Circumbinary disk evolution

Günther, Rainer; Kley, W.

doi:10.1051/0004-6361:20020407

Cited by 162 publications

(214 citation statements)

References 20 publications

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“…In reality, the distribution of dust material in the gap could be very complex due to the existence of two companions and the dust filtering in GW Ori (Artymowicz & Lubow 1996;Günther & Kley 2002;Rice et al 2006;Zhu et al 2012). In a binary system, simulations show that the material in the gap is mainly distributed in a set of two gas streams, which penetrate the gap and transfer the gas material from circumbinary disk to the central binary (Artymowicz & Lubow 1996;Günther & Kley 2002). In the simulations, the gas streams only account for ∼10% of the gap area and can carry at most 10 −3 of the mass that would exist inside the gap for an unperturbed disk (Artymowicz & Lubow 1996).…”

Section: Variations In the Sed Of Gw Orimentioning

confidence: 99%

GW Orionis: Inner disk readjustments in a triple system

Fang

Sicilia‐Aguilar

Roccatagliata

et al. 2014

A&A

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Context. Disks are expected to dissipate quickly in binary or multiple systems. Investigating such systems can improve our knowledge of the disk dispersal. The triple system GW Ori, still harboring a massive disk, is an excellent target. Aims. We study the young stellar system GW Ori, concentrating on its accretion, wind activity and disk properties. Methods. We use high-resolution optical spectra of GW Ori to do spectral classification and derive the radial velocities (RV). We analyze the wind and accretion activity using the emission lines in the spectra. We also use U-band photometry, which has been collected from the literature, to study the accretion variability of GW Ori. We characterize the disk properties of GW Ori by modeling its spectral energy distribution (SED).Results. By comparing our data to the synthetical spectra, we classify GW Ori as a G8 star. Based on the RVs derived from the optical spectra, we confirm the previous result as a close companion in GW Ori with a period of ∼242 days and an orbital semi-major axis of ∼1 AU. The RV residuals after the subtraction of the orbital solution with the equivalent widths (EW) of accretion-related emission lines vary with periods of 5−6.7 days during short-time intervals, which are caused by the rotational modulation. The Hα and Hβ line profiles of GW Ori can be decomposed in two central-peaked emission components and one blue-shifted absorption component. The blue-shifted absorption components are due to a disk wind modulated by the orbital motion of the close companion. Therefore, the systems like GW Ori can be used to study the extent of disk winds. We find that the accretion rates of GW Ori are rather constant but can occasionally be enhanced by a factor of 2−3. We reproduce the SED of GW Ori by using disk models with gaps ∼25−55 AU in size. A small population of tiny dust particles within the gap produces the excess emission at near-infrared bands and the strong and sharp silicate feature at 10 μm. The SED of GW Ori exhibits dramatic changes on timescales of ∼20 yr in the near-infrared bands, which can be explained as the change in the amount and distribution of small dust grains in the gap. We collect a sample of binary/multiple systems with disks in the literature and find a strong positive correlation between their gap sizes and separations from the primaries to companions, which is generally consistent with the prediction from the theory.

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Section: Variations In the Sed Of Gw Orimentioning

confidence: 99%

GW Orionis: Inner disk readjustments in a triple system

Fang

Sicilia‐Aguilar

Roccatagliata

et al. 2014

A&A

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“…Thus, an inner gap or cavity with very low density is produced (e.g., Bate & Bonnell 1997;Günther & Kley 2002). Two binary sources in the T Tauri stage have been imaged in great detail; GG Tau and UY Aur (e.g., Dutrey et al 1994;Duvert et al 1998).…”

