CH3OH Lines Research Articles

The Circumestellar Disk of the B0 Protostar Powering the HH 80-81 Radio Jet

Abstract We present subarcsecond angular resolution observations carried out with the Submillimeter Array (SMA) at 880 μm centered at the B0-type protostar GGD27 MM1, the driving source of the parsec scale HH 80-81 jet. We constrain its polarized continuum emission to ≲0.8% at this wavelength. Its submillimeter spectrum is dominated by sulfur-bearing species tracing a rotating-disk-like structure (SO and SO2 isotopologues mainly), but also shows HCN-bearing and CH3OH lines, which trace the disk and the outflow cavity walls excavated by the HH 80-81 jet. The presence of many sulfurated lines could indicate the presence of shocked gas at the disk’s centrifugal barrier or that MM1 is a hot core at an evolved stage. The resolved SO2 emission traces the disk kinematics very well and we fit the SMA observations using a thin-disk Keplerian model, which gives the inclination (47°), the inner (≲170 au) and outer (∼950–1300 au) radii, and the disk’s rotation velocity (3.4 km s−1 at a putative radius of 1700 au). We roughly estimate a protostellar dynamical mass of 4–18 . MM2 and WMC cores show, comparatively, an almost empty spectra, suggesting that they are associated with extended emission detected in previous low-angular resolution observations, and therefore indicating youth (MM2) or the presence of a less massive object (WMC).

The Molecular Gas Environment in the 20 km s−1 Cloud in the Central Molecular Zone

Abstract We recently reported a population of protostellar candidates in the 20 km s−1 cloud in the Central Molecular Zone of the Milky Way, traced by H2O masers in gravitationally bound dense cores. In this paper, we report molecular line studies with high angular resolution (∼3″) of the environment of star formation in this cloud. Maps of various molecular line transitions as well as the continuum at 1.3 mm are obtained using the Submillimeter Array. Five NH3 inversion lines and the 1.3 cm continuum are observed with the Karl G. Jansky Very Large Array. The interferometric observations are complemented with single-dish data. We find that the CH3OH, SO, and HNCO lines, which are usually shock tracers, are better correlated spatially with the compact dust emission from dense cores among the detected lines. These lines also show enhancement in intensities with respect to SiO intensities toward the compact dust emission, suggesting the presence of slow shocks or hot cores in these regions. We find gas temperatures of ≳100 K at 0.1 pc scales based on RADEX modeling of the H2CO and NH3 lines. Although no strong correlations between temperatures and linewidths/H2O maser luminosities are found, in high-angular-resolution maps we note several candidate shock-heated regions offset from any dense cores, as well as signatures of localized heating by protostars in several dense cores. Our findings suggest that at 0.1 pc scales in this cloud star formation and strong turbulence may together affect the chemistry and temperature of the molecular gas.

MERGER-INDUCED SHOCKS IN THE NEARBY LIRG VV 114 THROUGH METHANOL OBSERVATIONS WITH ALMA

ABSTRACT We report the detection of two CH3OH lines (J K = 2 K –1 K and 3 K –2 K ) between the progenitor’s disks (“Overlap”) of the mid-stage merging galaxy VV 114 obtained using the Atacama Large Millimeter/submillimeter Array (ALMA) Band 3 and Band 4. The detected CH3OH emission shows an extended filamentary structure (∼3 kpc) across the progenitor’s disks with relatively large velocity width (FWZI ∼ 150 km s−1). The emission is only significant in the “overlap” and not detected in the two merging nuclei. Assuming optically thin emission and local thermodynamic equilibrium, we found the CH3OH column density relative to H2 ( ) peaks at the “Overlap” (∼8 × 10−9), which is almost an order of magnitude larger than that at the eastern nucleus. We suggest that kpc-scale shocks driven by galaxy–galaxy collision may play an important role to enhance the CH3OH abundance at the “Overlap.” This scenario is consistent with shock-induced large velocity dispersion components of ionized gas that have been detected in optical wavelength at the same region. Conversely, low at the nuclear regions might be attributed to the strong photodissociation by nuclear starbursts and/or a putative active galactic nucleus, or inefficient production of CH3OH on dust grains due to initial high-temperature conditions (i.e., desorption of the precursor molecule, CO, into gas phase before forming CH3OH on dust grains). These ALMA observations demonstrate that CH3OH is a unique tool to address kpc-scale shock-induced gas dynamics and star formation in merging galaxies.

