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1.
The H profile in the spectrum of Orionis shows phase-dependent changes, with a period of variation equal to the orbital period fo the binary system. The profile shape changes from a normal absorption profile at zero phase to a P Cygni-type at a later phase, to an absorption profile having emission at the centre of the profile, to a normal absorption profile at the end of the period. The spectra have been obtained at the Cassegrain focus of Kavalur Observatory telescopes (50 and 100 cm) at 17.2 Å mm–1 reciprocal dispersion and resolution 0.3 Å at 6562.817 Å. Assuming that the P Cygni profile is formed by a spherically-symmetrical region, the analysis gives a shell radius of 2.18 stellar radius and an electron density in the shell equal to 6.54×10–9 cm–3, with the observed expansion velocity of 50 km/s–1, a mass loss of 1.3×10–7 M per year.An analysis has been carried on the radial velocity data of earlier observers and the present radial velocity data. It is found that the orbital elements change. The presence of apsidal motion is confirmed by the increasing value of . The radial velocity of the centre of mass, , shows periodic variation. These observations confirm the presence of a third body. The values ofK (mean amplitude),P (period),a sini, and mass functionf(m), indicate a regular decrease, thereby confirming the mass transfer/mass loss from the system.  相似文献   

2.
The coronal transient event of 20–21 November is unusual in that its appearance is distinctly non-loop-like; rather, the transient resembles a confined ray or fan-like volume. Studies of the distribution of the coronal material with time indicate that this is a mass ejection event, involving about 1 × 1015 g of material from the lower corona. Analysis of the polarization signal of the event suggests that the event is associated with chromospheric activity in a region near longitude E68. The observed properties (distributions in brightness and polarization) of the transient are compared with the properties of a well-studied event of typical loop-like appearance, but rotated to simulate an edge-on appearance; the differences suggest that the 20–21 November event is not such an edge-on, loop-like transient, but rather is most simply described as an axisymmetric-cylindrical or conical volume, the boundaries of which remain constant over the events' lifetime. On this basis, the variation of the transient spatial density with height and the variation of density with time can be specified rather more certainly than for previously-studied coronal mass ejection events. Densities are found to range from 3 × 10–16 g cm–3 at 2.1 R heliocentric height early in the event to 1 × 10–18 g cm–3 at 4.0 R late in the event. Typical temporal variations of the ejected material (at a given heliocentric height) are found to be on the order of 10–18 g cm–3 s–1. The mass and momentum balance in the event have been estimated from the observed parameters, employing a multiparameter approach. We find that a model with modest mass flux typified by material speed u 0 50 km s–1 and a near balance between the event's pressure gradient force and gravity — with possibly a small hydromagnetic wave contribution to the total pressure — is consistent with the observations. The kinetic energy of the event, determined from the motion of the center of mass of the ejected material, is only about 1026 ergs, and thus is the smallest for any solar mass ejection studied to date.The National Center for Atmospheric Research is sponsored by the National Science Foundation.  相似文献   

3.
A first detailed period study of the eclipsing RS CVn-binary system RW Com is presented. A new period (P=0d.2373455) based on 223 minima is given. The O–C diagrams of RW Com have been presented for the first time. Types of ten minima have been corrected judging the period trend. Period changes in different portions of the O–C diagram (Figure 2) have been estimated. The total change in period (P/P) ranges from 5.5×10–7 to 6.4×10–6. Thus, P ranges from 1.3×10–7 d to 1.5×10–6 d. Numerous minima are available in the time interval 1967 to 1986. This part of the O–C diagram (Figure 2) shows a sinusoidal variation, thus, it is suspected that RW Com could be a three-body system. The period of variation due to third body appears to be nearly 16 years.  相似文献   

