Monte Carlo radiation transfer in CV disk winds: application to the AM CVn prototype

Kusterer, D. J.; Nagel, T.; Hartmann, S.; Werner, K.; Feldmeier, Achim

doi:10.1051/0004-6361/201321438

Cited by 7 publications

(8 citation statements)

References 26 publications

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“…One of the striking features of the pure scattering profiles is the appearance of emission features at high inclination. This behavior is well-known from previous calculations of disc winds from cataclysmic variables (Shlosman & Vitello 1993;Knigge et al 1995;Long & Knigge 2002;Noebauer et al 2010;Kusterer et al 2014;Matthews et al 2015) and AGN (Matthews et al 2016). The FU Ori objects are generally surrounded by substantial dusty envelopes, in some cases optically visible only due to viewing along outflow holes (e.g., , so observing systems at inclinations as large as 80 • is unlikely, at least for Na I.…”

Section: Discussionsupporting

confidence: 71%

Disc wind models for FU Ori objects

Milliner

Matthews

Long

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We present disc wind models aimed at reproducing the main features of the strong Na I resonance line P-Cygni profiles in the rapidly-accreting pre-main sequence FU Ori objects. We conducted Monte Carlo radiative transfer simulations for a standard magnetocentrifugally driven wind (MHD) model and our own "Genwind" models, which allows for a more flexible wind parameterisation. We find that the fiducial MHD wind and similar Genwind models, which have flows emerging outward from the inner disc edge, and thus have polar cavities with no absorbing gas, cannot reproduce the deep, wide Na I absorption lines in FU Ori objects viewed at low inclination. We find that it is necessary to include an "inner wind" to fill this polar cavity to reproduce observations. In addition, our models assuming pure scattering source functions in the Sobolev approximation at intermediate viewing angles (30 • i 60 • ) do not yield sufficiently deep line profiles. Assuming complete absorption yields better agreement with observations, but simple estimates strongly suggest that pure scattering should be a much better approximation. The discrepancy may indicate that the Sobolev approximation is not applicable, possibly due to turbulence or non-monotonic velocity fields; there is some observational evidence for the latter. Our results provide guidance for future attempts to constrain FU Ori wind properties using full MHD wind simulations, by pointing to the importance of the boundary conditions necessary to give rise to an inner wind, and by suggesting that the winds must be turbulent to produce sufficiently deep line profiles.

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Section: Discussionsupporting

confidence: 71%

Disc wind models for FU Ori objects

Milliner

Matthews

Long

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…MC methods are routinely used to model, for example, SNe (e.g., [124][125][126]). Non-LTE MC codes have also been used to study disk winds in cataclysmic variables (CVs) (e.g., [127][128][129]) and Be stars (e.g., [130]). These codes tend to use the Sobolev approximation for the line transfer, which is reasonable for winds and SNe, but they cannot be used to study the photospheres and the acceleration of the wind around the sonic point.…”

Section: Binariesmentioning

confidence: 99%

UV Spectroscopy of Massive Stars

Hillier

2020

Galaxies

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We present a review of UV observations of massive stars and their analysis. We discuss O stars, luminous blue variables, and Wolf–Rayet stars. Because of their effective temperature, the UV (912−3200 Å) provides invaluable diagnostics not available at other wavebands. Enormous progress has been made in interpreting and analysing UV data, but much work remains. To facilitate the review, we provide a brief discussion on the structure of stellar winds, and on the different techniques used to model and interpret UV spectra. We discuss several important results that have arisen from UV studies including weak-wind stars and the importance of clumping and porosity. We also discuss errors in determining wind terminal velocities and mass-loss rates.

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“…When investigating multidimensional line-driven mass outflows, a generalisation of the line interaction treatment that goes beyond the Sobolev approximation used here should also be considered: this would be necessary to study the line-driving instability (Lucy & Solomon 1970;Owocki 1994) which should occur in linedriven outflows and may play a part in understanding the clumping mechanism (see discussion in Puls et al 2008 andVink 2015). Non-Sobolev Monte Carlo radiative transfer schemes have already been developed and used, for example by Knigge et al (1995) and Kusterer et al (2014) in the context of winds of cataclysmic variables. However, the computational costs of such schemes are significantly higher than their Sobolev counterparts.…”

Section: Multidimensionality and Non-sobolev Treatmentmentioning

confidence: 99%

Self-consistent modelling of line-driven hot-star winds with Monte Carlo radiation hydrodynamics

Noebauer

2015

Mon. Not. R. Astron. Soc.

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Radiative pressure exerted by line interactions is a prominent driver of outflows in astrophysical systems, being at work in the outflows emerging from hot stars or from the accretion discs of cataclysmic variables, massive young stars and active galactic nuclei. In this work, a new radiation hydrodynamical approach to model line-driven hot-star winds is presented. By coupling a Monte Carlo radiative transfer scheme with a finite-volume fluid dynamical method, line-driven mass outflows may be modelled self-consistently, benefiting from the advantages of Monte Carlo techniques in treating multi-line effects, such as multiple scatterings, and in dealing with arbitrary multidimensional configurations. In this work, we introduce our approach in detail by highlighting the key numerical techniques and verifying their operation in a number of simplified applications, specifically in a series of self-consistent, one-dimensional, Sobolev-type, hot-star wind calculations. The utility and accuracy of our approach is demonstrated by comparing the obtained results with the predictions of various formulations of the so-called CAK theory and by confronting the calculations with modern sophisticated techniques of predicting the wind structure. Using these calculations, we also point out some useful diagnostic capabilities our approach provides. Finally we discuss some of the current limitations of our method, some possible extensions and potential future applications.

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Monte Carlo radiation transfer in CV disk winds: application to the AM CVn prototype

Cited by 7 publications

References 26 publications

Disc wind models for FU Ori objects

Disc wind models for FU Ori objects

UV Spectroscopy of Massive Stars

Self-consistent modelling of line-driven hot-star winds with Monte Carlo radiation hydrodynamics

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