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Context. The migration of growing protoplanets depends on the thermodynamics of the ambient disc. Standard modelling, using locally isothermal discs, indicate an inward (type-I) migration in the low planet mass regime. Taking non-isothermal effects into account, recent studies have shown that the direction of the type-I migration can change from inward to outward.

Context. Numerical simulations of planets embedded in protoplanetary gaseous discs are a precious tool for studying the planetary migration; however, some approximations have to be made. Most often, the selfgravity of the gas is neglected. In that case, it is not clear in the literature how the material inside the Roche lobe of the planet should be taken into account.

Context. In isothermal discs, the migration of protoplanets is directed inwards. For small planetary masses, the standard type I migration rates are so high that this can result in an unrealistic loss of planets into the stars.

Context. Eccentric accretion disks in superoutbursting cataclysmic and other binary systems.

Context. The formation of resonant planet pairs in exoplanetary systems involves planetary migration inside the protoplanetary disc. After a resonant capture, subsequent migration leads to a large increase in planetary eccentricities, if no damping mechanism is applied. This has led to the conclusion that the migration of resonant planetary systems cannot take place across large radial distances, but must be terminated rapidly by disc dissipation.

Context.Young planets embedded in their protoplanetary disk interact gravitationally with it leading to energy and angular momentum exchange. This interaction determines the evolution of the planet through changes to the orbital parameters.

Context.Based on radial velocity measurements, it has been found that the two giant planets detected around the star HD 73526 are in 2:1 resonance. However, as our numerical integration shows, the derived orbital data for this system result in chaotic behavior of the giant planets, which is uncommon among the resonant extrasolar planetary systems.

Context.Following the recent insight in the material structure of comets, protoplanetesimals are assumed to have low densities and to be highly porous agglomerates. It is still unclear if planetesimals can be formed from these objects by collisional growth.

Context.A significant number of the known multiple exoplanetary systems contain a pair of giant planets engaged in low-order mean-motion resonance. Such a resonant condition protects the dynamics of these planets resulting in very stable orbits. According to recent studies, this capture into a resonance is the result of a planetary migration process induced by interaction of the planets with a protoplanetary disk. If the migration is slow enough (adiabatic) near a mean motion resonance, the two planets will also be in apsidal corotation.

Context.

We study the evolution of an embedded protoplanet in a circumstellar disk using the 3D-Radiation Hydro code TRAMP, and treat the thermodynamics of the gas properly in three dimensions. The primary interest of this work lies in the demonstration and testing of the numerical method. We show how far numerical parameters can influence the simulations of gap opening. We study a standard reference model under various numerical approximations. Then we compare the commonly used locally isothermal approximation to the radiation hydro simulation using an equation for the internal energy. Models with different treatments of the mass accretion process are compared. Often mass accumulates in the Roche lobe of the planet creating a hydrostatic atmosphere around the planet. The gravitational torques induced by the spiral pattern of the disk onto the planet are not strongly affected in the average magnitude, but the short time scale fluctuations are stronger in the radiation hydro models.
An interesting result of this work lies in the analysis of the temperature structure around the planet. The most striking effect of treating the thermodynamics properly is the formation of a hot pressure-supported bubble around the planet with a pressure scale height of $H/R \approx 0.5$rather than a thin Keplerian circumplanetary accretion disk.

We study the evolution and emission of circumbinary disks around close classical T Tauri binary systems. High resolution numerical hydrodynamical simulations are employed to model a system consisting of a central eccentric binary star within an irradiated accretion disk. A detailed energy balance including viscous heating, radiative cooling and irradiation from the central star is applied to calculate accurately the emitted spectral energy distribution.
Numerical simulations using two different methods, the previously developed Dual-Grid technique with a finite difference discretization, and the Smoothed Particle Hydrodynamics method are employed to compare the hydrodynamical features and strengthen our conclusions.
Physical parameters of the setup are chosen to model the close systems of DQ Tauand AK Sco. Using the self-consistent models, we are able to fit the observed spectral energy distributions by constraining parameters such as disk mass, density profile and radial extension for those systems. We find that the incorporation of irradiation effects is necessary to obtain correct disk temperatures.