Measuring the Distribution and Excitation of Cometary CH3OH Using ALMA

AbstractThe Atacama Large Millimeter/submillimeter Array (ALMA) was used to obtain measurements of spatially and spectrally resolved CH3OH emission from comet C/2012 K1 (PanSTARRS) on 28-29 June 2014. Detection of 12-14 emission lines of CH3OH on each day permitted the derivation of spatially-resolved rotational temperature profiles (averaged along the line of sight), for the innermost 5000 km of the coma. On each day, the CH3OH distribution was centrally peaked and approximately consistent with spherically symmetric, uniform outflow. The azimuthally-averaged CH3OH rotational temperature (Trot) as a function of sky-projected nucleocentric distance (ρ), fell by about 40 K between ρ= 0 and 2500 km on 28 June, whereas on 29 June,Trotfell by about 50 K between ρ =0 km and 1500 km. A remarkable (~50 K) rise inTrotat ρ = 1500-2500 km on 29 June was not present on 28 June. The observed variations in CH3OH rotational temperature are interpreted primarily as a result of variations in the coma kinetic temperature due to adiabatic cooling, and heating through Solar irradiation, but collisional and radiative non-LTE excitation processes also play a role.

METHANOL IN THE STARLESS CORE, TAURUS MOLECULAR CLOUD-1

To explore the formation mechanisms of gas phase CH3OH in cold starless cores, we have conducted high spectral resolution observations toward the cyanopolyyne peak of Taurus Molecular Cloud-1 (TMC-1 CP) with the IRAM 30 m telescope, the Green Bank Telescope, and the Nobeyama 45 m telescope. The spectral lines of CH3OH toward TMC-1 CP are found to have a double-peaked profile separated by 0.5 km s−1. Since the double-peaked profile is observed for 13CH3OH, it is not due to optical depth and/or self-absorption effects. The spectral line profile of CH3OH is much different from those of C34S, C3S, and HC7N observed toward this source. The H2 densities of the emitting region of CH3OH for the blueshifted and redshifted components are derived to be (1.7 ± 0.5) × 104 cm−3 and (4.3 ± 1.2) × 104 cm−3, respectively. These densities are similar to or slightly lower than those found for the other molecules. These results suggest a chemical differentiation between CH3OH and the other molecules, which has indeed been confirmed by mapping observations of the CH3OH and C34S lines. These results are consistent with the general idea that CH3OH is formed on dust grains and is liberated into the gas phase by non-thermal desorption. The grain-surface origin of CH3OH is further confirmed by the CH3OH/13CH3OH ratio. Weak shocks caused by accreting diffuse gas to the TMC-1 filament, photoevaporation caused by cosmic-ray induced UV radiation, and the desorption of excess reaction energy in the formation of CH3OH on dust grains are discussed for the desorption mechanisms.

Constraints on changes in the proton–electron mass ratio using methanol lines

Abstract We report Karl G. Jansky Very Large Array (VLA) absorption spectroscopy in four methanol (CH3OH) lines in the z = 0.885 82 gravitational lens towards PKS1830−211. Three of the four lines have very different sensitivity coefficients Kμ to changes in the proton–electron mass ratio μ; a comparison between the line redshifts thus allows us to test for temporal evolution in μ. We obtain a stringent statistical constraint on changes in μ by comparing the redshifted 12.179 and 60.531 GHz lines, [Δμ/μ] ≤ 1.1 × 10−7 (2σ) over 0 < z ≤ 0.885 82, a factor of ≈2.5 more sensitive than the best earlier results. However, the higher signal-to-noise ratio (by a factor of ≈2) of the VLA spectrum in the 12.179 GHz transition also indicates that this line has a different shape from that of the other three CH3OH lines (at >4σ significance). The sensitivity of the above result, and that of all earlier CH3OH studies, is thus likely to be limited by unknown systematic errors, probably arising due to the frequency-dependent structure of PKS1830−211. A robust result is obtained by combining the three lines at similar frequencies, 48.372, 48.377 and 60.531 GHz, whose line profiles are found to be in good agreement. This yields the 2σ constraint [Δμ/μ] ≲ 4 × 10−7, the most stringent current constraint on changes in μ. We thus find no evidence for changes in the proton–electron mass ratio over a lookback time of ≈7.5 Gyr.

