Presence Of Third Body Research Articles

HST astrometry of the closest brown dwarfs‐II. Improved parameters and constraints on a third body

AbstractLocated at less than two pc away, Luhman 16 AB (WISE J104915.57‐531906.1) is the closest pair of brown dwarfs and the third closest “stellar” system to Earth. An exoplanet candidate in the Luhman 16 binary system was reported in 2017 based on a weak astrometric signature in the analysis of 12 HST epochs. An additional epoch collected in 2018 and re‐analysis of the data with more advanced methods further increased the significance level of the candidate, consistent with a Neptune‐mass exoplanet orbiting one of the Luhman 16 brown dwarf components. We report the joint analysis of these previous data together with two new astrometric HST epochs we obtained to confirm or disprove this astrometric signature. Our new analysis rules out the presence of a planet orbiting one component of the Luhman 16 AB system for masses 1.5 M♆ (Neptune masses) and periods between 400 and 5000 days. However, the presence of third bodies with masses 3 M♆ and periods between 2 and 400 days (1.1 years) cannot be excluded. Our measurements make significant improvements to the characterization of this sub‐stellar binary, including its mass‐ratio 0.8305 , individual component masses 35.40.2 MꝜ and 29.40.2 MꝜ (Jupiter masses), and parallax distance 1.9960 pc 50 AU. Comparison of the masses and luminosities of Luhman 16 AB to several evolutionary models shows persistent discrepancies in the ages of the two components, but strengthens the case that this system is a member of the 51095 Myr Oceanus Moving Group.

Global parameters of the W UMa stars FI Lyn, UV Lyn, and NSVS 781878

AbstractPhotometric and spectral observations of the W UMa binaries FI Lyn, UV Lyn, and NSVS 781878 with periods of around 9.5–10 hr were carried out in order to determine their global parameters by simultaneous light curve and radial velocity curve solutions. We found that the three targets have shallow‐contact configurations with close in mass and radius components. UV Lyn is of W‐subtype, NSVS 781878 is of A‐subtype, while FI Lyn may be considered as binary in thermal contact. Our data show evidences of photospheric activity of the targets but not of emission in the Hα line. The surface inhomogeneity of UV Lyn is stable during the last several decades. Its O–C diagram implies presence of third body with a period of 24 years. The distances of FI Lyn, UV Lyn, and NSVS 781878 calculated from the derived luminosities coincide with those obtained by GAIA astrometrically.

Circumbinary planet study around NSVS 14256825

The period variability of (O-C) diagram of an eclipsing binary, NSVS 14256825, which is composed of a hot subdwarf type OB star (sdOB) and a main-sequence low-mass type M star (dM) in close orbit with period P=0.110374 days, previously showed sinusoidal signal cause by the light travel time effects. This signal can be caused by the presence of third bodies. We re-examined (O-C) diagram of the system. We combined eclipse timings from published data and the data taken from ULTRASPEC at 2.4 m at Thai National Telescope on November 2018. From the fitting model, the parameters of the third body in NSVS 14256825 system are obtained.

Retrieval analysis of TiN (titanium nitride) coated knee replacements: Coating wear and degradation in vivo.

Titanium nitride (TiN) coatings are used in joint arthroplasty to minimize wear and reduce the allergenic potential of metal implants, yet little is known about their performance in knee arthroplasty. This retrieval study examined TiN coated knee replacements to verify in vivo wear and degradation of the coating. This study included total and unicompartmental mobile bearing knee replacements retrieved from five patients (eight components) after 13-21 months due to aseptic loosening or infection. Implants were examined using scanning (SEM) and optical microscopy, surface damage was assessed using a semiquantitative scoring system, adhesion was determined using indentation technique testing, surface roughness was measured using contact profilometry. Although good coating adhesion and no gross failure were observed on all retrievals, coating wear and roughening were evident on tibial bearing surfaces. Multiple microscopic defects (pinholes, craters, titanium droplets) were observed on all samples in SEM studies. Microscopic wear scars indicated that particulate defects significantly contributed to coating wear, acting as third bodies. TiN coatings of knee replacements undergo wear and degradation related to presence of third bodies and microscopic defects on their surface. Since coating integrity may be compromised in vivo, such implants should be used with caution in metal sensitive patients.

