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The motion of bodies ejected from the Earth was studied, and the probabilities of collisions of such bodies with the present terrestrial planets were calculated. The dependences of these probabilities on velocities, angles and points of ejection of bodies were studied. These dependences can be used in the models with different distributions of ejected material. On average, about a half and less than 10\% of initial ejected bodies remained moving in elliptical orbits in the Solar System after 10 and 100 Myr, respectively. A few ejected bodies collided with planets after 250 Myr. As dynamical lifetimes of bodies ejected from the Earth can reach hundreds of million years, a few percent of bodies ejected at the Chicxulub and Popigai events about 36-65 Myr ago can still move in the zone of the terrestrial planets and have small chances to collide with planets, including the Earth. The fraction of ejected bodies that collided with the Earth was greater for smaller ejection velocity. The fractions of bodies delivered to the Earth and Venus probably did not differ much for these planets and were about 0.2-0.3 each. Such obtained results testify in favour of that the upper layers of the Ear

Ring systems have been observed around Centaur Chariklo (10199) and other small bodies but their origin and dynamical histories are still debated. These small body ring systems challenge conventional models for the origin of planetary rings, especially when considering Centaurs' often erratic cometary activity, their non-spherical shapes, and their relatively short dynamical lifetimes (~$10^7$ years). A collisional origin for these rings is disfavored based on the low probability of collisions within their lifetimes, and so their mechanism of formation remains an open question. In this work, we use Swiftest, a N-body integrator with collisional fragmentation and higher-order gravitational harmonics, to test a hypothesis that rings could be formed from regolith ejected from a cometary outburst that is subsequently captured into a stable orbit. We show that ejected surface regolith is captured in orbit around ellipsoidal Centaurs like Chariklo and Chiron to form a proto-ring disk for at least 100 rotations. This captured disk may serve as a starting point that can evolve into observed ring systems. Inter-particle collisions and the ellipsoidal gravity field facilitate this capture. A

This study analyzes the motion of bodies ejected from the Earth or the Moon. We studied the ejection of bodies from several points on the Earth's surface, as well as from the most far point of the Moon from the Sun. Different velocities and angles of ejection of bodies were considered. The dynamical lifetimes of bodies reached a few hundred million years. Over the entire considered time interval, the values of the probability of a collision of a body ejected from the Earth with the Earth were approximately 0.3, 0.2, and 0.15-0.2 at an ejection velocity vej equaled to 11.5, 12, and 14 km/s, respectively. At vej<11.3 km/s, most of the ejected bodies fell back onto the Earth. The total number of bodies delivered to the Earth and Venus probably did not differ much. The probabilities of collisions of bodies with Mercury and Mars usually did not exceed 0.1 and 0.02, respectively. At vej>11.5 km/s, the probability of a collision of a body ejected from the Earth with the Moon was about 15-35 times less than that with the Earth, and it was about 0.01. The probability of a collision with the Earth for a body ejected from the Moon moving in its present orbit was about 0.3-0.32, 0.2-0.22

Hypervelocity stars (HVSs) are stars ejected from the Galactic Centre (GC) through tidal interactions with the central supermassive black hole. Formed in the immediate vicinity of Sgr~A$^\ast$, these stars are accelerated to velocities high enough to escape the GC and be observable in the Galactic halo. Using spectroscopy from the Dark Energy Spectroscopic Instrument (DESI) and astrometry from Gaia, we conducted a six-dimensional search for HVSs and identified a compelling candidate, hereafter DESI-312, whose bound trajectory can be confidently traced back to the central 2 kpc of our galaxy. The star resides in the inner halo and exhibits supersolar metallicity ([Fe/H] $= 0.27\pm 0.09$), distinct from other known stellar populations with radial orbits. Its inferred GC ejection velocity of $698^{+35}_{-27}$ is consistent with a Hills mechanism ejection, supporting an origin in the innermost regions of the Milky Way. We considered alternative origins for the star, including disk ejections from young clusters and globular clusters, but these scenarios fail to explain both its orbit and metallicity. Unlike previously identified A- and B-type HVSs, DESI-312 is a $\sim 1\,M_{\odot}$ star

