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1.
PhotoelectricU , B andV observations of the eclipsing binary system FZ Orionis obtained by the author during three years 1984, 1985 and 1986 are presented and studied. The present photometry may settle the dispute regarding the class and the period of the system light variation between the GCVS 1969 ( Lyr;p = 1.597 d) and Figer (1983) and Le Brogneet al. (1984) (W UMa;p 0.4 d) in favour of the latter. A period change was detected which may be elucidated as due to the presence of a third body and mass exchange between the components. Times of ten minima were determined and new ephemeris have been deduced. The present light and colour curves were investigated and preliminary parameters for the system could be estimated.  相似文献   

2.
Radial velocity observations of V 1010 Oph obtained at Asiago from 23 spectra combined with those published by Guinan and Koch (1977) reveal a significant eccentricity (e0.20±0.03) with a periastron angle close to 90° at 1 level. This underlines the need for a new analysis of the light curve for photometric elements.On leave from Konkoly Observatory, Budapest, Hungary  相似文献   

3.
Photoelectric observations of the bright eclipsing binary system HU Tauri are presented. The observations were made with standardB andV filters. Observations made during the eclipses yielded six epochs of minimum light. A study of all the available times of minimum light has been made. Analysis of all the photoelectric times of minimum light yielded the following new ephemeris: JD 2441275.3166 +2 . d 0563107E. Asymmetries in the light curves of HU Tauri were noticed.  相似文献   

4.
FirstU, B, andV observations of UMa are presented. Light curves show light variations of varying amplitude. Colour indices also show small colour variations.  相似文献   

5.
The author considers current problems in the determination of the orbital and physical parameters for active close binaries (CB) of W Ser type based on the interpretation of photometric observations (Djuraevi, 1991). In this particular case, one analyses the light curves of CB SX Cas in the framework of the accretion-disc model explained in the second paper of this series (Djuraevi, 1992a). The light curve is analysed by applying the inverse-problem method described in the third paper of the series (Djuraevi, 1992b). On the basis of the observational material in theB andV filters (Shao, 1967), the light curves, the fundamental orbital and physical parameters of the system are estimated. In the paper a graphical illustration of the obtained solutions is also given. The obtained results confirm the general picture about the active processes in CB of W Ser type.  相似文献   

6.
Kopal's new iterative method for analysing partially eclipsing binary light curves in the frequency domain has been put into a form suitable for applications, and explicit forms for basic expressions developed. To facilitate the computations in practice, the required newS m -functions, which are expressed in terms ofJ , 0 -integrals, have been extensively tabulated by making use of hypergeometric series. The automated method has been tested successfully on the light curves of Persei (Algol). Short information on the system and the revised sets of elements including a new determination of the limb-darkening coefficient in the ultraviolet have been presented.  相似文献   

7.
Observations of the white light corona were made on over 900 days during the years 1964–67 at heights between 1.125 and 2.0 R with the K-coronameter at Mount Haleakala and Mauna Loa, Hawaii. The brightness distribution of the minimum corona was elliptical with average equatorial intensities three times the polar. Coronal features of the new cycle at 1.125 R occurred predominantly in the sunspot zones at 25–30° latitude and in a high latitude zone which migrated toward the North pole before solar maximum. The brightness of the inner corona doubled over this period and a close association is found between the average corona and 10.7-cm solar radio flux. Electron densities in the equatorial regions were nearly twice those of Van de Hulst's model corona, in agreement with the results of recent eclipse observations.At Hawaii Institute of Geophysics.  相似文献   

8.
The monthly number of polar faculae of the Sun were determined from white-light images at spectral band (eff) = (4100 ± 200) Å obtained at the Kislovodsk Solar Station during 1960–1994. Corrected monthly numbers were obtained with the help of the visibility function. The level of polar activity larger than 1 above the monthly running mean was calculated, and the relation between the polar faculae and sunspot cycle was studied. We confirmed earlier results (Makarov and Makarova, 1987) that the monthly number of polar faculae, NPF m (t) correlates with the monthly sunspot area A m (Sp)(t + T) with a time shift T 6 yr. The new polar faculae cycle began in the middle of 1991. Peculiarities of the first part of sunspot cycle 23 are discussed.Guest scientist with the University of Arizona and Zetetic Institute. Tucson, Arizona 85719, U.S.A.  相似文献   

