相关论文: The Ionization State of the Halo Planetary Nebula …

In recent times an increasing number of extended haloes and multiple shells around planetary nebulae have been discovered. These faint extensions to the main nebula trace the mass-loss history of the star, modified by the subsequent…

Many round or nearly roundish Planetary Nebulae (PNe) show multiple shells and halo structures during their evolutionary stage near the maximum temperature of their central star. Controversial debate is currently ongoing if these structures…

We investigate the electron temperature of the inner halo and nebular core regions of NGC 6543, using archival Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) images taken through narrow band [O III] filters. Balick et…

We report on our studies of the physical structure of the planetary nebula (PN) NGC7662. Using (3D) Integral Field Spectroscopy we have been able to measure the electron temperature more accurately and at a larger number of radial locations…

Optical integral-field spectroscopy was used to investigate the planetary nebula NGC 3242. We analysed the main morphological components of this source, including its knots, but not the halo. In addition to revealing the properties ofthe…

The spectra of the planetary nebula NGC2392 is reanalysed using spectral measurements made in the mid-infrared with the Spitzer Space Telescope. The aim is to determine the chemical composition of this object. We also make use of IUE and…

We present the first integral field spectroscopy observations of the two planetary nebulae NGC3242 and NGC4361 with the VIMOS instrument attached to VLT-UT3. By co-adding a large number of spaxels we reach an emission line detection limit…

We present imaging and spectroscopy of NGC 40 acquired using the Spitzer Space Telescope (Spitzer), and the Infrared Space observatory (ISO). These are used to investigate the nature of emission from the central nebular shell, from the…

We present a spectroscopic investigation of 25 objects previously reported as possible Planetary Nebulae (PNe) in recent catalogs to obtain their physical properties and to establish their true nature. We found 11 objects showing intense…

We present intermediate resolution long-slit spectra and narrow-band Halpha, [NII] and [OIII] images of PM1-242, PM318 and PM1-333, three IRAS sources classified as possible planetary nebulae. The spectra show that the three objects are…

Planetary nebulae (and in general any photoionized region) can be classified as ionization-bounded or density-bounded. It is important to determine in which case is the planetary nebula studied to be able to estimate from nebular…

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…

We have obtained medium-resolution, deep optical long-slit spectra of the bulge planetary nebula (PN) M 2-24. The spectrum covers the wavelength range from 3610--7330 A. Over two hundred emission lines have been detected. The spectra show a…

We examine 11 XMM-Newton observations of the giant spiral galaxy NGC 1961, allowing us to study the hot gaseous halo of a spiral galaxy in unprecedented detail. We perform a spatial and a spectral analysis; with the former, the hot halo is…

One key feature of the interacting stellar winds model of the formation of planetary nebulae (PNe) is the presence of shock-heated stellar wind confined in the central cavities of PNe. This so-called hot bubble should be detectable in…

Using spectroscopic data presented in Magrini et al. (2003), we have analyzed with the photoionization code CLOUDY 94.00 (Ferland et al. 1998) 11 Planetary Nebulae belonging to the spiral galaxy M 33. Central star temperatures and nebular…

This project sought to consider two important aspects of the planetary nebula NGC 3242 using new long-slit HST/STIS spectra. First, we investigated whether this object is chemically homogeneous by dividing the slit into different regions…

We present an observational study of the planetary nebula (PN) NGC 7354 consisting of narrowband Halpha and [NII]6584 imaging as well as low- and high-dispersion long-slit spectroscopy and VLA-D radio continuum. According to our imaging and…

After becoming ionized, low-density astrophysical plasmas will begin a process of slow recombination. Models for this still have significant uncertainties. The recombination cannot normally be observed in isolation, because the ionization…

Very recently, the discovery of the largest known planetary nebula on the sky surrounding the DO white dwarf PG1034+001 with an apparent diameter of about 2 degrees, corresponding to a linear diameter of 3.5 - 7.0 pc at the likely distance…