共查询到20条相似文献，搜索用时 15 毫秒
1.
Spectral reflectivities ?(λ) of the features on the disk of Jupiter (NTrZ, NEB, EZ, SEB, STrZ) and the center of the disk of Saturn were measured for different phase angles. The phase dependence of ?(λ) is shown to correspond to the shape of the phase function. 相似文献
2.
《Icarus》1987,71(3):386-396
Linear polarization was observed on the integrated disk of Mercury with seven filters between 0.3 and 1.0 μm, and between 53° and 130° phase angle. Polarization-time variations were found and they are mostly explained by longitude dependence through variation in brightness or other properties over the surface. The polarization-wave-length dependence is flatter than for the Moon, and the polarization-albedo relation also differs, indicating a difference in surface composition and/or texture. 相似文献
3.
V. G. Kaydash S. Yu. Gerasimenko Yu. G. Shkuratov N. V. Opanasenko Yu. I. Velikodsky V. V. Korokhin M. V. Kaydash 《Solar System Research》2010,44(4):267-280
From the ground-based colorimetry performed for two surface regions of the near side of the Moon, images of the phase ratio
of the color index C(600 nm/470 nm) have been built for the phase angles between 2° and 95°. It has been found that for phase angles smaller than
α ∼ 40°–50°, the color index of the highlands grows with the phase quicker than that of the mare regions. For larger phase
angles, α > 50°, a reverse situation is observed. The laboratory data on the spectrophotometry of the lunar samples confirm
the peculiarities found in the phase dependence of color. The influence of multiple scattering on the phase dependence of
the color of the mare and highland regions of the Moon are discussed. 相似文献
4.
《Icarus》1986,66(3):455-467
The wavelength dependence (0.4 to 1.2 μm) of the phase coefficients of powdered samples of a basalt, the ordinary (L6) chondrite Bruderheim, and the carbonaceous chondrite Allende are shown to be qualitatively similar to the observed wavelength dependence of the phase coefficients of the Moon and S- and C-class asteroids, respectively. Model calculations of the surface roughness indicate that the systematic difference between the visual (λ = 0.55 μm) phase coefficients of S- and C-class asteroids reflects primarily differences in composition and not necessarily differences in surface roughness. On the average the large scale surface roughness of both S and C asteroids is comparable to that of the Moon. The wavelength dependence (0.4 to 0.7 μm) of three particle size fractions of sulfur (diameters < 10 μm, < 150 μm, and 420–850 μm) show that particle size effects are important modifiers of the phase coefficient. Large scale surface roughness at least comparable to that of the Moon is required to explain the phase curve of Io if elemental sulfur is a dominant surface material. 相似文献
5.
S. S. Shabala S. Ash P. Alexander J. M. Riley 《Monthly notices of the Royal Astronomical Society》2008,388(2):625-637
We use a volume- and flux-limited sample of local (0.03 ≤ z ≤ 0.1) radio galaxies with optical counterparts to address the question of how long a typical galaxy spends in radio active and quiescent states. The length of the active phase has a strong dependence on the stellar mass of the host galaxy. Radio sources in the most massive hosts are also retriggered more frequently. The time spent in the active phase has the same dependence on stellar mass as does the gas cooling rate, suggesting the onset of the quiescent phase is due to fuel depletion. We find radio and emission-line active galactic nuclei (AGN) activity to be independent, consistent with these corresponding to different accretion states. 相似文献
6.
The dependence of asteroidal light curves has been derived from the obliquity, aspect and phase angles. The effects of an angle variation are discussed taking into account the possible geometry of an asteroidal body.The amplitude-aspect relation is discussed for different asteroidal shapes.On the basis of this relation a graphical attempt to determine the value of the aspect from the light curves' amplitude is described. 相似文献
7.
A new definition of the effective depth of line formation is given which incorporates its dependence on the angle of emergence as well as on the position within the line. Solution obtained for isotropic scattering in the third approximation of discrete ordinates explains: (i) Variation of equivalent widths over the disc; (ii) Inverse dependence of this variation on line strength; and (iii) The phase effect for relative equivalent widths. 相似文献
8.
