相关论文: Resonant temperature fluctuations in nebulae ioniz…
Diffuse X-ray emission has been detected in a small number of planetary nebulae (PNe), indicating the existence of shocked fast stellar winds and providing support for the interacting-stellar-winds formation scenario of PNe. However, the…
We have analysed optical spectra of two of the hydrogen-deficient knots (J1 & J3) in the born-again planetary nebula Abell 30, together with UV spectra of knots J3 & J4. We determine electron temperatures in the knots based on several…
We study the flight time fluctuations of a probe light propagating in a slab of nonlinear optical material with an effective fluctuating refractive index caused by thermal fluctuations of background photons at a temperature $T$, which are…
It appears inevitable that reionization processes would have produced large-scale temperature fluctuations in the intergalactic medium. Using toy temperature models and detailed heating histories from cosmological simulations of HeII…
We present results from integral field spectroscopy with the Potsdam multi-Aperture Spectrograph of the head of the Herbig-Haro object HH 202 with a spatial sampling of 1"x1". We have obtained maps of different emission lines, physical…
We consider an instability of rapidly rotating neutron stars in low-mass X-ray binaries (LMXBs) with respect to excitation of r-modes (which are analogous to Earth's Rossby waves controlled by the Coriolis force). We argue that finite…
Context: In recent years mid- and far infrared spectra of planetary nebulae have been analysed and lead to more accurate abundances. It may be expected that these better abundances lead to a better understanding of the evolution of these…
We performed Herschel/HIFI observations of intermediate-excitation molecular lines in the far-infrared/submillimeter range in a sample of ten protoplanetary nebulae and young planetary nebulae. The high spectral resolution provided by HIFI…
A mayor problem that arises in the computation of stellar atmosphere models is the self consistent determination of the temperature distribution via the constraint of energy conservation. The energy balance includes the gains due to the…
The determination of effective temperatures of very hot central stars (Teff>70000K) by model atmosphere analyses of optical H and He line profiles is afflicted with considerable uncertainty, primarily due to the lack of neutral helium…
Active galactic nuclei (AGN) have been observed to vary stochastically with 10-20 rms amplitudes over a range of optical wavelengths where the emission arises in an accretion disk. Since the accretion disk is unlikely to vary coherently,…
We formulate a general theory of thermal fluctuations within causal second-order viscous hydrodynamic evolution of matter formed in relativistic heavy-ion collisions. The fluctuation is treated perturbatively on top of a boost-invariant…
We study the conditions under which thermal fluctuations generated in the contracting phase of a non-singular bouncing cosmology can lead to a scale-invariant spectrum of cosmological fluctuations at late times in the expanding phase. We…
There is evidence for temperature fluctuations in Planetary Nebulae and in Galactic HII regions. If such fluctuations occur in the low-metallicity, extragalactic HII regions used to probe the primordial helium abundance, the derived 4He…
We study the long-time evolution of the ion temperature in an expanding ultracold neutral plasma using spatially resolved, laser-induced-fluorescence spectroscopy. Adiabatic cooling reduces the ion temperature by an order of magnitude…
In a very recent work, [1] claim that the scenario of temperature inhomogeneities proposed by [2] ($t2$ > 0) is not able to explain the O$^{2+}$/H$^{+}$ abundance discrepancy observed between the calculations based on the optical [OIII]…
Turbulence is a predominant process for energizing electrons and ions in collisionless astrophysical plasmas, and thus is responsible for shaping their radiative signatures (luminosity, spectra, and variability). To better understand the…
We present a survey for extended 2.2 $\mu$m emission in 20 new visual reflection nebulae, illuminated by stars with temperatures of 3,600 --- 33,000 K. We detect extended 2.2 $\mu$m emission in 13 new nebulae, illuminated by stars with…
We have monitored over a ten-year interval the light variations of five evolved stars with very large mid-infrared excesses. All five objects appear to have oxygen-rich or mixed oxygen-rich and carbon-rich chemistries. They all vary in…
The spectra of the planetary nebula M1-42 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 ISO, IUE and…