The astrophysical science case for a decihertz gravitational-wave detector

We discuss the astrophysical science case for a decihertz gravitational-wave mission. We focus on unique opportunities for scientific discovery in this frequency range, including probes of type IA supernova progenitors, mergers in the presence of third bodies, intermediate mass black holes, seeds of massive black holes, improved sky localization, and tracking the population of merging compact binaries.

Physical properties and catalog of EW-type eclipsing binaries observed by LAMOST

EW-type eclipsing binaries (hereafter called EWs) are strong interacting systems in which both component stars usually fill their critical Roche lobes and share a common envelope. Numerous EWs were discovered by several deep photometric surveys and there were about 40 785 EW-type binary systems listed in the international variable star index (VSX) by 2017 March 13. 7938 of them were observed with LAMOST by 2016 November 30 and their spectral types were identified. Stellar atmospheric parameters of 5363 EW-type binary stars were determined based on good spectroscopic observations. In the paper, those EWs are cataloged and their properties are analyzed. The distributions of orbital period (P), effective temperature (T), gravitational acceleration (log(g)), metallicity ([Fe/H]) and radial velocity (RV) are presented for these observed EW-type systems. It is shown that about 80.6% of sample stars have metallicity below zero, indicating that EW-type systems are old stellar populations. This is in agreement with the conclusion that EW binaries are formed from moderately close binaries through angular momentum loss via magnetic braking that takes a few hundred million to a few billion years. The unusually high metallicities of a few percent of EWs may be caused by contamination of material from the evolution of unseen neutron stars or black holes in the systems. The correlations between orbital period and effective temperature, gravitational acceleration and metallicity are presented and their scatters are mainly caused by (i) the presence of third bodies and (ii) sometimes wrongly determined periods. It is shown that some EWs contain evolved component stars and the physical properties of EWs mainly depend on their orbital periods. It is found that extremely short-period EWs may be older than their long-period cousins because they have lower metallicities. This reveals that they have a longer timescale of pre-contact evolution and their formation and evolution aremainly driven by angular momentum loss via magnetic braking.

Hubble Space Telescope astrometry of the closest brown dwarf binary system – I. Overview and improved orbit★

Located at ~2pc, the L7.5+T0.5 dwarfs system WISE J104915.57-531906.1 (Luhman16AB) is the third closest system known to Earth, making it a key benchmark for detailed investigation of brown dwarf atmospheric properties, thermal evolution, multiplicity, and planet-hosting frequency. In the first study of this series -- based on a multi-cycle Hubble Space Telescope (HST) program -- we provide an overview of the project and present improved estimates of positions, proper motions, annual parallax, mass ratio, and the current best assessment of the orbital parameters of the A-B pair. Our HST observations encompass the apparent periastron of the binary at 220.5+/-0.2 mas at epoch 2016.402. Although our data seem to be inconsistent with recent ground-based astrometric measurements, we also exclude the presence of third bodies down to Neptune masses and periods longer than a year.

First period investigation and light-curve study of the eclipsing contact binary V776 Cas

CCD photometry of the eclipsing binary system V776 Cas was carried out through Johnson-Cousins UBVR filters in Dr. Mojtahedi observatory of Birjand University during August and September 2014. The physical and geometrical parameters of the system were obtained by analyzing the light curves. Radial velocity data were used to determine the absolute parameters. Five new times of minimum light were found. The O-C diagram was plotted relying on these times and the previously reported times of minimum. New ephemeris of the system, the rate of orbital period variations and the mass transfer rate of the system were derived from the O-C diagram analysis. A periodic variation of about 8 years was found from the O-C diagram analysis. At first light-time effect was considered. Although the results confirmed the probability of the presence of third body, Applegate mechanism was checked as the reason for this periodic variation and this mechanism is also in agreement with the observations.