4.
Detailed period study of the eclipsing binary ST Per is presented. A new period (P=2d.648339) is given. Period changes in different portions of the O-C diagram with a new period have been estimated. The total changes in period (P) ranges from 2.17×10–5d to 2.64×10–4d which is appreciably large. Sufficient number of minima in the time interval 1934 to 1985 for this system are available. Distinct increasing and decreasing trends are evident, the change in the tendency appears to have occurred around 1947. Sinusoidal variation is seen between cycles 7000–10000, which indicates that ST Per is a three-body system, the period of the third body being about 22 years. However, the sinusoidal variation is not perfectly symmetric in shape, therefore, it is suspected that ST Per is a four-(or multi-) body system.  相似文献   

5.
The period variations of TV Cassiopeiae between 1901 and 1977 are discussed in the light of the period change model proposed by Biermann and Hall. During each period decrease 4.0×10–6 M of mass is transferred from the secondary star to the primary. The average observable mass transfer rate is found to be 4.3×10–7 M yr–1. This average rate corresponds to the thermal time-scale of the mass-losing star.  相似文献   

6.
Observations have been made in H of the vertical velocity distribution in a sunspot. Over the umbra the pattern consists of structures of scale-size 2–3. The velocity distribution undergoes oscillations with a period of about 165 s and typical amplitude ±3 km s–1, but the pattern breaks down after one or two cycles because the period of oscillation varies typically by ±20 s from place to place. Transverse waves develop in the outer 0.1 of the umbral radius and propagate outwards with a velocity of about 20 km s–1, becoming gradually invisible by or before the outer penumbral boundary; the amplitude is about ±1 km s–1 at the umbra-penumbra border.The penumbral waves are believed to be basically of the Alfvén type, with 3 × 10–8 g cm–3. The umbral oscillations presumably represent gravity waves. In both cases the fluxes are inadequate by two orders of magnitude to account for the sunspot energy deficit.  相似文献   

7.
The Advanced Technology Solar Telescope site survey Sky Brightness Monitor simultaneously images the solar disk and the sky to about 8 solar radii in four wavelengths at 450, 530, 890 and 940 nm. One day of data from Mees Solar Observatory on Haleakala and from the National Solar Observatory at Sacramento Peak (Sunspot, New Mexico) are analyzed. Both sites show strong Rayleigh extinction, but while Haleakala shows a larger aerosol component, Sunspot shows a large variation in the aerosol component. Overall the Haleakala extinction varies as –2 whereas the Sunspot extinction changes from about –3.5 to about –2, suggesting an increasing aerosol component during the day. Water vapor absorption measurements from both sites are similar, though Sunspot shows larger time variations than Haleakala. The instrument-corrected sky brightness from both sites show comparable values, and again the Sunspot data show more variations. The sky brightness values show a radial dependence of sky brightness of r –0.1 at Haleakala, but a dependence of r –1.0 at Sunspot. The wavelength variation of the sky brightness at Haleakala is relatively constant at –1.5 but varies at Sunspot from –1.5 to –0.1 again suggesting an increasing aerosol contribution during the day at Sunspot. Finally, dust measurements near the ground are compared with the extinction wavelength exponent for data taken at Haleakala on 24 Feb. 2003. The measurements suggest more large dust particles are present near the ground than averaged over the whole air column.  相似文献   

8.
Photometry and first results of extensive CCD-spectroscopy of the UX UMa system RW Sex are presented. The period is found to be P=0.24486 days and the semi-amplitude of the radial velocity is K1=101 km s–1. The mass of a Roche-lobe filling secondary is M2=(0.54±0.09) M0 and, for M1M2, the mass ratio is M1/M2=1.5±0.5. The accretion rate is about (2–3) 1017 g/s. The model for RW Sex by Greenstein and Oke is discussed and rejected.Paper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G., 16–19 June, 1986.  相似文献   

