Pre-Main Sequence Binaries with Aligned Disks?

Wolf, Sebastian; Stecklum, B.; Henning, Thomas

doi:10.1017/s0074180900225345

Cited by 20 publications

(24 citation statements)

References 21 publications

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“…Misaligned jets from protostellar systems (Davis et al 1994;) and inferred jet precession (Eisloffel et al 1996) also provided indirect evidence of misaligned discs. Polarimetry can also be used to study disc alignment (Monin et al 1998;Jensen et al 2004;Wolf et al 2001;Monin et al 2006). However, we now have a growing list of directly imaged misaligned discs in wide ( ∼ > 100 au) Class II systems (Koresko 1998;Stapelfeldt et al 1998;Kang et al 2008;Ratzka et al 2009;Roccatagliata et al 2011;Jensen & Akeson 2014;Salyk et al 2014;Williams et al 2014), including the recently observed system Ophiuchus SR24 that appears to have two discs misaligned by ≈ 108…”

Section: Misaligned Circumstellar Discs In Multiple Systemsmentioning

confidence: 99%

On the diversity and statistical properties of protostellar discs

Bate

2018

Monthly Notices of the Royal Astronomical Society

311

320

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We present results from the first population synthesis study of protostellar discs. We analyse the evolution and properties of a large sample of protostellar discs formed in a radiation hydrodynamical simulation of star cluster formation. Due to the chaotic nature of the star formation process, we find an enormous diversity of young protostellar discs, including misaligned discs, and discs whose orientations vary with time. Star-disc interactions truncate discs and produce multiple systems. Discs may be destroyed in dynamical encounters and/or through ram-pressure stripping, but reform by later gas accretion. We quantify the distributions of disc mass and radii for protostellar ages up to ≈ 10 5 yrs. For low-mass protostars, disc masses tend to increase with both age and protostellar mass. Disc radii range from of order ten to a few hundred au, grow in size on timescales ∼ < 10 4 yr, and are smaller around lower-mass protostars. The radial surface density profiles of isolated protostellar discs are flatter than the minimum mass solar nebula model, typically scaling as Σ ∝ r −1. Disc to protostar mass ratios rarely exceed two, with a typical range of M d /M * = 0.1−1 to ages ∼ < 10 4 yrs and decreasing thereafter. We quantify the relative orientation angles of circumstellar discs and the orbit of bound pairs of protostars, finding a preference for alignment that strengths with decreasing separation. We also investigate how the orientations of the outer parts of discs differ from the protostellar and inner disc spins for isolated protostars and pairs.

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Section: Misaligned Circumstellar Discs In Multiple Systemsmentioning

confidence: 99%

On the diversity and statistical properties of protostellar discs

Bate

2018

Monthly Notices of the Royal Astronomical Society

311

320

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“…Such systems do not show a preferred mass ratio or orbital eccentricity, but do exhibit preferentially aligned circumstellar disks on the pre-main-sequence and preferentially aligned stellar spin and orbital axes on the mainsequence. For example, the circumstellar disks of T Tauri star binaries with projected orbital separations spanning the range ∼100-1000 au are preferentially aligned to within a few tens of degrees (e.g., Wolf et al 2001;Jensen et al 2004;Monin et al 2006). Main-sequence solar-type binaries with orbital separations smaller than about 30-40 au (close to the median orbital separation) have approximately aligned spin and orbital axes, whereas those with larger orbital separations commonly show misaligned spin and orbital axes (Hale 1994).…”

Section: Future Evolutionmentioning

confidence: 99%

Rotationally Driven Fragmentation in the Formation of the Binary Protostellar System L1551 Irs 5