The evolution of the orbits of bodies ejected from the Earth has been studied at the stage of its accumulation and early evolution after impacts of large planetesimals. In the considered variants of calculations of the motion of bodies ejected from the Earth, most of the bodies left the Hill sphere of the Earth and moved in heliocentric orbits. Their dynamical lifetime reached several hundred million years. At higher ejection velocities vej the probabilities of collisions of bodies with the Earth and Moon were generally lower. Over the entire considered time interval at the ejection velocity vej, equal to 11.5, 12 and 14 km/s, the values of the probability of a collision of a body with the Earth were approximately 0.3, 0.2 and 0.15-0.2, respectively. At ejection velocities vej<11.25 km/s, i.e., slightly exceeding a parabolic velocity, most of the ejected bodies fell back to the Earth. The probability of a collision of a body ejected from the Earth with the Moon moving in its present orbit was approximately 15-35 times less than that with the Earth at vej>11.5 km/s. The probability of a collision of such bodies with the Moon was mainly about 0.004-0.008 at ejection velocities

Dynamical interactions between stars and the super massive black hole Sgr A* at the Galactic Centre (GC) may eject stars into the Galactic halo. While recent fast ejections by Sgr A* have been identified in the form of hypervelocity stars (hundreds to thousands km/s), it is also expected that the stellar halo contains slower stars, ejected over the last few billion years. In this study, we use the first data release of DESI to search for these slower GC ejecta, which are expected to stand out from the stellar halo population for their combined high metallicity (${\rm [Fe/H]}\gtrsim0$) and small values of their vertical angular momentum ($L_Z$), whose distribution should peak at zero. Our search does not yield a detection, but allows us to place an upper limit on the ejection rate of stars from the GC of $\sim2.8\times10^{-3}$ yr$^{-1}$ over the past ~5 Gyr, which is ejection model independent. This implies that our result can be used to put constraints on different ejection models, including that invoking mergers of Sgr A* with other massive black holes in the last last few billion years.

Within the RoadMap project we investigated the microphysical aspects of particle collisions during saltation on the Martian surface in laboratory experiments. Following the size distribution of ejected particles, their aerodynamic properties and aggregation status upon ejection, we now focus on the electrification and charge distribution of ejected particles. We analyzed rebound and ejection trajectories of grains in a vacuum setup with a strong electric field of 100 kV/m and deduced particle charges from their acceleration. The ejected particles have sizes of about 10 to 100 microns. They carry charges up to $10^5$ e or charge densities up to $> 10^7$ e/mm$^2$. Within the given size range, we find a small bias towards positive charges.

Protostellar outflows often present a knotty appearance, providing evidence of sporadic accretion in stellar mass growth. To understand the direct relation between mass accretion and ejection, we analyze the contemporaneous accretion activity and associated ejection components in B335. B335 has brightened in the mid-IR by 2.5 mag since 2010, indicating increased luminosity, presumably due to increased mass accretion rate onto the protostar. ALMA observations of 12CO emission in the outflow reveal high-velocity emission, estimated to have been ejected 4.6 - 2 years before the ALMA observation and consistent with the jump in mid-IR brightness. The consistency in timing suggests that the detected high-velocity ejection components are directly linked to the most recent accretion activity. We calculated the kinetic energy, momentum, and force for the ejection component associated with the most recent accretion activity and found that at least, about 1.0% of accreted mass has been ejected. More accurate information on the jet inclination and the temperature of the ejected gas components will better constrain the ejected mass induced by the recently enhanced accretion event.

Feedback processes are expected to shape galaxy evolution by ejecting gas from galaxies and their associated dark matter haloes, and also by preventing diffuse gas from ever being accreted. We present predictions from the EAGLE simulation project for the mass budgets associated with "ejected" and "prevented" gas, as well as for ejected metals. We find that most of the baryons that are associated with haloes of mass $10^{11} < M_{200} \, /\mathrm{M_\odot} < 10^{13}$ at $z=0$ have been ejected beyond the virial radius after having been accreted. When the gas ejected from satellites (and their progenitors) is accounted for, the combined ejected mass represents half of the total baryon budget even in the most massive simulated galaxy clusters ($M_{200} \approx 10^{14.5} \, \mathrm{M_\odot}$), with the consequence that the total baryon budget exceeds the cosmic average if ejected gas is included. We find that gas is only prevented from being accreted onto haloes for $M_{200} < 10^{12} \, \mathrm{M_\odot}$, and that this component accounts for about half the total baryon budget for $M_{200} < 10^{11} \, \mathrm{M_\odot}$, with ejected gas making up most of the remaining half.

