HYDRODYNAMIC AND RADIATIVE MODELING OF TEMPORAL Hα EMISSION<i>V/R</i>VARIATIONS CAUSED BY DISCONTINUOUS MASS TRANSFER IN BINARIES

Chadima, P.; Fiřt, Roman; Harmanec, P.; Wolf, M.; Ruždjak, Domagoj; Božić, H.; Koubský, P.

doi:10.1088/0004-6256/142/1/7

Cited by 3 publications

(3 citation statements)

References 6 publications

(7 reference statements)

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“…These effects, dust and Mie scattering were incorporated into the code Shellspec. It solves radiative transfer along the line of sight in 3D moving circumstellar environment (Budaj & Richards 2004, see also Budaj 2011, Miller et al 2007, Tkachenko et al 2010, Chadima et al 2011a for some modifications and applications). In the next sections we apply this code to ǫ Aur.…”

Section: And References Therein)mentioning

confidence: 99%

Effects of dust on light-curves ofϵAurigae-type stars

Budaj

2011

A&A

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Context. Auriga is one of the most mysterious objects in the sky. Previous modeling of its light-curve assumed a dark, inclined, non-transparent or semi-transparent dusty disk with a central hole. The hole was necessary to explain the light-curve with a sharp mid-eclipse brightening. Aims. The aim of the present paper is to study the effects of dust on the light-curves of eclipsing binary stars and to develop an alternative physical model for Aur-type objects that is based on the optical properties of dust grains. Methods. The code Shellspec was modified to calculate the light-curves and spectra of these objects. The code solves the radiative transfer along the line of sight in interacting binaries. Dust and angle-dependent Mie scattering were included in the code for this purpose. Results. Our model of Aur consists of two geometrically thick flared disks: an internal optically thick disk and an external optically thin disk, which absorbs and scatters radiation. Disks are in the orbital plane and are almost edge-on. We argue that there is no need for a highly inclined disk with a hole to explain the current eclipse of Aur even if there is a possible shallow mid-eclipse brightening. We demonstrate that phase-dependent light scattering and the optical properties of the dust can have a significant effect on the light-curves of these stars and can even produce a mid-eclipse brightening. This is a natural consequence of the strong forward scattering. We also demonstrate that shallow mid-eclipse brightening might result from eclipses by nearly edge-on flared (dusty or gaseous) disks.

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Section: And References Therein)mentioning

confidence: 99%

Effects of dust on light-curves ofϵAurigae-type stars

Budaj

2011

A&A

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“…Shellspec provides a flexible framework for modification and extension to related astrophysical topics; for example, Tkachenko et al (2009Tkachenko et al ( , 2010 created an inverted version of the code to determine properties of the component stars; Budaj (2011a) described an improved consideration of the reflection effect in Shellspec which he applied to modeling the temperature distribution over the surface of transiting exoplanets; Budaj (2011b) used Shellspec to model dust disks in ǫ Aur; and Chadima et al (2011) used Shellspec along with ZEUS-MP hydrodynamic models to illustrate the phase-varying Hα V/R asymmetry resulting from injection of a blob of gaseous material (such as could occur from discontinuous mass transfer prior to viscosity-driven smoothing).…”

Section: Introductionmentioning

confidence: 99%

MODELING THE ACCRETION STRUCTURE OF AU Mon

Atwood-Stone

Richards

Budaj

et al. 2012

ApJ

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AU Mon is a long-period (11.113 d) Algol-type binary system with a persistent accretion disk that is apparent as double-peaked Hα emission. We present previously unpublished optical spectra of AU Mon which were obtained over several years with dense orbital phase coverage. We utilize these data, along with archival UV spectra, to model the temperature and structure of the accretion disk and the gas stream. Synthetic spectral profiles for lines including Hα, Hβ, and the Al III and Si IV doublets were computed with the Shellspec program. The best match between the model spectra and the observations is obtained for an accretion disk of inner/outer radius 5.1/23 R ⊙ , thickness of 5.2R ⊙ , density of 1.0 × 10 −13 g cm −3 , and maximum temperature of 14000 K, along with a gas stream at a temperature of ∼8000 K transferring ∼2.4 × 10 −9 M ⊙ yr −1 . We show Hα Doppler tomograms of the velocity structure of the gas, constructed from difference profiles calculated through sequentially subtracting contributions from the stars and accretion structures. The tomograms provide independent support for the Shellspec modeling, while also illustrating that residual emission at sub-Keplerian velocities persists even after subtracting the disk and stream emission. Spectral variability in the Hα profile beyond that expected from either the orbital or the long-period cycle is present on both multi-week and multi-year timescales, and may reflect quasi-random changes in the mass transfer rate or the disk structure. Finally, a transient UV spectral absorption feature may be modeled as an occasional outflow launched from the vicinity of the disk-stream interaction region.

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“…There are versions of this code in Fortran90 which solve some particular restricted inverse problems (see Tkachenko et al 2010Tkachenko et al andŠejnová et al 2011. Chadima et al (2011a) modeled Hα emission V/R variations caused by discontinuous mass transfer in interacting binaries. Ghoreyshi et al (2010Ghoreyshi et al ( , 2011 applied the code to the eclipsing binary AV Del.…”

Section: J Budajmentioning

confidence: 99%

Synthetic Spectra and Light Curves of Interacting Binaries and Exoplanets with Circumstellar Material: SHELLSPEC

Budaj¹

2011

Proc. IAU

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Abstract. Program SHELLSPEC is designed to calculate light-curves, spectra and images of interacting binaries and extrasolar planets immersed in a moving circumstellar environment which is optically thin. It solves simple radiative transfer along the line of sight in moving media. The assumptions include LTE and optional known state quantities and velocity fields in 3D. Optional (non)transparent objects such as a spot, disc, stream, jet, shell or stars may be defined (embedded) in 3D and their composite synthetic spectrum calculated. The Roche model can be used as a boundary condition for the radiative transfer. Recently, a new model of the reflection effect, dust and Mie scattering were incorporated into the code.Aurigae is one of the most mysterious objects on the sky. Prior modeling of its light-curve assumed a dark, inclined, disk of dust with a central hole to explain the light-curve with a sharp mid-eclipse brightening. Our model consists of two geometrically thick flared disks: an internal optically thick disk and an external optically thin disk which absorbs and scatters radiation. Shallow mid-eclipse brightening may result from eclipses by nearly edge-on flared (dusty or gaseous) disks. Mid-eclipse brightening may also be due to strong forward scattering and optical properties of the dust which can have an important effect on the light-curves.There are many similarities between interacting binary stars and transiting extrasolar planets. The reflection effect which is briefly reviewed is one of them. The exact Roche shape and temperature distributions over the surface of all currently known transiting extrasolar planets have been determined. In some cases (HAT-P-32b, , departures from the spherical shape can reach 7-15%.

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HYDRODYNAMIC AND RADIATIVE MODELING OF TEMPORAL Hα EMISSIONV/RVARIATIONS CAUSED BY DISCONTINUOUS MASS TRANSFER IN BINARIES

Cited by 3 publications

References 6 publications

Effects of dust on light-curves ofϵAurigae-type stars

Effects of dust on light-curves ofϵAurigae-type stars

MODELING THE ACCRETION STRUCTURE OF AU Mon

Synthetic Spectra and Light Curves of Interacting Binaries and Exoplanets with Circumstellar Material: SHELLSPEC

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