9.
In order to study the electron density at the scale of the most encountered structures in coronal active regions a new multichannel coronagraph associated with a photoelectric spectrograph is now used at the Pic-du-Midi Observatory. In its quasi-routine mode this instrument, which is described in this paper, works with a 30 field aperture in a parallel manner with aK-polarimeter. On each observed region it obtains maps of intensities of the 3388, 10747, and 10798 Å emission lines due to Fexiii ion. Each measurement point is associated with a quasi-simultaneous image of the emission corona structures viewed in the light of the5303 Å line of Fexiv. Three examples of observations are given and the capabilities are discussed.Measuring electron density in coronal active regions. II A multichannel photoelectric coronagraph with a photo-electric spectrograph and a reflex monitor at5303 Å.LA du CNRS No. 040285.  相似文献   

10.
AK Herculis is a contact binary of spectral class F with a number of obvious peculiarities such as a displacement of secondary eclipse from phase 0 . P 500, unequal heights of the maxima, and a possibly sinusoidal (60 yr) period variation. The light curve is variable and shows erratic short-term behavior, although the latter effects are not unusual for a short period contact binary. Here we present new photoelectric light curves in theB andV passbands and derive several new times of minima. The new observations are compared graphically with seven earlier light curves. We analyzed the new observations and those by Bookmyer (1972) by the method of differential corrections. We find that the temperature difference between components is too large (1000 K) for AK Her to be considered a normal W UMa-system, but too small to allow a detached configuration obeying the mass-luminosity law. The solutions of both series of observations clearly indicate a contact configuration. Other unusual findings include a bolometric albedo greater than 2, and rather low values for the limb-darkening coefficients. We offer some possible reasons for these peculiarities. The mass ratio seems well determined from the photometry and is about 0.26, which is much lower than assumed in most earlier papers. The brightness and color of the known visual companion, ADS 10408B, were found by the differential corrections program. They agree, within observational error, with values found directly at the 200-in. telescope by Eggen, despite the fact that the B component contributes only a few percent of the light of the multiple system. The suggestion by Schmidt and Herczeg (1959) that a fourth body is responsible for the sinusoidal period variation seems stronger now than when first proposed. To encourage a search for this hypothetical component, we have tabulated expected values for its angular separation and relative mass with respect to the eclipsing pair, as well as the amplitude of the expected variable proper motion of the eclipsing pair. Discovery as a visual component seems impossible with present means, but the variable proper motion should be detectable. Thus we suggest that ADS 10408A (AK Her) be observed astrometrically. If a search for the predicted variable proper motion proves negative, mass transfer would remain the only plausible mechanism to explain the period change. We advance a different reason than did Schmidt and Herczeg to explain the phase lag of secondary eclipse.  相似文献   

11.
The basic physical picture of the Algol system is reviewed, and, using collected red and infrared observations, photometric curve fits are investigated by applying numerical quadratures to determine theoretical light curves appropriate to Roche model stars. The contact nature of Algol B appears to be confirmed, and effective temperatures of the three components areT A=11 400°,T B=5300°,T C=7600°. In terms of a Lambert's law approach to the reflection effect, the effective heat-albedo is required to be reduced from unity to one half; and it is also found that the averaged gravity-darkening coefficient is close to a value appropriate for a diffusion type of heat-transfer mechanism operating in sub-photospheric layers.  相似文献   

