相关论文: Dual Cometary HII Regions in DR21: Bow Shocks or C…

We present deep Very Large Array H66$\alpha$ radio recombination line (RRL) observations of the two cometary HII regions in DR 21. With these sensitive data, we test the "hybrid" bow shock/champagne flow model previously proposed for the DR…

We have developed a full numerical method to study the gas dynamics of cometary ultra-compact (UC) H II regions, and associated photodissociation regions (PDRs). The bow-shock and champagne-flow models with a $40.9/21.9 M_\odot$ star are…

We present numerical radiation-hydrodynamic simulations of cometary HII regions for a number of champagne flow and bowshock models. For the champagne flow models we study smooth density distributions with both steep and shallow gradients.…

We have mapped the velocity structure of the cometary compact HII region G29.96-0.02 using long-slit echelle spectra of the HI Br gamma line. This technique detects line emission over a much wider area at the necessary spatial resolution…

We have modelled the evolution of cometary HII regions produced by zero-age main-sequence stars of O and B spectral types, which are driving strong winds and are born off-centre from spherically symmetric cores with power-law ($\alpha = 2$)…

We present a new observation of the compact HII region, G29.96-0.02, that allows us to compare the velocity structure in the ionised gas and surrounding molecular gas directly. This allows us to remove most of the remaining ambiguity about…

Many ultracompact HII regions exhibit a cometary morphology in radio continuum emission. In such regions, a young massive star is probably ablating, through its ultraviolet radiation, the molecular cloud clump that spawned it. On one side…

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…

High-mass stars form in much richer environments than those associated with isolated low-mass stars, and once they reach a certain mass, produce ionised (HII) regions. The formation of these pockets of ionised gas are unique to the…

We report the results obtained from a multi-wavelength study of the HII region, G18.148$-$0.283, using the upgraded Giant Metre-wave Radio Telescope (uGMRT) at 1350 MHz along with other archival data. In addition to the radio continuum…

We probe the structure and kinematics of two neighbouring H II regions identified as cometary and bipolar, using radio recombination lines (RRL). The H172{\alpha} RRLs from these H II regions: G351.6-1.15 and G351.6-1.25, are mapped using…

A group of four compact HII regions associated with the well-known 50 km/s molecular cloud is the closest site of on-going star formation to the dynamical center of the Galaxy, at a projected distance of ~6 pc. We present a study of ionized…

Previous observations show that the hypercompact HII region W51e2 is surrounded by a massive molecular accretion flow centered on the HII region. New observations of the H53alpha radio recombination line made with the VLA at 0.45 arc second…

High spectral and spatial resolution, mid-infrared fine structure line observations toward two ultracompact HII (UCHII) regions (G29.96 -0.02 and Mon R2) allow us to study the structure and kinematics of cometary UCHII regions. In our…

Cometary ultracompact HII regions have been modelled as the interaction of the hypersonic wind from a moving star with the molecular cloud which surrounds the star. We here show that a similar morphology can ensue even if the star is…

We present high angular and spectral resolution HI 21~cm line observations toward the cometary-shaped compact HII region G213.880-11.837 in the GGD~14 complex.The kinematics and morphology of the photodissociated region, traced by the HI…

We have carried out 21 cm radio continuum, H76_\alpha radio recombination line, and various (CO, ^13CO, CS, & C^34S) molecular line observations of the W31 complex. Our radio continuum data show that W31 is composed of two extended HII…

The molecular gas in the DR21 massive star formation region is known to be affected by the strong UV field from the central star cluster and by a fast outflow creating a bright shock. The relative contribution of both heating mechanisms is…

Ultracompact HII regions are signposts of massive star formation and their properties provide diagnostics for the characteristics of very young O stars embedded in molecular clouds. While radio observations have given us a good picture of…

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…