We have performed Smoothed Particle Hydrodynamics (SPH) simulations to study the time evolution of one and two protoplanets embedded in a protoplanetary accretion disc. We investigate accretion and migration rates of a single protoplanet depending on several parameters of the protoplanetary disc, mainly viscosity and scale height. Additionally, we consider the influence of a second protoplanet in a long time simulation and examine the migration of the two planets in the disc, especially the growth of eccentricity and chaotic behaviour. One aim of this work is to establish the feasibility of SPH for such calculations considering that usually only grid-based methods are adopted. To resolve shocks and to prevent particle penetration, we introduce a new approach for an artificial viscosity, which consists of an additional artificial bulk viscosity term in the SPH-representation of the Navier-Stokes equation. This allows accurate treatment of the physical kinematic viscosity to describe the shear, without the use of artificial shear viscosity.

We study the time evolution of two protoplanets still embedded in a protoplanetary disk. The results of two different numerical approaches are presented and compared. In the first approach, the motion of the disk material is computed with viscous hydrodynamical simulations, and the planetary motion is determined by N-body calculations including exactly the gravitational forces exerted by the disk material. In the second approach, only the N-body integration is performed but with additional dissipative forces included such as to mimic the effect of the disk torques acting on the disk. This type of modeling is much faster than the full hydrodynamical simulations, and gives comparative results provided that parameters are adjusted properly. 
Resonant capture of the planets is seen in both approaches, where the order of the resonance depends on the properties of the disk and the planets. Resonant capture leads to a rise in the eccentricity and to an alignment of the spatial orientation of orbits. The numerical results are compared with the observed planetary systems in mean motion resonance (GJ 876, HD 82943, and 55 Cnc). We find that the forcing together of two planets by their parent disk produces resonant configurations similar to those observed, but that eccentricity damping greater than that obtained in our hydrodynamic simulations is required to match the GJ 876 observations.

Recently, 59 low-luminosity object transits were reported from the Optical Gravitational Lensing Experiment (OGLE). Our follow-up low-resolution spectroscopy of 16 candidates provided two objects, OGLE-TR-3and OGLE-TR-10, which have companions with radii compatible with those of gas-giant planets. Further high-resolution spectroscopy revealed a very low velocity variation (< 500 m s-1) of the host star OGLE-TR-3which may be caused by its unseen companion. An analysis of the radial velocity and light curve results in $M<2.5$$M_{{\rm Jup}}$, $R<1.6$$R_{{\rm Jup}}$, and an orbital separation of about 5 $R_{\odot}$, which makes it the planet with the shortest period known. This allows to identify the low-luminosity companion of OGLE-TR-3as a possible new gas-giant planet. If confirmed, this makes OGLE-TR-3together with OGLE-TR-56the first extrasolar planets detected via their transit light curves.

We study analytically and numerically the stability of the pressure-less, viscously spreading accretion ring. We show that the ring is unstable to small non-axisymmetric perturbations. To perform the perturbation analysis of the ring we use a stretching transformation of the time coordinate. We find that to 1st order, one-armed spiral structures, and to 2nd order additionally two-armed spiral features may appear. Furthermore, we identify a dispersion relation determining the instability of the ring. The theoretical results are confirmed in several simulations, using two different numerical methods. These computations prove independently the existence of a secular spiral instability driven by viscosity, which evolves into persisting leading and trailing spiral waves. Our results settle the question whether the spiral structures found in earlier simulations of the spreading ring are numerical artifacts or genuine instabilities.

Recently, 46 low-luminosity object transits were reported from the Optical Gravitational Lensing Experiment. Our follow-up spectroscopy of the 16 most promising candidates provides a spectral classification of the primary. Together with the radius ratio from the transit measurements, we derived the radii of the low-luminosity companions. This allows to examine the possible sub-stellar nature of these objects. Fourteen of them can be clearly identified as low-mass stars. Two objects, OGLE-TR-03and OGLE-TR-10have companions with radii of 0.15 $R_\odot$which is very similar to the radius of the transiting planet HD 209458 B. The planetary nature of these two objects should therefore be confirmed by dynamical mass determinations.