12.
An early estimate for the size of cycle 23   总被引：1，自引：0，他引：1  
Two features are found in the modern era sunspot record (cycles 10–22: ca. 1850-present) that may prove useful for gauging the size of cycle 23, the next sunspot cycle, several years ahead of its actual onset. These features include an inferred long-term increase against time of maximum amplitude (RM, the maximum value of smoothed sunspot number for a cycle) and the apparently inherent differing natures of even- and odd-numbered sunspot cycles, especially when grouped consecutively as even-odd cycle pairs. Concerning the first feature, one finds that 6 out of the last 6 sunspot cycles have had RM 110.6 (the median value for the modern era record) and that 4 out of 6 have had RM > 150. Presuming this trend to continue, one anticipates that cycle 23 will likewise have RM 110.6 and, perhaps, RM > 150. Concerning the second feature, one finds that, when one groups sunspot cycles into consecutively paired even-odd cycles, the odd-following cycle has always been the larger cycle, 6 out of 6 times. Because cycle 22 had RM = 158.5, one anticipates that cycle 23 will have RM > 158.5. Additionally, because the average difference between RM(odd) and RM(even) for consecutively paired even-odd cycles is 40.3 units (sd = 14.2), one expects cycle 23 to have RM 162.3 (RM = 198.8 ± 36.5 at the 95% level of confidence). Further, because of the rather strong linear correlation (r = 0,959, se = 13.5) found between RM(odd) and RM(even) for consecutively paired even-odd cycles, one infers that cycle 23 should have RM 176.4 (RM = 213.9 ± 37.5 at the 95% level of confidence). Since large values of RM tend to be associated with fast rising cycles of short ascent duration and high levels of 10.7-cm solar radio flux, cycle 23 is envisioned to be potentially one of the greatest cycles of the modern era, if not the greatest.  相似文献   

13.
The possibility of radio emission is considered within a model which produces the beam-plasma system near the pulsar. A longitudinal instability develops near the light cylinder for a particular choice of parameters adopted in the paper. The excited wave strongly oscillates the beam particles perpendicular to its average velocity on one hand, and forms bunches of them on the other hand. Consequently, coherent radiation is expected. The frequency of the emission falls within the radio band, but the intensity turns out to be too low to explain observations. An appreciable enhancement of the beam number density over the Goldreich-Julian value (n bB/2ec) is needed if the mechanism discussed in the present paper is responsible for the pulsar radio emission.  相似文献   

14.
The properties of solar flare continuum emission at energies >300 keV are discussed. Emphasis is placed on observations made during the 21st Solar Maximum by -ray detectors aboard the Solar Maximum Mission and Hinotori satellites. The statistical properties of high-energy flares are presented, including their size-frequency distribution, spectral-index distribution, position distribution, and associated soft X-ray size. The temporal structure of the high-energy continuum is reviewed as well as attempts to model the structure by two-step acceleration and particle trapping. Evidence for the directivity of flare radiation is presented and statistical and stereoscopic analysis techniques are compared and contrasted. The first observations of flare -rays at energies > 10 MeV are examined. We show that the very high-energy emission must be a mixture of pion-decay radiation and primary electron bremsstrahlung. Finally, we present high-energy observations from the extended phase of the giant 3 June, 1982 flare which seem to require a new acceleration component.  相似文献   

15.
The coronal hole observed on May 31, 1973 is studied using extreme ultraviolet and radio observations. The EUV line is the Fe xv at = 284 Å and the radio frequencies are 169 and 408 MHz. An unsuccessful attempt to deduce an homogeneous model of the hole from these observations, shows that EUV and radio observations are inconsistent if interpreted in such a frame and if the EUV line intensity measurements in the hole are reliable.Inhomogeneities are therefore required to account for both observations. An inhomogeneous model consisting of hot (T2×106K) elements covering 10% of the hole surface surrounded by regions of colder gas (T8×105K) is able to explain both observations.  相似文献   

