv2001

Submillimeter CO emission from shock-heated gas in the L1157 outflow

We present the CO J=6-5, 4-3, and 3-2 spectra from the blueshifted gas of the outflow driven by the low-mass class 0 protostar in the L1157 dark cloud. Strong submillimeter CO emission lines with T_mb > 30 K have been detected at 63" (~0.13 pc) south from the protostar. It is remarkable that the blue wings in the submillimeter lines are stronger by a factor of 3-4 than that of the CO J=1-0 emission line. The CO line ratios suggest that the blueshifted lobe of this outflow consists of moderately dense gas of n(H_2) = (1-3)x10^4 cm^-3 heated to T_kin = 50-170 K.It is also suggested that the kinetic temperature of the outflowing gas increases from ~80 K near the protostar to ~170 K at the shocked region in the lobe center, toward which the largest velocity dispersion of the CO emission is observed. A remarkable correlation between the kinetic temperature and velocity dispersion of the CO emission along the lobe provides us with direct evidence that the molecular gas at the head of the jet-driven bow shock is indeed heated kinematically. The lower temperature of ~80 K measured at the other shocked region near the end of the lobe is explained if this shock is in a later evolutionary stage, in which the gas has been cooled mainly through radiation of the CO rotational lines.

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arXiv2000

SiO Emission in the Multi-Lobe Outflow associated with IRAS 16293-2422

We have mapped the thermal emission line of SiO (v = 0; J = 2-1) associated with the quadrupolar molecular outflow driven by the very cold far-infrared source IRAS 16293-2422. The SiO emission is significantly enhanced in the northeastern red lobe and at the position ~50" east of the IRAS source. Strong SiO emission observed at ~50" east of the IRAS source presents evidence for a dynamical interaction between a part of the eastern blue lobe and the dense ambient gas condensation, however, such an interaction is unlikely to be responsible for producing the quadrupolar morphology. The SiO emission in the northeastern red lobe shows the spatial and velocity structure similar to those of the CO outflow, suggesting that the SiO emission comes from the molecular outflow in the northeastern red lobe itself. The observed velocity structure is reproduced by a simple spatio-kinematic model of bow shock with a shock velocity of 19-24 km/s inclined by 30-45 deg from the plane of the sky. This implies that the northeastern red lobe is independent of the eastern blue lobe and that the quadrupolar structure is due to two separate bipolar outflows. The SiO emission observed in the western red lobe has a broad pedestal shape with low intensity. Unlike the SiO emission in the northeastern red lobe, the spatial extent of the SiO emission in the western red lobe is restricted to its central region. The spatial and velocity structures and the line profiles suggest that three different types of the SiO emission are observed in this outflow; the SiO emission arises from the interface between the outflowing gas and the dense ambient gas clump, the SiO emission coming from the outflow lobe itself, and the broad SiO emission with low intensity observed at the central region of the outflow lobe.

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