We study the evolution of circumbinary disks surrounding classical T Tau stars. High resolution numerical simulations are employed to model a system consisting of a central eccentric binary star within an accretion disk. The disk is assumed to be infinitesimally thin, however a detailed energy balance including viscous heating and radiative cooling is applied. A novel numerical approach using a parallelized Dual-Grid technique on two different coordinate systems has been implemented. Physical parameters of the setup are chosen to model the close system of DQ Tauand AK Sco, as well as the wider systems of GG Tauand UY Aur. Our main findings are for the tight binaries a substantial flow of material through the disk gap which is accreted onto the central stars in a phase dependent process. We are able to constrain the parameters of the systems by matching both accretion rates and derived spectral energy distributions to observational data where available.

We study the evolution of embedded protoplanets in a protostellar disk using very high resolution nested-grid computations. This method allows us to perform global simulations of planets orbiting in disks and, at the same time, to resolve in detail the dynamics of the flow inside the Roche lobe of the planet. The primary interest of this work lies in the analysis of the gravitational torque balance acting on the planet. For this purpose we study planets of different masses, ranging from one Earth-mass up to one Jupiter-mass, assuming typical parameters of the protostellar disk. The high resolution supplied by the nested-grid technique permits an evaluation of the torques, resulting from short and very short range disk-planet interactions, more reliable than the one previously estimated with the aid of numerical methods. Likewise, the mass flow onto the planet is computed in a more accurate fashion. The obtained migration time scales are in the range from few times 104years, for intermediate mass planets, to 106years, for very low and high mass planets. These are longer than earlier assessments due to the action of circumplanetary material. Typical growth time scales depend strongly on the planetary mass. Below 64 Earth-masses, we find this time scale to increase as the $2/3$-power of the planet's mass; otherwise it rises as the $4/3$-power. In the case of Jupiter-size planets, the growth time scale is several times ten thousand years.

Context. Over 30 planetary systems have been discovered to reside in binary stars. As some of the binary separations are smaller than 20 astronomical units (AU) the gravitational perturbation of the secondary star has a very strong influence on the planet formation process, as it truncates the protoplanetary disc, possibly shortens its lifetime, and stirs up the embedded planetesimals. Due to its small semi-major axis (18.5?AU) and relatively large eccentricity e = 0.35 the binary star ??Cephei represents a particularly challenging example worthy of study in greater detail.Aims. In the present study we model the orbital evolution and growth of embedded protoplanetary cores of about 30?earth masses in the putative protoplanetary disc surrounding the primary star in the ??Cep system.Methods. We assume coplanarity of the disc, binary, and planet and perform two-dimensional hydrodynamic simulations of embedded cores in a protoplanetary disc perturbed by a secondary companion. Before embedding the planet, the equilibrium structure of the disc for the observed binary parameters of ??Cep is determined. We initiate the embedded planets in the disc on circular orbits with different initial distances from the primary. Results. The presence of the eccentric secondary star perturbs the disc periodically and generates strong spiral arms at periapse that propagate toward the disc centre. The disc perturbations then weaken as the secondary approaches apoapse. The disc also becomes slightly eccentric (edisc? 0.1?0.15), and displays a slow retrograde precession in the inertial frame. Embedded cores interact with the eccentric disc, and are periodically disturbed both by the strong spiral shocks and the eccentric binary. For all initial separations considered (from 2.5 to 3.5?AU) the cores migrate inward. In contrast, their eccentricity evolution depends primarily on the starting position in the disc. For initial semi-major axes ap? 2.7 we find a strong increase in the planetary eccentricity despite the presence of inward migration. Only cores that are initially far from the disc outer edge (ap? 2.7?AU) have a bounded orbital eccentricity that converges, after mass accretion, roughly to the value of the planet observed in the ??Cep system. Conclusions. Even though a close binary system such as ??Cep still presents a challenge to planet formation theory, we have shown that under the condition that protoplanetary cores can form at around 2.5?AU, it is possible to evolve and grow such a core to form a planet with a final configuration similar to what is observed.

We study the evolution of a system consisting of two protoplanets still embedded in a protoplanetary disk. Results of two different numerical approaches are presented. In the first kind of model the motion of the disk material is followed by fully viscous hydrodynamical simulations, and the planetary motion is determined by N-body calculations including exactly the gravitational potential from the disk material. In the second kind we only solve the N-body part and add additional analytically given forces which model the effect of the torques of the disk. This type of modeling is of course orders of magnitudes faster than the full hydro-model. Another advantage of this two-fold approach is the possibility of adjusting the otherwise unknown parameters of the simplified model. The results give very good agreement between the methods. Using two different initial setups for the planets and disk, we obtain in the first case a resonant trapping into the 3:1 resonance, and in the second case a trapping into the 2:1 resonance. Resonant capture leads to a rise in the eccentricity and to an alignment of the spatial orientation of orbits. The characteristics of the numerical results agree very favorably with those of three observed planetary systems (GJ 876, HD 82943, and 55 Cnc) known to be in mean motion resonances.

