Kinetic temperature of massive star-forming molecular clumps measured with formaldehyde VI. The photodissociation region M17SW
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Le résumé fourni par la source
The kinetic temperature structure of the photodissociation region M17SW was mapped using the IRAM 30 m telescope. This mapping employed the para-H2CO triplet (J(KaKc) = 303-202, 322-221, and 321-220) near 218 GHz on a scale of ~0.2 pc. The kinetic temperatures were derived by modeling the average H2CO line ratios (322-221/303-202 + 321-220/303-202) with the RADEX non-local thermodynamic equilibrium approach. These temperatures range from 28 to 181 K with an average of 54.2 +/- 0.3 K at a spatial density of 5.5x10^5 cm^-3. Comparing with the temperature measurements obtained from multiple transitions of NH3 (1,1)-(6,6) and the far infrared (FIR) dust continuum, the H2CO lines show temperatures similar to those measured by NH3 but slightly higher than values derived from FIR observations. The high kinetic temperatures observed from H2CO are associated with the ultracompact H II region UC1, dense clumps, as well as H2O and CH3OH masers, showing a similar distribution as NH3. This indicates that dense gas in the M17SW region is heated by star formation activity. The presence of a significant gas temperature gradient across the M17SW region, as measured by H2CO and NH3, provides direct evidence for gas heated predominantly by radiation emitted from the OB star cluster NGC 6618. On a smaller scale, the dense gas surrounding the dense clumps experiences significant heating from internal protostars and/or young stellar objects. Higher temperatures traced by H2CO are linked to turbulence on a scale of ~0.2 pc. The complex temperature structure of the M17SW region is revealed by H2CO and NH3, which may be attributed to both large-scale external radiative heating and small-scale internal radiative and turbulent heating.
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Xinjiang Astronomical Observatory pays non établi dans la noticeStructure de recherche
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University of Chinese Academy of Sciences Purple Mountain Observatory pays non établi dans la noticeUniversité ou école supérieure
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Max Planck Institute for Radio Astronomy pays non établi dans la noticeStructure de recherche
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Purple Mountain Observatory pays non établi dans la noticeStructure de recherche
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Shanghai Astronomical Observatory pays non établi dans la noticeStructure de recherche
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Peking University Kavli Institute for Astronomy and Astrophysics pays non établi dans la noticeUniversité ou école supérieure
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National Astronomical Observatories pays non établi dans la noticeStructure de recherche
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Astronomy and Space pays non établi dans la noticeStructure de recherche
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Nanjing University pays non établi dans la noticeUniversité ou école supérieure
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Jinggangshan University pays non établi dans la noticeUniversité ou école supérieure
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State Key Laboratory of Radio Astronomy and Technology pays non établi dans la noticeStructure de recherche
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Max-Planck-Institut für Radioastronomie pays non établi dans la noticeStructure de recherche
Xinjiang Astronomical Observatory, Purple Mountain Observatory — University of Chinese Academy of Sciences et Max Planck Institute for Radio Astronomy, avec 9 autres affiliations.
Une affiliation ne permet pas de déduire la nationalité d’un auteur.