Exchange of gravitational energy during a collision of galaxies

Sastry, K. S.; Alladin, S. M.

doi:10.1007/bf00653612

Cited by 21 publications

(3 citation statements)

References 3 publications

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“…Also, according to Morbidelli & Nesvorny (2012) and Birnstiel et al (2012) the number, mass and distribution of the planetary embryos in the proto-planetary disks are related to the time evolution of a star. These clumps would suffer a similar interaction as the one described in Bally et al (2015), such as a Rutherford dispersion originated by a gravitational force, affecting them drastically and changing their dynamical properties via one gravitational impulse (Sastry & Alladin 1970) produced by the passage of a massive object. As a first approximation, we describe the interaction of a fast massive star with a cluster of negligible mass objects.…”

Section: Introductionmentioning

confidence: 94%

Explosive ejections generated by gravitational interactions

Rivera-Ortiz,

Rodríguez-González,

Cantó

et al. 2021

Preprint

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During the fragmentation and collapse of a molecular cloud, it is expected to have close encounters between (proto)stellar objects that can lead to the ejection of a fraction of them as runaway objects. However, the duration and the consequences of such encounters perhaps are small such that there is no direct evidence of their occurrence. As a first approximation, in this work, we analytically analyze the interaction of a massive object that moves at high velocity into a cluster of negligible mass particles with an initial number density distribution ∝ R −α . We have found that the runaway conditions of the distribution after the encounter are related to the mass and the velocity of the star and the impact parameter of each particle to the stellar object. Then, the cluster particles are gravitationally accelerated by the external approaching star, destroying the cluster and the dispersion and velocities of the particles have explosive characteristics. We compare this analytical model with several numerical simulations and finally, we applied our results to the Orion Fingers in the Orion BN/KL region, which show an explosive outflow that could be triggered by the gravitational interaction of several (proto)stellar objects.

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Section: Introductionmentioning

confidence: 94%

Explosive ejections generated by gravitational interactions

Rivera-Ortiz,

Rodríguez-González,

Cantó

et al. 2021

Preprint

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“…A number of authors have recently studied the effect of galaxy collisions on the structure of spherical galaxies. Most investigations, such as those of Sastry and Alladin (1970), Gallagher andOstriker (1972), andRichstone (1975) have considered conditions comparable to those existing in dense clusters, where the relative orbits of interacting galaxies are highly hyperbolic. In this paper we consider a model which is more appropriate for a galaxy which is perturbed by the passage of a smaller companion, for example in a binary or small multiple system where the velocities are more nearly parabolic.…”

Section: Introductionmentioning

confidence: 99%

Tidal effects induced in a spherical galaxy by the passage of a companion

Gutowski¹,

Larson

1976

PASP

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A gravitational encounter between a spherical galaxy and a smaller companion is simulated by computing a large number of stellar orbits in the restricted three-body approximation. For the case considered, i.e., galaxies of 10 11 f Q and 5 X 10 10 Wo passing in parabolic orbits at a closest distance of 20 kpc, the larger galaxy loses about 8% of its mass, and its outer regions swell up by ~ 50% in radius. These effects may be important in interpreting the measured luminosities and light distributions of elliptical galaxies in cosmological studies.

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“…With this assumption it is convenient to represent the density distribution in galaxies by that of a polytrope and to derive the relevant forces from the theory of polytropes as explained in Alladin (1965), Sastry and Alladin (1970), and Potdar and Ballabh (1974). Rood (1965) indicated that the poly trope of index n = 4 closely represents the density distribution of a typical globular galaxy.…”

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confidence: 99%

Formation of Double Galaxies by Tidal Capture

Alladin

Potdar

Sastry

1975

Symp. - Int. Astron. Union

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Abstract.The conditions under which double galaxies may be formed by tidal capture are considered. Estimates for the increase in the internal energy of colliding galaxies due to tidal effects are used to de termine the magnitudes V cap and V dis of the maximum relative velocities at infinite separation required for tidal capture and tidal disruption respectively. A double galaxy will be formed by tidal capture without tidal disruption of a component if K cap > V { and K cap > V dis where K, is the initial relative speed of the two galaxies at infinite separation. If the two galaxies are of the same dimension, formation of double galaxies by tidal capture is possible in a close collision either if the two galaxies do not differ much in mass and density distribution or if the more massive galaxy is less centrally concentrated than the other. If we as sume, as statistics suggest, that the mass of a galaxy is proportional to the square of its radius, it follows that the probability of the formation of double galaxies by tidal capture increases with the increase in mass of the galaxies and tidal disruption does not occur in a single collision for any distance of closest approach of the two galaxies.We know from classical dynamics that two stars approaching each other from a distance cannot form a binary system without the aid of a third perturbing body. An encounter between two galaxies is, however, an inelastic collision and may lead to the formation of a double galaxy under certain circumstances.Consider a galaxy of mass M i approaching a galaxy of mass M 2 from a great dis tance. Let U be the total internal energy of a galaxy (i.e. the sum of the potential energy of the galaxy and the kinetic energy of the stars constituting the galaxy) and let E be the total external energy of the galaxies (i.e. the sum of the potential energy due to the mutual gravitational attraction of the two galaxies and the kinetic energy due to the orbital motion of the two galaxies). The total energy,is conserved. The tidal effects of the encounter result in increase in the velocities of the stars in the two galaxies, so that the total internal energy, L^ + U 2 of the galaxies increases at the expense of the external energy E. Let A U t and A U 2 be the increments in the internal energies of the two galaxies due to the encounter, then,where E ( and E f are the initial and final values of the external energy. Following Rood (1965) we define the capture velocity, V cap , as the initial relative velocity at infinite separation for which E f = 0, so that,

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Exchange of gravitational energy during a collision of galaxies

Cited by 21 publications

References 3 publications

Explosive ejections generated by gravitational interactions

Explosive ejections generated by gravitational interactions

Tidal effects induced in a spherical galaxy by the passage of a companion

Formation of Double Galaxies by Tidal Capture

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