Close Encounters Research Articles

Filmmaking as ‘Meaning-Making’ Activity: Robert Kegan’s Developmental Theory and Its Implications for Training Film Directing Students

Robert Kegan’s The Evolving Self: Problem and Process in Human Development (1982) is a psychological theory on personality development that is centered around the idea of meaning-making as the primordial activity of existence, and which proposes an understanding of the ways we conceptualize our self and other according to our current stage of development, with relevant implications for many types of care work, including education. This theory is presented here in the context of film education for film-directing university students, for which it hopes to inspire a more student-centered approach, which values process over outcome. As many of the professional abilities that are sought after in the training of film-directing students can be seen as intra- and interpersonal abilities, the conceptualization of self and other becomes especially relevant in this particular educational setup, where working with the students involves a close encounter, insufficiently recognized, with their meaning-making activity. This also brings into discussion the way we model ideals for teachers in terms of their own personal development and the role that the film school as an institution could play in this matter.

Japanese Acrobats as Athletes on the Victorian Stage: The Victorian Reception of Japanese Acrobatic Troupes, 1867–70

Abstract This article positions Japanese acrobats as athletes—rather than just performers—in the context of the rise of sports and athletic competitions in England, arguing that displays of Japanese athleticism onstage complicated Victorians’ sense of superiority over non-Western peoples. As the first Japanese people with whom many Britons at home had close encounters, Japanese acrobatic troupes shaped Victorian perceptions of Japan. This survey of Victorian periodicals unpacks how the Victorian reception of Japanese acrobatic troupes in the late 1860s refracted British beliefs about themselves in relation to the Japanese people.

Direct Measurements of Synchrotron-emitting Electrons at Near-Sun Shocks

In this study, we present the first-ever direct measurements of synchrotron-emitting heliospheric traveling shocks, intercepted by the Parker Solar Probe (PSP) during its close encounters. Given that much of our understanding of powerful astrophysical shocks is derived from synchrotron radiation, these observations by PSP provide an unprecedented opportunity to explore how shocks accelerate relativistic electrons and the conditions under which they emit radiation. The probe’s unparalleled capabilities to measure both electromagnetic fields and energetic particles with high precision in the near-Sun environment has allowed us to directly correlate the distribution of relativistic electrons with the resulting photon emissions. Our findings reveal that strong quasi-parallel shocks emit radiation at significantly higher intensities than quasi-perpendicular shocks due to the efficient acceleration of ultrarelativistic electrons. These experimental results are consistent with theory and recent observations of supernova remnant shocks and advance our understanding of shock physics across diverse space environments.

Close encounter of three black holes. III

Close encounter of three black holes. III

Close Encounters of the Archival Kind: Affect and Transnational Solidarities in African Diaspora Archives

Recent explorations of affect in the archives have focused on the experiences of users and particularly the distress archival collections could possibly cause them. Perhaps because they have, until recently, been trained to think of themselves as engaged in objective and neutral work collecting and preserving memory, archivists rarely reflect on or talk about their work, how they engage with the materials they manage, and how they personally feel about what they encounter in the course of their professional lives. Using an autoethnographic conceptual framing, this article uses four archival encounters in the Manuscripts, Archives and Rare Books Division of the Schomburg Center for Research in Black Culture to reflect on affect in the archives invoked by archival work. Through these encounters, the article seeks to demonstrate archives of the African diaspora as both a locus of transnational African diasporic identities and solidarities, as well as a critical site for the (re)building of the same. Finally, it also hints at how such affective experiences can, in fact, further the cultural and political work of Black archivists and archives.

A comparative study of the blue comets C/1908 R1 (Morehouse) and C/2016 R2 (Pan-STARRS)

