Star–disc alignment in the protoplanetary discs: SPH simulation of the collapse of turbulent molecular cloud cores

Takaishi, Daisuke; Tsukamoto, Yusuke; Suto, Yasushi

doi:10.1093/mnras/staa179

Cited by 30 publications

(22 citation statements)

References 70 publications

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“…1. a misalignment between the protoplanetary disk due to inhomogeneities in the molecular cloud (Bate et al 2010;Fielding et al 2015;Takaishi et al 2020), magnetic interactions (Lai et al 2011), or a companion star (Batygin 2012;Spalding & Batygin 2015;Zanazzi & Lai 2018); 2. ongoing nodal precession driven by a stellar companion or wide-orbiting giant planet on a highly inclined orbit (Anderson & Lai 2018); 3. a resonance between the nodal precession rates of an inner planet and an outer planet that occurs during the dissipation of the protoplanetary disk (Petrovich et al 2020); and 4. random tumbling of the spin-axis orientation of the photosphere due to stochastic internal gravity waves (Rogers et al 2012).…”

Section: Discussionmentioning

confidence: 99%

Hot Stars with Kepler Planets Have High Obliquities*

Louden

Winn

Petigura

et al. 2021

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It has been known for a decade that hot stars with hot Jupiters tend to have high obliquities. Less is known about the degree of spin-orbit alignment for hot stars with other kinds of planets. Here, we reassess the obliquities of hot Kepler stars with transiting planets smaller than Neptune, based on spectroscopic measurements of their projected rotation velocities (v i sin ). The basis of the method is that a lower obliquity-all other things being equal-causes i sin to be closer to unity and increases the value of v i sin . We sought evidence for this effect using a sample of 150 Kepler stars with effective temperatures between 5950 and 6550 K and a control sample of 101 stars with matching spectroscopic properties and random orientations. The planet hosts have systematically higher values of v i sin than the control stars, but not by enough to be compatible with perfect spin-orbit alignment. The mean value of i sin is 0.856±0.036, which is 4σ away from unity (perfect alignment), and 2σ away from p 4 (random orientations). There is also evidence that the hottest stars have a broader obliquity distribution: when modeled separately, the stars cooler than 6250 K have =  i sin 0.928 0.042 ⟨ ⟩ while the hotter stars are consistent with random orientations. This is similar to the pattern previously noted for stars with hot Jupiters. Based on these results, obliquity excitation for early-G and late-F stars appears to be a general outcome of star and planet formation, rather than being exclusively linked to hot Jupiter formation.

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Section: Discussionmentioning

confidence: 99%

Hot Stars with Kepler Planets Have High Obliquities*

Louden

Winn

Petigura

et al. 2021

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“…Turbulence (21) and disk-torquing (22) can lead to misaligned protoplanetary disks. However retrograde orbits, as observed for K2-290A, are difficult to achieve via turbulence and late infall of material will lead to a further reduction of any misalignment (23).…”

Section: Discussionmentioning

confidence: 99%

A backward-spinning star with two coplanar planets

Hjorth

Albrecht

Hirano

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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It is widely assumed that a star and its protoplanetary disk are initially aligned, with the stellar equator parallel to the disk plane. When observations reveal a misalignment between stellar rotation and the orbital motion of a planet, the usual interpretation is that the initial alignment was upset by gravitational perturbations that took place after planet formation. Most of the previously known misalignments involve isolated hot Jupiters, for which planet–planet scattering or secular effects from a wider-orbiting planet are the leading explanations. In theory, star/disk misalignments can result from turbulence during star formation or the gravitational torque of a wide-orbiting companion star, but no definite examples of this scenario are known. An ideal example would combine a coplanar system of multiple planets—ruling out planet–planet scattering or other disruptive postformation events—with a backward-rotating star, a condition that is easier to obtain from a primordial misalignment than from postformation perturbations. There are two previously known examples of a misaligned star in a coplanar multiplanet system, but in neither case has a suitable companion star been identified, nor is the stellar rotation known to be retrograde. Here, we show that the star K2-290 A is tilted by 124○±6○ compared with the orbits of both of its known planets and has a wide-orbiting stellar companion that is capable of having tilted the protoplanetary disk. The system provides the clearest demonstration that stars and protoplanetary disks can become grossly misaligned due to the gravitational torque from a neighboring star.

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“…We consider a triple protostar system, model C3, listed in Table 1 of our previous paper (Takaishi et al (2020), hereafter Paper I). Paper I describes details of the numerical simulation.…”

Section: Outline Of Our Sph Simulationmentioning

confidence: 99%

A new formation scenario of a counter-rotating circumstellar disk: spiral-arm accretion from a circumbinary disk in a triple protostar system

Takaishi,

Tsukamoto,

Suto

2021

Preprint

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We present the evolution of rotational directions of circumstellar disks in a triple protostar system simulated from a turbulent molecular cloud core with no magnetic field. We find a new formation pathway of a counter-rotating circumstellar disk in such triple systems. The tertiary protostar forms via the circumbinary disk fragmentation and the initial rotational directions of all the three circumstellar disks are almost parallel to that of the orbital motion of the binary system. Their mutual gravito-hydrodynamical interaction for the subsequent ∼ 10 4 yr greatly disturbs the orbit of the tertiary, and the rotational directions of the tertiary disk and star are reversed due to the spiral-arm accretion of the circumbinary disk. The counter-rotation of the tertiary circumstellar disk continues to the end of the simulation (∼ 6.4 × 10 4 yr after its formation), implying that the counter-rotating disk is long-lived. This new formation pathway during the disk evolution in Class 0/I Young Stellar Objects possibly explains the counter-rotating disks recently discovered by ALMA.

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Star–disc alignment in the protoplanetary discs: SPH simulation of the collapse of turbulent molecular cloud cores

Cited by 30 publications

References 70 publications

Hot Stars with Kepler Planets Have High Obliquities*

Hot Stars with Kepler Planets Have High Obliquities*

A backward-spinning star with two coplanar planets

A new formation scenario of a counter-rotating circumstellar disk: spiral-arm accretion from a circumbinary disk in a triple protostar system

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