共查询到20条相似文献，搜索用时 62 毫秒
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本文给出自1962年到1980年之间九个夜晚对VZ Cnc观测获得的光电测光资料,并利用迄今已收集到的136个极大光度发生时刻,讨论了该星的周期变化,得β=1/p dp/dt=-[1.1±0.2]×10~(-7)/年。指出文[4]中的UBV数据可靠性有问题。 相似文献
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蒋世仰 《中国天文和天体物理学报》1985,(2)
βCep型变星BW Vul的光变周期以(14.24±0.20)×10~(-10)天/天的变率在持续增长着。且它的光度极大时刻的(O-C)值还具有一个周期约26.3年、变幅约0.022—0.024天的类正弦形变化。若解释为双星轨道运动的光时效应,其轨道半长径αsin i=(1.91—2.08)天文单位;轨道偏心率约e=0.52。 相似文献
4.
我们于1980年5月18、19日及6月15日和1981年1月15日四夜,用高速光电光度计观测了天秤座EHLib,获得6个光度极大时刻。与前人的观测资料综合分析,得出该星的观测极大时刻与计算极大时刻间的差值(O—C)随周期数E的变化,可以定性地表示为其中T_o=H.J.D.2433438.6088,P_o=0.0884132445天,β6.0×10~(-13)天/周-2.4×10~(-9)天/年-2.8×10~(-8)/年,A0.0015天,E_o70700P_o6250天17.1年。假如用双星系统的光时效应来解释其中的正弦项,则双星系统轨道的半长径α近似为0.28天文单位,轨道视向速度峰值投影K=(2παsini)/(E_o)0.45km/s,质量函数f(m)6×10~(-5)M_☉。 相似文献
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在试验一台三通道光子计数式高速光电光度计的过程中,于1980年9月18、19及11月15三夜观测了DY Peg,获得7个光度极大时刻,综合过去三十余年的观测结果,重新算得极大时刻计算公式为 T_(max)=H.J.D.2432751.96182 0.072926362E-2.28×10~(-13)E~2 ±0.00008±0.000000001±0.09周期递减率约为(3.1±0.1)×10~(-3)年. 相似文献
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1979年4月23日—12月27日,我们用北京天文台40/200cm双筒天体照相仪对旋涡星系M100(NGC 4321)中的亮超新星SN1979c进行了照相观测.本文简述了观测情况,并结合前人的观测,分析讨论了我们的结果. 它的光变曲线可以`划分为四个阶段.5月8日—6月5日间光变曲线有驼峰状突起.其光度变化既不同于Ⅰ型超新星,也与典型的Ⅱ型超新星不完全吻合. 计算得到超新星亮度极大时的绝对照相星等为M_(pg)(max)=-19~(m)78;极大光度L_SN(max)=1.076×10~(10)L⊙. 我们利用Balinskaya和Carney等人1980年发表的三色测光资料计算了这颗超新星在不同时刻的色温度变化,推算出它极大时刻的色温度约为T_c(max)≈9.0×10~3K. 爆发期间超新星辐射的总能量E_t=4.2×10~(16)L⊙. 根据这颗超新星的光变曲线、在星系中的位置及爆发期间辐射的总能量等主要特征,我们认为SN1979c是某些性质比较特殊的II型超新星. 相似文献
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食变星 RZ Cas 于1906午5月24日为缪勒(Müller)和凯泊脱(Kempt)所发现.顿根(Dugan)用目视视测计算了这颗星的第一个轨道,同时还谈到这颗星的周期变化的问题.关于周期变化的问题后来的工作者也注意到.赫弗尔(Huffer)和柯帕(Kopal)于1951年发表了他们对这颗星的光电观测结果,并给出了带有一个周期项的极小时刻的公式.利用这个公式计算极小时刻和我们观测结果比较,是很符合的.(详见下文)我们对食变星 RZ Cas 于1957年11月12月间在主极小附近进行了五次观测,共得观测值137个.由于我们使用的15厘米蔡斯天体照相仪系紫外物镜,同时它的星等系统 相似文献
8.
