Molecular clumps towards compact H ii regions. Issue 2 (3rd June 2019)

• Record Type: Journal Article
• Authors: Saldaño, Hugo P; Rubio, M; Cappa, C E; Gómez, M
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 487:Issue 2(2019)
• Page Start: 2881
• Page End: 2899
• Publication Date: 2019-06-03
• Subjects: ISM: clouds -- (ISM:) H ii regions -- ISM: individual objects: (IRAS 08140−3559, IRAS 09014−4736, IRAS 09026−4842) -- ISM: abundances -- ISM: jets and outflows -- stars: formation; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stz1409
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: To better understand how the H ii regions can affect their surrounding molecular clouds we have studied the molecular distribution towards three compact H ii regions associated with IRAS sources (08140−3559, 09014−4736, and 09026−4842) by means of the observations of 12 CO, 13 CO, and C 18 O molecules in the J = 3−2 transition with the APEX telescope. In two cases, we show evidence of possible disruption of the molecular clouds and increasing turbulence towards the diffuse H α emissions, which could be due to the ionizing front. We find 11 clumps towards the IRAS sources either nearby or surrounding the H ii regions. Their parameters, such as the optical depths, column densities, masses, and [ 13 CO/C 18 O] abundances, were calculated assuming LTE conditions. We discuss the behaviour of such parameters and we have found that the [ 13 CO/C 18 O] abundances in the IRAS sources associated with a diffuse H α emission are higher than the abundances in regions where no H α emission is detected, indicating that such a parameter could be affected by the UV field coming from H ii region. We also discuss the rise of the average [H2 / 13 CO] and [H2 /C 18 O] abundances in the IRAS sources which show evidence of disruption of molecular clouds by the expansion of the H ii regions. With these average abundances, we estimate the LTE total mass of each clump and compare them with the virial mass to discuss whether our clumps are gravitationally stable.