Related papers: Broad Recombination Line Objects in W49N on 600 AU…
We have observed seven ultracompact HII regions in hydrogen recombination lines in the millimeter band. Toward four of these regions, there is a high velocity (full width to half maximum 60-80 km/s) component in the line profiles. The high…
We present a detailed characterization of the population of compact radio-continuum sources in W51 A using subarcsecond VLA and ALMA observations. We analyzed their 2-cm continuum, the recombination lines (RL's) H77$\alpha$ and H30$\alpha$,…
We present new Jansky Very Large Array (VLA) images of the central region of the W49A star-forming region at 3.6~cm and at 7~mm at resolutions of 0\farcs15 (1650 au) and 0\farcs04 (440 au), respectively. The 3.6~cm data reveal new…
HII regions are the ionized spheres surrounding high-mass stars. They are ideal targets for tracing Galactic structure because they are predominantly found in spiral arms and have high luminosities at infrared and radio wavelengths. In the…
We observed radio recombination lines (RRLs) toward the W51 molecular cloud complex, one of the most active star forming regions in our Galaxy. The UV radiation from young massive stars ionizes gas surrounding them to produce HII regions.…
We have carried out 21 cm radio continuum observations of 16 UC HII regions using the VLA (D-array) in search of associated extended emission. We have also observed H76$_\alpha$ recombination line towards all the sources and He76$_\alpha$…
We report radio recombination line (RRL) and continuum observations of a sample of 106 Galactic HII regions made with the NRAO 140 Foot radio telescope in Green Bank, WV. We believe this to be the most sensitive RRL survey ever made for a…
We have imaged the Sgr B2 Main region with the Very Large Array in the BnA configuration ($\theta_{beam}$ = 0\farcs13) in both the H52$\alpha$ (45.453 GHz) radio recombination line (RRL) and 7 mm continuum emission. At a distance of 8500…
We have detected C91$\alpha$ (8.5891 GHz) emission toward 4 ultra-compact \HII regions (\UCHII s; W49G, J, L & C) in the W49 North massive star forming region with the Very Large Array (VLA) at 3\arcsec resolution. No carbon line emission…
We report multifrequency radio continuum and hydrogen radio recombination line observations of HII regions near l=24.8d b=0.1d using the Giant Metrewave Radio Telescope (GMRT) at 1.28 GHz (n=172), 0.61 GHz (n=220) and the Very Large Array…
Hydrogen recombination lines (HRLs) are valuable diagnostics of the physical conditions in ionized regions around high-mass stars. Understanding their broadening mechanisms and intensity trends can provide insights into the densities,…
Sensitive spectral observations made in two frequency bands near 6.0 and 17.6 GHz are described for Orion and W51. Using frequency switching we were able to achieve a dynamic range in excess of 10,000 without fitting sinusoidal or…
We have detected the radio recombination lines H91-alpha and H92-alpha with rest frequencies of 8.6 GHz and 8.3 GHz from the starburst nucleus NGC 3256 at an angular resolution of 16.4" x 9.6" using the Australia Telescope Compact Array and…
Velocity shifts and differential broadening of radio recombination lines are used to estimate the densities and velocities of the ionized gas in several hypercompact and ultracompact HII regions. These small HII regions are thought to be at…
The 229 GHz (lambda 1.3mm) radio emission from Orion-KL was mapped with up to 0.14" angular resolution with CARMA, allowing measurements of the flux densities of Source I ('SrcI') and the Becklin-Neugebauer Object (BN), the 2 most massive…
We present sensitive 7 mm observations of the H53$\alpha$ recombination line and adjacent continuum, made toward the Orion BN/KL region. In the continuum we detect the BN object, the radio source I (GMR I) and the radio counterpart of the…
Problems where impact broadened radio recombination lines appeared narrower than predicted first showed up ~40 years ago at frequencies below ~3 GHz. But it was soon found that the observations could be explained by throwing out the uniform…
We report multi-frequency Very Large Array observations of three massive star formation regions (MSFRs) containing radio continuum components that were identified as broad radio recombination line (RRL) sources and hypercompact (HC) H II…
The study of the interaction between ionized jets, molecular outflows and their environments is critical to understanding high-mass star formation, especially because jets and outflows are thought to be key in the transfer of angular…
We present radio and infrared observations of 4 hyper-compact HII regions and 4 ultra-compact HII regions in the southern Galactic plane. These objects were selected from a blind survey for UCHII regions using data from two new radio…