SiO and CH<sub>3</sub>CCH abundances and dust emission in high-mass star-forming cores

Miettinen, O.; Harju, J.; Haikala, L. K.; Pomren, C.

doi:10.1051/0004-6361:20064815

Cited by 50 publications

(79 citation statements)

References 79 publications

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“…1 apply here. represents an evolutionary line for molecular outflows driven by massive YSOs, compatible with the scenario proposed by Beuther & Shepherd (2005) in which initially well collimated outflows gradually disappear to make way for a wide-angle wind-dominated outflow. Our result is consistent with the findings of Miettinen et al (2006), who measured a decrease of the SiO abundance with core temperature in a sample of 15 UC Hii regions and concluded that SiO outflows are less frequent in more evolved, warmer cores. Given that our sample, which includes IR-dark sources, presumably covers a wider range of evolutionary phases, this represents the first time that clear evidence of a decrease in jet/outflow activity with time is found in a sample of high-mass SFRs.…”

Section: Decrease Of Sio Outflow Activity With Timesupporting

confidence: 93%

SiO outflows in high-mass star forming regions: A potential chemical clock?

López-Sepulcre

Walmsley

Cesaroni

et al. 2010

A&A

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Context. Some theoretical models propose that O-B stars form via accretion, in a similar fashion to low-mass stars. Jet-driven molecular outflows play an important role in this scenario, and their study can help to understand the process of high-mass star formation and the different evolutionary phases involved. Aims. Observations towards low-mass protostars so far favour an evolutionary picture in which jets are always associated with Class 0 objects while more evolved Class I/II objects show less evidence of powerful jets. The present study aims at checking whether an analogous picture can be found in the high-mass case. Methods. The IRAM 30-m telescope (Spain) has been used to perform single-pointing SiO(2-1) and (3-2) observations towards a sample of 57 high-mass molecular clumps in different evolutionary stages. Continuum data at different wavelengths, from mid-IR to 1.2 mm, have been gathered to build the spectral energy distributions of all the clumps and estimate their bolometric luminosities. Results. SiO emission at high velocities, characteristic of molecular jets, is detected in 88% of our sources, a very high detection rate indicating that there is ongoing star formation activity in most of the sources of our sample. The SiO(2-1) luminosity drops with L bol /M, which suggests that jet activity declines as time evolves. This represents the first clear evidence of a decrease of SiO outflow luminosity with time in a homogeneous sample of high-mass molecular clumps in different evolutionary stages. The SiO(3-2) to SiO(2-1) integrated intensity ratio shows only minor changes with evolutionary state.

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Section: Decrease Of Sio Outflow Activity With Timesupporting

confidence: 93%

SiO outflows in high-mass star forming regions: A potential chemical clock?

López-Sepulcre

Walmsley

Cesaroni

et al. 2010

A&A

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“…Indeed, Sakai et al (2010) found a trend opposite to ours, and they proposed that the SiO emission from the mid-IR dark sources originates in newly formed shocks, while the SiO emission from more evolved, mid-IR bright sources could originate in gas that was shocked earlier in time. This could be related to the discovery by Miettinen et al (2006), namely that the SiO abundance in massive clumps appears to decrease as a function of gas kinetic temperature, which might reflect an evolutionary trend.…”

Section: Sio (Silicon Monoxide)mentioning

confidence: 63%

A MALT90 study of the chemical properties of massive clumps and filaments of infrared dark clouds

Miettinen

2014

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Context. Infrared dark clouds (IRDCs) provide a useful testbed in which to investigate the genuine initial conditions and early stages of massive-star formation. Aims. We attempt to characterise the chemical properties of a sample of 35 massive clumps of IRDCs through multi-molecular line observations. We also search for possible evolutionary trends among the derived chemical parameters.Methods. The clumps are studied using the MALT90 (Millimetre Astronomy Legacy Team 90 GHz) line survey data obtained with the Mopra 22 m telescope. The survey covers 16 different transitions near 90 GHz. The spectral-line data are used in concert with our previous LABOCA (Large APEX BOlometer CAmera) 870 μm dust emission data. Results. Eleven MALT90 transitions are detected towards the clumps at least at the 3σ level. Most of the detected species (SiO, C 2 H, HNCO, HCN, HCO + , HNC, HC 3 N, and N 2 H + ) show spatially extended emission towards many of the sources. Most of the fractional abundances of the molecules with respect to H 2 are found to be comparable to those determined in other recent similar studies of IRDC clumps. We found that the abundances of SiO, HNCO, and HCO + are higher in IR-bright clumps than in IR-dark sources, reflecting a possible evolutionary trend. A hint of this trend is also seen for HNC and HC 3 N. An opposite trend is seen for the C 2 H and N 2 H + abundances. Moreover, a positive correlation is found between the abundances of HCO + and HNC, and between those of HNC and HCN. The HCN and HNC abundances also appear to increase as a function of the N 2 H + abundance. The HNC/HCN and N 2 H + /HNC abundance ratios are derived to be near unity on average, while that of HC 3 N/HCN is ∼10%. The N 2 H + /HNC ratio appears to increase as the clump evolves, while the HNC/HCO + ratio shows the opposite behaviour. Conclusions. The detected SiO emission is probably caused by shocks driven by outflows in most cases, although shocks resulting from the cloud formation process could also play a role. Shock-origin for the HNCO, HC 3 N, and CH 3 CN emission is also plausible. The average HNC/HCN ratio is in good agreement with those seen in other IRDCs, but gas temperature measurements would be neeeded to study its temperature dependence. Our results support the finding that C 2 H can trace the cold gas, and not just the photodissociation regions. The HC 3 N/HCN ratio appears to be comparable to the values seen in other types of objects, such as T Tauri disks and comets.

