A short overview
Project A6 was initiated within the CRC 956 to study high-mass star-forming regions in our Galaxy following two highly-complementary approaches: (i) large, statistically-significant studies sensitive to cloud and clump scales (0.2-50 pc), and (ii) detailed, high-resolution studies of specific regions at clump and core scales (< 0.5 pc). On one hand, large surveys of thousands of objects allow us to build an evolutionary sequence for high-mass star formation and to derive average properties of regions distributed throughout the Galaxy. On the other hand, studies of specific sources provide detailed information on the fragmentation properties of star-forming regions, on the mass accretion process onto individual cores and their feedback, as well as on their chemical properties.
Thanks to the advent of new instruments and to the work done in the previous funding periods (e.g., development of analysis tools, analysis of complex datasets), we are now in an excellent position to compare the results of the two complementary parts. We have acquired detailed observations of large samples of sources, and thus, we can now perform statistical studies of detailed properties that will be compared to the results obtaiend for thousands of sources at larger spatial scales.
High-mass star formation: High-mass (O and B spectral type) stars play an important role in shaping the morphological, dynamical and chemical structure of their host galaxies. They have a profound impact on their local environment through powerful outflows, strong stellar winds and copious amounts of UV radiation, which shape the interstellar medium and regulate star formation. Moreover, emission from high-mass stars dominates the light seen from distant galaxies, and therefore, galaxy models are critically dependent on various assumptions that are made about high-mass star formation.
Statistical studies: This sub-project is mainly based on the ATLASGAL (APEX Telescope Large Area Survey of the Galaxy) survey. ATLASGAL cover an area of 420 square degrees of the inner Galactic plane, and is sensitive to the cold dust tracing the regions where stars form. Within the ATLASGAL survey, a catalogue of about 10,000 compact sources has been extracted. This catalog is, therefore, the first largest, unbiased catalog of star forming clouds. Several follow-up studies in spectral lines have been started in order to analyze the physical and chemical properties of a subset of these sources. This study will provide hints on a possible evolutionary sequence in the formation process of high-mass stars. See more details here.
Detailed studies: The formation of high-mass stars is a complex process due to the complexity of the regions where these stars are formed: for example, the large number of objects forming at the same time and acquiring material to grow up in mass. Due to this level of complexity, a statistical approach is not enough to obtain an accurate picture, and detailed observations are required. Within this sub-project we conduct observations of a number of specific regions, in order to obtain high fidelity images able to resolve the different objects forming as well as the clumps, filaments and clouds that transport the mass from large-scale clouds to the stars. These observations are analyzed by using 3D radiative transfer modelling, able to reproduce the observations and to provide with a 3-dimensional picture of the high-mass star forming picture. See more details here.
The A6 project provides a closer and detailed look at the small-scale regions (cores and clumps) where star formation occurs. These objects are embedded in large-scale clouds studied in projects A4 and A5. Moreover, the study of extreme Milky-Way high-mass star-forming sites like Sagittarius B2 (located close to the Galactic Center) provides constraints to and benefit from the studies of extreme regions in nearby galaxies studied in projects A2 and A3. On the modelling side, the A6 observational project develops particular tools that can be used in other projects (e.g., continuum and line identification tools). We also make use of the chemical codes developed in particular in project C3 but also in projects C1 and C6 for different environments, as well as the numerical simulations of star-forming clouds produced and analyzed in C5. For spectroscopic studies, we rely on the laboratory analysis of B2-B4 projects. Finally, a prerequisite for new astronomical discoveries is state-of-the-art instrumentation, as developed for the submm/FIR regime in the D and S sections.
- Pols, S., Schwoerer, A., Schilke, P., et al., The physical and chemical structure of Sagittarius B2. III. Radiative transfer simulations of the hot core SgrB2(M) for methyl cyanide. A&A, arXiv:1802.09231 (A6 participation: Pols, Schwoerer, Schilke, Schmiedeke, Sanchez-Monge).
- Sanchez-Monge, A., Schilke, P., Ginsburg, A., et al., STATCONT: A statistical continuum level determination method for line-rich sources. A&A, 2018, 609, A101 (A6 participation: Sanchez-Monge, Schilke, Schmiedeke).
- Urquhart, J.S., Koenig, C., Giannetti, A., et al., ATLASGAL - properties of a complete sample of Galactic clumps. MNRAS, 2018, 473, 1059 (A6 participation: Urquhart, Koenig, Giannetti, Menten, Wyrowski).
- Ginsburg, A., Bally, J. Barnes, A., et al., Distributed star formation throughout the galactic center cloud SgrB2. ApJ, 2018, 853, 171 (A6 participation: Meng, Sanchez-Monge, Schilke, Schmiedeke).
