| 1. |
- Gimalieva, A. D., et al.
(författare)
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A survey of molecular line emission towards Herbig Be star V645 Cyg
- 2024
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Ingår i: Monthly Notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 528:1, s. 108-121
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Tidskriftsartikel (refereegranskat)abstract
- We present a survey of molecular line emission towards the molecular cloud surrounding Herbig Be star V645 Cyg. The survey was performed with the 20-m Onsala space telescope at 3 and 4 mm. We detected emission lines of 33 molecules and their isotopologues from diatomic molecules to four COMs up to seven atoms. Using detected lines, we estimated molecular column densities and abundances relative to molecular hydrogen in local thermodynamic equilibrium (LTE) approximation for all molecules except for methanol, for which we obtained physical parameters using a non-LTE model. Moreover, in the basement of the non-LTE model of methanol line emission, we consider that there is a weak maser effect in the additional spectral component of 51–40 E methanol line at 84.521 GHz. We compared the molecular abundances with values found in several astrochemical templates: molecular clouds, hot cores, and photodissociation regions, and found that signatures of these different types can be found towards V645 Cyg. We also obtained maps of the cloud in several molecular emission lines. The peaks of CO and CH3OH emission are shifted from the direction of the star, but the CS, HCO+, HNC, HCN, and N2H+ emission peaks are observed directly towards the star. Exploring the gas kinematics around V645 Cyg, we found that velocity structure in the ambient molecular cloud on the scale ≈1.6–2.0 pc is not the same as within ≈0.5 pc found previously by other authors.
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| 2. |
- Kirsanova, M. S., et al.
(författare)
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Molecular gas in high-mass filament WB 673
- 2017
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Ingår i: Open Astronomy. - : Walter de Gruyter GmbH. - 2543-6376. ; 26:1, s. 99-105
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Tidskriftsartikel (refereegranskat)abstract
- We studied the distribution of dense gas in a filamentary molecular cloud containing several dense clumps. The center of the filament is given by the dense clump WB 673. The clumps are high-mass and intermediate-mass star-forming regions. We observed CS (2–1), 13 CO (1–0), C 18 O (1–0), and methanol lines at 96 GHz toward WB 673 with the Onsala Space Observatory 20-m telescope. We found CS (2–1) emission in the inter-clump medium so the clumps are physically connected and the whole cloud is indeed a filament. Its total mass is 10 4 M and mass-to-length ratio is 360 M pc 1 from 13 CO (1–0) data. Mass-to-length ratio for the dense gas is 3.4 34 M pc 1 from CS (2–1) data. The PV-diagram of the filament is V-shaped. We estimated physical conditions in the molecular gas using methanol lines. Location of the filament on the sky between extended shells suggests that it could be a good example to test theoretical models of formation of the filaments via multiple compression of interstellar gas by supersonic waves.
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