ATLASGAL-selected massive clumps in the inner Galaxy

Giannetti, A.; Leurini, S.; Wyrowski, F.; Urquhart, J. S.; Csengeri, T.; Menten, K. M.; König, C.; Güsten, R.

doi:10.1051/0004-6361/201630048

Cited by 75 publications

(198 citation statements)

References 88 publications

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“…We plot the relation between kinetic temperature derived from para-H 2 CO (3 21 -2 20 /3 03 -2 02 and 4 22 -3 21 /4 04 -3 03 ) ratios and L bol /M clump ratios in Figure 12. The plot shows that the kinetic temperature traced by para-H 2 CO is indeed a rising function of the luminosity-to-mass ratio, which is consistent with results found from CH 3 CN, CH 3 CCH, and CH 3 OH in massive star-forming clumps (Molinari et al 2016;Giannetti et al 2017). …”

Section: Gas Temperature and Clump Evolutionsupporting

confidence: 86%

“…We compare gas kinetic temperatures derived from para-H 2 CO and NH 3 (2,2)/(1,1) against dust temperatures in Figure 8. This comparison shows that the gas temperatures determined from NH 3 (2,2)/(1,1) agree with the dust temperatures (also see Giannetti et al 2017), but are lower than those derived from para-H 2 CO (3 21 -2 20 /3 03 -2 02 and 4 22 -3 21 /4 04 -3 03 ). Previous observations towards the Galactic CMZ, dense massive clumps, and star formation regions indicate that in many cases para-H 2 CO (3 21 -2 20 /3 03 -2 02 and 4 22 -3 21 /4 04 -3 03 ) traces a higher kinetic temperature than the NH 3 (2,2)/(1,1) transitions and dust (Ao et al 2013;Ott et al 2014;Ginsburg et al 2016;Immer et al 2016;Tang et al 2017a,c).…”

Section: Comparison Of Kinetic Temperatures Derived From Gas and Dustsupporting

confidence: 65%

“…Previous observations of our selected massive clump temperatures determined from CO, NH 3 , CH 3 CN, CH 3 CCH, and CH 3 OH (Wienen et al 2012;Giannetti et al 2014Giannetti et al , 2017 suggest that these clumps are heated by radiation from internal massive stars. The comparison between the kinetic temperature and luminosity further helps us to understand the internal heating of embedded infrared sources upon their surrounding dense gas.…”

Section: Correlation Of Gas Temperature With Luminositymentioning

confidence: 58%

“…The gas kinetic temperatures derived from the para-H 2 CO (3 21 -2 20 /3 03 -2 02 and 4 22 -3 21 /4 04 -3 03 ) line ratios are rather warm, ranging from 43 to >300 K with an unweighted aver- Giannetti et al (2017). The black straight lines in both panels indicate equal temperatures.…”

Section: Comparison Of Kinetic Temperatures Derived From Gas and Dustmentioning

confidence: 94%

“…The luminosity-to-mass ratio is a good evolutionary tracer for massive and dense cluster-progenitor clumps (Molinari et al 2008(Molinari et al , 2016Liu et al 2013;Ma et al 2013;Giannetti et al 2017). The fractional abundance of X(para-H 2 CO) shows a weak increasing trend with kinetic temperature, bolometric luminosity, and L bol /M clump ratio (see Fig.…”

Section: Variations Of Spatial Density and H 2 Co Abundancementioning

confidence: 98%

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ATLASGAL-selected massive clumps in the inner Galaxy

Tang

Henkel

Wyrowski

et al. 2018

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Context. Formaldehyde (H 2 CO) is a reliable tracer to accurately measure the physical parameters of dense gas in star-forming regions. Aims. We aim to determine directly the kinetic temperature and spatial density with formaldehyde for the ∼100 brightest ATLASGALselected clumps (the TOP100 sample) at 870 µm representing various evolutionary stages of high-mass star formation. Methods. Ten transitions (J = 3-2 and 4-3) of ortho-and para-H 2 CO near 211, 218, 225, and 291 GHz were observed with the Atacama Pathfinder EXperiment (APEX) 12 m telescope. Results. Using non-LTE models with RADEX, we derived the gas kinetic temperature and spatial density with the measured para-H 2 CO 3 21 -2 20 /3 03 -2 02 , 4 22 -3 21 /4 04 -3 03 , and 4 04 -3 03 /3 03 -2 02 ratios. The gas kinetic temperatures derived from the para-H 2 CO 3 21 -2 20 /3 03 -2 02 and 4 22 -3 21 /4 04 -3 03 line ratios are high, ranging from 43 to >300 K with an unweighted average of 91 ± 4 K. Deduced T kin values from the J = 3-2 and 4-3 transitions are similar. Spatial densities of the gas derived from the para-H 2 CO 4 04 -3 03 /3 03 -2 02 line ratios yield 0.6-8.3 × 10 6 cm −3 with an unweighted average of 1.5 (±0.1) × 10 6 cm −3 . A comparison of kinetic temperatures derived from para-H 2 CO, NH 3 , and dust emission indicates that para-H 2 CO traces a distinctly higher temperature than the NH 3 (2,2)/(1,1) transitions and the dust, tracing heated gas more directly associated with the star formation process. The H 2 CO line widths are found to be correlated with bolometric luminosity and increase with the evolutionary stage of the clumps, which suggests that higher luminosities tend to be associated with a more turbulent molecular medium. It seems that the spatial densities measured with H 2 CO do not vary significantly with the evolutionary stage of the clumps. However, averaged gas kinetic temperatures derived from H 2 CO increase with time through the evolution of the clumps. The high temperature of the gas traced by H 2 CO may be mainly caused by radiation from embedded young massive stars and the interaction of outflows with the ambient medium. For L bol /M clump 10 L ⊙ /M ⊙ , we find a rough correlation between gas kinetic temperature and this ratio, which is indicative of the evolutionary stage of the individual clumps. The strong relationship between H 2 CO line luminosities and clump masses is apparently linear during the late evolutionary stages of the clumps, indicating that L H 2 CO does reliably trace the mass of warm dense molecular gas. In our massive clumps H 2 CO line luminosities are approximately linearly correlated with bolometric luminosities over about four orders of magnitude in L bol , which suggests that the mass of dense molecular gas traced by the H 2 CO line luminosity is well correlated with star formation.

