共查询到9条相似文献，搜索用时 78 毫秒
1.
A morphological analysis study of open clusters’ properties has been achieved for a sample of 160 UBVCCD open star clusters of approximately 128,000 stars near the galactic plane. The data was obtained and reduced from Tadross (2001) using the same reduction procedures, which makes this catalogue the largest homogeneous source of open clusters’ parameters. 相似文献
2.
New photoelectric BVR light curves and radial velocity curves were obtained for the HIPPARCOS discovery DN Boo at the TÜBİTAK1 National Observatory of Turkey (TUG) and Dominion Astrophysical Observatory (DAO), respectively, to determine physical nature of the variable. The character of the obtained light curves and double-lined spectroscopic structures in the obtained spectra are revealed that DN Boo is a genuine EW type eclipsing binary. During the analysis of our new observations a simultaneous solution were derived for the photometric and spectroscopic data by using the Wilson–Devinney code and orbital parameters with absolute dimensions of the system were determined for the first time. Finally, the importance of very low mass-ratio contact binaries in the late stages of close binary evolution was discussed. 相似文献
3.
The analyses have been made with the emphasis on four existing criteria for calibrating the azimuth of the photospheric transverse magnetic field measured with a heliomagnetograph. The results indicate that the potential criterion, Krall's criterion, i.e. Bt · Bz < 0 and Wu-Ai's criterion, i.e.
, are applicable to different cases, and the criterion based on the assumption about azimuth continuity of the transverse field is unreliable for the magnetograms with discrete data. On the basis of these analyses, a synthesized method for determining the azimuth of the transverse magnetic field on solar photosphere has been suggested in this paper. The main points of the method are as follows:
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The transverse magnetic field observed with a heliomagnetograph could be calibrated, respectively, by means of potential criterion and Krall's criterion, and two different results could be obtained. By comparing the both results with one another, we can find that the azimuth distributions of transverse field are the same in some areas, which are named as areas with certain transverse field (CA), and different in other areas, which are named as areas with uncertain transverse field(UA). In order to determine the transverse field in UA, we introduce an assumption that the values of (the factor of force-free magnetic field) at neighbouring points are close. According to this assumption, the distribution of in UA could be determined through extrapolating from the CA, and hence the azimuth distribution of the transverse field in UA could be determined as well.
An observational example shown in this paper preliminarily demonstrates the availability of the synthesized method. 相似文献
4.
Peng Qiu-he 《Chinese Astronomy and Astrophysics》1993,17(4):363-372
Based on the method of Paper I and concentrating on the rigidly rotating, inner region of the galaxy, a theoretical investigation is carried out here on the asymptotic property of the projected surface density σ(r); combining with the asymptotic solution of Paper I for the outer region with flat rotation curve, I suggest the form
as a possible, reasonable mass model for the whole galactic disk. In the course of the study, an important relation between the masses of the bulge and the disk and certain parameters characterizing the distribution was found. 相似文献
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5.
Tongjiang Wang Nelson L. Reginald Joseph M. Davila O. Chris St. Cyr William T. Thompson 《Solar physics》2017,292(8):97
Three-dimensional electron density distributions in the solar corona are reconstructed for 100 Carrington rotations (CR 2054?–?2153) during 2007/03?–?2014/08 using the spherically symmetric method from polarized white-light observations with the inner coronagraph (COR1) onboard the twin Solar Terrestrial Relations Observatory (STEREO). These three-dimensional electron density distributions are validated by comparison with similar density models derived using other methods such as tomography and a magnetohydrodynamics (MHD) model as well as using data from the Solar and Heliospheric Observatory (SOHO)/Large Angle and Spectrometric Coronagraph (LASCO)-C2. Uncertainties in the estimated total mass of the global corona are analyzed based on differences between the density distributions for COR1-A and -B. Long-term variations of coronal activity in terms of the global and hemispheric average electron densities (equivalent to the total coronal mass) reveal a hemispheric asymmetry during the rising phase of Solar Cycle 24, with the northern hemisphere leading the southern hemisphere by a phase shift of 7?–?9 months. Using 14 CR (\(\approx13\)-month) running averages, the amplitudes of the variation in average electron density between Cycle 24 maximum and Cycle 23/24 minimum (called the modulation factors) are found to be in the range of 1.6?–?4.3. These modulation factors are latitudinally dependent, being largest in polar regions and smallest in the equatorial region. These modulation factors also show a hemispheric asymmetry: they are somewhat larger in the southern hemisphere. The wavelet analysis shows that the short-term quasi-periodic oscillations during the rising and maximum phases of Cycle 24 have a dominant period of 7?–?8 months. In addition, it is found that the radial distribution of the mean electron density for streamers at Cycle 24 maximum is only slightly larger (by \(\approx30\%\)) than at cycle minimum. 相似文献
6.
P. G. Brown P. J. A. McCausland A. R. Hildebrand L. T. J. Hanton L. M. Eckart H. Busemann D. Krietsch C. Maden K. Welten M. W. Caffee M. Laubenstein D. Vida F. Ciceri E. Silber C. D. K. Herd P. Hill H. Devillepoix Eleanor K. Sansom Martin Cupák Seamus Anderson R. L. Flemming A. J. Nelson M. Mazur D. E. Moser W. J. Cooke D. Hladiuk Barbara Malečić Maja Telišman Prtenjak R. Nowell The Golden Meteorite Consortium 《Meteoritics & planetary science》2023,58(12):1773-1807
7.
Yusuke Tsukamoto 《Icarus》2011,212(2):911-919
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