IRAS 16547–4247: A NEW CANDIDATE OF A PROTOCLUSTER UNVEILED WITH ALMA

We present the results of continuum and 12CO(3-2) and CH3OH(7-6) line observations of IRAS16547-4247 made with the Atacama Large Millimeter/submillimeter Array (ALMA) at an angular resolution of ~0.5". The 12CO(3-2) emission shows two high-velocity outflows whose driving sources are located within the dust continuum peak. The alignment of these outflows do not coincide with that of the wide-angle, large scale, bipolar outflow detected with APEX in previous studies. The CH3OH(7-6) line emission traces an hourglass structure associated with the cavity walls created by the outflow lobes. Taking into account our results together with the position of the H2O and class I CH3OH maser clusters, we discuss two possible scenarios that can explain the hourglass structure observed in IRAS16547-4247: (1) precession of a biconical jet, (2) multiple, or at least two, driving sources powering intersecting outflows. Combining the available evidence, namely, the presence of two cross-aligned bipolar outflows and two different H2O maser groups, we suggest that IRAS16547-4247 represents an early formation phase of a protocluster.

The origin of organic emission in NGC 2071

Context: The physical origin behind organic emission in embedded low-mass star formation has been fiercely debated in the last two decades. A multitude of scenarios have been proposed, from a hot corino to PDRs on cavity walls to shock excitation. Aims: The aim of this paper is to determine the location and the corresponding physical conditions of the gas responsible for organics emission lines. The outflows around the small protocluster NGC 2071 are an ideal testbed to differentiate between various scenarios. Methods: Using Herschel-HIFI and the SMA, observations of CH3OH, H2CO and CH3CN emission lines over a wide range of excitation energies were obtained. Comparisons to a grid of radiative transfer models provide constraints on the physical conditions. Comparison to H2O line shape is able to trace gas-phase synthesis versus a sputtered origin. Results: Emission of organics originates in three spots: the continuum sources IRS 1 ('B') and IRS 3 ('A') as well as a outflow position ('F'). Densities are above 10$^7$ cm$^{-3}$ and temperatures between 100 to 200 K. CH3OH emission observed with HIFI originates in all three regions and cannot be associated with a single region. Very little organic emission originates outside of these regions. Conclusions: Although the three regions are small (<1,500 AU), gas-phase organics likely originate from sputtering of ices due to outflow activity. The derived high densities (>10$^7$ cm$^{-3}$) are likely a requirement for organic molecules to survive from being destroyed by shock products. The lack of spatially extended emission confirms that organic molecules cannot (re)form through gas-phase synthesis, as opposed to H2O, which shows strong line wing emission. The lack of CH3CN emission at 'F' is evidence for a different history of ice processing due to the absence of a protostar at that location and recent ice mantle evaporation.

Water and methanol in low-mass protostellar outflows: gas-phase synthesis, ice sputtering and destruction

Water in outflows from protostars originates either as a result of gas-phase synthesis from atomic oxygen at T > 200 K, or from sputtered ice mantles containing water ice. We aim to quantify the contribution of the two mechanisms that lead to water in outflows, by comparing observations of gas-phase water to methanol (a grain surface product) towards three low-mass protostars in NGC1333. In doing so, we also quantify the amount of methanol destroyed in outflows. To do this, we make use of JCMT and Herschel-HIFI data of H2O, CH3OH and CO emission lines and compare them to RADEX non-LTE excitation simulations. We find up to one order of magnitude decrease in the column density ratio of CH3OH over H2O as the velocity increases in the line wings up to ~15 km/s. An independent decrease in X(CH3OH) with respect to CO of up to one order of magnitude is also found in these objects. We conclude that gas-phase formation of H2O must be active at high velocities (above 10 km/s, relative to the source velocity) to re-form the water destroyed during sputtering. In addition, the transition from sputtered water at low velocities to formed water at high velocities must be gradual. We place an upper limit of two orders of magnitude on the destruction of methanol by sputtering effects.

Molecular observations of comets C/2012 S1 (ISON) and C/2013 R1 (Lovejoy): HNC/HCN ratios and upper limits to PH3