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Section: Gas Temperature and Clump Evolutionsupporting

confidence: 86%

Section: Comparison Of Kinetic Temperatures Derived From Gas and Dustsupporting

confidence: 65%

Section: Correlation Of Gas Temperature With Luminositymentioning

confidence: 58%

Section: Comparison Of Kinetic Temperatures Derived From Gas and Dustmentioning

confidence: 94%

Section: Variations Of Spatial Density and H 2 Co Abundancementioning

confidence: 98%

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ATLASGAL-selected massive clumps in the inner Galaxy

Tang

Henkel

Wyrowski

et al. 2018

A&A

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Kinetic temperature of massive star forming molecular clumps measured with formaldehyde

Tang

Henkel

Menten

et al. 2017

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Context. For a general understanding of the physics involved in the star formation process, measurements of physical parameters such as temperature and density are indispensable. The chemical and physical properties of dense clumps of molecular clouds are strongly affected by the kinetic temperature. Therefore, this parameter is essential for a better understanding of the interstellar medium. Formaldehyde, a molecule which traces the entire dense molecular gas, appears to be the most reliable tracer to directly measure the gas kinetic temperature. Aims. We aim to determine the kinetic temperature with spectral lines from formaldehyde and to compare the results with those obtained from ammonia lines for a large number of massive clumps. Methods. Three 218 GHz transitions (J K A K C = 3 03 -2 02 , 3 22 -2 21 , and 3 21 -2 20 ) of para-H 2 CO were observed with the 15m James Clerk Maxwell Telescope (JCMT) toward 30 massive clumps of the Galactic disk at various stages of high-mass star formation. Using the RADEX non-LTE model, we derive the gas kinetic temperature modeling the measured para-H 2 CO 3 22 -2 21 /3 03 -2 02 and 3 21 -2 20 /3 03 -2 02 ratios. Results. The gas kinetic temperatures derived from the para-H 2 CO (3 21 -2 20 /3 03 -2 02 ) line ratios range from 30 to 61 K with an average of 46 ± 9 K. A comparison of kinetic temperature derived from para-H 2 CO, NH 3 , and the dust emission indicates that in many cases para-H 2 CO traces a similar kinetic temperature to the NH 3 (2,2)/(1,1) transitions and the dust associated with the HII regions. Distinctly higher temperatures are probed by para-H 2 CO in the clumps associated with outflows/shocks. Kinetic temperatures obtained from para-H 2 CO trace turbulence to a higher degree than NH 3 (2,2)/(1,1) in the massive clumps. The non-thermal velocity dispersions of para-H 2 CO lines are positively correlated with the gas kinetic temperature. The massive clumps are significantly influenced by supersonic non-thermal motions.

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ATLASGAL-selected massive clumps in the inner Galaxy

Navarete

Leurini

Giannetti

et al. 2019

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Context. High-mass stars are formed within massive molecular clumps, where a large number of stars form close together. The evolution of the clumps with different masses and luminosities is mainly regulated by their high-mass stellar content and the formation of such objects is still not well understood. Aims. In this work, we characterise the mid-J CO emission in a statistical sample of 99 clumps (TOP100) selected from the ATLASGAL survey that are representative of the Galactic proto-cluster population. Methods. High-spatial resolution APEX-CHAMP+ maps of the CO (6–5) and CO (7–6) transitions were obtained and combined with additional single-pointing APEX-FLASH+ spectra of the CO (4–3) line. The data were convolved to a common angular resolution of 13.′′4. We analysed the line profiles by fitting the spectra with up to three Gaussian components, classified as narrow or broad, and computed CO line luminosities for each transition. Additionally, we defined a distance-limited sample of 72 sources within 5 kpc to check the robustness of our analysis against beam dilution effects. We have studied the correlations of the line luminosities and profiles for the three CO transitions with the clump properties and investigate if and how they change as a function of the evolution. Results. All sources were detected above 3-σ in all three CO transitions and most of the sources exhibit broad CO emission likely associated with molecular outflows. We find that the extension of the mid-J CO emission is correlated with the size of the dust emission traced by the Herschel-PACS 70 μm maps. The CO line luminosity (LCO) is correlated with the luminosity and mass of the clumps. However, it does not correlate with the luminosity-to-mass ratio. Conclusions. The dependency of the CO luminosity with the properties of the clumps is steeper for higher-J transitions. Our data seem to exclude that this trend is biased by self-absorption features in the CO emission, but rather suggest that different J transitions arise from different regions of the inner envelope. Moreover, high-mass clumps show similar trends in CO luminosity as lower mass clumps, but are systematically offset towards larger values, suggesting that higher column density and (or) temperature (of unresolved) CO emitters are found inside high-mass clumps.

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ATLASGAL-selected massive clumps in the inner Galaxy

Cited by 75 publications

References 88 publications

ATLASGAL-selected massive clumps in the inner Galaxy

ATLASGAL-selected massive clumps in the inner Galaxy

Kinetic temperature of massive star forming molecular clumps measured with formaldehyde

ATLASGAL-selected massive clumps in the inner Galaxy

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