The long-period comet C/1908 R1 (Morehouse) is distinguished by its early spectroscopic tail photography, which uncovered notably intense emission bands of N2+ and CO+ similar to the unusual characteristics of the atypical blue comet C/2016 R2 (Pan-STARRS). To probe potential parallels with C/2016 R2 further, we revisited the historical spectroscopic plates of C/1908 R1 while leveraging the New Astrometric Reduction of Old Observations (NAROO) project's advanced sub-micrometric scanner. We first reviewed the intensity ratio method, followed by a comprehensive spectroscopic analysis of the original historical plates to determine the comet's composition. Our analysis also encompassed an evaluation of C/1908 R1's dynamic trajectory using an N-body integrator and a detailed examination of tail morphology records. Our findings suggest that C/1908 R1 experienced no significant close encounters as it crossed the inner Solar System, anchoring its origins directly in the Oort Cloud and allowing us to ascertain that this was its inaugural voyage near the Sun. We determined a N2+ CO+ ratio of $ along with a dust-poor composition, particularities it shares with C/2016 R2. Moreover, by synthesizing observations of the tail's structure over the three-month period of visibility, we uncovered a link between tail dislocation events and aurora borealis sightings on Earth. This association underscores the comet tail’s heightened sensitivity to solar wind fluctuations due to its volatile makeup. The comet C/1908 R1 (Morehouse) emerges as one of the most unaltered relics of our Solar System's formation, offering another instance of a C/2016 R2-analogous comet. This underscores the importance of preserving and reexamining historical astronomical datasets, not only for historical significance but as a critical resource for contemporary scientific advancement.

Mass octupole and current quadrupole corrections to gravitational wave emission from close hyperbolic encounters

Abstract In this paper, we study the next-to-leading order corrections in the mass multipole expansion, i.e. the mass octupole and current quadrupole, to gravitational wave production by close hyperbolic encounters of compact objects. We find that the signal is again, as in the simple quadrupole case, a burst event with the majority of the released energy occurring during the closest approach. In particular, we investigate the relative contribution to the power, both in the time and frequency domains, and total energy emitted by each order in the mass multipole expansion in gravitational waves. To do so, we include in the quadrupole term its first order post-Newtonian correction, giving this a contribution to the power of the same order as that of the mass octupole and the current quadrupole. We find specific configurations of systems where these corrections could be important and should be taken into account when analysing burst events.

Close Encounters of the Feathered Kind: Orpheus and the Birds

Birds were observed in divinatory rituals in antiquity. This was the most significant process that regularly involved looking closely at birds. At the same time, birds were intimately connected to human perceptions of the natural world and, through their capacity to ascend skywards, with the supernatural world. By studying two neighbouring areas connected by the myth of Orpheus and divinatory birds, we can begin to appreciate the role of birds (and bird-like beings) in the culture of Macedonia and Thrace. Birds played a central role in prophecy (ornithomancy). Literary, archaeological and zooarchaeological data from the 6th to 4th centuries BCE provide the means of uniting different types of evidence. The literary and archaeological evidence provides a broad perspective for understanding the still-limited zooarchaeological data. Birds of prey were among the key divinatory creatures regularly observed, while cranes and a variety of lacustrine and meadow birds were among those most regularly observed and hunted. Winged creatures (human–animal hybrids) form some of the most important creations of the human imagination in southern Europe, with distinctive local variants in Macedonia and Thrace.

Analytical Models for Secular Descents in Hierarchical Triple Systems

Three-body systems are prevalent in nature, from planetary to stellar to supermassive black hole scales. In a hierarchical triple system, oscillations of the inner orbit’s eccentricity and inclination can be induced on secular timescales. Over many cycles, the octupole-level terms in the secular equations of motion can drive the system to extremely high eccentricities via the eccentric Kozai–Lidov (EKL) mechanism. The overall decrease in the inner orbit’s pericenter distance has potentially dramatic effects for realistic systems, such as tidal disruption events. We present an analytical approximation in the test-particle limit to describe individual stepwise increases in eccentricity of the inner orbit. A second approximation, also in the test-particle limit, is obtained by integrating the equations of motion and calibrating to numerical simulations to estimate the overall octupole-level time evolution of the eccentricity. The latter approach is then extended beyond the test particle to the general case. The three novel analytical approximations are compared to numerical solutions to show that the models accurately describe the form and timescale of the secular descent from large distances to a close-encounter distance (e.g., the Roche limit). By circumventing the need for numerical simulations to obtain the long-term behavior, these approximations can be used to readily estimate properties of close encounters and descent timescales for populations of systems. We demonstrate this by calculating rates of EKL-driven migration for Hot Jupiters in stellar binaries.

