Modelling of Irradiated Molecular Clouds

A short overview

Project C1 tries to understand the local chemistry and physics in photon-dominated regions (PDRs), these are molecular clouds affected by the UV radiation from young stars, by means of constructing a sophisticated PDR model that fits the observations of cooling lines and continuum radiation. The model includes all relevant chemical and microphysical processes and a flexible geometry adaptable to any star-forming region. It represents the main tool to interpret the line and continuum radiation from these regions that is typically observed at far-infrared and radio wavelengths. By iteratively improving the existing PDR model code and fitting observed data with the model output this project will help to understand all processes governing the structure and emission of the extended gas in star-forming regions.

By developing a flexible three-dimensional model based on cells of clumpy PDR ensembles we predict the line
emission from individual, UV illuminated cores up to the structure of whole galaxies. This approach will be used on the subgrid level to be combined with the dynamical models in subprojects C5 and C6. This allows us to focus in the new application period on the impact of dynamic effects. After the fitting of individual velocity structures and dust surface effects in the current period we will investigate the impact of varying initial conditions and the effects of turbulent mixing.

The project will also focus on the expected observations of the James Webb Space Telescope, which will resolve
all details of the distribution of PAHs and warm H₂ across the PDRs. By comparing the spatial distribution of the PAHs and their charging state with the local heating traced by the cooling lines we will quantify the photoelectric
effect and the H₂ formation at the level of individual dust and PAH structures.

The results of project C1 are used to interpret the observations taken in projects A1-A5, where PDR material is observed in Galactic regions and in external galaxies. At the same time these observations serve as calibration for the PDR model. The treatment of dust-surface chemistry is based on results obtained in C3. Project C4 accesses the PDR database in order to calibrate and refine its numerical approach to the computation of the local thermal balance in galaxy formation. The instrumental developments planned in project group D will enable heterodyne observations of the OI 63µm line, the main PDR cooling line at high densities.

Selected Publications

• 2022

• Takemura, H., Nakamura, F., Arce, H. G., et al., CARMA-NRO Orion Survey: unbiased survey of dense cores and core mass functions in Orion A, arXiv e-prints 2022, arXiv:2211.10215
• Schneider, N., Ossenkopf-Okada, V., Clarke, S., et al., Understanding star formation in molecular clouds. IV. Column density PDFs from quiescent to massive molecular clouds, A&A 2022, 666, A165
• Röllig, M., & Ossenkopf-Okada, V., The KOSMA-τ PDR model. I. Recent updates to the numerical model of photo-dissociated regions, A&A 2022, 664, A67
• Habart, E., Le Gal, R., Alvarez, et al., High angular resolution near-IR view of the Orion Bar revealed by Keck/NIRC2, arXiv e-prints 2022, arXiv:2206.08245
• Berné, O., Habart, É., Peeters, E., A. et al., PDRs4All: A JWST Early Release Science Program on Radiative Feedback from Massive Stars, PASP 2022, 134, 054301
• Jacob, A. M., Neufeld, D. A., Schilke, P., et al., HyGAL: Characterizing the Galactic Interstellar Medium with Observations of Hydrides and Other Small Molecules. I. Survey Description and a First Look Toward W3(OH), W3 IRS5, and NGC 7538 IRS1, ApJ 2022, 930, 141
• Beuther, H., Schneider, N., Simon, R., et al., FEEDBACK from the NGC 7538 H II region, A&A 2022, 659, A77
• Kabanovic, S., Schneider, N., Ossenkopf-Okada, V. et al., Self-absorption in [C II], ¹²CO,, and H I in RCW120. Building up a geometrical and physical model of the region, A&A 2022, 659, A36

