The F-type asteroids with small inversion angles of polarization     

I.N. Belskaya  Yu.G. Shkuratov  N.M. Shakhovskoy  A. Cellino  A.A. Ovcharenko  V.G. Shevchenko  C. Barbieri 《Icarus》2005,178(1):213-221

UBVRI polarimetric observations carried out in 1997-2004 for the F-type Asteroids 302 Clarissa, 419 Aurelia, 704 Interamnia, and 762 Pulcova (V band only) are presented. Asteroid 419 Aurelia is characterized by a negative polarization branch which is unusual for low-albedo asteroids. Its depth is about 1%, while the inversion angle, close to 14°, reaches the smallest value ever observed for asteroids. This is the first definite example of a minor body exhibiting a considerable decrease of both the depth and width of the negative polarization branch in comparison with polarization properties of other low-albedo bodies, mimicking a behavior previously found in laboratory measurements of extremely dark surfaces. The F-type Asteroids 302 Clarissa and 704 Interamnia are also characterized by unusually small inversion angles compared to other asteroid types, while Asteroid 762 Pulcova seems to have an ordinary negative polarization branch. Laboratory measurements of low-albedo samples and computer simulations of light scattering by particles of irregular shapes were made to interpret observational data. We find that an optical homogeneity of regolith microstructure at scales of the order of visible light wavelengths may be responsible for relatively small values of the depth of the negative polarization branch and of the inversion angle. Peculiar features of the F-type asteroids compared to other taxonomic classes are discussed.  相似文献   

Multidisciplinary Investigation of the Transform Fault Zones Doldrums and Vema during Cruise 45 of the R/V “Akademik Nikolaj Strakhov”     

Ivanova  E. V.  Skolotnev  S. G.  Borisov  D. G.  Demidov  A. N.  Bich  A. S.  Gippius  F. N.  Gryaznova  A. S.  Dobroliubova  K. O.  Zinger  T. F.  Korshunov  D. M.  Levchenko  O. V.  Mashura  V. V.  Muccini  F.  Nemchenko  N. V.  Peyve  A. A.  Pertsev  A. N.  Sani  K.  Sanfilippo  A.  Simagin  N. V.  Sokolov  S. Yu.  Ferrando  C.  Chamov  N. P.  Shakhovskoy  I. B.  Sholukhov  K. N. 《Oceanology》2020,60(3):424-426

Oceanology - Herein we provide information on the integrated geological, geophysical, sedimentological, paleoceanographic, hydrophysical and biological investigations in the Central Atlantic during...  相似文献   

Integrated Oceanographic Research of Discovery Gap (Eastern North Atlantic) during the Cruise 43 of the R/V Akademik Nikolaj Strakhov     

Dorokhova  E. V.  Krechik  V. A.  Ponomarenko  E. P.  Dudkov  I. Yu.  Shakhovskoy  I. B.  Napreenko-Dorokhova  T. N.  Ezhov  V. E.  Malafeev  G. V.  Kuleshova  L. A.  Glazkova  T. A. 《Oceanology》2021,61(1):144-146

Oceanology - During cruise 43 of the R/V Akademik Nikolaj Strakhov (September 21–October 9, 2019), new data were obtained on the bottom relief, sedimentation, and hydrological regime of the...  相似文献   

Polarimetry of stellar active regions and flares     

I. Tuominen  J. Huovelin  Yu. S. Efimov  N. M. Shakhovskoy  A. G. Shcherbakov 《Solar physics》1989,121(1-2):419-429

Observations of regular and irregular polarimetric variability in late-type stars are reviewed, and the related physical and geometrical effects are discussed. There are indications that the irregular part of the variability could be caused by transient events, possibly associated with flares. Polarimetric observations during flares are reviewed, and preliminary results of new observations of a well-known flare star, YY Geminorum, are presented. The results show that the small flare in YY Gem did not cause any significant variations in linear polarization, while the binary eclipse evidently causes an enhancement in the polarization. The reasons for the difficulties in stellar flare polarimetry are discussed. Finally, future prospects for the observations of flaring stars and for the utilization of linear polarimetry as a complementary method to other techniques of surface imaging of stellar activity and flares are presented.  相似文献   

Evidence for pole switching in the magnetic cataclysmic variable BY Camelopardalis     

Paul A. Mason  Gavin Ramsay  Ivan Andronov  Sergey Kolesnikov  Nickolay Shakhovskoy  & Elana Pavlenko 《Monthly notices of the Royal Astronomical Society》1998,295(3):511-518

An analysis of X-ray and optical light curves of the magnetic cataclysmic variable (MCV) BY Cam is presented. This system is one of three MCVs in which the spin period of the white dwarf and the binary orbital period differ by ∼1 per cent. As such these 'BY Cam' stars are important objects with which to probe the field structure of the magnetic white dwarf and ultimately the nature of synchronization of AM Her binaries. We confirm asynchronous rotation of the magnetic white dwarf with respect to the binary. We find evidence that the accretion stream accretes directly on to the white dwarf as in AM Her systems, but further, the stream impacts on to different magnetic poles over the course of the beat period. We present evidence that the optical and hard X-ray light curves modulate in phase, but together they are out of phase with the soft X-ray light curve. We confirm the spin down of the white dwarf which is expected to lead to the synchronization of the spin and orbital periods of BY Cam.  相似文献   