B. Kmpfer 《Astronomische Nachrichten》1988,309(6):347-355
Classical nucleation theory is applied to follow the thermal history of a homogeneous and isotropic universe during a first-order phase transition. The dependence of possible supercooling and reheating scenarios on the surface tension and growth velocity of bubbles is discussed. 相似文献
9.
We performed photometry of Cassini Visual Infrared Mapping Spectrometer observations of Iapetus to produce the first phase integrals calculated directly from solar phase curves of Iapetus for the leading hemisphere and to estimate the phase integrals for the trailing hemisphere. We also explored the phase integral dependence on wavelength and geometric albedo. The extreme dichotomy of the brightness of the leading and trailing sides of Iapetus is reflected in their phase integrals. Our phase integrals, which are lower than the results of Morrison et al. (Morrison, D., Jones, T.J., Cruikshank, D.P., Murphy, R.E. [1975]. Icarus 24, 157-171) and Squyres et al. (Squyres, S.W., Buratti, B.J., Veverka, J., Sagan, C. [1984]. Icarus 59, 426-435), have profound implications on the energy balance and volatile transport on this icy satellite. 相似文献
10.
UBV observations of the Galilean satellites made at Lowell Observatory and Cerro Tololo Inter-American Observatory during 1973 and 1974 are reported. The dependence of brightness on solar phase angle for various faces of each satellite is determined. Significant differences in this dependence are found between different faces of the same satellite, between satellites, and between the present results and those of previous investigators. Rotational light and color-index curves are presented for the satellites and compared with earlier work. An apparent secular brightening of all four satellites between 1973 and 1974 is discussed. 相似文献
11.
There are two mechanisms which can account for the oxygen green line emission at 100 km Altitude, namely the Chapman and Barth mechanisms. Theoretical results and experimental data are used in order to discriminate which of these predominates in the atmosphere. In particular we have used an important new test which consists in comparing the phase of the mean diurnal variation of the green line intensity with the phase of the tide responsible for this variation. This is a powerful test because the phase of the green line variation calculated from the tidal phase has a very weak dependence on the atmospheric model used. Our conclusion is that in the atmosphere the Chapman mechanism predominates. 相似文献
12.
Observations of near-Earth asteroids at large phase angles made it possible to obtain a more complete (for ground-based observations) phase dependence of the polarization of the E-type asteroids’ radiation including the maximum of the positive branch of the linear polarization degree. It is shown that the position of the polarization maximum of high-albedo asteroids is noticeably shifted to the decrease of phase angles compared with S-type asteroids. Model calculations of polarimetric properties of random Gaussian particles that simulate dust particles on the regolith surface are carried out. Model calculations show a qualitatively similar behavior pattern of parameters of the positive polarization branch. The influence of the refractive index of individual scattering particles on the size and position of the maximum of the positive branch of the linear polarization degree is investigated within the considered model. 相似文献
13.
Low phase angle effects in photometry of trans-neptunian objects: 20000 Varuna and 19308 (1996 TO66)
We present the results of photometric observations of trans-neptunian object 20000 Varuna, which were obtained during 7 nights in November 2004-February 2005. The analysis of new and available photometric observations of Varuna reveals a pronounced opposition surge at phase angles less than 0.1 deg with amplitude of 0.2 mag relatively to the extrapolation of the linear part of magnitude-phase dependence to zero phase angle. The opposition surge of Varuna is markedly different from that of dark asteroids while quite typical for moderate albedo Solar System bodies. We find an indication of variations of the scattering properties over Varuna's surface that could result in an increase of the lightcurve amplitude toward zero phase angle. It is shown that a similar phase effect can be responsible for lightcurve changes found for TNO 19308 (1996 TO66) in 1997-1999. 相似文献
14.