• 2021

• Ladeyschikov, D. A., Kirsanova, M. S., Sobolev, A. M., et al., The link between gas and stars in the S254-S258 star-forming region, MNRAS 2021, 506, 4447
• Schneider, N., Röllig, M., Polehampton, E. T., et al., Globules and pillars in Cygnus X. III. Herschel and upGREAT/SOFIA far-infrared spectroscopy of the globule IRAS 20319+3958 in Cygnus X, A&A 2021, 653, A108
• Linz, H., Beuther, H., Gerin, M., et al., Bringing high spatial resolution to the far-infrared, Experimental Astronomy 2021, 51, 661
• García, P., Abel, N., Röllig, M., Simon, R., & Stutzki, J., Warm ISM in the Sgr A complex. II. The [C/N] abundance ratio traced by [CII] 158 μm and [NII] 205 μm observations toward the Arched Filaments at the Galactic center, A&A 2021, 650, A86
• Kong, S., Arce, H. G., Carpenter, J. M., et al., High-resolution CARMA Observation of Molecular Gas in the North America and Pelican Nebulae, AJ 2021, 161, 229
• Luisi, M., Anderson, L. D., Schneider, N., et al., Stellar feedback and triggered star formation in the prototypical bubble RCW 120, Science Advances 2021, 7, eabe9511
• Nakemura, H., Nakamura, F., Kong, S., et al., The Core Mass Function in the Orion Nebula Cluster Region: What Determines the Final Stellar Masses?, ApJL 2021, 910, L6
• Lim, W., Nakamura, F., Wu, B., et al., Star cluster formation in Orion A, PASJ 2021, 73, S239
• Kong, S., Ossenkopf-Okada, V., Arce, H. G., et al., The CARMA-NRO Orion Survey: Filament Formation via Collision-induced Magnetic Reconnection—the Stick in Orion A, ApJ 2021, 906, 80

• 2020

• Güsten, R., Anderson, L. D., Bally, J., et al., FEEDBACK: a SOFIA Legacy Program to Study Stellar Feedback in Regions of Massive Star Formation, PASP 2020, 132, 104301
• Kirsanova, M. S., Ossenkopf-Okada, V., Anderson, L. D., et al., The PDR structure and kinematics around the compact HII regions S235 A and S235 C with [CII], [¹³CII], [OI], and HCO⁺ line profiles, MNRAS 2020, 497, 2651
• Kramer, C., Nikola, T., Anderl, S., et al., Gas and dust cooling along the major axis of M 33 (HerM33es). Herschel/PACS [CII] and [OI] observations, A&A 2020, 639, A61
• Feddersen, J. R., Arce, H. G., Kong, S., et al., The CARMA-NRO Orion Survey: Protostellar Outflows, Energetics, and Filamentary Alignment, ApJ 2020, 896, 11
• Guevara, C., Stutzki, J., Ossenkopf-Okada, V., et al., [CII] 158 μm self-absorption and optical depth effects, A&A 2020, 636, A16

• 2019

• Schneider, N., Simon, R., Guevara, C., et al., First detection of [¹³CII] in the Large Magellanic Cloud, A&A 2019, 631, L12
• Anderson, L. D., Makai, Z., Luisi, M., et al., The Origin of [C II] 158 μm Emission toward the H II Region Complex S235, ApJ 2019, 882, 11
• Feddersen, J. R., Arce, H. G., Kong, S., Ossenkopf-Okada, V., & Carpenter, J. M., The CARMA-NRO Orion Survey: Statistical Signatures of Feedback in the Orion A Molecular Cloud, ApJ 2019, 875, 162
• Suri, S., Sánchez-Monge, Á., Schilke, P., et al., The CARMA-NRO Orion Survey. Filamentary structure as seen in C^₁₈O emission, A&A 2019, 623, A14

• 2018

• Okada, Y., Güsten, R., Requena-Torres, M. A., Röllig, M., Stutzki, J., Graf, U. U., & Hughes, A., Velocity profiles of [CII], [CI], CO, and [OI] and physical conditions in four star-forming regions in the Large Magellanic Cloud, A&A 2019, 621, A62
• Franeck, A., Walch, S., Seifried, D., et al., Synthetic [CII] emission maps of a simulated molecular cloud in formation, MNRAS 2018, 481, 4277
• Schneider, N., Röllig, M., Simon, R., et al., Anatomy of the massive star-forming region S106. The [O I] 63 μm line observed with GREAT/SOFIA as a versatile diagnostic tool for the evolution of massive stars, A&A 2018, 617, A45
• Joblin, C., Bron, E., Pinto, C., et al., Structure of photodissociation fronts in star-forming regions revealed by Herschel observations of high-J CO emission lines, A&A 2018, 615, A129
• Kong, S., Arce, H. G., Feddersen, J. R., et al., The CARMA-NRO Orion Survey, ApJS 2018, 236, 25
• Veltchev, T. V., Ossenkopf-Okada, V., Stanchev, O., Schneider, N., Donkov, S., & Klessen, R. S., Spatially associated clump populations in Rosette from CO and dust maps, MNRAS 2018, 475, 2215

