Zodiacal light gathered along the line of sight: The vicinity of the terrestrial orbit studied with photopolarimetry and with Doppler spectrometry     

R. Dumont 《Planetary and Space Science》1983,31(12):1381-1387

The expression for the zodiacal brightness integral is especially simple if the integrand contains the ‘directional scattering coefficient’, $\text{D}$, (a.u.^?1), or equivalently the scattering cross-section per unit-volume. The two intersections of the terrestrial orbit with a line of sight lying in the ecliptic offer the possibility of isolating the contribution of the chord, with a conservative assumption of steadiness, but without the controversial assumption of a homogeneous zodiacal cloud. The zodiacal brightnesses between 60 and 120° elongation can be used to derive $\text{D}$₀ and $\text{D}$, the value of $\text{D}$ and its heliocentric radial derivative, both at 1 a.u. and at a scattering angle of 90°. A polarimetric treatment leads to the local polarization degree, $\text{P}$₀, and to its heliocentric derivative, $\text{P}$. Applied to all three available observational sources, this method invalidates the assumption of homogeneity, leading to a rather high relative gradient $\text{P}\text{P}{}_0$ near 1 a.u. (? 12, ? 16 or ? 24%, according to the source, as the Sun's distance decreases from 1.0 to 0.9 a.u.).The method is extended to Doppler spectrometry, taking advantage of the two equal projections on the line of sight of the Earth's velocity vector. The brightness Z₀ and the Dopplershift Δλ₀ observed at 90° elongation, together with the derivatives w.r.t. elongation ε, of the brightness, $\text{Z}\text{?}$ and of the Dopplershift, Δλ, can be used to retrieve the mean orbital velocity, v, of the interplanetary scatterers in the region of the terrestrial orbit. The two most reliable observational sources lead, with fair agreement, to a relative excess $\text{(}\text{v ? V)}\text{V}$, over the terrestrial velocity, of the order of + 25%.  相似文献   

Phase function and polarization curve of interplanetary scatterers from zodiacal light photopolarimetry     

R. Dumont 《Planetary and Space Science》1973,21(12):2149-2155

Wide-angle ecliptic measurements of zodiacal light brightness (Z) and polarization (P) lead to fundamental results about optical properties of interplanetary scatterers, under a few reasonable assumptions (that they depend upon heliocentric distance by a r^?n law, and suffer no significant distortion of their scattering indicatrix between 0.5 and 2 a.u.): 1. The phase function σ(θ) is expressed (Equation 6) as a function of n and of (Z) data. 2. At the elongation ? = 90°, the derivative $\text{dZ}\text{d?}$ yields an absolute determination of the intensity $\text{T}$ scattered at right angles from the Sun by a single unit-volume of interplanetary medium (Equation 7). 3. The polarization degree $\text{P}$(θ) of the sunlight scattered by a single volume is derived (Equation 12) from n and from (Z + P) data. For two special values of the scattering angle θ, n vanishes in Equation (12), so that a fair knowledge of the polarization curve (Fig. 2) is reached prior to any assumption, or any forthcoming Jupiter-probe measure, about the value of n.Should n be provided by the Pioneers, then a thorough treatment of the whole problem of phase function and polarization curve can be performed by means of Equations (6) and (12) supplied with available zodiacal light photopolarimetric observations.  相似文献   

Mars: Subsurface properties from observed longitudinal variation of the 3.5-mm brightness temperature     

Eugene E. Epstein  Bryan H. Andrew  Frank H. Briggs  Bruce M. Jakosky  Frank D. Palluconi 《Icarus》1983,56(3):465-475

Measurements at 3.5 mm of the disk-average brightness temperature of Mars during the 1978 opposition can be represented by (The errors cited are from the internal scatter; the estimated absolute calibration uncertainty is 3%.) This longitudinal variation must be taken into account if Mars is to be used as a calibration source at millimeter wavelengths. The total range of the 3.5-mm variation is three to four times larger than both the 2.8-cm and 20-μm variations. This unexpected result can possibly be explained by subsurface scattering from rocks ?1.5-cm radius.  相似文献   

