相关论文: Radiation Transfer in the Cavity and Shell of Plan…

We present high sensitivity H91$\alpha$ and 3.5 cm radio continuum observations toward the planetary nebula NGC 3242. The electron temperature determined assuming local thermodynamic equilibrium is consistent within $\sim$10% with that…

To understand the mechanism behind high-$z$ Ly${\alpha}$ nebulae, we simulate the scattering of Ly${\alpha}$ in a $\rm H\,I$ halo about a central Ly${\alpha}$ source. For the first time, we consider both smooth and clumpy distributions of…

We have developed a new model that uses a cellular approach to calculate radiative transfer of starlight through dusty media. The model is designed to be user friendly enough to be distributed as a tool for use by the general astronomical…

The atmospheres of planets (including Earth) and the outer layers of stars have often been treated in radiative transfer as plane-parallel media, instead of spherical shells, which can lead to inaccuracy, e.g. limb darkening. We give an…

We present results from a program of optical spectroscopy for 23 nearby galaxy emission-line nuclei. This investigation takes advantage of the spatial resolution of the Hubble Space Telescope to study the structure and energetics of the…

Two methods are developed for solving the steady-state spherically symmetric radiative transfer equation for resonance line radiation emitted by a point source in the Intergalactic Medium. One method is based on solving the ray and moment…

Optical/UV photons and even harder radiation components in galaxies are absorbed and scattered by dust and re-emitted at infrared wavelengths. For a better understanding of the obscured regions of the galaxies detailed models of the…

We present Monte Carlo simulations of the Diffuse H$\alpha$ Galactic Background. Our models comprise direct and multiply scattered H$\alpha$ radiation from the kpc scaleheight Warm Ionized Medium and midplane H II regions. The scattering is…

Using three dimensional Monte Carlo radiation transfer models of photoionisation and dust scattering, we explore different components of the widespread diffuse H$\alpha$ emission observed in the interstellar medium of the Milky Way and…

We present a new model for computing consistently the line and continuum emission from galaxies, based on a combination of recent population synthesis and photoionization codes. We use effective parameters to describe the HII regions and…

We present the results of several collisional-radiative models describing optically-thin emissivities of the main lines in neutral helium formed by recombination, for a grid of electron temperatures and densities, typical of H II regions…

We present the high resolution spectra of the youn and compact planerary nebula NGC 6790 obtained with the echelle spectrograph at Bohyunsan Optical Astronomy Observatory and report the discovery of Raman scattered He II 6545 in this…

We study the standard spectral line radiative transfer equation for media consisting of resonant atoms and non-resonant components (the dust grains and the atoms without considered spectral transition). Our goal is to study the intensity…

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…

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 nebular evolution is followed from the vicinity of the asymptotic-giant branch across the Hertzsprung-Russell diagram until the white-dwarf domain is reached, using various central-star models coupled to different initial envelope…

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…

We present images and slitless spectra which were obtained in HST surveys of Planetary Nebulae (PNe) in both the Large and Small Magellanic Clouds, using the Space Telescope Imaging Spectrograph. These new data on 59 PNe (54 in the LMC and…

The dust shell around the evolved star HD 179821 has been detected in scattered light in near-IR imaging polarimetry observations. Here, we subtract the contribution of the unpolarized stellar light to obtain an intrinsic linear…

Planetary nebulae (PNe) are expected to have a ~10$^{5}$ K interface layer between the $\geq$10$^{6}$ K inner hot bubble and the ~10$^{4}$ K optical nebular shell. The PN structure and evolution, and the X-ray emission depend critically on…