Astrochemistry

  • Our Team

  • Prof. Peter Schilke (PI, PH1)
  • Nassim Tanha (PH1)
  • Andreas Schwörer (PH1)
  • Liem Ngo Thanh (PH1)
  • Gwendoline Stephan (now University of Virginia)
  • quite a number of collaborators within the CRC

A short overview

Project C3 provides the chemical framework in which many of the observations, particularly the ones in A6, can be interpreted.  The project has concentrated on the chemistry of hot cores, incorporating and extending grain chemistry to understand how complex molecules, such as the ones studied in B3, form in the best sources to study the extent of chemistry in interstellar space.

The project aims at providing a direct linkage between the chemical models and observations, aided by the laboratory efforts. It develops state of the art models that explore the formation of simple and complex molecules geared towards particular sources observed. These models were developed in collaboration with Edwin Bergin from the University of Michigan, who has a long standing history in innovative chemical models. The concrete long-term goals are to follow the astrochemistry in the framework of the dynamical evolution of star formation, and the feedback processes in hot cores all the way through eventual cloud dispersion. In doing so the variable source structure and chemistry is modeled in conjunction with source emission. So far the chemical network of the model has been expanded to include a complete dust surface chemistry and, more recently, the grain-mantle.  We have also investigated the effect of internal PDRs, which posed special challenges because it contained very high UV fields in very high density.  This formed the PhD thesis of Gwendoline Stéphan.

The distinguishing  feature of the model developed in the project, Saptarsy, is that it can calculate the chemcial and thermal structure of a (at present spherical) structure self-consistently, given the luminosity evolution of the central object, and calculate synthetic data cubes to compare with observations.  In the next funding period (if granted) we plan to speed up the calculation of data cubes and compare the results of chemical observations with actual observations.  We also want to couple the (so far static) structure to results from hydrodynamic modeling, in collaboration with C5, since dynamical timescales are similar to thermal and chemical timescales.  In addition, we would like to improve the grain mantle chemistry by including the effects of radiolysis and bulk diffusion.

Astrochemistry in its general form penetrates both the astrophysical and the laboratory parts of the SFB, and in fact forms a very strong link between the two. Together with C1 this project covers all the relevant processes active in astrochemistry and provides the necessary theoretical background for the interpretation of observations of project area A. C3 is an active customer of the B projects by using the results of laboratory experiments, while being in a constant dialogue about which laboratory experiments are needed to maximize the impact of modeling. With respect to the chemistry in dense star forming regions, the closest links are to the astrophysical A5 and A6 projects and to the laboratory project B3. With the modelling of the dynamic chemical evolution, C3 is also relevant for project areas A1 to A4 and relies on interaction with C5.

Selected Publications


In 2018

S. Pols, A. Schwörer, P. Schilke, A. Schmiedeke, Á. Sánchez-Monge, and T. Möller, “The phys-
ical and chemical structure of Sagittarius B2. III. Radiative transfer simulations of the hot core
SgrB2(M) for methyl cyanide”, ArXiv e-prints (2018)

G. Stéphan, P. Schilke, J. Le Bourlot, A. Schmiedeke, R. Choudhury, B. Godard, and Á. Sánchez-
Monge, “Chemical modeling of internal photon-dominated regions surrounding deeply embedded
HC/UCHII regions”, ArXiv e-prints (2018).

In 2017

Á. Sánchez-Monge, P. Schilke, A. Schmiedeke, A. Ginsburg, R. Cesaroni, D. C. Lis, S.-L. Qin,
H. S. P. Müller, E. Bergin, C. Comito, and T. Möller, “The physical and chemical structure of Sagit-
tarius B2. II. Continuum millimeter emission of Sgr B2(M) and Sgr B2(N) with ALMA”, A&A 604, A6
(2017).

In 2015

Choudhury, R.; Schilke, P.; Stéphan, G.; Bergin, E.; Möller, T.; Schmiedeke, A.; Zernickel, A., "Evolution of complex organic molecules in hot molecular cores. Synthetic spectra at (sub-)mm wavebands", 2015, A&A, 574, 68
 

In 2014
Neill, J.L., Bergin, E.A., Lis, D.C., Schilke, P., et al., “Herschel Observations of EXtraordinary Sources: Analysis of the Full Herschel/HIFI Molecular Line Survey of Sagittarius B2(N)”, 2014, ApJ, 789, 8

Crockett, N.R., Bergin,E.A., Neill, J.L, et al., “Herschel Observations of Extraordinary Sources: Analysis of the HIFI 1.2 THz Wide Spectral Survey toward Orion KL. I. Methods”, 2014, ApJ, 787, 112 (co-author Schilke)

In 2013
Belloche, A., Müller, H. S. P., Menten, K. M., Schilke, P., and Comito, C.: "Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)", Astronomy and Astrophysics, 559, A47, 11/2013

Emprechtinger, M., Lis, D. C., Rolffs, R., et al.: "The Abundance, Ortho/Para Ratio, and Deuteration of Water in the High-mass Star-forming Region NGC 6334 I", The Astrophysical Journal, 765, 61, 3/2013 (co-author Schilke)

Lis, Dariusz C., Bergin, Edwin A., Schilke, Peter, and van Dishoeck, Ewine F.: "Ortho-to-Para Ratio in Interstellar Water on the Sightline toward Sagittarius B2(N)", Journal of Physical Chemistry A, 117, 9661, 10/2013

Schilke, Peter, Lis, Dariusz C., Bergin, Edwin A., Higgins, Ronan, and Comito, Claudia: "Ortho/Para Ratio of H2O+ Toward Sagittarius B2(M) Revisited", Journal of Physical Chemistry A, 117, 9766, 10/2013

Tobin, John J., Bergin, Edwin A., Hartmann, et al.: "Resolved Depletion Zones and Spatial Differentiation of N2H+ and N2D+ , The Astrophysical Journal, 765, 18, 3/2013

In 2012
Zernickel, A., Schilke, P., Schmiedeke, A., et al.: "Molecular line survey of the high-mass star-forming region NGC 6334I with Herschel/HIFI and the Submillimeter Array", Astronomy and Astrophysics, 546, A87, 10/2012

In 2011
Bergin, E. A.: "Chemical Processes in the Dense Interstellar Medium", EAS Publications Series, 52, 207, 11/2011

In 2010
Comito, C., Schilke, P., et al.: "Herschel observations of deuterated water towards Sgr B2(M)", Astronomy and Astrophysics, 521, L38, 10/2010

Hassel, G. E., Herbst, E., and Bergin, E. A.: "Beyond the pseudo-time-dependent approach: chemical models of dense core precursors", Astronomy and Astrophysics, 515, A66, 6/2010