ESTIMATING THE PROPAGATION OF A UNIFORMLY ACCELERATED JET

We study the problem of a Herbig-Haro jet with a uniformly accelerating ejection velocity, travelling into a uniform environment. For the ejection density we consider two cases: a time-independent density, and a time-independent mass loss rate. For these two cases, we obtain analytic solutions for the motion of the jet head using a ram-pressure balance and a center of mass equation of motion. We also compute axisymmetric numerical simulations of the same flow, and compare the time-dependent positions of the leading working surface shocks with the predictions of the two analytic models. We find that if the jet is over-dense and over-pressured (with respect to the environment) during its evolution, a good agreement is obtained with the analytic models, with the flow initially following the center of mass analytic solution, and (for the constant ejection density case) at later times approaching the ram-pressure balance solution.

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Solar wind, mass and momentum losses during the solar cycle

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311017960 ◽

2010 ◽

Vol 6 (S271) ◽

pp. 395-396

Author(s):

R. Pinto ◽

S. Brun ◽

L. Jouve ◽

R. Grappin

Keyword(s):

Solar Wind ◽

Solar Cycle ◽

Wind Speed ◽

Mass Flux ◽

Solar Minimum ◽

Momentum Flux ◽

Loss Rate ◽

Convection Zone ◽

Mass Loss Rate ◽

Good Agreement

AbstractWe study the connections between the sun's convection zone evolution and the dynamics of the solar wind and corona. We input the magnetic fields generated by a 2.5D axisymmetric kinematic dynamo code (STELEM) into a 2.5D axisymmetric coronal MHD code (DIP). The computations were carried out for an 11 year cycle. We show that the solar wind's velocity and mass flux vary in latitude and in time in good agreement with the well known time-latitude assymptotic wind speed diagram. Overall sun's mass loss rate, momentum flux and magnetic breaking torque are maximal near the solar minimum.

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Delta-slow solution to explain B supergiant stars' winds

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314006401 ◽

2014 ◽

Vol 9 (S307) ◽

pp. 104-105

Author(s):

M. Haucke ◽

I. Araya ◽

C. Arcos ◽

M. Curé ◽

L. Cidale ◽

...

Keyword(s):

Mass Loss ◽

Loss Rate ◽

Mass Loss Rate ◽

Radiation Force ◽

Terminal Velocity ◽

Radiative Transport ◽

Synthetic Spectra ◽

Transport Code ◽

Fast Solution ◽

Good Agreement

AbstractA new radiation-driven wind solution called δ-slow was found by Curé et al. (2011) and it predicts a mass-loss rate and terminal velocity slower than the fast solution (m-CAK, Pauldrach et al. 1986). In this work, we present our first synthetic spectra based on the δ-slow solution for the wind of B supergiant (BSG) stars. We use the output of our hydrodynamical code HYDWIND as input in the radiative transport code FASTWIND (Puls et al. 2005). In order to obtain stellar and wind parameters, we try to reproduce the observed Hα, Hβ, Hγ, Hδ, Hei 4471, Hei 6678 and Heii 4686 lines. The synthetic profiles obtained with the new hydrodynamical solutions are in good agreement with the observations and could give us clues about the parameters involved in the radiation force.

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The nature of V861 Sco (=HD 152667)

International Astronomical Union Colloquium ◽

10.1017/s0252921100095166 ◽

1981 ◽

Vol 59 ◽

pp. 481-486

Author(s):

Ian D. Howarth ◽

R. Wilson

Keyword(s):

Light Curve ◽

Loss Rate ◽

Mass Loss Rate ◽

Curve Analysis ◽

Physical Parameters ◽

Evolutionary Models ◽

Light Curve Analysis ◽

Phase Dependence ◽

Large Phase ◽

Good Agreement

AbstractThe physical parameters of the components of V861 Sco are derived from light-curve analysis and published spectroscopy. Good agreement with evolutionary models is obtained. The stellar wind is investigated using IUE data; the results include no large phase dependence of the mass loss rate and insensitivity of the velocity of the wind (measured with respect to interstellar lines) to changes in the photospheric velocity, even near the base of the wind. However, small random changes in velocity near the base of the wind are amplified to larger changes further out.

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Application of Zone Models for Under-Ventilated Compartment Fires

Heat Transfer, Volume 2 ◽

10.1115/imece2006-15135 ◽

2006 ◽

Cited By ~ 1

Author(s):

T. Mizukami ◽

Y. Utiskul ◽

J. G. Quintiere

Keyword(s):

Loss Rate ◽

Lower Layer ◽

Mass Loss Rate ◽

Thermal Conditions ◽

Small Scale ◽

Zone Model ◽

Fuel Type ◽

Ambient Oxygen ◽

Good Agreement ◽

Lower Compartment

A model is presented that explains the mass loss rate in a compartment as a function of fuel type and scale. The effect of ventilation is included in the model by the inclusion of the ambient oxygen concentration in the lower layer that results due to vent mixing. The model is executed in BRI2002, a zone model, capable of computing species and thermal conditions in the upper and lower compartment gas layers. Computations show good agreement with small-scale compartment data for heptane pools. The results can accurately portray extinction, oscillations in burning, reduction in the flaming area, and quasi-steady behaviors.

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ASYMPTOTIC INTERNAL WORKING SURFACES OF PERIODICALLY VARIABLE JETS

Revista Mexicana de Astronomía y Astrofísica ◽

10.22201/ia.01851101p.2021.57.01.10 ◽

2021 ◽

Vol 57 (1) ◽

pp. 147-155

Author(s):

A. C. Raga ◽

J. Cantó ◽

A. Castellanos-Ramírez

Keyword(s):

General Solution ◽

Asymptotic Solution ◽

Mass Loss ◽

Loss Rate ◽

Mass Loss Rate ◽

Center Of Mass ◽

Time Variability ◽

Ejection Time ◽

Internal Working ◽

Functional Forms

We present a derivation based on the “center of mass formalism”; of the asymptotic behaviour of internal working surfaces produced in a variable HerbigHaro (HH) jet. We obtain the general solution for an arbitrary periodic ejection time-variability, and then show examples for a limited set of functional forms for the velocity and density time-evolutions. Finally, we derive a prescription for obtaining the time-averaged mass loss rate from observations of knots along an HH jet (based on the asymptotic solution), and apply it to derive the mass loss rate of the HH 1 jet.

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