On the Polarization Opposition Effect of E-Type Asteroid 64 Angelina     

N.N. Kiselev  N.M. Shakhovskoy  Yu.S. Efimov 《Icarus》1996,120(2):408-411

Polarimetric observations of the high-albedo asteroid 64 Angelina were done for the purpose of searching for a polarization opposition effect at phase angles of less than 2.4°. We have found a second inversion angle of about 1.5° and positive polarization of 0.5% at a phase angle of 0.5°. For comparison the polarimetric observations of Comet P/Ashbrook–Jackson are given. Different theoretical approaches to the explanation of this phenomenon are discussed.  相似文献   

Circular polarization in comets: Observations of Comet C/1999 S4 (LINEAR) and tentative interpretation     

Vera Rosenbush  Ludmilla Kolokolova  Nikolai Shakhovskoy 《Icarus》2007,186(2):317-330

Comet C/1999 S4 (LINEAR) was exceptional in many respects. Its nucleus underwent multiple fragmentations culminating in the complete disruption around July 20, 2000. We present circular polarization measurements along the cuts through the coma and nucleus of the comet during three separate observing runs, in June 28-July 2, July 8-9, and July 21-22, 2000. The circular polarization was detected at a rather high level, up to 0.8%. The left-handed as well as right-handed polarization was observed over the coma with the left circularly polarized light systematically observed in the sunward part of the coma. During our observations the phase angle of the comet varied from 61 up to 122°, which allowed us to reveal variations of circular polarization with the phase angle. Correlation between the degree of circular polarization, visual magnitude, water production rate, and linear polarization of Comet C/1999 S4 (LINEAR) during its final fragmentation in July 2000 was found. The mechanisms that may produce circular polarization in comets and specifically in Comet C/1999 S4 (LINEAR) are discussed and some tentative interpretation is presented.  相似文献   

Comet C/2002 T7 (LINEAR): Polarimetric and photometric studies     

V. K. Rosenbush  F. P. Velichko  N. N. Kiselev  S. F. Velichko  N. M. Shakhovskoy  Yu. S. Efimov  K. A. Antonyuk  S. V. Kolesnikov  D. N. Shakhovskoy 《Solar System Research》2006,40(3):230-238

We present the results of polarimetric and photometric observations of dynamically new comet C/2002 T7 (LINEAR) at phase angles from 6° to 26°. During the observations, the comet was at a distance of 2.7–1.3 AU from the Sun and 1.7–2.0 AU from the Earth. The aperture polarimetry was made with the 2.6-m Shain telescope and the 1.25-m AZT-11 telescope of the Crimean Astrophysical Observatory and with the 0.7-m telescope of the Astronomical Institute of the Kharkiv National University during the period from November 21, 2003, to February 21, 2004. The wideband UBVRI and WRC (λ7228/1142 Å) filters and the narrowband GC (λ5260/56 Å) filter were used. The photometric observations of the comet were carried out on February 21, 2004, with narrowband filters isolated the BC (λ4845/65 Å) and RC (λ6840/90 Å) continuum and the C₂ emission (λ5140/90 Å). The phase-angle dependence of linear polarization of the comet has been obtained, and its parameters, such as the minimal polarization P _min = ?1.63%, the phase angle of the minimal polarization α_min = 10.6°, the inversion angle α_inv = 22.7°, and the slope of the phase curve at the inversion angle h = 0.24% per degree, were found. From the photometric observations, the following quantities have been obtained: the column density of molecules C₂ in the line of sight logN (C₂) = ?9.15 mol/cm² and their production rate log Q (C₂) = 27.11 mol/s, the spectral gradient of reflectivity for the dust S′(BC, RC) ≈ 3%/1000 Å, and the dust production parameter Afρ equal to 371 and 273 cm for the blue and red continuum ranges, respectively. According to these results, the physical parameters of comet C/2002 T7 are close to the average characteristics of typical dusty comets.  相似文献   

UBVRI Photometry and Polarimetry of the Eclipsing Binary RY Per     

N. M. Shakhovskoy  K. A. Antonyuk 《Astrophysics》2004,47(2):143-154

Results are presented from multicolor photometric and polarimetric studies of the eclipsing binary RY Per during 2001-2003. Light curves in the UBVRI bands are shown. An analysis of the variations in the linear polarization makes it possible to separate it into interstellar and intrinsic components. The degree of intrinsic polarization of the system away from the eclipse attains a maximum (0.23%) in the B band and falls off rapidly with increasing wavelength. This dependence is indicative of the existence of optically thick gas in the system. An analysis of the polarimetric data also shows that: the total mass of optically thin gas in the system is about 2·10^-10 M , while the total mass of the shell must be several times that; and, the inclination of the orbital plane of the binary system relative to the galactic plane is 4° or 18°.  相似文献   

Detection of high‐frequency optical oscillation during the flare phase of EV Lac in 1999     

M. E. Contadakis  S. Avgoloupis  J. Seiradakis  B. E. Zhilyaev  Ya. O. Romanyuk  I. A. Verlyuk  O. A. Svyatogorov  V. R. Khalack  A. V. Sergeev  R. K. Konstantinova‐Antova  A. P. Antov  R. S. Bachev  I. Y. Alekseev  V. E. Chalenko  D. N. Shakhovskoy 《Astronomische Nachrichten》2004,325(5):427-432

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