Bidirectional reflectance spectroscopy: 3. Correction for macroscopic roughness     

Bruce Hapke 《Icarus》1984,59(1):41-59

A mathematically rigorous formalism is derived by which an arbitrary photometric function for the bidirectional reflectance of a smooth surface may be corrected to include effects of general macroscopic roughness. The correction involves only one arbitrary parameter, the mean slope angle $\text{θ}$, and is applicable to surfaces of any albedo. Using physically reasonable assumptions and mathematical approximations the correction expressions are evaluated analytically to second order in $\text{θ}$. The correction is applied to the bidirectional reflectance function of B. Hapke (1981, J. Geophys. Res.86, 3039–3054). Expressions for both the differential and integral brightnesses are obtained. Photometric profiles on hypothetical smooth and rough planets of low and high albedo are shown to illustrate the effects of macroscopic roughness. The theory is applied to observations of Mercury and predicts the integral phase function, the apparent polar darkening, and the lack of limb brightness surge on the planet. The roughness-corrected bidirectional reflectance function is sufficiently simple that it can be conveniently evaluated on a programmable hand-held calculator.  相似文献   

Electric fields and potential patterns in the high-latitude ionosphere for different situations in interplanetary space     

Y.I. Feldstein  A.E. Levitin  D.S. Faermark  R.G. Afonina  B.A. Belov  V.Y. Gaidukov 《Planetary and Space Science》1984,32(7):907-923

The potential ? of the electric field at high latitudes has been obtained by solving numerically the second order differential equation in spherical coordinates: , where θ is colatitude, λ is longitude, σ^H and σ^P are the height-integrated Hall and Perdersen ionospheric conductivities, r = sinθ, and ψ is the current function. The boundary condition is ? = 0 on the geomagnetic parallel θ = 34°. Values of ψ are determined from geomagnetic field variations at the Earth's surface from geomagnetic field variations at the Earth's surface for various conditions in interplanetary space. σ^P and σ^H are taken to vary with season, local time, tilt of the geomagnetic dipole axis (UT), and intensity of corpuscular precipitation (the model proposed by Wallis and Budzinski, 1981). The model distributions of ?^M and E^M = -▽?^m so obtained are compared with observational results. The feasibility has been demonstrated of interpreting the statistical results and individual measurement data in terms of a unified dynamic model of ionospheric electric fields. The model makes allowance for the changes of electromagnetic “weather” in interplanetary space.  相似文献   

Analysis of the orbit of cosmos 395 rocket (1971-13B) near 15th-order resonance     

D.G. King-Hele  A.N. Winterbottom 《Planetary and Space Science》1974,22(7):1045-1057

Cosmos 395 rocket (1971-13B) is moving in a near-circular orbit inclined at 74° to the equator. Its average height, near 540 km after launch in February 1971, slowly decreased under the action of air drag and on 24 March 1972 it experienced exact 15th-order resonance, with the successive equator crossings 24° apart in longitude. Its orbit has been determined at 21 epochs between September 1971 and September 1972 using 1100 observations, including 55 from the Malvern Hewitt camera: the mean S.D. in inclination is 0.001° and in eccentricity 0.00001.The variations in inclination i, eccentricity e, right ascension of the node $\text{Ω}$, and argument of perigee ω, near 15th-order resonance are analysed to determine values of lumped 15th-order harmonic coefficients in the geopotential. The inclination yields equations accurate to 4 per cent for coefficients of order 15 and degree 15,17,19..., which are in excellent agreement with those from Cosmos 387 (1970-111A) in an orbit of similar inclination but different resonant longitude. Analysis of the variations in e gives two pairs of equations for the coefficients of order 15 and degree 16, 18..., which are used to obtain tentative values of the (16,15) coefficients. For the first time the resonant variation of other elements ($\text{Ω}\text{and}\text{ω}$) has also been analysed with partial success.  相似文献   

Determination of magnetic field direction in a comet's head     

D.A. Varshalovich  G.F. Chörny 《Icarus》1980,43(3):385-390

The Stokes parameters of resonance radiation scattered by a Na atom with the angular momentum F aligned by directed unpolarized radiation in a magnetic field H ～ 10^?5?10^?1 Oe are presented. An influence of the orientation of the magnetic field on these parameters are studied; the intensity ratio $\text{I(D}{}_2\text{)}\text{I(D}{}_1\text{)}$ changes within ±5%, and the polarization degree P(D₂) within ±25%. Measurements of $\text{I(D}{}_2\text{)}\text{I(D}{}_1\text{)}$ and P(D₂), if the geometry of scattering is known, may give information on the direction of the magnetic field in the sodium atmospheres of comets, as well as Io's sodium cloud or man-made cosmic clouds.  相似文献   

