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Full-Text Articles in Physics
Infrared Emission And Dynamics Of Outlfows In Late-Type Stars, Željko Ivezić, Moshe Elitzur
Infrared Emission And Dynamics Of Outlfows In Late-Type Stars, Željko Ivezić, Moshe Elitzur
Physics and Astronomy Faculty Publications
The dynamical structure and infrared emission of winds around late-type stars are studied in a self-consistent model that couples the equations of motion and radiative transfer. Thanks to its scaling properties, both the dynamics and IR spectrum of the solution are fully characterized by τF, the flux-averaged optical depth of the wind. Five types of dust grains are considered: astronomical silicate, crystalline olivine, graphite, amorphous carbon and SiC, as well as mixtures. Analysis of infrared signatures provides constraints on the grain chemical composition and indications for the simultaneous existence of silicate and carbon grains. The abundances of crystalline …
A Protostellar Jet Model For The Water Masers In W49n, Mordecai-Mark Mac Low, Moshe Elitzur, James M. Stone, Arieh Königl
A Protostellar Jet Model For The Water Masers In W49n, Mordecai-Mark Mac Low, Moshe Elitzur, James M. Stone, Arieh Königl
Physics and Astronomy Faculty Publications
Observations by Gwinn, Moran, & Reid of the proper motions of water masers in W49N show that they have elongated distribution expanding from a common center. Features with high space velocity only occur far from the center, while low-velocity features occur at all distances. We propose that these observations can be interpreted in terms of a shell of shocked molecular gas that is driven by the expanding cocoon of a high-velocity protostellar jet. We present three-dimensional numerical simulations in support of this interpretation and argue that this source provides a unique oppurtunity for a detailed study of jet-driven cocoons.
Hot Gas And The Origin Of The Nebular Continuum In Novae, Pedro Saizar, Gary J. Ferland
Hot Gas And The Origin Of The Nebular Continuum In Novae, Pedro Saizar, Gary J. Ferland
Physics and Astronomy Faculty Publications
A featureless blue continuum (with constant fν) is a defining feature of declining classical novae. The fact that fν is constant into the infrared, and the absence of a Balmer jump, suggests that this continuum originates in hot tenous gas. The electron temperature and density of the hot gas phase of classical nova QU Vul 1984 are estimated from ground-based optical and IUE ultraviolet observations. This region has a temperature of 105 - 106, and a density in the range of 2 x 104 to 3 x 105cm-3. …
The Dynamics Of Stellar Outflows Dominated By Interaction Of Dust And Radiation, Nathan Netzer, Moshe Elitzur
The Dynamics Of Stellar Outflows Dominated By Interaction Of Dust And Radiation, Nathan Netzer, Moshe Elitzur
Physics and Astronomy Faculty Publications
Wind outflow around a late-type star driven by radiation pressure on dust grains is investigated in detail. The equation of motion for the outflow coupled with the equation of radiative transfer is solved treating the circumstellar envelope, which consists of gas and dust, as a two-component fluid. Because of the drift of the dust particles through the gas, the dust-to-gas ratio varies with distance even if grain formation is a prompt process. The coupling between dust and gas weakens as the mass-loss rate decreases until finally the rate of momentum transfer to the gas is insufficient to overcome gravity when …
Water Masers In W49n - The Youngest Stellar Jet?, Mordecai-Mark Mac Low, Moshe Elitzur
Water Masers In W49n - The Youngest Stellar Jet?, Mordecai-Mark Mac Low, Moshe Elitzur
Physics and Astronomy Faculty Publications
Observations by Gwinn, Moran, and Reid of the proper motions of water masers in W49N show that they have an elongated distribution expanding from a common center. Features with high space velocity only occur far from the center, while low-velocity features occur at all distances. It is proposed that water masers in star-forming regions occur in expanding shells swept up by high-velocity winds from young, massive stars during the early phases of the expansion. In W49N, confinement of the bubble by a density distribution with an axial cavity can explain both the velocity field and the shape of the maser …
Iue Observations Of Dq Herculis And Its Nebula, And The Nature Of The Cold Nova Shells, Gary J. Ferland, R. E. Williams, D. L. Lambert, G. A. Shields, M. Slovak, P. M. Gondhalekar, J. W. Truran
Iue Observations Of Dq Herculis And Its Nebula, And The Nature Of The Cold Nova Shells, Gary J. Ferland, R. E. Williams, D. L. Lambert, G. A. Shields, M. Slovak, P. M. Gondhalekar, J. W. Truran
Physics and Astronomy Faculty Publications
The nebula ejected in the 1934 outburst of the classical nova DQ Her is remarkable for its unprecedentedly low temperature of Te 500 K as measured by Williams et al. (1978). In this paper, IUE observations are combined with Steward optical spectra. It is confirmed that the gas is quite cold. It is further shown that the gas is ionized by the radiation field of the central object. X-ray, ultraviolet, optical and infrared observations of the underlying binary are combined with the extreme-ultraviolet continuum deduced from the level of ionization of the nebula to obtain a composite energy …