9.
A general Hamiltonian for a rotating Moon in the field of the Earth is expanded in terms of parameters orienting the spin angular momentum relative to the pricipal axes of the Moon and relative to coordinate axes fixed in the orbital plane. The effects of elastic distortion are included as modifications of the moment of inertia tensor, where the magnitude of the distortion is parameterized by the Love numberk 2. The principal periodic terms in the longitude of a point on the Moon due to variations of the tide caused by the Earth are shown to have amplitudes between 3.9 × 10–3 and 1.6 × 10–2 with a period of an anomalistic month, 3.0 × 10–4 and 1.2 × 10–3 with a period of one-half an anomalistic month and 2.4 × 10–4 and 9.6 × 10–4 with a period of one-half of a nodical month. The extremes in the amplitudes correspond to rigidities of 8 × 1011 cgs and 2 × 1011 cgs, respectively, the former rigidity being comparable to that of the Earth. Only the largest amplitude given above is comparable to that detectable by the projected precision of the laser ranging to the lunar retrorereflectors, and this amplitude corresponds to an improbably low rigidity for the Moon. A detailed derivation of the free wobble of the lunar spin axis about the axis of maximum moment of inertia is given, where it is shown that elasticity can alter the period of the free wobble of 75.3 yr by only 3 × 10–4 to 10–3 of this period. Also, the effect of elasticity on the period of free libration is completely negligible by many orders of magnitude. If the Moon's rigidity is close to that of the Earth there is no effect of elasticity on the rotation which can be measured with the laser ranging and, therefore, no elastic properties of the Moon can be determined from variations in the rotation.Currently on leave from the Dept. of Physics, University of California, Santa, Barbara, California.Communication presented at the conference on Lunar Dynamics and Observational Coordinate Systems held January 15–17, 1973 at the Lunar Science Institute, Houston, Tex., U.S.A.  相似文献   

10.
A new period (P=1d.7175405) of the eclipsing binary system SZ Arietis has been presented. Period changes in different portions of the O-C diagram, with new period, have been estimated. The total change in period (P) ranges from 3.64×10–5 d to 4.24×10–4 d, which is appreciably large. However, leaving the unusual value, the average period change comes out to be of the order of 6×10–5 d. The period changes around the years 1903, 1943, and 1977 are apparent in the O-C diagrams. A sinusoidal variation is also visible in the O-C diagrams which indicates that SZ Ari may be a three-body system, having a period of nearly 66 years.  相似文献   

11.
Iapetus (S8) is unique in our solar system in that the albedo of its leading hemisphere is only 0.05 while that of the trailing side is 0.5. Several existing hypotheses are examined and found inadequate. Photometric studies of the dark side are compared to comet nuclei and class D asteroids. It is hypothesized that in the last 106–108 yrs the leading side suffered a high-velocity collision with a cometary body of mass 1013–1015 kg and traveling at a speed of 20 km s–1. About 5–16% of the excavated material was ejected into space, where the vaporized ices dissipated while the dark carbonaceous/silicate material was reaccreted on the leading side. The collision, although not sufficient to break Iapetus' tidal lock, resulted in a period of oscillation of about 5 yr. Until tidal friction reasserted a lock, the oscillation gave rise to the longitude effect, viz., the observed fact that the dark material covers more than 220 of longitude but only 110 of latitude.  相似文献   

12.
Summary In the solar neighborhood, approximately half of all intermediate mass main sequence stars with initially between 1 and about 5 Mbecome carbon stars with luminosities near 104 L for typically less than 106 years. These high luminosity carbon stars lose mass at rates nearly always in excess of 10–7 M yr–1 and sometimes in excess of 10–5 M yr–1. Locally, close to half of the mass returned into the interstellar medium by intermediate mass stars before they become white dwarfs is during the carbon star phase. A much greater fraction of lower metallicity stars become carbon-rich before they evolve into planetary nebulae than do higher metallicity stars; therefore, carbon stars are much more importan t in the outer than in the inner Galaxy.  相似文献   

13.
We present the results of the photometric observations, in theUBVRJHKLMNQ system, of CH Cyg, made in the period 1978–1987. They have shown that from 1985 to 1987 dust condensed in its circumstellar envelope have taken place the condensation of the dust matter. In 1987 its mass and temperature were about 3×10–8 M and 800 K, respectively.  相似文献   