Io's sodium emission cloud and the voyager 1 encounter     

B.A. Goldberg  Yu. Mekler  R.W. Carlson  T.V. Johnson  D.L. Matson 《Icarus》1980,44(2):305-317

Io's neutral sodium emission cloud was monitored during the period of Voyager 1 encounter from two independent ground-based sites. Observations from Table Mountain Observatory verified the continued existence of the “near-Io cloud” (d < 1.5 × 10⁵ km, for 4πI > 1 kR; R denotes Rayleigh) while those from Wise Observatory showed a deficiency in the weaker emission at greater distances from Io. The sodium cloud has been monitored from both observatories for several years. These and other observations demonstrate that the behavior of the cloud is complex since it undergoes a variety of changes, both systematic and secular, which can have both time and spatial dependencies. The cloud also displays some characteristics of stability. Table Mountain images and high-dispersion spectra (resolution $\text{～0.2}\text{A}\text{?}$) indicate that the basic shape and intensity of the “near cloud” have remained relatively constant at least since imaging observations began in 1976. Wise Observatory low-dispersion spectra (resolution $\text{～1}\text{A}\text{?}$) which have been obtained since 1974 demonstrate substantial variability of the size and intensity of the “far cloud” (d ? 1.5 × 10⁵ km) on a time scale of months or less. Corresponding changes in the state of the plasma associated with the Io torus are suggested, with the period of Voyager 1 encounter represented as a time of unusually high plasma temperature and/or density. Dynamic models of the sodium cloud employing Voyager 1 plasma data provide a reasonable fit to the Table Mountain encounter images. The modeling assumptions of anisotropic ejection of neutral sodium atoms from the leading, inner hemisphere of Io with a velocity distribution characteristic of sputtering adequately explain the overall intensity distribution of the “near cloud”. During the Voyager 1 encounter period there appeared a region of enhanced intensity projecting outward from Io's orbit and inclined to the orbital plane. This region is clearly distinguished from the sodium emission normally aligned with the plane of Io's orbit. The process responsible for this phenomenon is not yet understood. Similar but less pronounced features are also present in several Table Mountain images obtained over the past few years.  相似文献   

Photometric properties of zodiacal light particles     

Kari Lumme  Edward Bowell 《Icarus》1985,62(1):54-71

From published ground-base, spacecraft, and rocket photometry and polarimetry of the zodiacal light, a number of optical and physical parameters have been derived. It was assumed that the number density, mean particle size, and albedo vary with heliocentric distance, and shown that average individual interplanetary particles have a small but definite opposition effect, a mean single-scattering albedo in the V band at 1-AU heliocentric distance of 0.09 ± 0.01, and a zero-phase geometric albedo of 0.04. Modeled by a power law, both albedos decrease with increasing heliocentric distance as r^?0.54. The corresponding exponents for changes in mean particle size and number density are related in a simple way. The median orbital inclination of zodiacal light particles with respect to the ecliptic is 12°, close to the observed median value for faint asteroids and short-period comets. Furthermore, the color of dust particles and its variation with solar phase angle closely resemble those of C asteroids. These findings are, at least, consistent with the zodiacal cloud originating primarily from collisions among asteroids. Finally, a value of ?10¹⁸?_ErmE g was derived for the mass of the zodiacal cloud, where ?_E is the mean particle radius (in micrometers) at 1-AU-heliocentric distance. For extinction in the ecliptic, $\text{Δm = 10}{}^{\mathrm{?5}}\text{?}{}^{\mathrm{<mtext>?1</mtext><mtext>2</mtext>}}\text{mag}$ was obtained, where ? is the solar elongation in degrees.  相似文献   

Low-frequency upstream wave as a probable source of low-latitude Pc 3–4 magnetic pulsations     