Using a high-resolution cosmological $N$-body simulation, we identify the ejected population of subhalos, which are halos at redshift $z=0$ but were once contained in more massive `host' halos at high redshifts. The fraction of the ejected subhalos in the total halo population of the same mass ranges from 9% to 4% for halo masses from $\sim 10^{11}$ to $\sim 10^{12}\msun$. Most of the ejected subhalos are distributed within 4 times the virial radius of their hosts. These ejected subhalos have distinct velocity distribution around their hosts in comparison to normal halos. The number of subhalos ejected from a host of given mass increases with the assembly redshift of the host. Ejected subhalos in general reside in high-density regions, and have a much higher bias parameter than normal halos of the same mass. They also have earlier assembly times, so that they contribute to the assembly bias of dark matter halos seen in cosmological simulations. However, the assembly bias is {\it not} dominated by the ejected population, indicating that large-scale environmental effects on normal halos are the main source for the assembly bias.

The orbital architecture of the Solar System is thought to have been sculpted by a dynamical instability among the giant planets. During the instability a primordial outer disk of planetesimals was destabilized and ended up on planet-crossing orbits. Most planetesimals were ejected into interstellar space but a fraction were trapped on stable orbits in the Kuiper belt and Oort cloud. We use a suite of N-body simulations to map out the diversity of planetesimals' dynamical pathways. We focus on two processes: tidal disruption from very close encounters with a giant planet, and loss of surface volatiles from repeated passages close to the Sun. We show that the rate of tidal disruption is more than a factor of two higher for ejected planetesimals than for surviving objects in the Kuiper belt or Oort cloud. Ejected planetesimals are preferentially disrupted by Jupiter and surviving ones by Neptune. Given that the gas giants contracted significantly as they cooled but the ice giants did not, taking into account the thermal evolution of the giant planets decreases the disruption rate of ejected planetesimals. The frequency of volatile loss and extinction is far higher for ejected planete

We present a sample of normal type Ia supernovae from the Nearby Supernova Factory dataset with spectrophotometry at sufficiently late phases to estimate the ejected mass using the bolometric light curve. We measure $^{56}$Ni masses from the peak bolometric luminosity, then compare the luminosity in the $^{56}$Co-decay tail to the expected rate of radioactive energy re- lease from ejecta of a given mass. We infer the ejected mass in a Bayesian context using a semi-analytic model of the ejecta, incorporating constraints from contemporary numerical models as priors on the density structure and distribution of $^{56}$Ni throughout the ejecta. We find a strong correlation between ejected mass and light curve decline rate, and consequently $^{56}$Ni mass, with ejected masses in our data ranging from 0.9-1.4 $M_\odot$. Most fast-declining (SALT2 $x_1 < -1$) normal SNe Ia have significantly sub-Chandrasekhar ejected masses in our fiducial analysis.

Galaxies that are several virial radii beyond groups/clusters show preferentially quiescent star formation rates. Using a galaxy group/cluster catalog from the Sloan Digital Sky Survey, together with a cosmological N-body simulation, we examine the origin of this environmental quenching beyond the virial radius. Accounting for the clustering of groups/clusters, we show that central galaxies show enhanced SFR quenching out to 2.5 virial radii beyond groups/clusters, and we demonstrate that this extended environmental enhancement can be explained simply by 'ejected' satellite galaxies that orbit beyond their host halo's virial radius. We show that ejected satellites typically orbit for several Gyr beyond the virial radius before falling back in, and thus they compose up to 40% of all central galaxies near groups/clusters. We show that a model in which ejected satellites experience the same SFR quenching as satellites within a host halo can explain essentially all environmental dependence of galaxy quenching. Furthermore, ejected satellites (continue to) lose significant halo mass, an effect that is potentially observable via gravitational lensing. The SFRs/colors and stellar-to-halo

R144 is a recently confirmed very massive, spectroscopic binary which appears isolated from the core of the massive young star cluster R136. The dynamical ejection hypothesis as an origin for its location is claimed improbable by Sana et al. due to its binary nature and high mass. We demonstrate here by means of direct N-body calculations that a very massive binary system can be readily dynamically ejected from a R136-like cluster, through a close encounter with a very massive system. One out of four N-body cluster models produces a dynamically ejected very massive binary system with a mass comparable to R144. The system has a system mass of $\approx$ 355 Msun and is located at 36.8 pc from the centre of its parent cluster, moving away from the cluster with a velocity of 57 km/s at 2 Myr as a result of a binary-binary interaction. This implies that R144 could have been ejected from R136 through a strong encounter with an other massive binary or single star. In addition, we discuss all massive binaries and single stars which are ejected dynamically from their parent cluster in the N-body models.

