共查询到20条相似文献,搜索用时 46 毫秒
1.
依巴谷星表给出了223颗经典造父变星的天体测量和光度观测资料。根据近年来的光谱和光度观测成果,从不同渠道收集了有关视向速度和光度等资料。基于Feast和Catchpole建立的PL关系,给出造父变星的距离估计。 相似文献
2.
δScuti型变星是赫罗图上A3-F5区间的主序及其以上的一种周期短于0.3d的单周期或多周期小变幅脉动变星,与它们相关的变星有矮造父变星,γDol变星,蓝离散星,金属线星,A型特殊星,λBoo变星的δDel变星,有些赫比格Ae/Be星也存在类似的脉动,对自1964年起的研究工作进行了系统的总结,给出了1995年后新发现的相关变星数和最可靠的周期变化表,提出应当用双星轨道光时效应来解释实测得到的变星周期变化中的幅度很大的成分,统计表明自转越快变幅越小,因此年轻星团中不可能存在大变幅变星,变幅随周期的分布有3个极大值,最大变由是周期0.17d处的1.0mag,恒星系统内变星的平均周期越短系统的年龄越大,金属丰度也越低。 相似文献
3.
δScuti型变星是赫罗图上A3~F5区间的主序及其以上的一种周期短于0.3 d的单周期或多周期小变幅脉动变星.与它们相关的变星有矮造父变星、γ Dol变星、蓝离散星、金属线星、A型特殊星、λBoo变星和δDel变星.有些赫比格Ae/Be星也存在类似的脉动.对自1964年起的研究工作进行了系统的总结,给出了1995年后新发现的相关变星数和最可靠的周期变化表,提出应当用双星轨道光时效应来解释实测得到的变星周期变化中的幅度很大的成分.统计表明自转越快变幅越小,因此年轻星团中不可能存在大变幅变星.变幅随周期的分布有3个极大值,最大变幅是周期0.17d处的1.0 mag.恒星系统内变星的平均周期越短系统的年龄越大,金属丰度也越低. 相似文献
4.
根据最近发表的新编依巴谷星表数据,重新研究了经典造父变星周光关系零点问题.利用运动学模型对自行数据和视向速度分别拟合奥尔特常数及本地静止标准的旋转速度,得到太阳的银心距R0=8.0±0.8kpc.从太阳附近的旋转曲线,发现银河系盘的引力势具有弱椭圆分布的迹象.通过-个简单的非对称模型,得到太阳附近盘引力势的椭率e(R0)=0.067±0.036,其短轴指向φb=32°±15°. 相似文献
5.
本文以亮星星表1982年版的资料为依据,统计了双星比例随光谱型的变化。发现巨星的双星比例由B、A型的50%左右逐渐下降到M型的24%,而矮星的双星比例不随光谱型下降,都在50%左右。还发现各主要类型脉动变星中的双星比例比上述相应光谱区内的双星比例高约10%。这可能说明成双性与恒星演化和脉动特性均有某种关系。造父变星中双星比例高达53%是很值得仔细研究的问题。 相似文献
6.
7.
8.
利用一种非局部和非定常的恒星对流理论,计算了0.6~3.0 M☉恒星演化模型的线性非绝热脉动.结果表明,赫罗图上脉动不稳定带右方的脉动不稳定的低温恒星可以分成2大类(群).一类由主序矮星、亚巨星和中低光度红巨星组成的类太阳振荡恒星,它们的中高阶(径向阶nr≥12)p模是脉动不稳定的,而低阶(nr≤ 5)模是脉动稳定的;另一类是由亮的红巨星和渐近巨星支星(AGB)组成的类长周期变星,它们的低阶模(nr≤5)是脉动不稳定的,而高阶模(nr≥12)却是脉动稳定的.能利用对流与脉动的耦合统一解释造父变星脉动不稳定带红边界、类太阳和类长周期变星脉动.对赫罗图右方的低温恒星的中低阶p模振荡,对流与脉动的耦合是主要的脉动激发和阻尼机制,而湍流的随机激发机制仅对类太阳振荡高阶p模重要. 相似文献
9.
热超短周期造父变星的周期≤0.~d1、变幅≥0.~m2、光谱型为A.在银河系中呈延仲球状分布;在银晕星族的球状星团和年老盘族的运动星群中都有.在色星等图上,处于造父不稳定带的左外侧而温度较高,故简称热造父变星.球状星团中超短周期造父变星现知五颗.三颗是热造父变星:半人马ω的V65星(M_v= 0.~m82),M56的V11星(M_v= 0.~m10)和M15的K1082星(M_v=0.~m09)。它们在色星等图上的位置紧邻,亮度和天琴RR型星相近,但色均较蓝.它们都处在银河系中呈延伸球状分布的贫金属星团中.银河系中已知超短周期造父变星的周期变幅图上,有可用0.~m2简示的变幅分布隙,和两条周期分布隙.其中变幅≥0.~m2、周期≤ 0.~d1的-群共九颗,是银河系一般星场的热造父变星.其银纬分布除一颗是b= 10°44′外,余均为|h|>20°.这九颗中的两颗是年老盘族的运动星群的成员,-颗具有空间速度高和金属线强度ΔS≥2的星族Ⅱ星的特点. 相似文献
10.