Kiyohumi Yumoto 《Planetary and Space Science》1985,33(2):239-249

Daytime Pc 3–4 pulsation activities observed at globally coordinated low-latitude stations [SGC (L = 1.8,λ = 118.0°W), EWA(1.15,158.1°W), ONW(1.3,141.5°E)] are evidently controlled by the cone angle θ_XB of the IMF observed at ISEE 3. Moreover, the Pc 3–4 frequencies ($\text{?}$) at the low latitudes and high latitude (COL; L = 5.6 and λ = 147.9°W) on the ground and that of compressional waves at geosynchronous orbit (GOES 2; L = 6.67 and λ = 106.7°W) are also correlated with the IMFmagnitude(B_IMF).The correlation of $\text{?}$ of the compressional Pc 3–4 waves at GOES 2 against B_IMF is higher than those of the Pc 3–4 pulsations at the globally coordinated ground stations, i.e., γ = 0.70 at GOES 2, and (0.36,0.60,0.66,0.54) at (COL, SGC, EWA, ONW), respectively. The standard deviation ($\text{σ}{}_{\mathrm{n}}\text{= ± Δ?}\text{mHz}$) of the observed frequencies from the form $\text{?}$ (mHz) = 6.0 × B_IMF (nT) is larger at the ground stations than at GOES 2, i.e., $\text{Δ? = ± 6.6}\text{mHz at}$GOES 2, and ±(13.9, 9.1, 10.7, 12.1) mHz at (COL, SGC, EWA, ONW), respectively. The correlations between the IMF magnitude B_IMF and Pc 3–4 frequencies at the low latitudes are higher than that at the high latitude on the ground, which can be interpreted by a “filtering action” of the magnetosphere for daytime Pc 3–4 magnetic pulsations. The scatter plots of pulsation frequency $\text{?}$ against the IMF magnitude B_IMF for the compressional Pc 3–4 waves at GOES 2 are restricted within the forms $\text{? = 4.5 × B}{}_{\mathrm{<mtext>IMF</mtext>}}\text{and}\text{? = 7.5 × B}{}_{\mathrm{<mtext>IMF</mtext>}}$. The frequency distribution is in excellent agreement with the speculation ($\text{<ω}{}_{\mathrm{sc}}\text{Ω}{}_{\mathrm{i}}\text{= 0.3 ～ 0.5}$) of the spacecraft frame frequency of the magnetosonic right-hand waves excited by the anomalous ion cyclotron resonance with reflected ion beams with V₆ = 650 ～ 1150 km s^?1 in the solar wind frame observed by the ISEE satellite in the Earth's foreshock. These observational results suggest that the magnetosonic right-handed waves excited by the reflected ion beams in the Earth's foreshock are convected through the magnetosheath to the magnetopause, transmitted into the magnetosphere without significant changes in spectra, and then couple with various HM waves in the Pc 3–4 frequency range at various locations in the magnetosphere.  相似文献   

The orbit of the Dhajala meteorite     

G.M. Ballabh  A. Bhatnagar  Narendra Bhandari 《Icarus》1978,33(2):361-367

Observations of the trail caused by the meteorite which fell around Dhajala, Gujarat (India), on 28 January 1976 have been used to compute the probable orbit of the meteoroid in space. The cosmic ray effects in the meteorite fragments indicate high mass ablation (?90%), suggesting a high velocity (?20 km/sec) of entry into the Earth's atmosphere. The atmospheric trajectory is reasonably well documented and its deviation from the projected ground fallout can be understood in terms of the ambient wind pattern. The apparent radiant of the trail was at a point in the sky with right ascension 165°, declination +60°. Considering the errors in estimating the radiant, we get a range of orbits with a = 2.3 ± 0.8 AU, e = 0.6 ± 0.1, and i = 28 ± 4° with the constraints of a ? 1.5 AU and V_∞ < 25 km/sec (which causes nearly complete evaporation of the meteoroid). Taking V_∞ = 21.5 lm/sec as indicated by the measured mass ablation of the meteorite, the orbital elements are deduced to be $\text{a = 1.8}\text{AU}\text{, e = 0.59, i = 27°.6, ω = 109°.1, Ω = 307°.8,}\text{and}\text{q = 0.74}$.  相似文献   

Exospheric perturbations by radiation pressure: II. Solution for orbits in the ecliptic plane     

Joseph W. Chamberlain 《Icarus》1980,44(3):651-656

An earlier paper gave solutions for the mean time rates of change of orbital elements of satellite atoms in an exosphere influenced by solar radiation pressure. Each element was assumet to beahve independently. Here the instantaneous rates of change for three elements $\text{(e, ω,}\text{and}\text{θ = ω + Ω)}$ are integrated simultaneously for the case of the inclination i = 0. The results (a) confirm the validity of using mean rates when the orbits are tightly bound to the planet and (b) serve as examples to be reproduced by the complicated numerical solutions required for arbitrary inclination. Strongly bound hydrogen atoms perturbed in Earth orbit by radiation pressure do not seem a likely cause of the geotail extending in the anti-Sun direction. Instead, radiation pressure wil cause those particles' orbits to form a broad fan-shaped tail and to deteriorate into the Earth's atmosphere. Whether loosely bound H atoms are plentiful enough to create the geotail depends on their source function versusr; that question is beyond the scope of this paper.  相似文献   