We present molecular observations carried out with the IRAM 30m telescope at wavelengths around 1.15 mm towards the Oort cloud comets C/2012 S1 (ISON) and C/2013 R1 (Lovejoy) when they were at 0.6 and 1 au, respectively, from the Sun. We detect HCN, HNC, and CH3OH in both comets, together with the ion HCO+ in comet ISON and a few weak unidentified lines in comet Lovejoy, one of which might be assigned to methylamine (CH3NH2). The monitoring of the HCN J = 3-2 line showed a tenfold enhancement in comet ISON on November 14.4 UT due to an outburst of activity whose exact origin is unknown, although it might be related to some break-up of the nucleus. The set of CH3OH lines observed was used to derive the kinetic temperature in the coma, 90 K in comet ISON and 60 K in comet Lovejoy. The HNC/HCN ratios derived, 0.18 in ISON and 0.05 in Lovejoy, are similar to those found in most previous comets and are consistent with an enhancement of HNC as the comet approaches the Sun. Phosphine (PH3) was also searched for unsuccessfully in both comets through its fundamental 1-0 transition, and 3 sigma upper limits corresponding to PH3/H2O ratios 4-10 times above the solar P/O elemental ratio were derived.

Warm formaldehyde in the Ophiuchus IRS 48 transitional disk

Simple molecules like H2CO and CH3OH in protoplanetary disks are the starting point for the production of more complex organic molecules. So far, the observed chemical complexity in disks has been limited due to freeze out of molecules onto grains in the bulk of the cold outer disk. Complex molecules can be studied more directly in transitional disks with large inner holes, as these have a higher potential of detection, through UV heating of the outer disk and the directly exposed midplane at the wall. We use Atacama Large Millimeter/submillimeter Array (ALMA) Band 9 (~680 GHz) line data of the transitional disk Oph IRS 48, previously shown to have a large dust trap, to search for complex molecules in regions where planetesimals are forming. We report the detection of the H2CO 9(1,8)-8(1,7) line at 674 GHz, which is spatially resolved as a semi-ring at ~60 AU radius centered south from the star. The inferred H2CO abundance is ~10^{-8} derived by combining a physical disk model of the source with a non-LTE excitation calculation. Upper limits for CH3OH lines in the same disk give an abundance ratio H2CO/CH3OH>0.3, which points to both ice formation and gas-phase routes playing a role in the H2CO production. Upper limits on the abundances of H13CO+, CN and several other molecules in the disk are also derived and found to be consistent with full chemical models. The detection of the H2CO line demonstrates the start of complex organic molecules in a planet-forming disk. Future ALMA observations should be able to push down the abundance detection limits of other molecules by 1-2 orders of magnitude and test chemical models of organic molecules in (transitional) disks.

Sgr A West in the light of molecules: cold and dense gas east of the circumnuclear disk

AbstractWe present the very first detection of N2H+J = (1 – 0) and CH3OH(2k−1k) line emission on 5″ scales in the circumnuclear disk (CND) around Sgr A*. The emission matches the position and shape of the dark clouds in the near-infrared. Our findings suggest that these molecular clouds in the eastern CND are significantly colder and denser than the rest of the CND, and partially shocked. The research on these dark clouds will contribute to understanding the processes of star formation close to a supermassive black hole.

3 mm band line survey toward the high-velocity compact cloud CO−0.40−0.22

AbstractHigh-velocity compact clouds (HVCCs) are a population of molecular clouds which have compact appearance (d &lt; 10 pc) and large velocity width (Δ V &gt; 50 km s−1), and are found in the central molecular zone of our Galaxy. We performed a 3 mm band line survey toward CO−0.40−0.22, a spatially unresolved HVCC with an extremely large velocity width (Δ V ≃ 90 km s−1), using the Mopra 22 m telescope. We surveyed the frequency range between 76 GHz and 116 GHz with a 0.27 MHz frequency resolution. We detect at least 54 lines from 32 molecules. Many line profiles show a prominent peak at vLSR ∼ 70 km s−1 with very large velocity width, indicating they are emitted by the HVCC. Detections of largish molecules are indicative of non-equilibrium chemistry. We extracted some prominent lines based on velocity structure, intensity ratios, and PCA analyses. Shock diagnostic lines (SiO, SO, CH3OH, HNCO) and dense gas probes (HCN, HCO+) appear to be prominent. Excitation analysis of CH3OH lines show an enhancement in Trot in the negative high-velocity end of the profile. These results suggest that CO−0.40−0.22 has experienced a shock, acceleration, compression, and heating in the recent past.

