共查询到20条相似文献，搜索用时 78 毫秒
1.
本文提出了1981年4月27日日面西边缘耀斑以后的爆发环珥的H_a观测资料和分析.在这事件中,我们可以清楚地看到环的缠绕过程.从这些资料可看出环的运动与缠绕有紧密的联系.我们还观测到一些有趣的现象:在08~(h)29~(m)30~(s)和08~(h)33~(m)UT时在环顶(其高度约为2.6×10~4公里)分别出现持续时间约为1分钟的奇特的“吸收结构”,同时观测到3厘米波段的射电辐射强度相应有例外的下降,而8毫米和10厘米波段的射电辐射强度无此变化. 相似文献
2.
本文利用能量守恒的方法,对光学厚Mira变星NV Aur在其相位0.206处的光学及红外波段的观测值进行模型拟合处理,得到其中心星有效温度值T_*=1750K,亮层有效温度T_d=250K。我们发现富氧AGB星的25μm处的光度和周期有很好的相关,通过此周光关系,算出了NV Aur的距离d≈590pc,中心星光度约为9.4×10~4L_⊙,中心星半径为3.4×10~3R_⊙,尘埃壳层光学厚度τ_v=2.7,显示其为一光学厚Mira星,中心星为一红超巨星。我们所得质量流失率(?)=3.1×10~(-6)M_⊙/yr,与Knapp等人从CO观测得到的5.7×10~(-6)M_⊙/yr在量级上相符。在本文中还给出了NV Aur的球对称壳层黑体谱模型。 相似文献
3.
本文叙述了以下内容: (1)对在1963年5月18日到8月8日拍摄的7条武仙座1963年新星的光谱作了发射带相对强度的测定(表2)。 (2)按新星光度变化的统计规律得到上述新星的距离模数值(10~m),用平均消光法求得目视总吸光值A_v=0~m.23,距离900秒差距,井由此得到改正星际选择吸光后的谱带的相对强度(表3)。 (3)由新星绝对星等M_B和发射带的相对强度求得了谱带的绝对强度(表4)。 (4)对于一些发射带的绝对强度作Δm-lgt图,发现发射带绝对强度的变化也存在Δm=blgt的线性关系。对于不同的谱线,系数b是不同的。 (5)根据测定的相对强度,用安巴楚勉和斯托伊两种方法求得核星温度,它们分别在150000°—160000°和30000°—60000°之间,由于前者是上限,后者是下限,真实的核星温度应当在两种方法求得的值之间。 (6)用H_β的绝对强度和[OⅢ]5007+4959对[OⅢ]4363的强度比两种方法分别求得不同电子温度T_e相对应的电子密n_e。并且用由上述两个方法求得的T_e—n_e曲线的交点,同时求得了T_e和n_e的值。由此法求得的结果是:在所讨论的期间内,T_e由10800°K逐渐上升到17500°K,然后又下降至13000°K。n_e则单调的由5.0×10~7cm~(-3)逐渐下降到7.0×10~6cm~(-3)。 (7)求得壳层质量约为2.3×10~(-5)M_⊙。 (8)初步分析了一些壳层物理参数变化的原因。 相似文献
4.
本文分析了1982年10月——1983年5月期间YLF的SPA事件的数据和太阳x—射线爆发资料.并且和文献[1]中LF的SPA事件的分析作了比较。可以看出,VLF的SPA事件和太阳x—射线爆发有较好的相关性;在1—8埃频段的太阳x—射线爆发能产生VLF的SPA事件的门限值为1×10~(-6)Wm~(-2).这个值比LF的SPA事件的门限值(2×10~(-6)Wm~(-2))要低一倍. 相似文献
5.
本文分析了1981年1月至5月期间记录的低电离层突然骚扰(SID)和太阳X射线爆发数据发现:1.几乎所有的研究情况,每一个低电离层的突然骚扰都是太阳X射线爆发引起的。且SID与太阳X射线爆发之间有着相同的开始和极值时间;2.能够引起低电离层产生较明显的SID的太阳X射线爆发的峰值流量下限对于0.5～4A频段是约4×10~(-3)w/m~2,对1～8A频段是2×10~(-6)w/m~2;3.相关分析表明,太阳X射线爆发的流量变化量与低频记录的突然相位异常(SPA)的变化量之间有好的相关性。根据这个初步的研究有可能利用低频SPA的监测来较好地检测太阳X射线爆发。 相似文献
6.