Distribution functions for energetic oxygen atoms in the earth's lower atmosphere     

Jennifer A. Logan  Michael B. McElroy 《Planetary and Space Science》1977,25(2):117-122

Direct photolysis of O₃ and quenching of $\text{O}\text{(}{}^1\text{D}\text{)}$ by N₂ provide abundant sources of fast oxygen atoms for the Earth's lower atmosphere. The concentration of atoms with energy above 0.7 eV may exceed the concentration of $\text{O}\text{(}{}^1\text{D}\text{)}$ for all altitudes below 18 km and these atoms may play an important role in lower atmospheric chemistry. Distribution functions for $\text{O}\text{(}{}^3\text{P}\text{)}$ are given for the energy interval 0.1-1.3 eV, for a range of altitudes from 0 to 62 km.  相似文献   

Out of ecliptic zodiacal cloud profile     

A. Mujica  G. López  F. Sánchez 《Planetary and Space Science》1983,31(8):871-873

In a previous paper, Mujica et al (1980), the optical homogeneity of the medium in the ecliptic plane was established calculating, for the ecliptic, the density and scattering functions ρ(r) and σ(θ) respectively. Starting with these results, we attempt now to find the zodiacal cloud shape out of the ecliptic.  相似文献   

Aeronomical determination of the efficiency of O¹D) production by dissociative recombination of O₂⁺     

L.L. Cogger  L.S. Smith  R.M. Harper 《Planetary and Space Science》1977,25(2):155-159

Simultaneous measurements of the 6300 Å airglow intensity, the electron density profile, and F-region ion temperatures and vertical ion velocities taken at the Arecibo Observatory in March 1971 are utilized in the height integrated continuity equation to extract the number of photons'of 6300 Å emitted per recombination. After accounting for quenching of $\text{O}\text{(}{}^1\text{D}\text{)}$ and the electrons lost via NO⁺ recombination, the efficiency of $\text{O}\text{(}{}^1\text{D}\text{)}$ production by the dissociative recombination of O₂⁺ is determined to be 0.6 ± 0.2 including cascading from the $\text{O}\text{(}{}^1\text{S}\text{)}$ state. The uncertainty includes both random measurement errors and estimates of possible systematic errors.  相似文献   

Ring current simulation in connection with interplanetary space conditions     

Y.I. Feldstein  V.YU. Pisarsky  N.M. Rudneva  A. Grafe 《Planetary and Space Science》1984,32(8):975-984

A ring current model has been obtained which permits calculations ofD_st variations on the Earth's surface during magnetic storms. The changes in D_st are described by the equation where $\text{D}{}_{\mathrm{sto}}\text{= D}{}_{\mathrm{st}}\text{-bp}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{+~tc}$; p = mnv² is solar wind pressure; F(EM) is the function, controlled by the electromagnetic parameters of interplanetary medium, of injection into ring current ; τ is the constant of ring current decay. $\text{C}\text{= C}\text{u}\text{τ?=18}\text{nT}$, where C is the level of the D_st-variation field measurements; ? is the injection function characterizing the quasisteady-state injection of energy into the ring-current region. The constant Ç is determined from the condition that the change of the ring current energy from magnetic storm commencement to end should equal the difference between the injected and dissipated energy throughout the storm. The values of the factors b and τ were found by the method of minimizing the sum of the quadratic deviations of the calculated D_st from the values observed throughout the storm : b = 0.23 nT/(eV cm^?3)^{$\text{1}\text{2}$}, τ = 8.2 h at D_st? ? 55 nT and τ = 5.8 h at -120 ? D_st ? — 55 nT. The injection function F(EM) is of the form F(EM) = d(E_y? A) at the values of the azimuthal component of the solar wind electric field E_y ? A, and F(EM) =0 at A?E_y.d = ? 1.2 × 10^?3 Ts^?1 (mV/m)^?1 and A = ? 0.9 mV m^?1 . Thus, the injection to ring current is possible at the northward B_z component of the IMF.  相似文献   

Application of methane band-model parameters to the visible and near-infrared spectrum of Uranus     