16.
The aim of the present paper will be to introduce a new definition of the loss of light suffered by mutual eclipses of the components of close binary systems: namely, as across-correlation of two apertures representing the eclipsing and eclipsed discs.The advantages of such a strategy over the more conventional (geometrical) approach are (a) greater symmetry of the respective expressions; (b) greater affinity of expressions arising from distortion with those expressing the light changes due to eclipses of spherical stars; and (c) greater freedom in dealing with the effects of particular distribution of brightness over the disc of the star undergoing eclipse (generalized limb-darkening), as well as of possible semi-transparency of the eclipsing component (Wolf-Rayet stars!). In point of fact, none of these tasks could be handled with equal ease by any other technique; nor could the corresponding loss of light be so automated by any other approach.In Section 2 which follows brief introductory remarks we shall evaluate the loss of light arising from distribution of brightness within the aperture undergoing eclipse, and appropriate opacity of the occulting disc. In Section 3 we shall take advantage of these new forms of our results to deduce a number of new properties of the eclipse functions — both algebraic and differential — which have so far escaped attention and which are of considerable practical interest. Lastly, in Section 4 we shall generalize the same concepts to the modification of the light changes caused by the departures of the respective apertures from circular forms.It will be shown that all these phenomena can be most naturally described in terms of Hankel transforms of the products of two Bessel functions with orders depending on the physical characteristics (distribution of brightness; opacity) of the two components; while the geometry of the system (i.e., the fractional radiir 1,2 of the two stars; or the inclinationi of their orbit) enter only through their arguments. Such formulation of our problem should bring a theory of the light changes of eclipsing variables in much closer contact with the adjacent parts of physical optics.  相似文献   

17.
The cycle durationC in some dwarf novae underwent abrupt significant changes, as was found by using our own photometric data and the published moments of maxima. For the analysis, the DMRT method (Dumontet al., 1978) as well as least-squares (LS) routine were used. The DMRT method is more appropriate for a search for mean period, if the cycle numeration is unknown. Such changes may be possibly explained by a solar-type activity of convective secondary stars in cataclysmic binaries. However, the abrupt character of the changes ofC (i.e., the time of switchings from one cycle to another is sufficiently small as compared with the lifetime of a given cycle) is an observational puzzle which is to be interpreted theoretically.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.  相似文献   

18.
It is shown that in a heliomagnetic field the presence of a magnetic quadrupole in addition to a magnetic dipole introduces a north-south asymmetry in the heliospheric current sheet (HCS) about the heliographic equator. The dominant polarity of the interplanetary magnetic field (IMF) for the above type of current sheet reverses sign at a transition latitude T, which lies in a heliohemisphere opposite to the one in which the HCS has more heliolatitudinal extension. The position of T in the heliosphere and the north-south asymmetry introduced in the HCS change with the relative phase of the dipole and quadrupole components present in the solar magnetic field. The effect of the above type of asymmetric HCS in the IMF mean sector width is evaluated and the results are in agreement with the observations during the minima of solar cycle 21.  相似文献   

19.
We have investigated ROSAT X-ray data of OB stars to search for evidence of time variability in the X-ray emission from early-type stars. As an example for such studies we present a detailed variability analysis for our two program stars Ori and Ori which have been multiply observed with ROSAT. The long-term analysis of both stars now covers a time range of 2.5 years and includes six pointed PSPC observations, an additional pointed HRI observation of Ori and the ROSAT all-sky survey data of both stars. Over a long time range the X-ray light curves of Ori and Ori show no evidence for variability. In the case of Ori we detected a moderate increase in X-ray count rate during a period of 2 days which can be explained as a strong shock propagating in the wind of an O-type star.  相似文献   

20.
Ground-based optical observations coordinated with Yohkoh/SXT X-ray observations of an old, disintegrating bipolar active region AR NOAA 7493 (May 1, 1993) provided a multiwavelength data base to study a flaring active region X-ray bright point (XBP) of about 16 hr lifetime, and the activity related to it in different layers of the solar atmosphere. The XBP appeared to be related to a new minor bipole of about 1020 Mx. Superposed on a global evolution of soft X-ray brightness, the XBP displayed changes of brightness, lasting for 1–10 min. During the brightenings the XBP apparently had a spatial structure, which was (tiny) loop-like rather than point-like. The X-ray brightenings were correlated with chromospheric activity: (i) brightenings of underlying chromospheric faculae, and (ii) appearance of strong turbulent velocities in the arch filament system. We propose that the XBP brightenings were due to reconnection of the magnetic field lines (sketched in 3D) between the new bipole and a pre-existing plage field induced by the motion of one of the new pores (v = 0.2 km s–1) towards the plage, and that the XBP itself was a reconnected hot loop between them.  相似文献   

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