Study of Knowledge, Attitude, and Practices of Use of Masks among Health-care Workers at a Tertiary Care Center in Mumbai

ABSTRACT Introduction: Airborne transmission of infectious diseases poses a significant public health challenge. Nosocomial outbreaks of airborne infections such as influenza H1N1, H5N1, and drug-resistant tuberculosis (TB) variants have been documented, with substantial morbidity and mortality attributed to inadequate airborne infection control strategies. N-95 respirators and surgical masks (face masks) are the examples of personal protective equipment that are used to protect the wearer from airborne particles and liquid contamination of the face. Aim and Objectives: The aim of this study was to assess the knowledge, practices, and attitude of health-care workers (HCWs) regarding the use of mask, especially N-95 mask. Materials and Methods: A prospective, was conducted over a period of 6 months at a tertiary care hospital. This study was carried out in the department of microbiology of a tertiary care hospital over a period of 6 months. A total of 500 HCWs from various departments of the hospital were included in the study. HCWs were given a questionnaire based on N-95 respirator usage, and participation was voluntary. Results: The analysis of survey data provides insightful perspectives on respondents’ comprehension and attitudes toward airborne infection transmission and the usage of N-95 masks. 68.6% of respondents recognized that all listed diseases (measles, TB, and chickenpox) were spread by the airborne route. 55.6% of respondents correctly acknowledged that all masks, including surgical masks, N-95 masks, and cotton masks, do not offer airborne protection. 76.0% of respondents acknowledged that N-95 masks possess a high filtration efficiency against 0.3-micron particles, 58.3% correctly identified that “N” in N-95 stands for “not resistant to oil,” and 90.8% acknowledged that the N-95 respirator as the most common type of respirators. 41.7% correctly acknowledged that N-95 masks with an exhalation valve are not recommended for use. 22.2% of respondents incorrectly believe that wearing a face mask can lead to carbon dioxide poisoning, and 52.1% of respondents correctly identified that pulmonary TB patients need not be provided with N-95 masks in isolation rooms. 76.8% of respondents understood that fit testing is required every time one dons an N-95 mask. 95.5% of respondents recognized the necessity of hand hygiene before donning and after doffing N-95 masks. 82.7% of respondents agreed regarding the necessity for consultation before N-95 mask usage for chronic lung disease and asthma patients. 93.7% are aware that there is a protocol for donning and doffing N-95 masks. 71.3% of respondents understood that extended use involves wearing the same N-95 respirator for repeated close contact encounters without removing the mask between patient encounters, while 64.4% correctly define reuse as using the same N-95 respirator for multiple encounters but removing it after each encounter.

Citizen Scientists Discover “Asteroid in a Cometary Orbit” 2010 MK43 has a Comet Tail

We present the discovery of a short, diffuse tail on minor planet 2010 MK43 (alternate designation 2010 RA78)—an object previously identified as an asteroid in a cometary orbit—by volunteers of our Citizen Science program Active Asteroids. Our follow-up investigation revealed eight Dark Energy Camera images showing 2010 MK43 with a tail spanning UT 2024 February 12–UT 2024 February 18 when the object was outbound from perihelion. We now classify 2010 MK43 as a Jupiter-family comet based on its Tisserand parameter with respect to Jupiter T J = 2.888, though our dynamical simulations reveal that, due to frequent close encounters with Jupiter, 2010 MK43 was likely a quasi-Hilda within the last 10 kyr.

Kinematic study of the orion complex: Analysing the young stellar clusters from big and small structures

Abstract In this work, we analysed young stellar clusters with spatial and kinematic coherence in the Orion star-forming complex. For this study, we selected a sample of pre-main sequence candidates using parallaxes, proper motions and positions on the colour-magnitude diagram. After applying a hierarchical clustering algorithm in the 5D parameter space provided by Gaia DR3, we divided the recovered clusters into two regimes: Big Structures and Small Structures, defined by the number of detected stars per cluster. In the first regime, we found 13 stellar groups distributed along the declination axis in the regions where there is a high density of stars. In the second regime, we recovered 34 clusters classified into two types: 14 as small groups completely independent from the larger structures, including four candidates of new clusters, and 12 classified as sub-structures embedded within five larger clusters. Additionally, radial velocity data from APOGEE-2 and GALAH DR3 was included to study the phase space in some regions of the Orion complex. From the Big Structure regime, we found evidence of a general expansion in the Orion OB1 association over a common centre, giving a clue about the dynamical effects the region is undergoing. Likewise, in the Small Structure regime, the projected kinematics shows the ballistic expansion in the λ Orionis association and the detection of likely events of clusters’ close encounters in the OB1 association.