The interaction of 52 MeV deuterons with lithium was investigated, in view of the optimization of a lithium target for an intense neutron source, based on the d-Li stripping reaction. The experimental results of this experiment as well as those from other experiments (alphas of 241Am with aluminum) are compared with theoretical calculations obtained from an updated version of the BRAGG code. This code describes in detail the interaction of charged particles with matter. Within the experimental uncertainties the theoretical results are well reproduced by the experiments.

Nearly half of the total available accretion energy can be released in the boundary layer (BL) if the accreting object is slowly rotating. The spectral distribution of the emitted radiation depends crucially on the internal structure of the BL. Up to now no detailed models concerning the BL exist. We have developed an explicit two-dimensional numerical method written for axisymmetric accretion flows including viscosity effects and angular momentum. We display our first models concerning the BL structure incorporating variation of the stellar rotation and of the fraction of the released energy. The first results show a strong dependence of the BL structure on the local rate of cooling and on the rotation of the primary.

Miniplate osteosynthesis is an osteoplastic procedure that achieves secure stabilization of the midface, even following extensive fractures of the midface and the floor of the anterior cranial fossa. This procedure can be considered a satisfactory operative treatment in terms of cosmetic and functional results. Correlative osteology is discussed and clinical experiences are reviewed.

A D-T fusion cycle produces five times more neutrons per unit of energy released than a fission cycle, with about twice the damage energy and the capability to produce ten times more hydrogen, helium and transmutation products than fission neutrons. They determine, together with other parameters, the lifetime of the construction materials for the low plasma-density fusion reactors (tokamak, tandem-mirror, etc.), which require a first wall. For the economie feasibility of fusion power reactors the first wall and blanket materials must withstand a dose approaching 300 to 400 dpa. Arguments are presented that demonstrate that today's simulation techniques using existing fission reactors and charged particle beams are excellent tools to study the underlying basic physical phenomena of the evolving damage structures but are not sufficient to provide a valid technological data base for the design of economie fusion power reactors. It is shown than an optimized spallation neutron source based on a continuous beam of 600 MeV, 6 mA protons is suitable to simulate first wall conditions. Comparing it with FMIT the 35 MeV, 100 mA D+-Li neutron source, we arrive at the following figure of merit: FM = (dpa·volume) EURAC(dpa·volume) FMIT= 〈 93162 〈83 × 10 〉= 111reflecting the fact that the proton beam generates about 100 times more neutrons than the deuteron beam in FMIT for the same beam power.

Zusammenfassung Mißerfolge nach hörverbessernden Operationen können vielerlei Ursachen haben. Neben mangelhafter Operationstechnik, konstitutioneller Faktoren, Reinfektionen der Mittelohrräume usw. sind es vor allem auch Heilungsstörungen des freien Hauttransplantates, die den Erfolg des Eingriffes gefährden. Vorliegende Arbeit befaßt sich deshalb mit den Problemen der freien Hautverpflanzung in Ohrhöhlen und den von der Transplantation auf die Körperoberfläche abweichenden Bedingungen. Klinische Erfahrungen an einem großen Krankengut werden durch mikroskopische Untersuchungen untermauert. Das histologische Material stammt von Patienten mit zweizeitig durchgeführten Eingriffen oder mit Nachoperationen. Die Zweckmäßigkeit der Verwendung von autoplastischer Vollhaut wird begründet. Mikroskopische Schnitte zeigen funktionell gut eingeheilte Transplantate als Trommelfellersatz und als Auskleidung der Ohrhöhle sowie die verschiedenen Möglichkeiten von Heilungsstörungen der verpflanzten Haut und ihre Folgen. Die Kenntnis der feingeweblichen Veränderungen und Umbauvorgänge in den Transplantaten kann dazu beitragen, Mi\erfolge der Hautverpflanzung zu verringern und ein einmal gewonnenes funktionell günstiges Resultat durch entsprechendes Verhalten in der Nachbehandlung zu erhalten.