• 2017

• Andree-Labsch, S.; Ossenkopf-Okada, V.; Röllig, M., Modelling clumpy photon-dominated regions in 3D. Understanding the Orion Bar stratification. A&A 2017, 598, A2
• Glück, C.B.; Stutzki, J.; Röllig, M.; et al., SOFIA/GREAT [C ii] observations in nearby clouds near the lines of sight towards B0355+508 and B0212+735. A&A 2017, 600, A94.
• Nagy, Z.; Choi, Y.;  Ossenkopf-Okada, V.; et al., Herschel/HIFI spectral line survey of the Orion Bar. Temperature
  and density differentiation near the PDR surface. A&A 2017, 599, A22
• Veltchev, T.V.; Ossenkopf-Okada, V.; Stanchev, O.; et al., Spatially associated clump populations in Rosette from CO and dust maps, MNRAS, 2018, 475, 2215

• 2016

• Röllig, M.; Simon, R.; Güsten, R.; et al., [C II] 158 μ m and [N II] 205 μ m emission from IC 342. Disentangling the emission from ionized and photo-dissociated regions. A&A 2016, 591, A33
• M. Röllig, Violent emissions of newborn stars. Nature 2016, 537, 174

• 2015

• Nagy, Z.; Ossenkopf, V.; van der Tak, F.F.S, et al., C2H observations toward the Orion Bar. A&A 2015, 578, A124
• Koumpia,  E.; Harvey, P.M.; Ossenkopf, V.;  et al., Temperatures of dust and gas in S 140. A&A, 2015, 580, A68
• Ossenkopf, V.; Koumpia, E.; Okada, Y., et al., Fine-structure line deficit in S 140. A&A, 2015, 580, A83
• Pérez-Beaupuits, J.P.; , Güsten, R.; Spaans, M., Ossenkopf, V.; et al., Disentangling the excitation conditions of the dense gas in M17 SW. A&A 2015, 583, A107
• Pérez-Beaupuits, J.P.; Stutzki, J.;  Ossenkopf, V.; et al., Detection of a large fraction of atomic gas not asso-
  ciated with star-forming material in M17 SW. A&A 2015, 575, A9

• 2014

• Beuther, H.; Ragan, S. E.; Ossenkopf, V.; et al.; Carbon in different phases ([CII], [CI], and CO) in infrared dark clouds: Cloud formation signatures and carbon gas fractions, A&A, 2014, 571, 53

• 2013

• Ossenkopf, V.; Röllig, M.; Neufeld, D.; et al., Herschel/HIFI observations of [CII] and [ ¹³CII] in PDRs, A&A, 2013, 550, 57.
• Röllig, M.; Ossenkopf, V., Carbon Fractionation in PDRs, A&A, 2013, 550, 56
• van der Tak, F. F. S.; Nagy, Z.; Ossenkopf, V.; et al., Spatially extended OH⁺ emission from the Orion Bar and Ridge, A&A, 2013, 560, 95-104
• Nagy, Z.; Van der Tak, F. F. S.; Ossenkopf, V.; et al. The chemistry of ions in the Orion Bar I. - CH⁺, SH⁺, and CF⁺. The effect of high electron density and vibrationally excited H₂ in a warm PDR surface, A&A, 2013, 550, 96-106
• Okada, Y.; Pilleri, P.; Berné, O.; Ossenkopf, V.; et al., Probing the role of polycyclic aromatic hydrocarbons in the photoelectric heating within photodissociation regions, A&A, 2013, 553, 2