Lim

Yeung

Hanawa

et al. 2016

ApJ

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Both bulk rotation and local turbulence have been widely suggested to drive the fragmentation in collapsing cores that produces multiple star systems. Even when the two mechanisms predict different alignments for stellar spins and orbits, subsequent internal or external interactions can drive multiple systems toward or away from alignment, thus masking their formation processes. Here, we demonstrate that the geometrical and dynamical relationship between a binary system and its surrounding bulk envelope provide the crucial distinction between fragmentation models. We find that the circumstellar disks of the binary protostellar system L1551 IRS 5 are closely parallel, not just with each other but also with their surrounding flattened envelope. Measurements of the relative proper motion of the binary components spanning nearly 30 years indicate an orbital motion related to that of the envelope rotation. Eliminating orbital solutions whereby the circumstellar disks would be tidally truncated to sizes smaller than observed, the remaining solutions favor a circular or low-eccentricity orbit tilted by up to ∼25°from the circumstellar disks. Turbulence-driven fragmentation can generate local angular momentum to produce a coplanar binary system, but this would have no particular relationship to the system's surrounding envelope. Instead, the observed properties conform with predictions for rotationally driven fragmentation. If the fragments were produced at different heights or on opposite sides of the mid-plane in the flattened central region of a rotating core, the resulting protostars would then exhibit circumstellar disks parallel with the surrounding envelope but tilted from the orbital plane, as is observed.

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“…Polarimetric studies on the disc orientations have been carried out by, e.g., Monin et al (1998), Wolf et al (2001) and Monin et al (2006). They all observed T Tauri stars and found that discs tend to be aligned in young binaries.…”

Section: Comparison To Previous Workmentioning

confidence: 99%

“…Previous studies have determined the inclination by means of polarimetry (e.g., Monin et al 1998;Wolf et al 2001;Monin et al 2006), orientation of the jets (e.g., Eislöffel et al 1996;Davis et al 1997), and direct observations of the discs (e.g., Koresko 1998;Stapelfeldt et al 1998b). Another technique, which allows us to directly measure the size, inclination, and orientation of the inner parts of protoplanetary discs is long-baseline interferometry at infrared wavelengths.…”

Section: Introductionmentioning

confidence: 99%

Multi-wavelength observations of the young binary system Haro 6-10: The case of misaligned discs

Roccatagliata

Ratzka

Henning

et al. 2011

A&A

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Context. We present a multi-wavelength, high-resolution observational survey of the young binary system Haro 6-10 (GV Tau, IRAS 04263+2426), which harbours one of the few known infrared companions. Aims. The primary goal of this project is to determine the physical and geometrical properties of the circumstellar and circumbinary material in the Haro 6-10 system. Methods. High-resolution optical (HST/WFPC2) and near-infrared (VLT/NACO) images in different bands were analysed to investigate the large-scale structures of the material around the binary. Mid-infrared interferometry (VLTI/MIDI) and spectroscopy (TIMMI2 at the 3.6 m ESO telescope) were carried out to determine the structure and optical depth of the circumstellar material around the individual components.Results. The multi-wavelength observations suggest that both components of the binary system Haro 6-10 are embedded in a common envelope. The measured extinction indicates a dust composition of the envelope similar to that of the interstellar medium. Each component of the system has a circumstellar disc-like structure typical of young stars. The discs are highly misaligned: the northern component is seen almost edge-on and the southern component is an almost face-on disc. Conclusions. The two main formation scenarios of binary systems with misaligned discs are the gravitational capture of a passing object in a dense environment and the fragmentation of the collapsing molecular cloud. Given the low-density environment of the Taurus-Aurigae star-forming region, the first scenario is unlikely for Haro 6-10. The binary system most probably formed via fragmentation of two different parts of the collapsing molecular cloud combined with other dynamical processes related to the cloud and/or the protostars. This can also be the explanation for other binary systems with an infrared companion.

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Pre-Main Sequence Binaries with Aligned Disks?

Cited by 20 publications

References 21 publications

On the diversity and statistical properties of protostellar discs

On the diversity and statistical properties of protostellar discs

Rotationally Driven Fragmentation in the Formation of the Binary Protostellar System L1551 Irs 5

Multi-wavelength observations of the young binary system Haro 6-10: The case of misaligned discs

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