Exploring morphological correlations among H2CO, 12CO, MSX and continuum mappings

There are relatively few H2CO mappings of large-area giant molecular cloud (GMCs). H2CO absorption lines are good tracers for low-temperature molecular clouds towards star formation regions. Thus, the aim of the study was to identify H2CO distributions in ambient molecular clouds. We investigated morphologic relations among 6-cm continuum brightness temperature (CBT) data and H2CO (111-110; Nanshan 25-m radio telescope), 12CO (1--0; 1.2-m CfA telescope) and midcourse space experiment (MSX) data, and considered the impact of background components on foreground clouds. We report simultaneous 6-cm H2CO absorption lines and H110\alpha radio recombination line observations and give several large-area mappings at 4.8 GHz toward W49 (50'\times50'), W3 (70'\times90'), DR21/W75 (60'\times90') and NGC2024/NGC2023 (50'\times100') GMCs. By superimposing H2CO and 12CO contours onto the MSX color map, we can compare correlations. The resolution for H2CO, 12CO and MSX data was about 10', 8' and 18.3", respectively. Comparison of H2CO and 12CO contours, 8.28-\mu m MSX colorscale and CBT data revealed great morphological correlation in the large area, although there are some discrepancies between 12CO and H2CO peaks in small areas. The NGC2024/NGC2023 GMC is a large area of HII regions with a high CBT, but a H2CO cloud to the north is possible against the cosmic microwave background. A statistical diagram shows that 85.21% of H2CO absorption lines are distributed in the intensity range from -1.0 to 0 Jy and the \Delta V range from 1.206 to 5 km/s.Comment: 18 pages, 22 figures, 5 tables. Accepted to be published in Astrophysics and Space Scienc

The structure of gould's belt

A comparative study of optical and radio-astronomical data was made of a section of Gould's Belt from l l = 300°–12°. Two strong neutral hydrogen concentrations are associated with Sco OB2 and with the Lupus section of the Sco-Cen association. The mean plane of the gas is slightly below the optical equator. A plane self-gravitating model was applied to obtain a mean total density of 0.23 MΘ pcˉ³ in the plane of the Belt, giving a total mass of ~7 10⁶ MΘ, out of which about 7% is in the form of neutral hydrogen. In the Lupus gas concentration the hydrogen content is about 14%, indicating that star formation is less advanced there. Finally, the possibility that Gould's Belt is either rotating or oscillating rigidly is discussed

The structure of gould's belt

A comparative study of optical and radio-astronomical data was made of a section of Gould's Belt from l l = 300°–12°. Two strong neutral hydrogen concentrations are associated with Sco OB2 and with the Lupus section of the Sco-Cen association. The mean plane of the gas is slightly below the optical equator. A plane self-gravitating model was applied to obtain a mean total density of 0.23 MΘ pcˉ³ in the plane of the Belt, giving a total mass of ~7 10⁶ MΘ, out of which about 7% is in the form of neutral hydrogen. In the Lupus gas concentration the hydrogen content is about 14%, indicating that star formation is less advanced there. Finally, the possibility that Gould's Belt is either rotating or oscillating rigidly is discussed