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A Search for Extremely Young Stellar Objects |
| WU Yue-Fang;WANG Jun-Zhi;WU Jing-Wen |
| Astronomy Department and CAS-PKU Joint Beijing Astrophysics Centre, Peking University, Beijing 100871 |
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| Cite this article: |
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WU Yue-Fang, WANG Jun-Zhi, WU Jing-Wen 2003 Chin. Phys. Lett. 20 1409-1412 |
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Abstract We have observed 22 sources in 13CO and C18O J = 1 - 0 lines with a 13.7-m telescope at Qinghai station of PMO, NAOC. The samples were chosen with new criteria so that the sources are much redder and fainter than those chosen before. All the 22 sources were detected with the pair lines of 13CO and C18O and are suitable for analysing star formation except one multiple emission source IRAS 20300+3909. Physical parameters were derived from the local thermodynamic equilibrium assumption. The excitation temperature and column density of C18O are 13 K and 1.5 x 1015cm-2, respectively, on the average. Eleven sources in the samples have line widths larger than 3 km/s. The IRAS color indices are larger than those of class-0 objects. The intermediate and far infrared energy distributions show that the emission peaks of the samples fall in far infrared or longer wavelengths except IRAS 20149+3955, indicating that they may be very young stellar objects. Analyses of line widths and bolometric luminosity show that seven of those sources may be extremely young high or intermediate mass stellar objects.
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| Keywords:
98.58.Db
98.62.Ai
98.58.Jg
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Published: 01 August 2003
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| PACS: |
98.58.Db
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(Molecular clouds, H2 clouds, dense clouds, and dark clouds)
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98.62.Ai
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(Origin, formation, evolution, age, and star formation)
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98.58.Jg
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(Infrared emission)
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