Related papers: Massive molecular outflows associated with UCHII/H…
Among the tracers of the earliest phases in the massive star formation process, methanol masers have gained increasing importance. The phenomenological distinction between Class I and II methanol masers is based on their spatial association…
The hydroxyl radical (OH) is found in various environments within the interstellar medium (ISM) of the Milky Way and external galaxies, mostly either in diffuse interstellar clouds or in the warm, dense environments of newly formed low-mass…
We present [Fe II] 1.644 um features around ultracompact H II regions (UCHIIs) found on a quest for the "footprint" outflow features of UCHIIs---the feature produced by the outflowing materials ejected during the earlier, active accretion…
We present Submillimeter Array (SMA) observations in the CO J=3-2, SiO J=5-4 and 8-7, and SO 9_8-8_7 lines, as well as Atacama Pathfinder EXperiment (APEX) observations in the CO J=6-5 line, of an extremely high-velocity and jet-like…
We present deep observations of the 12CO(1-0) and (3-2) lines in the ultra-luminous infrared and radio galaxy 4C12.50, carried out with the 30m telescope of the Institut de Radioastronomie Millimetrique. Our observations reveal the cold…
We report the discovery of nearly a dozen collimated outflows from young stellar objects embedded in the molecular filament that extends north of the Orion Nebula towards the H II region NGC 1977. The large number of nearly co-eval outflows…
Methanol masers and molecular shock tracers were observed in the W3(OH)/W3(H$_2$O) region with the BIMA array and the Onsala 20m radiotelescope. Characteristics of the outflows in the region are discussed. A model of the W3(OH) methanol…
Studies of molecular outflows in high-mass young stellar objects reveal important information about the formation process of massive stars. We therefore selected the close-by IRAS 17233-3606 massive star-forming region to perform SiO…
We report a multi-epoch, simultaneous 22 GHz H2O and 44 GHz class I CH3OH maser line survey towards 180 intermediate-mass young stellar objects, including 14 Class 0, 19 Class I objects, and 147 Herbig Ae/Be stars. We detected H2O and CH3OH…
Massive stars form deeply embedded in dense molecular gas, which they stir and heat up and ionize. During an early phase, the ionization is confined to hypercompact HII regions, and the stellar radiation is entirely absorbed by dust, giving…
We present a survey in the 6_{16}-5_{23} rotational water transition toward 33 galactic ultracompact HII regions. Maser emission is detected toward 18 of these sources; two are new detections. High quality spectra are provided for all 18…
Methanol masers are often found in linear distributions, and it has been hypothesized that these masers are tracing circumstellar accretion disks around young massive stars. However, recent observations in H2 emission have shown what appear…
In this paper we present Combined Array for Research in Millimeter-wave Astronomy (CARMA) 3.5 mm observations and SubMillimeter Array (SMA) 870 microns observations toward the high-mass star-forming region IRAS 1816-2048, the core of the HH…
Large scale spectral maps of star forming regions enable the comparative study of the gas excitation around an ensemble of sources at a common frame of reference, providing direct insights in the multitude of processes involved. In this…
High mass stars form in groups or clusters within massive cores in dense molecular clumps with sizes of 1pc and masses of 200Msun which are important laboratories for high-mass star formation in order to study the initial conditions. We…
We have undertaken the largest survey for outflows within the Galactic Plane using simultaneously observed 13CO and C18O data. 325 out of a total of 919 ATLASGAL clumps have data suitable to identify outflows, and 225 (69+-3%) of them show…
Hypercompact (HC) HII regions are, by nature, very young HII regions, associated with the earliest stages of massive star formation. They may represent the transition phase as an early B-type star grows into an O-type star. Unfortunately,…
We have searched for water vapor emission at 183 GHz, redshifted at 157 GHz and 161 GHz, in the two ultraluminous starburst galaxies Mrk1014 and VIIZw244. Due to the low energy level of the upper state of the 183 GHz transition (\approx…
We present the hot molecular and warm ionised gas kinematics for 33 nearby ($0.001\lesssim z\lesssim0.056$) X-ray selected active galaxies using the H$_2 2.1218 \mu$m and Br$\gamma$ emission lines observed in the K-band with the Gemini…
The results of a survey searching for outflows using near-infrared imaging is presented. Targets were chosen from a compiled list of massive young stellar objects (YSOs) associated with methanol masers in linear distributions. Presently, it…