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“…Faúndez et al (2004) reported a luminosity of 1.7 × 10 4 L obtained by integrating the spectral energy distribution and assuming d = 0.8 kpc. Distances between 700 pc and 2.2 kpc are reported in the literature (i.e., Miettinen et al 2006;Forster & Caswell 1989). However, the latter is based on maser emission lines.…”

Section: Introductionmentioning

confidence: 88%

“…However, the latter is based on maser emission lines. Using the rotation curve determined by Brand & Blitz (1993) and velocities based on thermal lines (Bronfman et al 1996;MacLeod et al 1998;Miettinen et al 2006;Leurini et al 2011), the kinematical distance of IRAS 17233 is constrained to ≤1 kpc. The far distance (∼15 kpc) is unlikely because of the source extremely bright continuum and line emission at practically all observed wavelengths, which would indicate exceedingly high luminosities if the source were at the far distance.…”

Section: Introductionmentioning

confidence: 99%

On the kinematics of massive star forming regions: the case of IRAS 17233–3606

Leurini

Codella

Zapata

et al. 2011

A&A

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Context. Direct observations of accretion disks around high-mass young stellar objects would help to discriminate between different models of formation of massive stars. However, given the complexity of massive star forming regions, such studies are still limited in number. Additionally, there is still no general consensus on the molecular tracers to be used for such investigations. Aims. Because of its close distance and high luminosity, IRAS 17233−3606 is a potential laboratory to search for traces of rotation in the inner gas around the protostar(s). Therefore, we selected the source for a detailed analysis of its molecular emission at 230 GHz with the SMA. Methods. We systematically investigated the velocity fields of transitions in the SMA spectra which are not affected by overlap with other transitions, and searched for coherent velocity gradients to compare them to the distribution of outflows in the region. Beside CO emission we also used high-angular H 2 images to trace the outflow motions driven by the IRAS 17233−3606 cluster. Results. We find linear velocity gradients in many transitions of the same molecular species and in several molecules. We report the first detection of HNCO in molecular outflows from massive YSOs. We discuss the CH 3 CN velocity gradient taking into account various scenarios: rotation, presence of multiple unresolved sources with different velocities, and outflow(s). Although other interpretations cannot be ruled out, we propose that the CH 3 CN emission might be affected by the outflows of the region. Higher angular observations are needed to discriminate between the different scenarios.Conclusions. The present observations, with the possible association of CH 3 CN with outflows in a few thousands AU around the YSOs' cluster, (i) question the choice of the tracer to probe rotating structures, and (ii) show the importance of the use of H 2 images for detailed studies of kinematics.

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SiO and CH₃CCH abundances and dust emission in high-mass star-forming cores

Cited by 50 publications

References 79 publications

SiO outflows in high-mass star forming regions: A potential chemical clock?

SiO outflows in high-mass star forming regions: A potential chemical clock?

A MALT90 study of the chemical properties of massive clumps and filaments of infrared dark clouds

On the kinematics of massive star forming regions: the case of IRAS 17233–3606

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SiO and CH3CCH abundances and dust emission in high-mass star-forming cores

Cited by 50 publications

References 79 publications

SiO outflows in high-mass star forming regions: A potential chemical clock?

SiO outflows in high-mass star forming regions: A potential chemical clock?

A MALT90 study of the chemical properties of massive clumps and filaments of infrared dark clouds

On the kinematics of massive star forming regions: the case of IRAS 17233–3606

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SiO and CH₃CCH abundances and dust emission in high-mass star-forming cores