11.
银河系的银盘、银晕、核球的平均金属丰度为-0.2,-1.6,-0.2。年龄-金属丰度关系给出了银河系形成和演化的线索。为了解释观测的年龄-金属丰度关系及其弥散,银河系化学演化模型必须考虑恒星轨道运动、非瞬时混合等机制。 相似文献
12.
Published photoelectric and CCD photometric data for fundamental-mode Cepheids in the Large Magellanic Cloud are analyzed. The inferred scatter of the observed period-luminosity relation decreases with increasing quality of the light curves used. The observed scatter of the period-luminosity relations in the V and IC bands is as low as 0m.11 and 0m.07, respectively, i.e., a factor of 1.5 smaller than the lowest published estimates. This, in particular, suggests that the intrinsic scatter might be lower than previously believed. 相似文献
13.
O. G. Kashibadze 《Astrophysics》2008,51(3):336-348
The peculiar velocity field for 907 galaxies with heliocentric radial velocities VH ≤ 3000 km/s is examined. The data are divided into three samples, organized according to the principles behind the method
for determining the distance to the galaxies: the luminosity of the tip of the red giant branch (TRGB), fluctuations in the
surface brightness, and the infrared Tully-Fisher relation for spiral galaxies viewed edge-on. The latter sample includes
410 galaxies. For determining the distance to the galaxies in this sample, additional regressors were introduced into the
Tully-Fisher relation, in particular the “color index” K-m21, which make it possible significantly to reduce the dispersion with respect to the regression curve. All three samples showed
good agreement in the peculiar velocity distribution. Based on each of these samples, as well as on the combined sample, detailed
maps of the field of peculiar velocities of the galaxies are constructed for VH ≤ 3000 km/s. An analysis shows that most of the observed features of this map can be explained by large-scale density variations
in the galactic distribution.
__________
Translated from Astrofizika, Vol. 51, No. 3, pp. 409–422 (August 2008). 相似文献
14.
I. D. Karachentsev Yu. N. Kudrya V. E. Karachentseva S. N. Mitronova 《Astrophysics》2006,49(4):450-461
The 2MFGC catalog we have used contains 18020 galaxies selected from the extended objects in the 2MASS infrared sky survey
as having apparent ratios of the axes b/a<0.3. Most of them are spiral galaxies of later morphological types whose disks are
seen almost edge-on. The individual distances to the 2724 2MFGC galaxies with known rotation velocities and radial velocities
are determined using a multiparameter infrared Tully-Fisher relation. A list of the distances and peculiar velocities of these
galaxies is presented. The collective motion of the 2MFGC galaxies relative to the cosmic microwave background is characterized
by a velocity V = 199 ± 37 km/s in the direction l = 304° ±11°, b = −8°±8°. Our list is currently the most representative
and uniform sample for analyzing non-Hubble motions of galaxies on a scale of ∼100 Mpc.
__________
Translated from Astrofizika, Vol. 49, No. 4, pp. 527–540 (November 2006). 相似文献
15.
G. Contopoulos 《Journal of Astrophysics and Astronomy》1980,1(1):79-95
The Lin-Shu dispersion relation is applicable in the (asymptotic) case of tight spirals (large wave numberk
R). Here we reconsider the various steps leading to the Lin-Shu dispersion relation in higher approximation, under the assumption
that the wave numberk
R is not large [(k
Rr) =O(1)], and derive a new dispersion relation. This is valid for open spiral waves and bars. We prove that this dispersion relation
is the appropriate limit of the nonlinear self-consistency condition in the case where the linear theory is applicable. 相似文献
16.
Wang Hong-zhang 《Chinese Astronomy and Astrophysics》1990,14(4):361-370
Based on spacecraft observations of the giant planets we call attention to an apparent regular mass-luminosity relation for the large planets (giant planets plus Earth). It can provide important clues and constraints on the question of their energy source, including various relevant theories and their difficulties. We describe in some detail a new thermonuclear reaction mechanism, valid for plasma fusions at both super—high and low temperatures, and including the original thermonuclear mechanism as a particular case. It can explain not only the internal energy souce of the large planets, but also many anomalous fusion phenomena observed in the laboratory and in astronomical bodies. Although these appear in various guises, their basic principle is the same, that is, they can all be understood in terms of the new mechanism. 相似文献
17.
Juan Zhao Yan-Ben Han Zhi-An LiDepartment of Astronomy Beijing Normal University Beijing zj@bnu.edu.cnNational Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2004,4(2):189-197
Using continuous wavelet transform, we examine the relationship between solar activity and the annual precipitation in the Beijing area. The results indicate that the annual precipitation is closely related to the variation of sunspot numbers, and that solar activity probably plays an important role in influencing the precipitation on land. 相似文献
18.
本文叙述利用Delphi的数据库功能进行的CCD数据文件管理程序的设计。着重介绍了数据库生成、按日期和类型访问文件、暗流文件选取、头文件修改等问题的处理。这个程序是为紫金山天文台双瞳望远镜开发的CCD图象处理软件的组成部分 相似文献
19.