Cloud structure of galactic OB cluster-forming regions from combining ground- and space-based bolometric observations
- National Astronomical Observatories, Chinese Academy of Sciences (China)
- European Southern Observatory (ESO), Karl-Schwarzschild-Str. 2, D-85748 Garching (Germany)
- Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)
- Max-Planck-Institut für Extraterrestrische Physik, Gießenbach-str 1, D-85748, Garching bei München (Germany)
- Instituto de Radioastronomía y Astrofísica, UNAM, Apdo. Postal 3-72 (Xangari), 58089 Morelia, Michoacán, México (Mexico)
- Department of Physics, University of Alberta, 4-181 CCIS, Edmonton, AB T6G 2E1 (Canada)
- Universitäts–Sternwarte München, Scheinerstr. 1, D-81679 München (Germany)
- Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF (United Kingdom)
We have developed an iterative procedure to systematically combine the millimeter and submillimeter images of OB cluster-forming molecular clouds, which were taken by ground-based (CSO, JCMT, APEX, and IRAM-30 m) and space telescopes (Herschel and Planck). For the seven luminous (L>10{sup 6} L {sub ⊙}) Galactic OB cluster-forming molecular clouds selected for our analyses, namely W49A, W43-Main, W43-South, W33, G10.6-0.4, G10.2-0.3, and G10.3-0.1, we have performed single-component, modified blackbody fits to each pixel of the combined (sub)millimeter images, and the Herschel PACS and SPIRE images at shorter wavelengths. The ∼10″ resolution dust column density and temperature maps of these sources revealed dramatically different morphologies, indicating very different modes of OB cluster-formation, or parent molecular cloud structures in different evolutionary stages. The molecular clouds W49A, W33, and G10.6-0.4 show centrally concentrated massive molecular clumps that are connected with approximately radially orientated molecular gas filaments. The W43-Main and W43-South molecular cloud complexes, which are located at the intersection of the Galactic near 3 kpc (or Scutum) arm and the Galactic bar, show a widely scattered distribution of dense molecular clumps/cores over the observed ∼10 pc spatial scale. The relatively evolved sources G10.2-0.3 and G10.3-0.1 appear to be affected by stellar feedback, and show a complicated cloud morphology embedded with abundant dense molecular clumps/cores. We find that with the high angular resolution we achieved, our visual classification of cloud morphology can be linked to the systematically derived statistical quantities (i.e., the enclosed mass profile, the column density probability distribution function (N-PDF), the two-point correlation function of column density, and the probability distribution function of clump/core separations). In particular, the massive molecular gas clumps located at the center of G10.6-0.4 and W49A, which contribute to a considerable fraction of their overall cloud masses, may be special OB cluster-forming environments as a direct consequence of global cloud collapse. These centralized massive molecular gas clumps also uniquely occupy much higher column densities than what is determined by the overall fit of power-law N-PDF. We have made efforts to archive the derived statistical quantities of individual target sources, to permit comparisons with theoretical frameworks, numerical simulations, and other observations in the future.
- OSTI ID:
- 22868740
- Journal Information:
- Astrophysical Journal, Vol. 828, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COSMOLOGY AND ASTRONOMY
BOLOMETERS
CLASSIFICATION
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
CORRELATION FUNCTIONS
COSMIC DUST
DENSITY
DISTRIBUTION
DISTRIBUTION FUNCTIONS
IMAGE PROCESSING
MASS
PERTURBED ANGULAR CORRELATION
PROBABILITY
RESOLUTION
SPACE
STARS
TELESCOPES
WAVELENGTHS