Close encounters of the primordial kind: A new observable for primordial black holes as dark matter

Close encounters of the primordial kind: A new observable for primordial black holes as dark matter

Parametric approximations of fast close encounters of the planar three-body problem as arcs of a focus-focus dynamics

Abstract A gravitational close encounter of a small body with a planet may produce a substantial change of its orbital parameters which can be studied using the circular restricted three-body problem. In this paper we provide parametric representations of the fast close encounters with the secondary body of the planar CRTBP as arcs of non-linear focus-focus dynamics. The result is the consequence of a remarkable factorisation of the Birkhoff normal forms of the Hamiltonian of the problem represented with the Levi–Civita regularisation. The parameterisations are computed using two different sequences of Birkhoff normalisations of given order N. For each value of N, the Birkhoff normalisations and the parameters of the focus-focus dynamics are represented by polynomials whose coefficients can be computed iteratively with a computer algebra system; no quadratures, such as those needed to compute action-angle variables of resonant normal forms, are needed. We also provide some numerical demonstrations of the method for values of the mass parameter representative of the Sun–Earth and the Sun–Jupiter cases.

QCD-gravity double-copy in the Regge regime: Shock wave propagators

In a previous paper [H. Raj and R. Venugopalan, ], we demonstrated a double-copy relation between inclusive gluon radiation in shock wave collisions of ultrarelativistic nuclei and inclusive graviton radiation in trans-Planckian gravitational shock wave collisions. We compute here the corresponding gravitational shock wave propagators in general relativity and demonstrate that they too obey a double-copy relation to gluon shock wave propagators computed previously. These results provide key input in a renormalization group approach toward computing the high frequency radiation spectrum in close black hole encounters. Published by the American Physical Society 2024

Magnetic field and kinetic helicity evolution in simulations of interacting disk galaxies

Context. There are indications that the magnetic field evolution in galaxies is influenced by tidal interactions and mergers between galaxies. Aims. We carried out a parameter study of interacting disk galaxies with impact parameters ranging from central collisions to weakly interacting scenarios. The orientations of the disks were also varied. In particular, we investigated how magnetic field amplification depends on these parameters. Methods. We used magnetohydrodynamics for gas disks in combination with live dark-matter halos in adaptive mesh refinement simulations. The disks were initialized using a setup for isolated disks in hydrostatic equilibrium. Since we focused on the impact of tidal forces on magnetic field evolution, adiabatic physics was applied. Small-scale filtering of the velocity and magnetic field allowed us to estimate the turbulent electromotive force (EMF) and kinetic helicity. Results. Time series of the average magnetic field in central and outer disk regions show pronounced peaks during close encounters and mergers. This agrees with observed magnetic fields at different interaction stages. The central field strength exceeds 10 μG (corresponding to an amplification factor of 2–3) for small impact parameters. As the disks are increasingly disrupted and turbulence is produced by tidal forces, the small-scale EMF reaches a significant fraction of the total EMF. The small-scale kinetic helicity is initially antisymmetric across the disk plane. Though its evolution is sensitive to both the impact parameter and inclinations of the rotation axes with respect to the relative motion of the disks, antisymmetry is generally broken through interactions and the merger remnant loses most of the initial helicity. The EMF and the magnetic field also decay rapidly after coalescence. Conclusions. The strong amplification during close encounters of the interacting galaxies is mostly driven by helical flows and a mean-field dynamo. The small-scale dynamo contributes significantly in post-interaction phases. However, the amplification of the magnetic field cannot be sustained.

Close Encounters of Wide Binaries Induced by the Galactic Tide: Implications for Stellar Mergers and Gravitational-wave Sources

A substantial fraction of stars can be found in wide binaries with projected separations between ∼102 and 105 au. In the standard lore of binary physics, these would evolve as effectively single stars that remotely orbit one another on stationary Keplerian ellipses. However, embedded in their Galactic environment, the low binding energy of wide binaries makes them exceptionally prone to perturbations from the gravitational potential of the Milky Way and encounters with passing stars. Employing a fully relativistic N-body integration scheme, we study the impact of these perturbations on the orbital evolution of wide binaries along their trajectory through the Milky Way. Our analysis reveals that the torques exerted by the Galaxy can cause large-amplitude oscillations of the binary eccentricity to 1 − e ≲ 10−8. As a consequence, the wide binary members pass close to each other at periapsis, which, depending on the type of binary, potentially leads to a mass transfer or collision of stars or to an inspiral and subsequent merger of compact remnants due to gravitational-wave radiation. Based on a simulation of 105 wide binaries across the Galactic field, we find that this mechanism could significantly contribute to the rate of stellar collisions and binary black hole mergers as inferred from observations of luminous red novae and gravitational-wave events by LIGO/Virgo/Kagra. We conclude that the dynamics of wide binaries, despite their large mean separation, can give rise to extreme interactions between stars and compact remnants.