中国古代火流星记录的统计分析 总被引：1，自引：0，他引：1
柳卸林 《中国天文和天体物理学报》1987,(3)
本文对中国古代火流星记录,按年统计,用功率谱这一数学方法对它们进行分析。结果发现声音是衡量火流星起源的一个重要参数。有声音的火流星具有170.6±0.0,102.4±0.0,66.1±2.2,27.3±0.4,23.3±0.0,17.9±0.4,14.8±0.1,12.4±0.1,10.5±0.3年的可能周期。有声火流星与陨石坠落周期基本相同,是与陨石同源的,来自小行星带。我们认为影响有声火流星和陨石下落的因素是太阳辐射引起的Yarkovsky效应和木星摄动。有声火流星的10.5±0.3,23.2±0.0,66.1±2.2年周期与Yarkovsky效应有关。12.4±0.1,17.9±0.4,102.4±0.0,170.6±0.0周期与木星摄动有关。至于14.8±0.1,27.3±0.4的周期,可能是木星摄动与Yarkovsky效应联合作用或其他原因所致。 相似文献
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陆文贤 《中国天文和天体物理学报》1990,(2)
使用加拿大自治领天体物理台(DAO)的视向速度仪及光栅摄谱仪,获得了分光双星HD144515和HD178428的新的视向速度。结合文献中前人的观测资料,HD144515的轨道运动周期测定为4.285439±0.000009天;HD178428的为21.95582±0.00032天。HD144515的速度曲线的半变幅K有重要的改进。两双星的轨道偏心率e获得显著的修正。 相似文献
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In this paper we first emphasize why it is important to know the successive zonal harmonics of the Sun's figure with high
accuracy: mainly fundamental astrometry, helioseismology, planetary motions and relativistic effects. Then we briefly comment
why the Sun appears oblate, going back to primitive definitions in order to underline some discrepancies in theories and to
emphasize again the relevant hypotheses. We propose a new theoretical approach entirely based on an expansion in terms of
Legendre's functions, including the differential rotation of the Sun at the surface. This permits linking the two first spherical
harmonic coefficients (J
2 and J
4) with the geometric parameters that can be measured on the Sun (equatorial and polar radii). We emphasize the difficulties
in inferring gravitational oblateness from visual measurements of the geometric oblateness, and more generally a dynamical
flattening. Results are given for different observed rotational laws. It is shown that the surface oblateness is surely upper
bounded by 11 milliarcsecond. As a consequence of the observed surface and sub-surface differential rotation laws, we deduce
a measure of the two first gravitational harmonics, the quadrupole and the octopole moment of the Sun: J
2=−(6.13±2.52)×10−7 if all observed data are taken into account, and respectively, J
2=−(6.84±3.75)×10−7 if only sunspot data are considered, and J
2=−(3.49±1.86)×10−7 in the case of helioseismic data alone. The value deduced from all available data for the octopole is: J
4=(2.8±2.1)×10−12. These values are compared to some others found in the literature.
Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1005238718479 相似文献
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B. P. Kondratyev 《Solar System Research》2013,47(1):1-10
A two-component theoretical model of the physical libration of the Moon in longitude is constructed with account taken of the viscosity of the core. In the new version, a hydrodynamic problem of motion of a fluid filling a solid rotating shell is solved. It is found that surfaces of equal angular velocity are spherical, and a velocity field of the fluid core of the Moon is described by elementary functions. A distribution of the internal pressure in the core is found. An angular momentum exchange between the fluid core and solid mantle is described by a third-order differential equation with a right-hand side. The roots of a characteristic equation are studied and the stability of rotation is proved. A libration angle as a function of time is found using the derived solution of the differential equation. Limiting cases of infinitely large and infinitely small viscosity are considered and an effect of lag of a libration phase from a phase of action of an external moment of forces is ascertained. This makes it possible to estimate the viscosity and sizes of the lunar fluid core from data of observations. 相似文献
14.
Yoshio Kubo 《Celestial Mechanics and Dynamical Astronomy》2009,105(4):261-274
We calculate the so-called convective term, which shows up in the expression for the angular velocity of the elastic Earth,
within the Andoyer formalism. The term emerges due to the fact that the elasticity-caused perturbation depends not only on
the instantaneous orientation of the Earth but also on its instantaneous angular velocity. We demonstrate that this term makes
a considerable contribution into the overall angular velocity. At the same time the convective term turns out to be automatically
included into the correction to the nutation series due to the elasticity, if the series is defined by the perturbation of
the figure axis (and not of the rotational axis) in accordance with the current IAU resolution. Hence it is not necessary
to take the effect of the convective term into consideration in the perturbation of the elastic Earth as far as the nutation
is related to the motion of the figure axis. 相似文献
15.