14.
Stars with a core mass greater than about 30 M become dynamically unstable due to electron-positron pair production when their central temperature reaches 1.5–2.0×109 oK. The colapse and subsequent explosion of stars with core masses of 45, 52, and 60 M is calculated. The range of the final velocity of expansion (3400–8500 km/sec) and of the mass ejected (1–40 M ) is comparable to that observed for type II supernovae. A dynamical model of convection is derived and included in the calculations. It was found that the effect of the convection on the explosions is probably not important.Work supported in part by the U.S. National Aeronautics and Space Administration under Grant NsG-426.  相似文献   

15.
A first period study of the eclipsing binary XY Ceti is presented. A new period (P=2d.7807135), based on all available times of minima, is given. Period changes in different portions of the O–C diagram, with a new period, have been estimated. The total change in period (P/P) ranges from 1.1×10–5 d to 1.2×10–4 d, thus, P ranges from 3.1×10–5 d to 3.3×10–4 d. The O–C diagram suggests that the trend of the period has changed around the year 1959. Two portions of increasing and decreasing trends also reveal that the period changes (P/P) of the order of 10–5 d are present, which are appreciably large.  相似文献   

16.
The time variation of the gravitational constantG is discussed in the light of the gravity modified form of quantum electrodynamics. From the experimental upper limit |a/| < 5 × 10–15 yr–1 on the time variation of the electromagnetic fine structure constant one finds |/G| < 5 × 10–13 yr–1.  相似文献   

17.
The galactic nebula S206 contains a half shell of high excitation nebulosity which is centred on the associated exciting star. The suggestion has been made that this structure is caused by the interaction of stellar mass loss from the star with nebular gas. A steady state model of such an interaction is investigated quantitatively. The required mass loss rate from the star is about 10–7 M yr–1 which is compatible with the observationally derived mass-loss rates from early-type stars.  相似文献   

18.
A maximal spectrum of gravitational radiation from sources outside our galaxy is calculated. The sources are galaxies, quasars and events that occur in the early history of the universe. The major contribution is from galaxies whose effect extends over the frequency region 10–810+4Hz, peaking at 10–110 Hz, with a spectral flux of 10 erg cm–2, s–1. The main processes of gravitational radiation in the galaxies are stellar collapse into a black hole and dying binary systems. In the region 10–4104 Hz the background spectrum is well above the detection levels of currently proposed detectors. FromMinimal considerations of this spectrum it is determined that the density of gravitational radiation is 10–39g cm–3. This background spectrum is sensitive to galactic evolution and especially sensitive to the upper mass limits and mass distribution of stars in galactic models. Therefore, the spectrum could provide information about galactic evolution complementary to that obtained by electromagnetic investigations.  相似文献   

19.
The assumption that the very low albedo determined for Halley's comet is typical of all short period comets, taken together with the assumption that the average sizes of long and short period comets are approximately equal, leads to an increase in the total mass of comets in the solar system by almost two orders of magnitude. If gravitational ejection from the Uranus - Neptune zone during the later phases of planet formation is indeed responsible for the classical Oort cloud between 104–1015 AU, then the mass of comets in this transplanetary region during cosmogonie times has to exceed the combined masses of Uranus and Neptune by over an order of magnitude. Furthermore, if the recent arguments for as many as 1014 comets in an inner Oort cloud between ~40– 104AU are valid, then the total mass of comets in the solar system approaches 2% of a solar mass.  相似文献   

20.
The detailed evolution of low-mass main-sequence stars (M < 1M ) with a compact companion is studied. For angular momentum loss associated with magnetic braking it is found that about 10–11–10–12 M yr–1 in stellar wind loss would be required. This wind is 102–103 times stronger than the solar wind, so we believe here magnetic stellar wind is insufficient. It is well known that there is mass outflow in low-mass close binary systems. We believe here that these outflows are centrifugal driven winds from the outer parts of the accretion disks. The winds extract angular momentum from these systems and therefore drive secular evolution. Disk winds are preferred to winds from the secondary, because of the lower disk surface gravity.  相似文献   

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