We report here results from a study of X-ray bursts from 3 magnetar candidates (SGR 1806-20, SGR 1900+14 and AXP 1E 2259+586).
We have searched for a pulse phase dependence of the X-ray burst rate from these sources. X-ray light curves were obtained
with the Proportional Counter Array on-board the Rossi X-ray Timing Explorer during the periods of intense burst activity
in these sources. On detailed analysis of the three sources, we found a very significant burst rate for all pulsar phases.
However, some locations appear to produce bursts slightly more often, rendering the non-isotropic distribution. Only in the
case of SGR 1900+14, there is a clear pulse phase dependence of burst rate. 相似文献
15.
The polarization of Pluto has been measured for a range of solar phase angles from 0.8 to 1.8°. A mean linear polarization of 0.29 ± 0.01% (error of the mean) was found. No dependence of both the amount of polarization and position angles with rotational phase or solar phase angle could be detected. The positional angles of polarization agree with calculated position angles of the defect of illumination and are therefore parallel to the scattering plane. The observed polarization cannot be explained as resulting purely from a surface material which is similar to asteroidal surfaces. A hypothesis of polarization from a thin atmosphere, in addition to the surface polarization, is advanced. 相似文献
16.
Analysis of 206 high-quality plates from three recent apparitions taken in five colors has yielded several photometric parameters for Saturn and its A and B rings. Phase curves and geometric albedos are derived for two regions of Saturn and for each ring. The phase coefficients of the rings are found to be independent of the ring-plane inclination angle. A comparison of the phase curves shows that the particles of ring A exhibit a larger phase coefficient than do those of ring B. When examined with a multiple-scattering model using Henyey-Greenstein phase functions, the observations of the ring tilt effect indicate that the particles of ring A may also have lower single-scattering and geometric albedos. The color dependence of the geometric albedo of the particles in ring B is shown to be very similar to that of Europa (J II). We find for ring A an optical thickness of 0.50 (0.45 ≤ τA ≤ 0.57) and for the Cassini division, 0.018 ± 0.004. 相似文献
17.
The strengths of 10 bands in the absorption spectrum of liquid methane betwen 19 400 and 6190 Å have been measured. After a small correction for the polarizability of the liquid is applied, for the purpose of comparison with similar gas phase measurements, it is found that there is no temperature dependence of the band strengths between 95 and 295°K. Changes of band shape with temperature cause the 95°K laboratory spectra to resemble Saturn more than room temperature observations do. Gas phase absorption clearly dominates the liquid in planetary spectra, so liquid methane cannot be detected in the outer Solar System by Earth-based observations. 相似文献
18.
A. V. Morozhenko 《Kinematics and Physics of Celestial Bodies》2010,26(1):36-38
We propose a modification of the method of polarimetric measurements of the twilight sky, traditionally performed in a zenith
direction, to study physical properties of the stratospheric aerosol (at altitudes higher than 30 km). The measurements carried
out in zenith directions as a rule limit phase angles by values of 80–100°. We suggest setting up the declination of the telescope
equal to the declination of the sun and measuring the polarization degree of the twilight sky at different values of the right
ascension. It will allow us not only to enhance the range of the phase angles but also to plan observations in a way to obtain
data on the phase dependence of the polarization degree of the light scattered by atmospheric layers at different altitudes. 相似文献
19.
P. I. Duhlev 《Solar physics》1992,140(1):195-198
The long-lived filaments (existing of two and more rotations) published in the Meudon Catalogues of Solar Filaments for the period 1931–1987 are studied. The dependence of the number and lifetime distribution of the filaments on the solar cycle phase is analyzed. A tendency of long-term variation in the distributions is discussed. 相似文献
20.
Peter Rovithis 《Icarus》1973,20(4):507-510
New measurements of the Venus diameter in four wavelengths are presented. These measurements refer to phase angles between 92° and 145° completing those by other observers. No dependence on the wavelength of the diameter of the planet is found. The resulted value is : 16.86 ± 0.02 arcsec. 相似文献