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1.
The asteroids 82 Alkmene and 444 Gyptis were observed photoelectrically at Table Mountain Observatory and at Torino Observatory during their 1979 oppositions. The rotation periods and amplitudes of variation observed were, for 82: Psyn = 12.h999, Δm = 0.55; and for 444: Psyn = 6.h214, Δm = 0.15. The phase relation of 82 Alkmene can be well fit to the theory of K. Lumme and E. Bowell (Astron. J. (1981), 86, 1705). It showed a probable decrease in brightness of ~0.04 mag from 1 month before opposition to 2 months after opposition, which can be attributed to the changing viewing aspect coupled with polar flattering of the asteroid. The phase relation of 444 Gyptis is poorly fit by the Lumme and Bowell theory when only Q and V(0η) are treated as variables. A good fit can be obtained by adjusting some of the other parameters of their theory, but the physical interpretation is ambiguous.  相似文献   

2.
Speckle interferometry of 532 Herculina performed on January 17 and 18, 1982, yields triaxial ellipsoid dimensions of (263 ± 14) × (218 ± 12) × (215 ± 12) km, and a north pole for the asteroid within 7° of RA = 7b47m and DEC = ?39° (ecliptic coordinates γ = 132° β = ?59°). In addition, a “spot” some 75% brighter than the rest of the asteroid is inferred from both speckle observations and Herculina's lightcurve history. This bright complex, centered at asterocentric latitude ?35°, longitude 145–165°, extends over a diameter of 55° (115 km) of the asteroid's surface. No evidence for a satellite is found from the speckle observations, which leads to an upper limit of 50 km for the diameter of any satellite with an albedo the same as or higher than Herculina.  相似文献   

3.
Photoelectric observations of seven asteroids were made from Gila Observatory between October 14, 1983, and June 21, 1984. The following synodic rotational periods and amplitudes are reported: 9 Metis, P = 5.04 hr, ΔM = 0.05; 18 Melpomene, P = 11.570 hr, ΔM = 0.22; 60 Echo, P = 25.208 hr, ΔM = 0.22; 116 Sirona, P = 12.028 hr, ΔM = 0.42; 230 Athamantis, P = 23.99 hr, ΔM > 0.20; 694 Ekard, P = 5.925 hr, ΔM = 0.50; 1984 KD, P = 1.97 hr, ΔM = 0.26. The rotational periods reported for asteroid 60 Echo, 116 Sirona, 694 Ekard, and 1984 KD represent completely new results. The synodic rotational period reported for asteroid 1984 KD is tentative and is based largely upon the observations of a single night. The reported synodic periods of the remaining six asteroids are based upon a minimum of 3 nights of photometric observations.  相似文献   

4.
C. Blanco  S. Catalano 《Icarus》1979,40(3):359-363
A lightcurve of Vesta, obtained on four nights between June 23 and 30 June 1978 during the coordinated campaign for the determination of the rotation period, is presented. The observations were performed at the 91-cm telescope of the Catania Observatory employing UBV filters and a photon counting photometer. The V lightcurve apparently shows a single maximum, suggesting that the 5h20m29s.2 period is the correct one. Features are evident near the maximum and the minimum closely resembling those of Johnson's lightcurve of 22 December 1950 and Taylor's of January 21, 1973. The amplitude in V light is 0m.105 and small variations are also found in the color indices. The largest color variation is for the U-V with Δm = 0.m.05, which is slightly larger than the value 0m.02 found by T. Gehrels [Astron. J.72, 929 (1967)]. The maximum and minimum values occur at the same phase with respect to the maximum V light as found by Gehrels, i.e., Vesta appears bluer near 0p.25 and redder near 0p.7. Corrections with the solar phase angle were made using the coefficients given by Gehrels for the B-V and U-V while a new value of 0.036 mag/deg was assumed for the V observations. The available amplitudes of Vesta's lightcurve were analyzed with respect to the longitude position and the solar phase angle.  相似文献   