- Sanchez-Monge, A., Schilke, P., Schmiedeke, A., et al., The physical and chemical structure of Sagittarius B2. II. Continuum millimeter emission of SgrB2(M) and SgrB2(N) with ALMA. A&A, 2017, 604, A6 (A6 participation: Sanchez-Monge, Schilke, Schmiedeke, Comito).
- Giannetti, A., Leurini, S., Koenig, C., et al., Galactocentric variation of the gas-to-dust ratio and its relation with metallicity. A&A, 2017, 606, L12 (A6 participation: Giannetti, Koenig, Urquhart, Wyrowski, Menten).
- Giannetti, A., Leurini, S., Wyrowski, F., et al., ATLASGAL-selected massive clumps in the inner Galaxy. V. Temperature structure and evolution. A&A, 2017, 603, A33 (A6 participation: Gianneti, Wyrowski, Urquhart, Menten, Koenig).
- Koenig, C., Urquhart, J.S., Csengeri, T., et al., ATLASGAL-selected massive clumps in the inner Galaxy. III. Dust continuum characterization of an evolutionary sample. A&A, 2017, 599, A139 (A6 participation: Koenig, Urquhart, Wyrowski, Giannetti, Menten).
- Schmiedeke, A., Schilke, P., Moeller, T., et al., The physical and chemical structure of Sagittarius B2. I. Three-dimensional thermal dust and free-free continuum modeling on 100 au to 45 pc scales. A&A, 2016, 588, A143 (A6 participation: Schmiedeke, Schilke, Sanchez-Monge, Comito).
- Csengery, T., Weiss, A., Wyrowski, F., et al., The ATLASGAL survey: distribution of cold dust in the Galactic plane. Combination with Plank data. A&A, 2016, 585, A104 (A6 participation: Wyrowski, Menten, Urquhart).
- Csengeri, T., Urquhart, J.S., Schuller, F., et al., The ATLASGAL survey: a catalog of dust condensation in the Galactic plane. A&A, 2014, 565, 75 (A6 participation: Urquhart, Wyrowski, Menten).
- Schilke, P., Neufeld, D.A., Mueller, H.S.P., et al., Ubiquitous argonium (ArH+) in the diffuse interstellar medium: A molecular tracer of almost purely atomic gas. A&A, 2014, 566, 29 (A6 participation: Schilke, Comito, Menten, Sanchez-Monge).
- Bisschop, S.E., Schilke, P., Wyrowski, F., et al., Dimethyl ether in its ground state, v=0, and lowest two torsionally excited states, v11=1 and v15=1, in the high-mass star-forming region G327.3-0.6. A&A, 2013, 552, 122 (A6 participation: Schilke, Wyrowski, Belloche, Menten).
- Contreras, Y., Schuller, F., Urquhart, J.S., et al., ATLASGAL – compact source catalogue: 330o < l< 21o. A&A, 2013, 549, 45 (A6 participation: Urquhart, Wyrowski, Schilke).
- Urquhart, J.S., Moore, T.J.T., Schuller, F., et al., ATLASGAL – environments of 6.7 GHz methanol masers. 2013, MNRAS, 431, 1752 (A6 participation: Urquhart, Wyrowski, Menten).
- Urquhart, J.S., Thompson, M.A., Moore, T.J.T., et al., ATLASGAL – properties of compact HII regions and their natal clumps. MNRAS, 2013, 435, 400 (A6 participation: Urquhart, Wyrowski, Menten).
- Zernickel, A., Schilke, P., Smith, R.J., The global velocity field of the filament in NGC 6334. A&A, 2013, 554, L2 (A6 participation: Zernickel, Schilke).
- Wienen, M. Wyrowski, F., Schuller F., et al., Ammonia from cold high-mass clumps discovered in the inner Galactic disk by the ATLASGAL survey. A&A, 2012, 544, 146 (A6 participation: Wienen, Wyrowski, Menten).
- 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. A&A, 2012, 546, 87 (A6 participation: Zernickel, Schilke, Schmiedke, Comito).
- Qin, S.-L., Schilke, P., Rolffs, R., et al., Submillimeter continuum observations of Sagittarius B2 at subarcsecond spatial resolution. A&A, 2011, 530, L9 (A6 participation: Qin, Schilke, Comito).
Dr. Álvaro Sánchez-Monge (PI, Ph1), Dr. Friedrich Wyrowski (PI, MPIfR ), Dr. Frantisek Dinnbier (Ph1), Dr. Rebekka Grellmann (Ph1), Dr. Min-Young Lee (MPIfR), Prof. Dr. Karl Menten (MPIfR), Prof. Dr. Peter Schilke (Ph1), Dr. Robert Simon (Ph1), Prof. Dr Stefanie Walch (Ph1), Atefeh Aghababaei (Ph1), Carsten König (MPIfR), Yuxin Lin (MPIfR), Parichay Mazumdar (MPIfR), Fanyi Meng (Ph1), Mahya Sadaghiani (Ph1)