8 research outputs found
Collision of molecular outflows in the L1448--C system
We present a study of the central zone of the star-forming region L1448 at
217--230 GHz ( 1.3 mm) using ALMA observations. Our study focuses on the
detection of proto-stellar molecular outflows and the interaction with the
surrounding medium toward 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 CO(J=21) and SiO(J= 54) emissions associated with
L1448--C(N) trace a bipolar outflow and a jet oriented along the
northwest-southeast direction. The CO(J=21) 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 CO(J=21) emission. There is not SiO(J= 54)
emission towards L1448--C(S), but there is CO(J=21)
emission. The observations revealed that the red-shifted lobes of the CO(J=21) 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=
54) 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.Comment: 11 pages, 7 figures, Accepted for publication in Monthly Notices of
the Royal Astronomical Society (MNRAS) DOI: 10.1093/mnras/stad98
Ultracompact HII regions with extended emission: The case of G43.89-0.78 and its molecular environment
The Karl Jansky Very Large Array (VLA), Owens Valley Radio Observatory
(OVRO), Atacama Large Millimetric Array (ALMA), and the infrared
\textit{Spitzer} observatories, are powerful facilities to study massive star
formation regions and related objects such as ultra--compact (UC) \hii regions,
molecular clumps, and cores. We used these telescopes to study the \uchiir
G43.89--0.78. The morphological study at arcminute scales using NVSS and
\textit{Spitzer} data shows that this region is similar to those observed in
the \textit{ bubble--like} structures revealed by \textit{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 \uchiir 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 \uchii region. Using ALMA observations, we detect the
presence of a dense ( cm) and small ( 2.0\arcsec;
0.08 pc) molecular clump with a mass of 220 M and average kinetic
temperature of 21~K, located near to the \uchii 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 = 50 K; M = 11 M), and G43.888--0.787
(T = 50 K; M = 15 M).Comment: 13 pages, 8 figures, 2 tables. Accepted for publication in the
Monthly Notices of the Royal Astronomical Society Main Journal (2020
Cosmic Ray Astrophysics using The High Altitude Water Cherenkov (HAWC) Observatory in MĂ©xico
Cosmic Ray Astrophysics using The High Altitude Water Cherenkov (HAWC) Observatory in MĂ©xico
The High-Altitude Water Cherenkov (HAWC) TeV gammaâray Observatory in MĂ©xico is ready to search and study gamma-ray emission regions, extremely high-energy cosmic-ray sources, and to identify transient phenomena. With a better Gamma/Hadron rejection method than other similar experiments, it will play a key role in triggering multiâwavelength and multiâmessenger studies of active galaxies (AGN), gamma-ray bursts (GRB), supernova remnants (SNR), pulsar wind nebulae (PWN), Galactic Plane Sources, and Cosmic Ray Anisotropies. It has an instantaneous field-of-view of âŒ2 str, equivalent to 15% of the whole sky and continuous operation (24 hours per day). The results obtained by HAWCâ111 (111 detectors in operation) were presented on the proceedings of the International Cosmic Ray Conference 2015 and in [1]. The results obtained by HAWCâ300 (full operation) are now under analysis and will be published in forthcoming papers starting in 2017 (see preliminary results on http://www.hawc-observatory.org/news/). Here we present the HAWC contributions on cosmic ray astrophysics via anisotropies studies, summarizing the HAWC detector and its upgrading by the installation of âoutriggersâ
Cosmic Ray Astrophysics using The High Altitude Water Cherenkov (HAWC) Observatory in MĂ©xico
The High-Altitude Water Cherenkov (HAWC) TeV gammaâray Observatory in MĂ©xico is ready to search and study gamma-ray emission regions, extremely high-energy cosmic-ray sources, and to identify transient phenomena. With a better Gamma/Hadron rejection method than other similar experiments, it will play a key role in triggering multiâwavelength and multiâmessenger studies of active galaxies (AGN), gamma-ray bursts (GRB), supernova remnants (SNR), pulsar wind nebulae (PWN), Galactic Plane Sources, and Cosmic Ray Anisotropies. It has an instantaneous field-of-view of âŒ2 str, equivalent to 15% of the whole sky and continuous operation (24 hours per day). The results obtained by HAWCâ111 (111 detectors in operation) were presented on the proceedings of the International Cosmic Ray Conference 2015 and in [1]. The results obtained by HAWCâ300 (full operation) are now under analysis and will be published in forthcoming papers starting in 2017 (see preliminary results on http://www.hawc-observatory.org/news