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- de la Fuente, Eduardo, et al.
(författare)
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Ultracompact H II regions with extended emission: the case of G43.89-0.78 and its molecular environment
- 2020
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 497:4, s. 4436-4447
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Tidskriftsartikel (refereegranskat)abstract
- The Karl Jansky Very Large Array (VLA), Owens Valley Radio Observatory (OVRO), Atacama Large Millimetric Array (ALMA), and the infrared Spitzer observatories are powerful facilities to study massive star formation regions and related objects such as ultra-compact (UC) H II regions, molecular clumps, and cores. We used these telescopes to study the UC H II region G43.89-0.78. The morphological study at arcminute scales using NVSS and Spitzer data shows that this region is similar to those observed in the bubble-like structures revealed by Spitzer observations. With this result, and including a physical characterization based on 3.6 cm data, we suggest G43.89-0.78 be classified as an UC H II region with Extended Emission because it meets the operational definition given in this paper comparing radio continuum data at 3.6 and 20 cm. For the ultra-compact component, we use VLA data to obtain physical parameters at 3.6 cm confirming this region as an UC H II region. Using ALMA observations, we detect the presence of a dense (2.6 x 10(7) cm(-3)) and small (similar to 2.0 arcsec; 0.08 pc) molecular clump with a mass of 220 M-circle dot and average kinetic temperature of 21 K, located near to the UC H II region. In this clump, catalogued as G43.890-0.784, water masers also exist, possibly tracing a bipolar outflow. We discover in this vicinity two additional clumps which we label as G43.899-0.786 (T-d = 50 K; M = 11 M-circle dot) and G43.888-0.787 (T-d = 50 K; M = 15 M-circle dot).
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| 2. |
- Toledano-Juárez, Iván, et al.
(författare)
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Collision of molecular outflows in the L1448-C system
- 2023
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Ingår i: Monthly Notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 522:1, s. 1591-1600
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Tidskriftsartikel (refereegranskat)abstract
- We present a study of the central zone of the star-forming region L1448 at 217-230 GHz (∼1.3 mm) using Atacama Large Millimeter Array observations. Our study focuses on the detection of proto-stellar molecular outflows and the interaction with the surrounding medium towards sources L1448-C(N) and L1448-C(S). Both sources exhibit continuum emission, with L1448-C(N) being the brightest one. Based on its spectral index and the associated bipolar outflow, the continuum emission is the most likely to be associated with a circumstellar disk. The 12CO(J = 2→1) and SiO(J = 5→4) emissions associated with L1448-C(N) trace a bipolar outflow and a jet oriented along the northwest-southeast direction. The 12CO(J = 2→1) outflow for L1448-C(N) has a wide-open angle and a V-shape morphology. The SiO jet is highly collimated and has an axial extent comparable with the 12CO(J = 2→1) emission. There is not SiO(J = 5→4) emission towards L1448-C(S), but there is 12CO(J = 2→1) emission. The observations revealed that the red-shifted lobes of the 12CO(J = 2→1) outflows of L1448-C(N) and L1448-C(S) are colliding. As a result of this interaction, the L1448-C(S) lobe seems to be truncated. The collision of the molecular outflows is also hinted by the SiO(J = 5→4) emission, where the velocity dispersion increases significantly in the interaction zone. We also investigated whether it could be possible that this collision triggers the formation of new stars in the L1448-C system.
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