Zusammenfassung Zwischen der Wirkung der konventionellen Röntgenbestrahlung und der Bestrahlung mit dem Isotop Co 60 besteht in der Reaktion auf das lymphatische Gewebe kein qualitativer, höchstens ein quantitativer Unterschied.

Ohne Zusammenfassung:

Ohne Zusammenfassung:

Summary In fractures of the anterior and middle fossa of the skull the chances of survival and of recovery of function will be best where surgeons specialized in the fields of neurosurgery, oto-Rhnology and possibly also facio-maxillary surgery, are available and are able to work as a team.

The various possibilities are examined how to measure the frequency distribution of solids by the inelastic scattering of thermal and subthermal neutrons. Particular attention is drawn on measuring-techniques that allow the determination of the frequency distribution even if the scattering cross section of the target material is not totally incoherent but a mixture of a coherent and an incoherent component. It is shown how the frequency distribution of solids can be measured even if the cross section is totally coherent by the use of a doping technique. Atoms as H and V, that have an almost entirely incoherent scattering cross section, are used as impurities in the solid of interest, serving as a probe of the host lattice vibrations. By studiing the difference of the two independent inelastic scattering experiments, one with the pure, the other with the impure solid, it is possible to derive the frequency distribution function of the host lattice itself. Examples are given for Vanadium and Niobium. In addition, evidence is given how the best experimental conditions are selected for this type of inelastic neutron scattering experiments.

After surgical removal of benign tumors there may remain a postoperative defect of the facial skin because of the great loss of tissue. Fibrin foam was used as temporary filling material to avoid the defect of the facial surface.

Summary Guinea pigs are exposed for this experiment in a special constructed box to formalin vapours. The formalin vapours concentrations are noted exactly, depending on the maximum of concentration at work.

In dependence of the resection limits it is possible to give a systemical classification of plastic reconstructions after laryngectomy. Basing on this fact a new method of operation developed at the ENT-Univ. Clinic of Würzburg is demonstrated. In a high percentage it is possible to have a rehabilitation of the voice in the same stage with the laryngectomy, also in cases of partial pharyngectomy. Aspirations were not seen up to now.

Summary In facial palsy the following diagnostic techniques are used: inspection of the tympanic membrane, audiograms, and X-ray pictures of the temporal bone, including tomography and CT as well as electromyography. Investigation of the function of sympathetic and parasympathetic nerve fibers (topical diagnosis) enables us to localize the lesion. Idiopathic Bell's palsy is not yet operated upon. The indications for operative therapy are discussed in facial paralysis due to trauma, intratemporal tumors, otitis media and tuberculosis. In cases of intact continuity, decompression of the nerve is sufficient. In other cases end-to-end suture, rerouting technique or autogenous free-nerve grafting are necessary.

Two spectrometers, utilizing interference filter wedges, have been constructed for measurements under field conditions. One, operating from 1.6 μ. to 5.4 μ, has been flown unpressurized in an airplane to 12.2 km; the other, operating from 7.4 μ to 14.6 μ has been flown in a balloon to 33.3 km. Both instruments performed well, proving the interference filter wedge as a valuable tool for spectral measurements, especially in hostile environments.

Context.In the framework of the coagulation scenario, kilometre-sized planetesimals form by subsequent collisions of pre-planetesimals of sizes from centimetre to hundreds of metres. Pre-planetesimals are fluffy, porous dust aggregates, which are inhomogeneous owing to their collisional history. Planetesimal growth can be prevented by catastrophic disruption in pre-planetesimal collisions above the destruction velocity threshold.

Context.The migration of planets plays an important role in the early planet-formation process. An important problem has been that standard migration theories predict very rapid inward migration, which poses problems for population synthesis models. However, it has been shown recently that low-mass planets (20–30 MEarth) that are still embedded in the protoplanetary disc can migrate outwards under certain conditions. Simulations have been performed mostly for planets at given radii for a particular disc model.

Context.Within the collision growth scenario for planetesimal formation, the growth step from centimetre-sized pre-planetesimals to kilometre-sized planetesimals remains unclear. The formation of larger objects from the highly porous pre-planetesimals may be halted by a combination of fragmentation in disruptive collisions and mutual rebound with compaction. However, the right amount of fragmentation is necessary to explain the observed dust features in late T Tauri discs. Therefore, detailed data on the outcome of pre-planetesimal collisions is required and has to be presented in a suitable and precise format.

