Three-dimensional hydrodynamical simulations of stellar collisions. I - Equal-mass main-sequence stars

1987 ◽  
Vol 323 ◽  
pp. 614 ◽  
Author(s):  
Willy Benz ◽  
Jack G. Hills
Keyword(s):  
Main Sequence ◽  
Three Dimensional ◽  
Equal Mass ◽  
Main Sequence Stars ◽  
Stellar Collisions ◽  
Hydrodynamical Simulations

scholarly journals Building Blue Stragglers with Stellar Collisions

2007 ◽  
Vol 3 (S246) ◽  
pp. 363-364
Author(s):  
Evert Glebbeek ◽  
Onno R. Pols
Keyword(s):  
Main Sequence ◽  
Main Sequence Star ◽  
Main Sequence Stars ◽  
Blue Stragglers ◽  
Stellar Collisions ◽  
Hydrodynamical Simulations

AbstractThe evolution of stellar collision products in cluster simulations has usually been modelled using simplified prescriptions. Such prescriptions either replace the collision product with an (evolved) main sequence star, or assume that the collision product was completely mixed during the collision.It is known from hydrodynamical simulations of stellar collisions that collision products are not completely mixed, however. We have calculated the evolution of stellar collision products and find that they are brighter than normal main sequence stars of the same mass, but not as blue as models that assume that the collision product was fully mixed during the collision.

scholarly journals Disc formation and jet inclination effects in common envelopes

2020 ◽  
Vol 497 (2) ◽  
pp. 2057-2065 ◽  
Author(s):  
Diego López-Cámara ◽  
Enrique Moreno Méndez ◽  
Fabio De Colle
Keyword(s):  
Main Sequence ◽  
Three Dimensional ◽  
Compact Object ◽  
Main Sequence Stars ◽  
Common Envelope ◽  
Ejection Process ◽  
The Common ◽  
Red Giant ◽  
Hydrodynamical Simulations ◽  
Disc Formation

ABSTRACT The evolution and physics of the common envelope (CE) phase are still not well understood. Jets launched from a compact object during this stage may define the evolutionary outcome of the binary system. We focus on the case in which jets are launched from a neutron star (NS) engulfed in the outer layers of a red giant (RG). We run a set of three-dimensional hydrodynamical simulations of jets with different luminosities and inclinations. The luminosity of the jet is self-regulated by the mass accretion rate and an efficiency η. Depending on the value of η the jet can break out of the previously formed bulge (‘successful jet’) and aligns against the incoming wind, in turn, it will realign in favour of the direction of the wind. The jet varies in size and orientation and may present quiescent and active epochs. The inclination of the jet and the Coriolis and centrifugal forces, only slightly affect the global evolution. As the accretion is hypercritical, and the specific angular momentum is above the critical value for the formation of a disc, we infer the formation of a disc and launching of jets. The discs’ mass and size would be ∼10−2 M⊙ and ≳1010 cm, and it may have rings with different rotation directions. In order to have a successful jet from a white dwarf, the ejection process needs to be very efficient (η ∼ 0.5). For main-sequence stars, there is not enough energy reservoir to launch a successful jet.

scholarly journals Simulations of Stellar Collisions Involving Pre–Main‐Sequence Stars

2005 ◽  
Vol 627 (1) ◽  
pp. 277-285 ◽  
Author(s):  
Daniel Laycock ◽  
Alison Sills
Keyword(s):  
Main Sequence ◽  
Main Sequence Stars ◽  
Stellar Collisions

scholarly journals Planet formation and stability in polar circumbinary discs

2019 ◽  
Vol 628 ◽  
pp. A119 ◽  
Author(s):  
Nicolás Cuello ◽  
Cristian A. Giuppone
Keyword(s):  
Three Dimensional ◽  
Orbital Plane ◽  
Equal Mass ◽  
Wide Range ◽  
Rotation Vectors ◽  
Hydrodynamical Simulations ◽  
Binary Orbit ◽  
The Stability ◽  
P Type

Context. Dynamical studies suggest that most circumbinary discs (CBDs) should be coplanar (i.e. the rotation vectors of the binary and the disc should be aligned). However, some theoretical works show that under certain conditions a CBD can become polar, which means that its rotation vector is orthogonal with respect to the binary orbital plane. Interestingly, very recent observations show that polar CBDs exist in nature (e.g. HD 98800). Aims. We test the predictions of CBD alignment around eccentric binaries based on linear theory. In particular, we compare prograde and retrograde CBD configurations. Then, assuming planets form in these systems, we thoroughly characterise the orbital behaviour and stability of misaligned (P-type) particles. This is done for massless and massive particles. Methods. The evolution of the CBD alignment for various configurations was modelled through three-dimensional hydrodynamical simulations. For the orbital characterisation and the analysis stability, we relied on long-term N-body integrations and structure and chaos indicators, such as Δe and MEGNO. Results. We confirm previous analytical predictions on CBD alignment, but find an unexpected symmetry breaking between prograde and retrograde configurations. More specifically, we observe polar alignment for a retrograde misaligned CBD that was expected to become coplanar with respect to the binary disc plane. Therefore, the likelihood of becoming polar for a highly misaligned CBD is higher than previously thought. Regarding the stability of circumbinary P-type planets (also know as Tatooines), polar orbits are stable over a wide range of binary parameters. In particular, for binary eccentricities below 0.4 the orbits are stable for any value of the binary mass ratio. In the absence of gas, planets with masses below 10−5 M⊙ have negligible effects on the binary orbit. Finally, we suggest that mildly eccentric equal-mass binaries should be searched for polar Tatooines.

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