Related papers: Nebular vs. Stellar Wind Abundances in NGC 6543

We have searched the entire ROSAT archive for useful observations to study X-ray emission from Galactic planetary nebulae (PNs). The search yields a sample of 63 PNs, which we call the ROSAT PN sample. About 20-25% of this sample show X-ray…

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,…

The relatively nearby (distance=24.1 Mpc) elliptical galaxy NGC821, hosting a central massive black hole but inactive at all wavelengths, was observed with Chandra for a total exposure of 230 ksec, to search for nuclear emission and gas…

We present a Chandra ACIS-S observation of the nearby bulge-dominated Sa galaxy NGC1291. The X-ray emission from the bulge resembles the X-ray emission from a sub-class of elliptical and S0 galaxies with low L_X/L_B luminosity ratios. The…

We present preliminary results from a systematic spectral study of pulsars and their wind nebulae using the Chandra X-Ray Observatory. The superb spatial resolution of Chandra allows us to differentiate the compact object's spectrum from…

We present new XMM-Newton observation of the Ultra Luminous Infrared Galaxy (ULIRG) NGC 6240. We analyze the reflecting grating spectrometer (RGS) data, and data from the other instruments, and find a starburst dominated 0.5-3 keV spectrum…

Our 5 ks Chandra ACIS-S observation of the globular cluster NGC 6652 detected 7 X-ray sources, 3 of which are previously unidentified. This cluster hosts a well-known bright low-mass X-ray binary, source A (or XB 1832-330). Source B shows…

We present an X-ray and radio study of the wind nebula surrounding the central pulsar PSR J1811-1925 in the supernova remnant G11.2-0.3. Using high resolution data obtained with the Chandra X-ray observatory and with the VLA radio telescope…

We present a study of the X-ray emission from numerical simulations of hot bubbles in planetary nebulae (PNe). High-resolution, two-dimensional, radiation-hydrodynamical simulations of the formation and evolution of hot bubbles in PNe, with…

We present new identifications of infrared counterparts to the population of hard X-ray sources near the Galactic center detected by the Chandra X-ray Observatory. We have confirmed 16 new massive stellar counterparts to the X-ray…

In this contribution, we present the results of a study on the high abundance discrepancy factor (ADF $\sim$ 10) planetary nebula (PN) NGC 6153 with MUSE. We have constructed flux maps for dozens of emission lines, that allowed us to build…

We report results of XMM-Newton observations of a $\gamma$-ray pulsar J0633+0632 and its wind nebula. We reveal, for the first time, pulsations of the pulsar X-ray emission with a single sinusoidal pulse-profile and a pulsed fraction of $23…

We report on a recent ~150-ks long Chandra observation of the ultraluminous infrared galaxy merger NGC 6240, which allows a detailed investigation of the diffuse galactic halo. Extended soft X-ray emission is detected at the 3-sigma…

We investigate the possibility of obscuring supersoft X-ray sources in the winds of companion stars. We derive limits on the amount of circumstellar material needed to fully obscure a 'canonical' supersoft X-ray source in the Large…

We present new optical spectra of the nearby, bright, planetary nebula NGC 6778. The nebula has been known to emit strong recombination lines for more than 40 years but this is the first detailed study of its abundances. Heavy element…

We present new narrow-band filter imagery in H-alpha and [N II] 6584 along with UV and optical spectrophotometry measurements from 1200 to 9600 Angstroms of NGC 7293, the Helix Nebula, a nearby, photogenic planetary nebula of large diameter…

If ultraluminous X-ray sources (ULXs) are powered by accretion onto stellar remnant black holes, then many must be accreting at super-Eddington rates. It is predicted that such high accretion rates should give rise to massive,…

We present a detailed case study of the diffuse X-ray and H-alpha emission in the halo of NGC 253, a nearby edge-on starburst galaxy driving a galactic superwind. The arcsecond spatial resolution of the Chandra ACIS instrument allows us to…

We present analysis of a second observation of the young planetary nebula (PN) NGC 7027 by the Chandra X-ray Observatory. This latest 59.2 ks exposure with ACIS-S was acquired approximately 14 years after the initial 18.2 ks ACIS-S…

We observed the globular cluster NGC 6652 with Chandra for 47.5 ks, detecting six known X-ray sources, as well as five previously undetected X-ray sources. Source A (XB 1832-330) is a well-known bright low-mass X-ray binary (LXMB). The…