Performing N-body simulations, we examine the dynamics of BH-BH (10 Msun each) and NS-NS (1.4 Msun each) binaries formed in a cluster and its implications for gravitational wave detection. A significant fraction of compact binaries are ejected from a globular cluster after core collapse. Among the total number of ejected compact objects, 30 per cent of them are in binaries. Merging time-scales of ejected binaries, which depend on the cluster's velocity dispersion, are in some cases shorter than the age of the universe. During the merging event, these dynamically formed compact mergers are expected to produce gravitational waves that can be detectable by the advanced ground-based interferometers. Based on our reference assumptions, merger rates of ejected BH-BH and NS-NS binaries per globular cluster are estimated to be 2.5 and 0.27 per Gyr, respectively. Assuming the spatial density of globular clusters to be 8.4 h^3 clusters Mpc^-3 and extrapolating the merger rate estimates to the horizon distance of the advanced LIGO-Virgo network, we expect the detection rates for BH-BH and NS-NS binaries with cluster origin are to be 15 and 0.024 yr^-1, respectively. We find out that some of t

We explore the population of mass-transferring binaries ejected from globular clusters (GCs) with both black hole (BH) and neutron star (NS) accretors. We use a set of 137 fully evolved globular cluster models which span a large range in cluster properties and, overall, match very well the properties of old GCs observed in the Milky Way. We identify all binaries ejected from our set of models that eventually undergo mass-transfer. These binaries are ejected from their host clusters over a wide range of ejection times and include white dwarf, giant, and main sequence donors. We calculate the orbits of these ejected systems in the Galactic potential to determine their present-day positions in the Galaxy and compare to the distribution of observed low-mass X-ray binaries (XRBs) in the Milky Way. We estimate $\sim 300$ mass-transferring NS binaries and $\sim 180$ mass-transferring BH binaries may currently be present in the Milky Way that originated from within GCs. Of these, we estimate, based on mass-transfer rates and duty cycles at the present time, at most a few would be observable as BH--XRBs and NS--XRBs at the present day. Based on our results, XRBs that originated from GCs are

Hypervelocity stars have been recently discovered in the outskirts of galaxies, such as the unbound star in the Milky Way halo, or the three anomalously fast intracluster planetary nebulae (ICPNe) in the Virgo Cluster. These may have been ejected by close 3-body interactions with a binary supermassive black hole (SMBBH), where a star which passes within the semimajor axis of the SMBBH can receive enough energy to eject it from the system. Stars ejected by SMBBHs may form a significant sub-population with very different kinematics and mean metallicity than the bulk of the intracluster stars. The number, kinematics, and orientation of the ejected stars may constrain the mass ratio, semimajor axis, and even the orbital plane of the SMBBH. We investigate the evolution of the ejected debris from a SMBBH within a clumpy and time-dependent cluster potential using a high resolution, self-consistent cosmological N-body simulation of a galaxy cluster. We show that the predicted number and kinematic signature of the fast Virgo ICPNe is consistent with 3-body scattering by a SMBBH with a mass ratio $10:1$ at the center of M87.

According to recent general-relativistic simulations, the coalescence of two spinning black holes (BHs) could lead to recoil speeds of the BH remnant of up to thousands of km/s as a result of the emission of gravitational radiation. Such speeds would enable the merger product to escape its host galaxy. Here we examine the circumstances resulting from a gas-rich galaxy merger under which the ejected BH would carry an accretion disk with it and be observable. As the initial BH binary emits gravitational radiation and its orbit tightens, a hole is opened around it in the disk which delays the consumption of gas prior to the eventual BH ejection. The punctured disk remains bound to the ejected BH within the region where the gas orbital velocity is larger than the ejection speed. For a ~10^7 solar mass BH the ejected disk has a characteristic size of tens of thousands of Schwarzschild radii and an accretion lifetime of ~10^7 years. During that time, the ejected BH could traverse a considerable distance and appear as an off-center quasar with a feedback trail along the path it left behind. A small fraction of all quasars could be associated with an escaping BH.