ALMA OBSERVATIONS OF THE IRDC CLUMP G34.43+00.24 MM3: HOT CORE AND MOLECULAR OUTFLOWS

We have observed a cluster forming clump (MM3) associated with the infrared dark cloud G34.43+00.24 in the 1.3 mm continuum and the CH3OH, CS, 13CS, SiO, CH3CH2CN, and HCOOCH3 lines with the Atacama Large Millimeter/submillimeter Array and in K-band with the Keck telescope. We have found a young outflow toward the center of this clump in the SiO, CS, and CH3OH lines. This outflow is likely driven by a protostar embedded in a hot core, which is traced by the CH3CH2CN, HCOOCH3, 13CS, and high excitation CH3OH lines. The size of the hot core is about 800 x 300 AU in spite of its low mass (<1.1 M_sun), suggesting a high accretion rate or the presence of multiple star system harboring a few hot corinos. The outflow is highly collimated, and the dynamical timescale is estimated to be less than 740 yr. In addition, we have also detected extended emission of SiO, CS, and CH3OH, which is not associated with the hot core and the outflow. This emission may be related to past star formation activity in the clump. Although G34.43+00.24 MM3 is surrounded by a dark feature in infrared, it has already experienced active formation of low-mass stars in an early stage of clump evolution.

High-angular resolution observations towards OMC-2 FIR 4: Dissecting an intermediate-mass protocluster

OMC-2 FIR 4 is one of the closest known young intermediate-mass protoclusters, located at a distance of 420 pc in Orion. This region is one of the few where the complete 500-2000 GHz spectrum has been observed with the heterodyne spectrometer HIFI on board the Herschel satellite, and unbiased spectral surveys at 0.8, 1, 2 and 3 mm have been obtained with the JCMT and IRAM 30-m telescopes. In order to investigate the morphology of this region, we used the IRAM Plateau de Bure Interferometer to image OMC-2 FIR 4 in the 2-mm continuum emission, as well as in DCO+(2-1), DCN(2-1), C34S(3-2), and several CH3OH lines. In addition, we analysed observations of the NH3(1,1) and (2,2) inversion transitions made with the Very Large Array of the NRAO. The resulting maps have an angular resolution which allows us to resolve structures of 5", equivalent to 2000 AU. Our observations reveal three spatially resolved sources within OMC-2 FIR 4, of one or several solar masses each, with hints of further unresolved substructure within them. Two of these sources have elongated shapes and are associated with dust continuum emission peaks, thus likely containing at least one molecular core each. One of them also displays radio continuum emission, which may be attributed to a young B3-B4 star that dominates the overall luminosity output of the region. The third source identified displays a DCO+(2-1) emission peak, and weak dust continuum emission. Its higher abundance of DCO+ relative to the other two regions suggests a lower temperature and therefore its possible association with either a younger low-mass protostar or a starless core. It may alternatively be part of the colder envelope of OMC-2 FIR 4. Our interferometric observations evidence the complexity of this region, where multiple cores, chemical differentiation and an ionised region all coexist within an area of only 10000 AU.

FORMING AN O STAR VIA DISK ACCRETION?

We present a study of outflow, infall, and rotation in a ~10^5 Lsun (solar luminosity) star-forming region, IRAS 18360-0537, with Submillimeter Array (SMA) and IRAM 30m observations. The 1.3 mm continuum map shows a 0.5 pc dust ridge, of which the central compact part has a mass of ~80 Msun (solar mass) and harbors two condensations, MM1 and MM2. The CO (2--1) and SiO (5--4) maps reveal a biconical outflow centered at MM1, which is a hot molecular core (HMC) with a gas temperature of 320+/-50 K and a mass of ~13 Msun. The outflow has a gas mass of 54 Msun and a dynamical timescale of 8,000 yr. The kinematics of the HMC is probed by high-excitation CH3OH and CH3CN lines, which are detected at sub-arcsecond resolution and unveil a velocity gradient perpendicular to the outflow axis, suggesting a disk-like rotation of the HMC. An infalling envelope around the HMC is evidenced by CN lines exhibiting a profound inverse P-Cygni profile, and the estimated mass infall rate, 1.5x10^{-3} Msun/yr, is well comparable to that inferred from the mass outflow rate. A more detailed investigation of the kinematics of the dense gas around the HMC is obtained from the 13CO and C18O (2--1) lines; the position-velocity diagrams of the two lines are consistent with the model of a free-falling and Keplerian-like rotating envelope. The observations suggest that the protostar of a current mass ~10 Msun embedded within MM1 will develop into an O star via disk accretion and envelope infall.