An elastic–plastic investigation of third body effects on fretting contact in partial slip

In this investigation, the third body effects in fretting contact is modeled using the commercially available ABAQUS finite element (FE) software. A two dimensional Hertzian line contact model is simulated in the presence of third bodies at the contact interface. The third bodies are modeled using simplified geometry like cylinders. Elastic–plastic material properties are used to model both the first bodies and third bodies. The FE model is used to investigate fretting phenomena under different displacement amplitudes and the influence of third body particles on contact stress and contact slip. In addition, the effects of different factors such as material properties of the third bodies and number of third body particles on fretting are investigated. Fretting loops obtained from the model show notable differences in shear stress distribution when compared to smooth Hertzian line contacts in the absence of third body particles. The results indicate that the third bodies deformed to platelet like structures as observed in experiments. The obtained results also indicate that contact stress decreases with the increase in the number of third bodies. As the number of third bodies in contact is increased, the contact shear force between the first bodies decreases while the contact slip increases. Due to this phenomenon, the dissipated energy is not affected and therefore does not influence fretting wear rate significantly. Although fretting wear rate is not directly influenced by the presence of third bodies, plastic deformation of the first body surfaces influences contact parameters which in turn impacts fretting wear.

Retrieval analysis of titanium nitride (TiN) coated prosthetic femoral heads articulating with polyethylene

Data regarding in vivo performance of titanium nitride (TiN) coated prosthetic femoral heads is scarce, and available studies of older generations of implants demonstrated coating wear in vivo. That is why we conducted a retrieval analysis of 11 femoral heads (articulating in vivo for 1–56 months) with TiN film formed using physical vapor deposition (PVD), to verify if coating failure is a problem in contemporary implants. Retrieved implants were examined using scanning electron microscope, coating roughness was evaluated with a contact profilometer and adhesion was tested using a Rockwell HRC test according to VDI 3824 guideline. Although no gross failure of the TiN coating was observed in our retrievals, all implants had defects typical for PVD coatings, such as pinholes, small titanium droplets and blisters with delaminated coating. In some heads the coating was contaminated with small niobium (Nb) droplets uniformly scattered on the entire surface of the film. Presence of Nb contamination was associated with an increased number and area of other types of defects and poorer coating adhesion. In one component, subjected to multiple dislocations we found severe delamination and cracking of the coating, increased roughness and the presence of third bodies. Our results indicate, that although wear of the coating is lower than seen in older generations of implants, inconsistent quality of the TiN film among different implants indicates the need for strict monitoring of the manufacturing process.

Evaluation of the real contact area in three-body dry friction by micro-thermal analysis

Many tribological properties and wear mechanisms occurring on the micro-and nanoscale are strongly controlled by the so-called real contact area ( A r ) which is a small fraction of the nominal or apparent contact area ( A a ). The determination of A r is often based on either (i) a geometrical approach describing the real geometry of contacting surfaces or (ii) a mechanical approach involving contact mechanics and physical-mechanical properties. In addition some experimental methods have also been attempted but they generally do not take into account the presence of third body at the interface—i.e. the wear debris trapped within the contact. In this paper we propose an experimental approach to estimate the dynamic real contact area from the operating parameters ( F n , v, T) and the tribological responses ( μ, F t ) in presence of third body. A scanning thermal microscope (SThM) is used for determining both the thermal conductivity of the third body and the relationship between the contact temperature and the thermal power really dissipated at the micro-asperity level. These results are combined with a thermal model of the macro-tribocontact for computing the real contact area and the real contact pressure. Validation of these results is carried out using a classical Greenwood Williamson model and finite element models built from the real AFM maps.

The Apsidal Motion Test in Eclipsing Binaries

AbstractThe use of eccentric eclipsing binaries to test stellar internal structure models, as well as the equations of motion provided by General Relativity, is reviewed. Close to 80 years have elapsed since the first ideas were produced in this field and many results have been obtained since then. It appears that, in general, a good understanding of stellar structure within the main sequence is available while the same level of knowledge can not be claimed beyond the termination age. The equations of general relativity could not be disproved with observational data though some systems cannot still be fully explained. In the near future, the analysis of evolved systems, very low mass stars, the effects of tidal resonances and the presence of third bodies has to be further explored. In addition, the analysis of large data bases obtained by means of extensive photometric surveys will certainly change the picture from an observational point of view.