Range of values of the Sun's mass quadrupole moment of coefficient J2 arising both from experimental and theoretical determinations enlarge across literature on two orders of magnitude, from
around 10-7 until to 10-5. The accurate knowledge of the Moon's physical librations, for which the Lunar Laser Ranging data reach an outstanding precision
level, prove to be appropriate to reduce the interval of J2 values by giving an upper bound of J2. A solar quadrupole moment as high as 1.1 10-5 given either from the upper bounds of the error bars of the observations, or from the Roche's theory, is not compatible with
the knowledge of the lunar librations accurately modeled and observed with the LLR experiment. The suitable values of J2 have to be smaller than 3.0 10-6.
As a consequence, this upper bound of 3.0 10-6 is accepted to study the impact of the Sun's quadrupole moment of mass on the dynamics of the Earth-Moon system. Such as
effect (with J2 = 5.5±1.3 × 10-6) has been already tested in 1983 by Campbell & Moffat using analytical approximate equations, and thus for the orbits of
Mercury, Venus, the Earth and Icarus. The approximate equations are no longer sufficient compared with present observational
data and exact equations are required. As if to compute the effect on the lunar librations, we have used our BJV relativistic
model of solar system integration including the spin-orbit coupled motion of the Moon. The model is solved by numerical integration.
The BJV model stems from general relativity by using the DSX formalism for purposes of celestial mechanics when it is about
to deal with a system of n extended, weakly self-gravitating, rotating and deformable bodies in mutual interactions.
The resulting effects on the orbital elements of the Earth have been computed and plotted over 160 and 1600 years. The impact
of the quadrupole moment of the Sun on the Earth's orbital motion is mainly characterized by variations of
,
, and
. As a consequence, the Sun's quadrupole moment of mass could play a sensible role over long time periods of integration of
solar system models.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
Wu Lin-xiang 《Chinese Astronomy and Astrophysics》1992,16(4):427-433
By means of a simple relation between the velocity v of the fluid particle and the velocity vf of the photospheric footpoint of the magnetic field line vz and Bz being respectively the components of v and the magnetic field B normal to the photospheric surface, it is shown formally that through the phtospheric surface the transport of all the quantities attributed to the magnetic field, such as the magnetic flux, the magnetic energy and the helicity, is independent of vz, and vf is the only kinematical quantity on which the transport depends. In addition, in the neighborhood of the neutral line the velocity vl of the moving curve of constant Bz is found to be equal approximately to the component of v or vf in the direction of vl. Since vl can be measured or extimated, so can the components of v and vf near the neutral line. 相似文献
17.
L. E. Cram 《Solar physics》1976,48(1):3-19
When the K-corona is formed by the scattering of photospheric radiation from free electrons, the Fraunhofer lines are greatly broadened by the thermal motions of the hot electrons. This paper discusses the possibility of measuring the coronal electron temperature from the residual depressions in the K-coronal spectrum. If the ratio of the intensities at 4100 Å and 3900 Å can be measured to an accuracy of ±1%, the coronal temperature can be inferred to an accuracy of ±0.2 MK. The temperature of a coronal inhomogeneity may also be measured by this method, provided the position angle is known.Now at Fraunhofer Institute, Freiburg, Germany. 相似文献
18.
M. V. Samokhin 《Earth, Moon, and Planets》1993,61(1):29-37
Using the well-known equation for the normal component of the current which exist near the tangential discontinuity in the plasma in the case of the frozen-in magnetic field, and supposing that the current closes in the ionosphere in the auroral oval in the region 1, one calculates and compares with the data of observations the dependence of the density of the field-aligned current at the level of the ionosphere on the local time. 相似文献
19.
G. M. Petrov 《Astrophysics and Space Science》1991,177(1-2):269-270
The classical method of determination of the absolute azimuth (or Bessel's parameter n) can secure sufficiently precision for RA from observations of stars at high geographical latitudes during polar night only. 相似文献