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Type I planetary nebulae (PNe) are defined as those with high He and N abundances (Peimbert & Torres-Peimbert 1983). These objects present in general bipolar geometries and have high stellar temperatures (Corradi & Schwarz 1995,…

天体物理学 · 物理学 2009-10-30 Ruth Gruenwald , Sueli M. Viegas

High-resolution mid-infrared images have been obtained in N-band and Q-band for the proto-planetary nebula IRAS 16594-4656. A bright equatorial torus and a pair of bipolar lobes can clearly be seen in the infrared images. The torus appears…

天体物理学 · 物理学 2008-11-26 Kevin Volk , Bruce J. Hrivnak , Kate Y. L. Su , Sun Kwok

Extragalactic planetary nebulae (PNe) are detectable through relatively strong nebulous [OIII] emission and act as direct probes into the local stellar population. Because they have an apparently universal invariant magnitude cut-off, PNe…

We present ten years of new photometric monitoring of the light variability of five evolved stars with strong mid-infrared emission from surrounding dust. Three are known carbon-rich proto-planetary nebulae (PPNe) with F$-$G spectral types;…

太阳与恒星天体物理 · 物理学 2020-01-08 Bruce J. Hrivnak , Gary Henson , Todd C. Hillwig , Wenxian Lu , Brian W. Murphy , Ronald H. Kaitchuck

We investigate the sources and amount of dust in early galaxies. We discuss dust nucleation in stellar atmospheres using published extended atmosphere models, stellar evolution tracks and nucleation conditions and conclude that the (TPAGB)…

天体物理学 · 物理学 2009-11-07 H L. Morgan , M G. Edmunds

Supernova may be the dominant channel by which dust grains accumulate in galaxies during the first Gyr of cosmic time as formation channels important for lower redshift galaxies, e.g., AGB stars and grain growth, may not have had sufficient…

We present the results of a detailed modeling aimed to reproduce the spectral energy distribution (SED) of dust and molecular line emission of massive protostars under the hypothesis that they form via an accretion process. We model the…

天体物理学 · 物理学 2007-12-17 Mayra Osorio

Accurate emission line fluxes from planetary nebulae (PNe) provide important constraints on the nature of the final phases of stellar evolution. Large, evolved PNe may trace the latest stages of PN evolution, where material from the AGB…

天体物理学 · 物理学 2009-11-11 G. J. Madsen , D. J. Frew , Q. A. Parker , R. J. Reynolds , L. M. Haffner

Scattering of re-emitted flux is considered to be at least partially responsible for the observed polarisation in the (sub-)millimetre wavelength range of several protoplanetary disks. Although the degree of polarisation produced by…

太阳与恒星天体物理 · 物理学 2020-08-26 Robert Brunngräber , Sebastian Wolf

We present a reanalysis (using the Minnaert limb-darkening approximation) of visible/near-infrared (0.3 - 2.5 micron) observations of Uranus and Neptune made by several instruments. We find a common model of the vertical aerosol…

Can the distribution of warm-dust compositions in IR-bright galactic disk PNe be linked to the underlying stellar population? The PNe with warm dust emission represent a homogeneous population, which is presumably young and minimally…

天体物理学 · 物理学 2009-10-31 S. Casassus , P. F. Roche

It has been more than 30 years since the enigmatic 21 {\mu}m emission feature was first discovered in protoplanetary nebulae (PPNs). Although dozens of different dust carrier candidates have been proposed, there is as yet no widely accepted…

I study some effects of aspherical mass loss during the last stages of the asymptotic giant branch (AGB) on the appearance of proto planetary nebulae (PNs) and young PNs. The aspherical mass loss can be small scale inhomogeneities, and/or…

天体物理学 · 物理学 2009-10-31 Noam Soker

The carrier of the 21 ${\mu}$m emission feature discovered in a handful of protoplanetary nebulae (PPNe) is one of the most intriguing enigmas in circumstellar chemistry. Investigating the gas-phase molecules in PPNe could yield important…

Recent surveys have revealed that protoplanetary discs typically have dust masses that appear to be insufficient to account for the high occurrence rate of exoplanet systems. We demonstrate that this observed dust depletion is consistent…

地球与行星天体物理 · 物理学 2020-09-30 Johan Appelgren , Michiel Lambrechts , Anders Johansen

Supernova (SN) rates serve as an important probe of star-formation models and initial mass functions. Near-infrared seeing-limited ground-based surveys typically discover a factor of 3-10 fewer SNe than predicted from far-infrared (FIR)…

In the last decade, ground-based Imaging Atmospheric Cherenkov Telescopes have discovered about 175 very-high-energy (VHE; $E >$ 100 GeV) gamma-ray sources, with more to follow with the development of H.E.S.S. II and CTA. Nearly 40 of these…

高能天体物理现象 · 物理学 2018-02-02 Carlo van Rensburg , Christo Venter , Paulus Kruger

I explore models of the dust-scattered component of the Cosmic Ultraviolet Background (CUVB) at the North Galactic Pole (NGP) in order to develop a framework for calculating the dust-scattered light as a function of the optical depths. As…

天体物理仪器与方法 · 物理学 2025-07-08 Jayant Murthy

In spite of making a small contribution to total protoplanetary disk mass, dust affects the disk temperature by controlling absorption of starlight. As grains grow from their initial ISM-like size distribution, settling depletes the disk's…

地球与行星天体物理 · 物理学 2019-03-27 Debanjan Sengupta , Sarah E. Dodson-Robinson , Yasuhiro Hasegawa , Neal J. Turner

Core--collapsed supernovae (CCSNe) have been considered to be one of sources of dust in the universe. What kind and how much mass of dust are formed in the ejecta and are injected into the interstellar medium (ISM) depend on the type of…

星系天体物理 · 物理学 2009-03-05 Takashi Kozasa , Takaya Nozawa , Nozomu Tominaga , Hideyuki Umeda , Keiichi Maeda , Ken'ichi Nomoto