Similarity and randomness in the molecular clouds associated with Spitzer GLIMPSE Extended Green Objects (EGOs)

AbstractEGOs are candidates of massive star forming regions that show signatures of outflows. A 1.1mm line survey has been performed to 89 EGOs using the AROSMT. Our high detection rates of H13CO+ 3-2 and SiO 6-5 lines support EGOs to be dense clouds harboring outflows.Ubiquitous line luminosity linear correlations are found among different kinds of tracer lines: dense gas tracer H13CO+ 3-2, outflow tracer SiO 6-5, mixed dense gas and outflow tracers SO3Σ 65 − 54 and CH3OH lines, and relatively lower density gas tracers 12CO, 13CO, C18O 1-0 (see an example in Fig. 1). This can be explained if a universal similarity of density and thermal structures and probably of shock properties among all these EGO clouds are assumed. Furthermore, the outflow shocks are also required to be produced mainly inside of the natal clouds of the YSOs.The data scatter of the luminosity (and line width) correlations show a clear trend of worsening across larger cloud substructure size scales or toward larger cloud sizes, which demonstrates the growth of randomness in cloud structures and velocity fields. See more details in our paper (He et al. 2012).

A Sensitive Survey of Dense Parts of Outflows toward Massive Cores

A set of samples of 13 massive star-forming cores were observed in SiO (2-1), CH3OH (2-1) and C34S (2-1) thermal lines. Nine of these cores were detected in all three lines. Among the nine SiO detections, three were new detections, and relatively faint. Most of the lines have wide wings, which might be interpreted as the evidence of ongoing energetic outflows in the cores. The line widths of SiO are generally the broadest, which might further suggest that the SiO emissions are due to higher velocity outflow, and closer to the excited source. We derive the rotational temperatures, column densities and chemical relative abundances of the cores. There is a strong correlation between SiO and CH3OH abundances, with correlation coeffcient R = 0.77, but no correlation is observed between SiO and C34S.

Time-dependent modelling of the molecular line emission from shock waves in outflow sources

We have developed further the technique of time-dependent modelling of magnetohydrodynamic shock waves, with a view to interpreting the molecular line emission from outflow sources. The extensively observed source L1157 B1 was chosen as an exemplar of the application of this technique. The dynamical age of the shock wave model was varied in the range 500 ≤t≤ 5000 yr, with the best fit to the observed line intensities being obtained for t= 1000 yr; this is of the same order as the dynamical age derived by Gueth, Guilloteau & Bachiller from their observations of L1157 B1. The emission line spectra of H2, CO, SiO, ortho- and para-H2O, ortho- and para-NH3, and A- and E-type CH3OH were calculated in parallel with the dynamical and chemical parameters of the model, using the ‘large velocity gradient’ (LVG) approximation to the line transfer problem. We compared the predictions of the models with the observed intensities of emission lines of H2, CO, SiO, ortho-H2O, ortho-NH3 and CH3OH, which include recent Herschel satellite measurements. In the case of SiO, we show (in Appendix A) that extrapolations of the collisional rate coefficients beyond the range of kinetic temperature for which they were originally calculated lead to spurious rotational line intensities and profiles. The computed emission-line spectra of SiO, NH3 and CH3OH are shown to depend on the assumed initial composition of the grain mantles, from whence they are released, by sputtering in the shock wave, into the gas phase. The dependence of the model predictions on the adopted form of the grain-size distribution is investigated in Appendix B; the corresponding integral line intensities are given in tabular form, for a range of C-type shock speeds, in the online Supporting Information.

Outflow activities in the young high-mass stellar object G23.44–0.18

Abstract We present an observational study towards the young high-mass star-forming region G23.44-0.18 using the Submillimeter Array. Two massive, radio-quiet dusty cores MM1 and MM2 are observed in 1.3-mm continuum emission and dense molecular gas tracers including thermal CH3OH, CH3CN, HNCO, SO, and OCS lines. The 12CO (2–1) line reveals a strong bipolar outflow originating from MM2. The outflow consists of a low-velocity component with wide-angle quasi-parabolic shape and a more compact and collimated high-velocity component. The overall geometry resembles the outflow system observed in the low-mass protostar which has a jet-driven fast flow and entrained gas shell. The outflow has a dynamical age of 6 × 103 yr and a mass loss rate ∼10−3 M ⊙ yr-1. A prominent shock emission in the outflow is observed in SO and OCS, and also detected in CH3OH and HNCO. We investigated the chemistry of MM1, MM2 and the shocked region. The dense core MM2 have molecular abundances of three to four times higher than those in MM1. The abundance excess, we suggest, can be a net effect of the stellar evolution and embedded shocks in MM2 that calls for further inspection.