Mini-Volume: LAMOST Experiment for Galactic Understanding and Exploration

Properties of the high-mass star forming region IRAS 22475+5939

Xiao-Lan Liu, Jun-Jie Wang


Abstract IRAS 22475+5939 has been well studied by previous astronomers, but we can still discover new characteristics about it, using the first observations of the lines from CO J=2–1, 13CO J=2–1 and 13CO J=3–2 by the KOSMA 3m telescope. The mapping of the intensity ratio of 13CO J=3–2 and 13CO J=2–1 shows that the distribution of the temperature has two peaks, neither of which coincide with the IRAS 22475+5939 source or the center of the HII region, but rather are located at the edge of the HII region. Overlays of the Spitzer IRAC 8 μm with CO contours indicate that they are associated with each other and that the strongest polycyclic aromatic hydrocarbon (PAH) emission is at the IRAS 22475+5939 source position. The IRAS LRS spectrum at 7 μm ~ 23 μm and the PHT-s spectrum at 2 μm ~ 12 μm of the IRAS 22475+5939 source also exhibit strong PAH emission characteristics in the main PAH bands. The diversity of the PAH family should be responsible for the plateaus in the PAH emission in the PHT-s and IRAS-LRS spectra. Analysis and modeling in the infrared bands suggest that IRAS 22475+5939 is more likely to be a class I young stellar object. Where this is the case, the star is likely to have a temperature of Teff ~ 9995.8 K, mass ~ 15.34 M⊙, luminosity ~ 1.54 × 104 L⊙ and age ~ 1.54 × 104 yr. The model shows that circumstellar disc emission is important for wavelengths between 1 and 10 μm, otherwise, the envelope fluctuates for λ > 10μm. Bipolar outflow is confirmed in the molecular cloud, and the excited star of the HII region could be the driving source of the outflow. High resolution is required for better results.


Keywords ISM: jets and outflow — ISM: molecular — ISM: kinematical and dy- namics — star formation

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