Issue |
A&A
Volume 643, November 2020
|
|
---|---|---|
Article Number | A178 | |
Number of page(s) | 19 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/202037659 | |
Published online | 20 November 2020 |
Ammonia observations towards the Aquila Rift cloud complex
1
Xinjiang Astronomical Observatory, Chinese Academy of Sciences,
830011
Urumqi,
PR China
e-mail: jarken@xao.ac.cn; tangxindi@xao.ac.cn
2
University of Chinese Academy of Sciences,
100080
Beijing,
PR China
3
Key Laboratory of Radio Astronomy, Chinese Academy of Sciences,
830011
Urumqi,
PR China
4
Max-Planck-Institut für Radioastronomie,
Auf dem Hügel 69,
53121
Bonn,
Germany
e-mail: chenkel@mpifr-bonn.mpg.de
5
Astronomy Department, King Abdulaziz University,
PO Box 80203,
21589
Jeddah,
Saudi Arabia
6
Department of Solid State Physics and Nonlinear Physics, Faculty of Physics and Technology, AL-Farabi Kazakh National University,
050040
Almaty,
Kazakhstan
Received:
4
February
2020
Accepted:
23
September
2020
We surveyed the Aquila Rift complex including the Serpens South and W 40 regions in the NH3 (1,1) and (2,2) transitions making use of the Nanshan 26-m telescope. Our observations cover an area of ~ 1.5° × 2.2° (11.4 pc × 16.7 pc). The kinetic temperatures of the dense gas in the Aquila Rift complex obtained from NH3 (2,2)/(1,1) ratios range from 8.9 to 35.0 K with an average of 15.3 ± 6.1 K (errors are standard deviations of the mean). Low gas temperatures are associated with Serpens South ranging from 8.9 to 16.8 K with an average of 12.3 ± 1.7 K, while dense gas in the W 40 region shows higher temperatures ranging from 17.7 to 35.0 K with an average of 25.1 ± 4.9 K. A comparison of kinetic temperatures derived from para-NH3 (2,2)/(1,1) against HiGal dust temperatures indicates that the gas and dust temperatures are in agreement in the low-mass-star formation region of Serpens South. In the high-mass-star formation region W 40, the measured gas kinetic temperatures are higher than those of the dust. The turbulent component of the velocity dispersion of NH3 (1,1) is found to be positively correlated with the gas kinetic temperature, which indicates that the dense gas may be heated by dissipation of turbulent energy. For the fractional total-NH3 (para+ortho) abundance obtained by a comparison with Herschel infrared continuum data representing dust emission, we find values from 0.1 ×10−8 to 2.1 ×10−7 with an average of 6.9 (±4.5) × 10−8. Serpens South also shows a fractional total-NH3 (para+ortho) abundance ranging from 0.2 ×10−8 to 2.1 ×10−7 with an average of 8.6 (±3.8) × 10−8. In W 40, values are lower, between 0.1 and 4.3 ×10−8 with an average of 1.6 (±1.4) × 10−8. Weak velocity gradients demonstrate that the rotational energy is a negligible fraction of the gravitational energy. In W 40, gas and dust temperatures are not strongly dependent on the projected distance to the recently formed massive stars. Overall, the morphology of the mapped region is ring-like, with strong emission at lower and weak emission at higher Galactic longitudes. However, the presence of a physical connection between the two parts remains questionable.
Key words: surveys / radio lines: ISM / ISM: molecules / ISM: kinematics and dynamics / stars: formation
© ESO 2020
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