Related papers: Diffuse X-ray Emission from Planetary Nebulae with…
Chandra X-ray Observatory (CXO) images have revealed that the X-ray emitting regions of the molecule-rich young planetary nebulae (PNs) BD+30 3639 (BD+30) and NGC 7027 are much more asymmetric than their optical nebulosities. To evaluate…
Galaxies with intense star formation often host multiphase, galaxy-scale winds powered by supernovae and fast stellar winds. These are strong enough to disrupt the star-forming interstellar medium, and they chemically enrich the surrounding…
Chu et al (2001; ApJ, 533, L69) report that they find the diffuse X-ray emission from the Cat's Eye Nebula, NGC 6543, to be inconsistent with nebular abundances but consistent with abundances expected for the stellar wind although the…
We present observations of planetary nebulae with the LOw Frequency ARray (LOFAR) between 120 and 168 MHz. The images show thermal free-free emission from the nebular shells. We have determined the electron temperatures for spatially…
Direct imagery and long-slit, spatially resolved echellograms of the high excitation planetary nebula NGC 1501 allowed us to study in detail the expansion velocity field, the physical conditions (electron temperature, electron density,…
We present a catalogue of 17 filamentary X-ray features located within a 68\times34 arcmin^2 view centred on the Galactic Centre region from images taken by Chandra. These features are described by their morphological and spectral…
X-ray emission from cool stars is an important tracer for stellar activity. The X-ray luminosity reflects different levels of activity and covers four orders of magnitude in stars of spectral types M-F. Low spectral resolution provided by…
We present the analysis of XMM-Newton archival observations towards the Wolf-Rayet (WR) bubble around WR16. Despite the closed bubble morphology of this WR nebula, the XMM-Newton observations show no evidence of diffuse emission in its…
We report the IR properties of planetary nebulae with WR type and $wels$ central stars known to date and compare them with the IR properties of a sample of PNe with H-rich central stars. We use near-, mid- and far-IR photometric data from…
Supermassive black holes in galaxies spend majority of their lifetime in the low-luminosity regime, powered by hot accretion flow. Strong winds launched from the hot accretion flow have the potential to play an important role in active…
The study presents a detailed spectroscopic analysis of the planetary nebulae (PNe) NGC~2392 and NGC~4361 using optical spectra obtained from the 2-m Himalayan Chandra Telescope (HCT) and mid-infrared spectra from archival \textit{Spitzer}…
We present a systematic study of line widths in the [\ion{O}{3}]$\lambda$5007 and H$\alpha$ lines for a sample of 86 planetary nebulae in the Milky Way bulge based upon spectroscopy obtained at the \facility{Observatorio Astron\'omico…
The Bubble Nebula (or NGC 7635) is a parsec-scale seemingly spherical wind-blown bubble around the relatively unevolved O star BD+60$^\circ$2522. The small dynamical age of the nebula and significant space velocity of the star suggest that…
The X-ray emission properties from the hot thermalized plasma that results from the collisions of individual stellar winds and supernovae ejecta within rich and compact star clusters are discussed. We propose a simple analytical way of…
The optical [N I] doublet near 5200 {\AA} is anomalously strong in a variety of emission-line objects. We compute a detailed photoionization model and use it to show that pumping by far-ultraviolet (FUV) stellar radiation previously posited…
We present the first high-spatial-resolution X-ray images of two high-mass star forming regions, the Omega Nebula (M 17) and the Rosette Nebula (NGC 2237--2246), obtained with the Chandra X-ray Observatory Advanced CCD Imaging Spectrometer…
We present high spatial resolution ($\approx$ 60--90 milliarcseconds) images of the molecular hydrogen emission in the Planetary Nebula (PN) NGC 2346. The data were acquired during the System Verification of the Gemini Multi-Conjugate…
(Abridged) The abundance discrepancy problem in planetary nebulae (PNe) has long puzzled astronomers. NGC6153, with its high Abundance Discrepancy Factor (ADF~10), provides an opportunity to understand the chemical structure and ionisation…
This paper reports the first study of the O VI resonance line emission (1032, 1038 Angstroms) originating in the Local Bubble (or Local Hot Bubble) surrounding the solar neighborhood. In spite of the fact that O VI absorption within the…
We present the XMM-Newton discovery of X-ray emission from the planetary nebula (PN) A78, the second born-again PN detected in X-rays apart from A30. These two PNe share similar spectral and morphological characteristics: They harbor…