Context.While planets in the solar system only have a low inclination with respect to the ecliptic there is mounting evidence that in extrasolar systems the inclination can be very high, at least for close-in planets. One process to alter the inclination of a planet is through planet-disc interactions. Recent simulations considering radiative transport have shown that the evolution of migration and eccentricity can strongly depend on the thermodynamic state of the disc. So far, this process has only been studied for a few selected planet masses using isothermal discs.Aims.We extend previous studies to investigate the planet-disc interactions of fixed and moving planets on inclined and eccentric orbits. We also analyse the effect of the disc’s thermodynamic properties on the orbital evolution of embedded planets in detail.Methods.The protoplanetary disc is modelled as a viscous gas where the internally produced dissipation is transported by radiation. To solve the equations we use an explicit three-dimensional (3D) hydrodynamical code NIRVANA that includes full tensor viscosity, as well as implicit radiation transport in the flux-limited diffusion approximation. To speed up the simulations we apply the FARGO-algorithm in a 3D context.Results.For locally isothermal discs, we confirm previous results and find inclination damping and inward migration for planetary cores. For low inclinations (i≲ 2H/r), the damping is exponential, while it follows di/dt∝ i-2for larger i. For radiative discs, the planetary migration is very limited, as long as their inclination exceeds a certain threshold. If the inclination is damped below this threshold, planetary cores with a mass up to  ≈33   MEarthstart to migrate outwards, while larger cores migrate inwards right from the start. The inclination is damped for all analysed planet masses. Conclusions.In a viscous disc an initial inclination of embedded planets will be damped for all planet masses. This damping occurs on timescales that are shorter than the migration time. If the inclination lies beneath a certain threshold, the outward migration in radiative discs is not handicapped. However, only planets with a mass up to  ≈33   MEarthare prone to this outward migration. Outward migration is strongest for circular and non-inclined orbits.

Context.A large fraction of stars, including young T Tauri stars, are observed to be members of binary or multiple systems. During the early stages of evolution when the individual binary stars are surrounded by a gaseous and dusty disc, the binary orbit plane and disc midplane may be mutually inclined. For the relatively thick protostellar discs associated with T Tauri stars, it is expected that in this scenario the disc will become mildly warped and undergo solid body precession around the angular momentum vector of the binary system. At the present time it is unclear how solid bodies such as planetesimals embedded in such a disc will evolve dynamically and affect the formation of planets.

Context.With an average eccentricity of about 0.29, the eccentricity distribution of extrasolar planets is markedly different from the solar system. Among other scenarios considered, it has been proposed that eccentricity may grow through planet-disc interaction. Recently, it has been noticed that the thermodynamical state of the disc can significantly influence the migration properties of growing protoplanets. However, the evolution of planetary eccentricity in radiative discs has not been considered yet.

Planets orbiting post-common envelope binaries provide fundamental information on planet formation and evolution. We searched for such planets in NN Ser ab, an eclipsing short-period binary that shows long-term eclipse time variations. Using published, reanalysed, and new mid-eclipse times of NN Ser ab obtained between 1988 and 2010, we find excellent agreement with the light-travel-time effect produced by two additional bodies superposed on the linear ephemeris of the binary. Our multi-parameter fits accompanied by N-body simulations yield a best fit for the objects NN Ser (ab)c and d locked in the 2:1 mean motion resonance, with orbital periods Pc$\simeq$15.5 yrs and Pd$\simeq$7.7 yrs, masses Mcsin ic$\simeq$6.9 MJupand Mdsin id$\simeq$2.2 MJupand eccentricities ec$\simeq$0 and ed$\simeq$0.20. A secondary χ2minimum corresponds to an alternative solution with a period ratio of 5:2. We estimate that the progenitor binary consisted of an A star with ~2 $M_\odot$and the present M dwarf secondary at an orbital separation of ~1.5 AU. The survival of two planets through the common-envelope phase that created the present white dwarf requires fine tuning between the gravitational force and the drag force experienced by them in the expanding envelope. The alternative is a second-generation origin in a circumbinary disk created at the end of this phase. In that case, the planets would be extremely young with ages not exceeding the cooling age of the white dwarf of 106yrs.