Section: Iras 16293-2422mentioning

confidence: 99%

On the origin of H$_\mathsf{2}$CO abundance enhancements in low-mass protostars

Schöier

Jørgensen

Dishoeck

et al. 2004

A&A

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Abstract.High angular resolution H 2 CO 218 GHz line observations have been carried out toward the low-mass protostars IRAS 16293-2422 and L1448-C using the Owens Valley Millimeter Array at ∼2 resolution. Simultaneous 1.37 mm continuum data reveal extended emission which is compared with that predicted by model envelopes constrained from single-dish data. For L1448-C the model density structure works well down to the 400 AU scale to which the interferometer is sensitive. For IRAS 16293-2422, a known proto-binary object, the interferometer observations indicate that the binary has cleared much of the material in the inner part of the envelope, out to the binary separation of ∼800 AU. For both sources there is excess unresolved compact emission centered on the sources, most likely due to accretion disks < ∼ 200 AU in size with masses of IRAS 16293-2422). The H 2 CO data for both sources are dominated by emission from gas close to the positions of the continuum peaks. The morphology and velocity structure of the H 2 CO array data have been used to investigate whether the abundance enhancements inferred from single-dish modelling are due to thermal evaporation of ices or due to liberation of the ice mantles by shocks in the inner envelope. For IRAS 16293-2422 the H 2 CO interferometer observations indicate the presence of rotation roughly perpendicular to the large scale CO outflow. The H 2 CO distribution differs from that of C 18 O, with C 18 O emission peaking near MM1 and H 2 CO stronger near MM2. For L1448-C, the region of enhanced H 2 CO emission extends over a much larger scale >1 than the radius of 50−100 K (0. 6−0. 15) where thermal evaporation can occur. The red-blue asymmetry of the emission is consistent with the outflow; however the velocities are significantly lower. The H 2 CO 3 22 −2 21 /3 03 −2 02 flux ratio derived from the interferometer data is significantly higher than that found from single-dish observations for both objects, suggesting that the compact emission arises from warmer gas. Detailed radiative transfer modeling shows, however, that the ratio is affected by abundance gradients and optical depth in the 3 03 −2 02 line. It is concluded that a constant H 2 CO abundance throughout the envelope cannot fit the interferometer data of the two H 2 CO lines simultaneously on the longest and shortest baselines. A scenario in which the H 2 CO abundance drops in the cold dense part of the envelope where CO is frozen out but is undepleted in the outermost region provides good fits to the single-dish and interferometer data on short baselines for both sources. Emission on the longer baselines is best reproduced if the H 2 CO abundance is increased by about an order of magnitude from ∼10 −10 to ∼10 −9 in the inner parts of the envelope due to thermal evaporation when the temperature exceeds ∼50 K. The presence of additional H 2 CO abundance jumps in the innermost hot core region or in the disk cannot be firmly established, however, with the present sensitivity and resolution. Other scenarios, includi...

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“…The comparable mass case has also been extensively investigated in the context of binary star formation (Artymowicz & Lubow 1994;Bate & Bonnell 1997;Günther & Kley 2002;Günther et al 2004), where a boost of activity has been triggered by imaging of nearby young binary stars embedded in hollow circumbinary discs (Dutrey et al 1994). More recently, the techniques adopted in these fields have been applied to the BHB case.…”

Section: Introductionmentioning

confidence: 99%

Evolution of binary black holes in self gravitating discs

Roedig

Sesana

Dotti

et al. 2012

A&A

178

212

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Context. Massive black hole binaries, formed in galaxy mergers, are expected to evolve in dense circumbinary discs. Understanding of the disc-binary coupled dynamics is vital to assess both the final fate of the system and its potentially observable features. Aims. Aimed at understanding the physical roots of the secular evolution of the binary, we study the interplay between gas accretion and gravity torques in changing the binary elements (semi-major axis and eccentricity) and its total angular momentum budget. We pay special attention to the gravity torques, by analysing their physical origin and location within the disc. Methods. We analysed three-dimensional smoothed particle hydrodynamics simulations of the evolution of initially quasi-circular massive black hole binaries (BHBs) residing in the central hollow (cavity) of massive self-gravitating circumbinary discs. We performed a set of simulations adopting different thermodynamics for the gas within the cavity and for the "numerical size" of the black holes. Results. We show that (i) the BHB eccentricity growth found in our previous work is a general result, independent of the accretion and the adopted thermodynamics; (ii) the semi-major axis decay depends not only on the gravity torques but also on their subtle interplay with the disc-binary angular momentum transfer due to accretion; (iii) the spectral structure of the gravity torques is predominately caused by disc edge overdensities and spiral arms developing in the body of the disc and, in general, does not reflect directly the period of the binary; (iv) the net gravity torque changes sign across the BHB corotation radius (positive inside vs negative outside) We quantify the relative importance of the two, which appear to depend on the thermodynamical properties of the instreaming gas, and which is crucial in assessing the disc-binary angular momentum transfer; (v) the net torque manifests as a purely kinematic (nonresonant) effect as it stems from the low density cavity, where the material flows in and out in highly eccentric orbits. Conclusions. Both accretion onto the black holes and the interaction with gas streams inside the cavity must be taken into account to assess the fate of the binary. Moreover, the total torque exerted by the disc affects the binary angular momentum by changing all the elements (mass, mass ratio, eccentricity, semimajor axis) of the black hole pair. Commonly used prescriptions equating tidal torque to semi-major axis shrinking might therefore be poor approximations for real astrophysical systems.

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Circumbinary disk evolution

Cited by 162 publications

References 20 publications

GW Orionis: Inner disk readjustments in a triple system

GW Orionis: Inner disk readjustments in a triple system

On the origin of H$_\mathsf{2}$CO abundance enhancements in low-mass protostars

Evolution of binary black holes in self gravitating discs

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