5.
《Icarus》1987,69(2):354-369
Photoelectric lightcurves of 532 Herculina in 1984 show two maxima and two minima with a synodic rotation period of 0.39185 ± 0.00002 day (1σ). During some other oppositions the Herculina lightcurve has only one maximum and one minimum over that same rotation period. The absolute magnitude in V is 6.13 ± 0.02 mag, the phase coefficient in V is 0.037 ± 0.002, and the mean colors are BV = +0.86 ± 0.04 and UB = +0.43 ± 0.02. We applied photometric astrometry and the results indicate a sideral period of 0.3918711 ± 0.0000001 day with retrograde rotation for a north pole at 276° long and +1° lat. The uncertainty of the pole is ±1°. A model of Herculina is presented that generates lightcurves consistent with both the observed amplitudes and the timings of extrema over precisely 28,630 sideral rotations during 30 years. The model is a sphere with two dark regions that are each about 0.13 times the brightness of the surrounding surface. The regions are at 0° asterocentric longitude, +15° lat, with a radius of 30°, and 170° long, −38° lat, with a radius of 26°. With the photometric astrometry pole and the model with two dark regions, predicted lightcurves are shown for the next four oppositions.  相似文献   

6.
Results of photoelectric observations of the asteriods 46 Hestia and 115 Thyra, performed in a cooperative program between the Torino and Table Mountain Observatories, are presented. The rotation periods and the maximum amplitudes are: Psyn = 21h.0.4 ± 0h.01, Amplitude = 0.12 mag and Psyn = 7h.241 ± 0.h.001, Amplitude = 0.20 mag, for Hestia and Thyra, respectively. The multiple-scattering factors, Q, inferred from the phase relation data are 0.054 ± 0.003 and 0.058 ± 0.002 for Hestia and Thyra, respectively. The low value obtained for Thyra disagrees with the mean one given by Bowell and Lumme (1979, in Asteroids (T. Gehrels, Ed.), pp. 132–169. University of Arizona Press, Tucson) for S-type asteroids.  相似文献   

7.
The structure of the A1035 cluster of galaxies (10h32m + 40°13′, cz ~ 22000 kms?1), which exhibits a bimodal distribution of galaxy radial velocities (ΔV ≈ 3000 kms?1), is analyzed using three methods of determining the relative distances to clusters from early-type galaxies: the Kormendy relation corrected for the dependence of residuals on galaxy magnitude, the photometric plane, and the fundamental plane. We use the data obtained with the l-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences and SDSS (DR5) data to show that A1035 consists of two gravitationally unbound independent clusters. These clusters with the velocity dispersions of 566 km s?1 and 610 km s?1 and masses within R 200 equal to 2.7 · 1014 and 3.5 · 1014 M , respectively, obey the Hubble law.  相似文献   

8.
The asteroid 133 Cyrene was observed photometrically on 17 nights during oppositions in 1979 and 1980. The synodic period of rotation was found to be 12.h708 ± 0.h001 with an amplitude of ~0.m30 during both oppositions. At large phase angles, the phase relation is quite ordinary (βv ≈ 0.025 mag/degree); however, the low phase angle observations reveal a dramatic opposition brightening, ~0.2 mag/degree near zero phase angle. The absolute magnitude, V(1,0), extrapolated with the above linear phase coefficient, is 8.40. The following color indicates were also measured: B- V = 0.90, U-B = 0.51.  相似文献   

9.
We obtained ~1000 B, V, and R magnitude measurements for asteroid 21 Lutetia quasi-simultaneously with the digital TV system of a 0.5-m MTM-500 meniscus telescope from November 3 through November 11, 2004. We performed a frequency analysis of the B-V and V-R color indices and the V magnitudes based on data averaged over five measurements, which provided an accuracy of the mean color indices and magnitudes of ~0. m 005 and 0. m 08, respectively. Our analysis of the color indices showed the absence of the known period, 0.d3405 (8.h172), and the presence of several periods at a confidence level of 7–10 σ, including P 0 = 2.h93 (1/P = 8.17c/d) and its alias 2.h64 (1/P = 9.17c/d). Our analysis of the V-band data revealed the periods P 1 = 0.d70 and P 2 = 3.d20; both periods yielded double-peaked light curves with amplitudes of 0. m 12 and 0. m 10. The first period is probably the rotation period of the main component, while the second period may be equal to the orbital period of the satellite with one side facing the main body. Another model of the asteroid is also possible: P 0 = 2.h93 is the rotation period of the main body, P 1 = 0.d70 is the orbital period of the synchronous satellite, and P 2 = 3.d20 is the precession period.  相似文献   