D.Chris Benner  Uwe Fink 《Icarus》1980,42(3):343-353

Laboratory band-model absorption coefficients of CH₄ are used to calculate the Uranus spectrum from 5400 to 10,400 Å. A good fit of both strong and weak bands for the Uranus spectrum over the entire wavelength interval is achieved for the first time. Three different atmospheric models are employed: a reflecting layer model, a homogeneous scattering layer model, and a clear atmosphere sandwiched between two scattering layers. The spectrum for the reflecting layer model exhibits serious discrepancies but shows that large amounts of CH₄ (5–10 km-am) are necessary to reproduce the Uranus spectrum. Both scattering models give reasonably good fits. The homogeneous model requires a particle scattering albedo $\text{(}\text{g}\text{?}\text{w}{}_{\mathrm{<mtext>p</mtext>}}\text{) ? 0.998}$ and an abundance per scattering mean free path $\text{(}\text{a}\text{?}\text{)}\text{of}\text{a}\text{?}\text{1}\text{km-am}$. The parameters derived from the sandwich layer model are: forsb the upper scattering layer a continuum single scattering albedo ($\text{g}\text{?}\text{w}{}_0$) of 0.995 and a scattering optical depth variable with wavelength consistent with Rayleigh scattering; for the clear layer they are a CH₄ abundance (a) of 2.2 km-am and an effective pressure (p) ? 0.1 atm; for the lower cloud deck a Lambert reflectivity (L) of 0.9 resulted. A severe depletion of CH₄ in the upper scattering layer is required. An enrichment of CH₄/H₂ over the solar ratio by a factor of 4–14 in the lower atmosphere is, however, indicated.  相似文献   

On the possibility of detecting solar flare effects in the zodiacal light     

N.Y. Misconi  M.S. Hanner 《Planetary and Space Science》1975,23(9):1329-1335

To evaluate possible effects of solar flares on the brightness of the inner zodiacal light, it is necessary to consider the brightness contribution along the line of sight and as a function of Sun-particle distance. For this purpose, models of the brightness contribution along the line of sight are presented for both dielectric and metallic particles with a spatial distribution of the form r^?ν, ν = 0, 1, 2. These models are discussed in terms of the geometry of shock front interaction. A reported zodiacal light enhancement following a solar flare (Blackwell and Ingham, 1961) is analyzed on the basis of the shock front geometry.  相似文献   

Temperature variation of the plasma sheet during substorms     

A.T.Y. Lui  C.-I. Meng  L.A. Frank  K.L. Ackerson  S.-I. Akasofu 《Planetary and Space Science》1981,29(8):837-842

The temperature and density of the plasma in the Earth's distant plasma sheet at the downstream distances of about 20–25 R_e are examined during a high geomagnetic disturbance period. It is shown that the plasma sheet cools when magnetospheric substorm expansion is indicated by the AE index. During cooling, the plasma sheet temperature, T, and the number density, N, are related by $\text{T ∝ N}{}^{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}$ (adiabatic process) in some instances, while by T ∝ N^?1 (isobaric process) in other cases. The total plasma and magnetic pressure decreases when $\text{T ∝ N}{}^{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}$ and increases when T ∝ N^?1. Observation also indicates that the dawn-dusk component of plasma flow is frequently large and comparable to the sunward-tailward flow component near the central plasma sheet during substorms.  相似文献   

The semi-detached binary system RZ draconis     

《Chinese Astronomy and Astrophysics》1982,6(3):199-204

The 1978 photoeletric observations of the late type close binary RZ Dra were reanalyzed with the Wilson and Devinney approach. Photometric parameters were determined (in Tab. 1.). The system is found to be semi-detached where the less massive component fills its Roche surface, whereas the other component almost does so. The configuration of the system is shown in Fig. 1. The absolute dimensions of the system are found to be M₁ = 0.61M⊙, $\text{M}{}_2\text{= 0.41}\text{M}\text{⊙}\text{R}{}_1\text{= 1.15}\text{R}\text{,}\text{?}\text{and}\text{R}{}_2\text{= 0.96}\text{R}\text{⊙}$. Both components appear to be overluminous and oversized for their masses and spectral types. Its evolutionary stage is also discussed. The variability in the brightness of the primary mlnimum(Fig. 4) indicates mass loss from the vicinity of L₂, which would be mainly responsible for the long-term decrease in its period.  相似文献