Related papers: The Circumstellar Matter Around OH44.8-2.3
High spatial and sensitivity images of the Luminous Blue Variable IRAS 18576+0341 were obtained using the mid infrared imager VISIR at the Very Large Telescope and the Very Large Array interferometer. The resulting mid-infrared continuum…
The evolution of asymptotic giant branch stars from the spherical symmetry into the diverse shapes of planetary nebulae (PNe) is a topic of intensive research. Young PNe provide a unique opportunity to characterize the onset of this…
Although the Orion Nebula Cluster is one of the most studied clusters in the solar neighborhood, the evolution of the very low-mass members ($M_* < 0.25 \, M_\odot$) has not been fully addressed due to their faintness. Our goal is to verify…
We present the first detailed study of the bipolar planetary nebula (PN) IPHASX J191104.8$+$060845 (PN G040.6$-$01.5) discovered as part of the Isaac Newton Telescope Photometric H$\alpha$ Survey of the Northern Galactic plane (IPHAS). We…
This paper presents a homogeneous study of abundances in a sample of 79 northern galactic planetary nebulae whose morphological classes have been uniformly determined. Ionic abundances and plasma diagnostics were derived from selected…
The nature of the extended hard X-ray source XMMU J061804.3+222732 and its surroundings is investigated using XMM-Newton, Chandra, and Spitzer observations. This source is located in an interaction region of the IC 443 supernova remnant…
The European gamma-ray observatory INTEGRAL has found a group of hard X-ray sources which are highly absorbed, i.e., with column densities higher than about 10^{23}/cm^2. Here I give an overview of this class of INTEGRAL sources. The X-ray,…
We present high-dispersion spectroscopic data of the compact planetary nebula Vy 1-2, where high expansion velocities up to 100 km/s are found in the Ha, [N II] and [O III] emission lines. HST images reveal a bipolar structure. Vy 1-2…
In this work we report spectrophotometric observations of a planetary nebula sample towards the galactic bulge. A total of 45 PNe was observed and their physical parameters (electron density and temperature) were derived. Ionic abundances…
We present full resolution (~0.2mas, ~0.1 A.U.) Very Long Baseline Interferometry maps of the v=1, J=1-0 SiO masers in the Orion-KL nebula. The morphology and turbulent nature of the maser emission argues against models in which the masers…
We use a 3D Monte Carlo radiative transfer code to study the projection of large shadows by circumstellar disks around young stellar objects on surrounding reflection nebulosity. It is shown that for a wide range of parameters a small…
We used Herschel Hi-GAL survey data to determine whether massive young stellar objects (MYSOs) are resolved at 70$\mu$m and to study their envelope density distribution. Our analysis of three relatively isolated sources in the l=30{\deg}…
We report a result of an interferometric observation toward an SiO maser source, IRAS 19312+1950, in the HCO+ J=1-0 line with the Berkeley-Illinois-Maryland-Association (BIMA) Millimeter Array. In the spatially integrated spectrum of HCO+,…
Context. Many protoplanetary nebulae show strong asymmetries in their surrounding shell, pointing to asymmetries during the mass loss phase. Questions concerning the origin and the onset of deviations from spherical symmetry are important…
We present new, NTT longslit spectroscopy of the B[e] supergiant in the binary system R4 in the Small Magellanic Cloud. The data show extended, forbidden N and S emissions which are typical signatures of circumstellar matter. Their…
We present new observations of IRAS 04000+5052, a Galactic HII region associated with a young stellar cluster and possibly located at the Perseus arm. Contrary to previous claims, we have found that this object is not a compact metal-poor…
The three dimensional structure of the brightest part of the Orion Nebula is assessed in the light of published and new data. We find that the widely accepted model of a concave blister of ionized material needs to be altered in the…
The OH Megamaser emission in the merging galaxy Arp220 has been re-observed with the Multi-Element Radio Linked Interferometer Network (MERLIN) and the European VLBI Network (EVN). Imaging results of the OH line emission at the two nuclei…
We derive the stellar and circumstellar parameters of the Galactic compact planetary nebula Hen 2-90 with two models: the classical constant density nebula model where the emission (especially of the forbiden lines) is formed in a sphere or…
We present a survey of OH maser emission towards a sample of high mass protostellar objects made using the Nancay and GBT telescopes.OH maser emission was detected towards 63 objects with 36 new detections. There are 56 star-forming regions…