10.
Ben Zellner 《Icarus》1976,28(1):149-153
Newly available photometric, polarimetric, spectroscopic, thermal-radiometric, radar, and occultation results are synthesized in order to derive a coherent model for Eros. The geometric albedo is 0.19±0.01 at the visual wavelength, and the overall dimensions are approximately 13 × 15 × 36km. The rotation is about the short axis, in the direct sense, with a sidereal period of 5h16m13s.4. The pole of rotation lies within a few degrees of ecliptic coordinates λ = 16° and β = + 11°.Eros is uniformly coated with a particulate surface layer several millimeters thick. It has an iron-bearing silicate composition, similar to that of a minority of main-belt asteroids, and probably identifiable with H-type ordinary chondrites.  相似文献   

11.
In 1996, photometric observations of the near-Earth asteroid NEA 4197 (1982 TA) were performed at the Crimean Astrophysical Observatory. More than 2000 brightness measurements in the V band were made. The harmonic data analysis at a fairly high significance level revealed two close periods, P 1= 3h .5372 ± 0h .0005 (amplitude 0 m .4) and P 2= 4h .367 ± 0h .001 (amplitude 0 m .2). The third period, P 3= 20h .26 ± 0h .05 (amplitude about 0 m .15), was found at a lower significance level. The conclusion was drawn that the asteroid is a binary system. Its components rotate with the periods P 1and P 2, and P 3is probably related to the orbital motion of the components. Assuming that the diameters of both components are equal to 2 km, the orbital radius equals 4.4 km.  相似文献   

12.
The BL Lac object S5 0716+714 was monitored in the optical band during October 2008, December 2008 and February 2009. We achieved a best temporal resolution of about 5 min in the BVRI bands. The source was active during the whole monitoring campaign. It showed microvariability in 13 days out of 14 days of observation. Four fast flares were observed with amplitudes ranging from 0.3–0.75 mag. The overall amplitude changes during the whole campaign are ΔB ~ 0. m 89, ΔV ~ 0. m 80, ΔR ~ 0. m 73, and ΔI ~ 0. m 51. On internight time scales, strong bluer-when-brighter chromatism was found while different spectral behaviours were found on intranight time scales.  相似文献   

13.
The discovery of a flare star (R.A. (1950)=6h43m6s.07, Decl.(1950)=?16°45′24″) located about 6 arc min south of Sirius is reported. During photometric observations on the night of 13 January, 1982, using the 102 cm telescope at Kavalur, India, the star was seen to brighten by 2.55 mag. inV band over a duration of about 200 s. Observations on this object for a duration of about 10.5 hr spread over seven more nights indicate the star to be variable. The results of these observations are presented.  相似文献   

14.
Based on the Ogorodnikov-Milne model, we analyze the proper motions of Tycho-2 and UCAC2 stars. We have established that the model component that describes the rotation of all stars under consideration around the Galactic y axis differs significantly from zero at various magnitudes. We interpret this rotation found using the most distant stars as a residual rotation of the ICRS/Tycho-2 system relative to the inertial reference frame. For the most distant (d≈900 pc) Tycho-2 and UCAC2 stars, the mean rotation around the Galactic y axis has been found to be M 13 ? =?0.37±0.04 mas yr?1. The proper motions of UCAC2 stars with magnitudes in the range 12–15m are shown to be distorted appreciably by the magnitude equation in μα cos δ, which has the strongest effect for northern-sky stars with a coefficient of ?0.60±0.05 mas yr?1 mag?1. We have detected no significant effect of the magnitude equation in the proper motions of UCAC2 stars brighter than ≈11m.  相似文献   