NEOROCKS color survey: Final results

Context. Near-Earth objects (NEOs) are the most accessible small Solar System bodies by both spacecrafts and ground-based telescopes. Close encounters of these objects with Earth represent opportunities to characterize their physical and mineralogical properties. They are also a constant threat to humanity due to possible impact events with Earth. In this context, the NEOROCKS project has been financed by the European Union’s Horizon 2020 research and innovation program. Aims. We present the final results on photometry of the NEOROCKS project, with the aim of extending the dataset of surface colors for small NEOs with unknown properties and, when possible, characterizing newly discovered NEOs. Methods. Photometric observations were performed using the 1.2 m telescope at the Haute-Provence observatory (in France) in the BVRI filters of the Johnson-Cousins photometric systems between May 2022 and June 2023. The stability and dynamics of objects from the NEOROCKS database was investigated by numerical integration. Results. We obtained new surface colors for 83 NEOs. Overall, the NEOROCKS color database contains 170 objects. The majority of the objects in the dataset with diameters D<500 m belong to a group of silicate bodies. We estimated the unbalanced percentage between S- and C-type objects as an observational bias due to reflective proprieties of the surface of objects. The average of Lyapunov time of about 100 years is evidence of highly chaotic orbits of objects from the color database of NEOROCKS. Asteroid 2011 OL51 has a reasonable probability of being a parent body contributor to the October Capricornidis meteor shower. Asteroids 2004 HK33, 2022 VV (D-type), 2003 WR21, and 2017 SE1 (A-type) belong to end-member classes and have ΔV<7 km/s; thus, they are possible candidates for in situ investigations.

Intraspecific encounters can lead to reduced range overlap

Direct encounters, in which two or more individuals are physically close to one another, are a topic of increasing interest as more and better movement data become available. Recent progress, including the development of statistical tools for estimating robust measures of changes in animals’ space use over time, facilitates opportunities to link direct encounters between individuals with the long-term consequences of those encounters. Working with movement data for coyotes (Canis latrans) and grizzly bears (Ursus arctos horribilis), we investigate whether close intraspecific encounters were associated with spatial shifts in the animals’ range distributions, as might be expected if one or both of the individuals involved in an encounter were seeking to reduce or avoid conflict over space. We analyze the movement data of a pair of coyotes in detail, identifying how a change in home range overlap resulting from altered movement behavior was apparently a consequence of a close intraspecific encounter. With grizzly bear movement data, we approach the problem as population-level hypothesis tests of the spatial consequences of encounters. We find support for the hypotheses that (1) close intraspecific encounters between bears are, under certain circumstances, associated with subsequent changes in overlap between range distributions and (2) encounters defined at finer spatial scales are followed by greater changes in space use. Our results suggest that animals can undertake long-term, large-scale spatial changes in response to close intraspecific encounters that have the potential for conflict. Overall, we find that analyses of movement data in a pairwise context can (1) identify distances at which individuals’ proximity to one another may alter behavior and (2) facilitate testing of population-level hypotheses concerning the potential for direct encounters to alter individuals’ space use.

TRACE: a code for time-reversible astrophysical close encounters

Abstract We present TRACE, an almost time-reversible hybrid integrator for the planetary N-body problem. Like hybrid symplectic integrators, TRACE can resolve close encounters between particles while retaining many of the accuracy and speed advantages of a fixed timestep symplectic method such the Wisdom–Holman map. TRACE switches methods time-reversibly during close encounters following the prescription of Hernandez & Dehnen. In this paper we describe the derivation and implementation of TRACE and study its performance for a variety of astrophysical systems. In all our test cases TRACE is at least as accurate and fast as the hybrid symplectic integrator MERCURIUS. In many cases TRACE’s performance is vastly superior to that of MERCURIUS. In test cases with planet-planet close encounters, TRACE is as accurate as MECURIUS with a 12x speedup. If close encounters with the central star are considered, TRACE achieves good error performance while MERCURIUS fails to give qualitatively correct results. In ensemble tests of violent scattering systems, TRACE matches the high-accuracy IAS15 while providing a 15x speed-up. In large N systems simulating lunar accretion, TRACE qualitatively gives the same results as IAS15 but at a 41x speedup. We also discuss some cases such as von Zeipel-Lidov-Kozai cycles where hybrid integrators perform poorly and provide some guidance on which integrator to use for which system. TRACE is freely available within the REBOUND package.