Presence and role of the third body in a wheel–rail contact

Note: Persons concerned by modelling wheel–rail contacts should take into account the existence of the third body as a boundary condition of their models. Similar articles have been published in two journals: one dealing specifically with this subject in Fatigue Fract. Eng. Mater. Struct. while the other, in this special issue of Wear, describes a more general experimental approach. Some parts of this article, which describe in details the reality of the wheel–rail contact, have been used in the synthesising article: Y. Berthier, S. Descartes, M. Busquet, E. Niccolini, C. Desrayaud, L. Baillet, M.C. Baietto-Dubourg, The role and effects of the third body in the wheel–rail interaction, Fatigue Fract. Eng. Mater. Struct. 27 (5) (2004) 423–436. doi: 10.1111/j.1460-2695.2004.00764.x Published by Blackwell. This paper focuses on the presence of the third body, a solid interfacial layer, in the wheel–rail contact. A phenomenological analysis is carried out as thoroughly as possible of the real tribological behaviour of this contact. To improve the understanding of the wheel–rail contact reality and the reconstitution of contact dynamics, this paper is presented a synthesis of different studies coming from: analysis of specimens taken out periodically from rails and wheels in service, and thus under real contact conditions, test laboratories, allowing us to impose rolling–sliding conditions with very high precision. The results show the presence of natural third body ranging in thickness from a few micrometers to several dozen micrometers on the rail and wheel. Initially composed of particles stemming from wheels and rails, it flows into the contact to accommodate the sliding between wheel and rail while absorbing and digesting solid and fluid contaminants. Up to now, the third body is a means of tracing local conditions in the wheel–rail contact, in order to pass through the difficulties of in situ instrumentation. From all these studies and results, a better understanding of the role of the third body and its influence on friction is reached. It also controls the rail's lifetime, the lubrication as well as the wheel–rail adherence via its “degradation and/or reformation” mechanisms.

Orbital Period Studies of Three Algols: TW And, RW Leo, and AY Vul

Abstract The changes in the orbital periods of three EA-type eclipsing binaries, TW And, RW Leo, and AY Vul, are discussed based on an analysis of their $O-C$ curves. For RW Leo, its orbital period was revised and, assuming a cyclic oscillation in the orbital period, a period of 38.4 yr was determined. For the other two systems, TW And and AY Vul, their $O-C$ diagrams show complex variations. Under the assumption of periodic oscillation, cyclic changes with periods of 56.4 and 78.6 yr were discovered to superimpose on upward parabolic changes, indicating a secular period increase. The secular period increases for the two binary systems indicate that they are on an active phase of mass transfer. Assuming the oscillations in the periods to be caused by light-time effects due to the presence of “third bodies” rotating around these binary stars, the orbital parameters of the third bodies were determined. For RW Leo, it is possible to detect an additional third body photometrically and spectroscopically. However, for the other two systems, TW And and AY Vul, it is less likely to see additional bodies, unless the orbital inclination is very small (i.e., $i^{\prime}<30^{\circ}$). New photometric and spectroscopic observations and a careful analysis of those data are needed to check the presence of third bodies.

Mercury-photosensitized luminescence of NH 3 and ND 3 at low pressure

The mercury-photosensitized luminescence of ammonia has been investigated at low pressures. The emission spectrum with [ND 3] = 0.005 torr consisted of two peaks at 305 and 340 nm. The 305 nm band was assigned to the complex in the higher electronic state which correlates with Hg( 3P 1). At limiting zero pressure, the complex formation in the higher state predominates, while the 340 nm band is in the ascendant at higher pressure. Results obtained in the presence of third-bodies, M = C 2H 6, CH 4, CF 4, N 2, and Ne have been also reported.

THREE-BODY RECOMBINATION OF GASEOUS IONS

The recombination of gaseous ions in the presence of third bodies is assumed to follow a sequence of two bimolecular steps: M + X+ [Formula: see text] MX+ and MX+ + Y− [Formula: see text] XY + M. The termolecular rate constants of the over-all processes are calculated for several ionized gases at various temperatures. For the calculation, the equilibrium internuclear separation and the corresponding binding energy of a complex ion, MX+, are obtained by minimizing the interaction energy between M and X+, which is approximated to the sum of the Lennard-Jones potential for the M–X interaction and the polarization energy between M and X+. The recombination coefficients of some ionized gases at 288 °K and various pressures are calculated and compared with the observed data. The agreement is found to be satisfactory. The limitations of this theoretical approach are discussed.