15.
V.S. Safronov  E.L. Ruskol 《Icarus》1982,49(2):284-296
A two-stage growth of the giant planets, Jupiter and Saturn, is considered, which is different from the model of contraction of large gaseous protoplanets. In the first stage, within a time of ~3 × 107 years in Jupiter's zone and ~2 × 108 years in Saturn's zone, a nucleus forms from condensed (solid) material having the mass, ~1028 g, necessary for the beginning of acceleration. The second stage may gravitating body, and a relatively slow accretion begins until the mass of the planet reaches ~10 m. Then a rapid accretion begins with the critical radius less than the radius of the Hill lobe, so that the classical formulae for the rate of accretion may be applied. At a mass m > m1 ≈ 50 m accretion proceeds slower than it would according to these formulae. When the planet sweeps out all the gas from its nearest zone of feeding (m = m2 ≈ 130 m), the width of the exhausted zone being built13 of the whole zone of the planet) growth is provided the slow diffusion of gas from the rest of the zone (time scale increases to 105?106 years and more). The process is terminated by the dissipation of the remnants of gas. In Saturn's zone m1 > m2 ≈ 30 m. The initial mass of the gas in Jupiter's zone is estimated. Before the beginning of the rapid accretion about 90% of the gas should have been lost from the solar system, and in the planet's zone less than two Jupiter masses remain. The highest temperature of Jupiter's surface, ≈5000°K, is reached at the stage of rapid accretion, m < 100 m, when the luminosity of the planet reaches 3 × 10?3 L. This favors an effective heating of the inner parts of the accretionary disk and the dissipation of gas from the disk. The accretion of Saturn produced a temperature rise up to 2000?2400° K (at m ≈ 20?25 m) and a luminosity up to 10?4 L.  相似文献   

16.
The physical and orbital elements of the binary star ADS 1156 = B 1164 (α1900 = 01h 22m.0, δ1900 = + 04°50′) are determined. The absolute visual magnitudes of the two components are 3m.72 resp. 3m.97, the masses 1.43 M⊙ resp. 1.33 M⊙.  相似文献   

17.
Photographic observations of Jupiter and its Red Spot between 13 November 1969 and 21 September 1970 are reported. The Red Spot continues its 90-day oscillation in longitude with considerable regularity. An outstanding event of the apparition was the appearance of a new disturbance in the South Tropical Zone. A bright spot at zenographic latitude 23°.8 N displayed the shortest rotation period ever recorded on Jupiter, 9h47m3s.  相似文献   

18.
The radial optical depth profile of the Encke ringlet obtained by the occultation experiment of the Voyager photopolarimeter (PPS data) is explained to be caused by the gravitational action of the recently discovered stallite 1981 S13 and a second smaller moonlet orbiting near one of its either libration points — L4 or L5. To this aim the results of previous and new numerical particle simulations as well as an extension of the scattering theory concerning a single moonlet to a pair of satellites have been used leading to a triple-peaked ringlet near the orbits of the moonlets. The width and the shape of that ringlet and its separate peaks depend on the mass ratio of both moonlets and on their orbital eccentricites. The best resemblance between the PPS data and the theoretical profile is obtained if the mass ratio of the either moonlets takes M2/M1981S13 ≈ (0.8 … 3.0) × 10−2 and the eccentricities hold: e1981S13 < h1981S13; e2h2 (the values h are the Hill scales of either moonlets defined by h1981S13/2 ≈ (M1981S13/2/3Mh)1/3, Mh = Saturn mass). Furthermore, our results yield a size of 1981 S13 of < 15 km in diameter.  相似文献   

19.
In an area of nearly 23.1 square degrees centered at α(1950) = 23h57m and δ(1950) = + 59δ48' magnitudes, colors, and spectral classes were determined for 1419 stars brighter than mpg = 13m.00. Star counts were made in this area for all objects brighter than mpg = mpv = 15m.5. Altogether 50585 stars were included in the pv counts. The original photographic data have been transformed to the B, V system. From star counts the ratio of total-to-selective extinction was derived to be R ≉ 4.0 ± 0.2. It depends on the distance to the stars under consideration as well as on the surface density of the objects inside the considered region. In einem Gebiet von annähernd 23.1 Quadratgrad mit den Mittelpunktskoordinaten α(1950) = 23h57m und δ(1950) = 59°48' werden für 1419 Sterne heller als mpg = 13m.00 Helligkeiten, Farben und Spektraltypen bestimmt. Sternzählungen in Helligkeitsintervallen mpg und mpv wurden für alle Objekte heller als mpg = mpv = 15m.5 durchgeführt. Für diese 50585 Sterne wurden die gemessenen photographischen und photovisuellen Helligkeiten in das B, V-System transformiert. Im Ergebnis dieser Sternzählungen wurde ein Wert von R ≉ 4.0 ± 0.2 abgeleitet. Er hängt sowohl von der Entfernung der betrachteten Objektgruppen als auch von der Flächendichte der Sterne innerhalb der Region ab.  相似文献   

20.
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