《天文学报》2017,(5)
最近的研究结果表明,目前流行的~(13)C壳层(~(13)C pocket)在热脉冲间隔期间辐射燃烧的低质量AGB(Asymptotic Giant Branch)星s-过程核合成模型,其核合成区域的中子辐照量分布可视为指数形式,平均中子辐照量τ0和模型参量之间的关系为τ0=-?τ/ln[q/(1-r+q)],式中?τ为每次照射的中子辐照量,r为重叠因子,q为~(13)C壳层占氦中间壳层的质量比例.利用文献中参数化AGB星s-过程核合成模型对20颗CEMP(Carbon-Enhanced Metal-Poor)-s和CEMP-s/r星观测丰度的拟合结果,对该平均中子辐照量计算公式的可靠性进行了检验,并初步探讨其在重元素s-过程核合成理论研究中的作用.研究结果表明:在辐射s-过程核合成机制下,对于经历连续多次中子照射的CEMP星,公式是适用的;和参数化AGB星s-过程核合成模型结合,公式可以作为单辐照或特殊CEMP星的一个有效筛选工具.考虑到~(13)C壳层的不确定性,公式在理解CEMP星中子俘获元素观测丰度产生的物理条件方面的作用值得做进一步的探讨. 相似文献
7.
用"多云模型"光谱方法分析1991年3月5日喷泉状爆发日珥的Hα光谱观测资料,导出了该日珥视向速度的二维分布;通过速度场分析,我们探测到日珥喷射速度和旋转角速度随高度的分布,结果表明该日珥的蓝移速度占绝对优势,速度变化范围为8～110km/s,速度分布不均衡、不对称,日珥中部和底部速度较大、顶部速度较小;日珥南边缘的速度梯度比北边缘的更大;日珥的喷射除表现为上升运动外还显示出向着观测者的、平均速度约为50km/s的视向运动;该日珥的旋转角速度约为7×10-4rad/s,两者随高度的变化显示出相反的特征。 相似文献
8.
本文给出了云南天文台监测长波(BPL)时号的结果。地波定时平均精度达±0.22μw,日校频精度优于2.3×10~(12);天波定时精度为±1.65μs,日校频精度优于1.9×10~(-11)μs。 相似文献
9.
根据13C辐射燃烧的低质量AGB(Asymptotic Giant Branch)星s-过程核合成模型,考察了氦壳层核合成区域中子辐照量分布(以下简称DNE)的特点.结果表明,该模型的DNE同以前的对流核合成模型一样仍然非常接近指数分布,但是每个脉冲的中子辐照量△r和平均中子辐照量To之间的关系却不再是To=-△T/lnr,而近似为To=-△r/ln{q[1.0020 0.6602(r-q) 4.6125(r-q)2-10.8962(r-q)3 13.9138(r-q)4]}(r为重叠因子, q为13C壳层占氦壳层的质量比例).该式从DNE角度将辐射s-过程恒星模型和经典模型统一起来. 相似文献
10.
11.
12.
《中国天文和天体物理学报》2014,(10)
正Research in Astronomy and Astrophysics publishes original research papers and reviews on all branches of astronomy and astrophysics.Reviews are by invitation only.Important new results that require rapid publication can be submitted as a Letter(Letters must be restricted in length to 6 printed pages).Authors who submit a paper are expected to be able to certify that the paper is original work, 相似文献
13.
14.
Laura Schaefer 《Icarus》2005,173(2):454-468
We use chemical equilibrium calculations to model the speciation of alkalis and halogens in volcanic gases emitted on Io. The calculations cover wide temperature (500-2000 K) and pressure (10−6 to 10+1 bars) ranges, which overlap the nominal conditions at Pele (T=1760 K, P=0.01 bars). About 230 compounds of 11 elements (O, S, Li, Na, K, Rb, Cs, F, Cl, Br, I) are considered. The elemental abundances for O, S, Na, K, and Cl are based upon observations. CI chondritic elemental abundances relative to sulfur are used for the other alkalis and halogens (as yet unobserved on Io). We predict the major alkali species in Pele-like volcanic gases and the percentage distribution of each alkali are LiCl (73%), LiF (27%); NaCl (81%), Na (16%), NaF (3%); KCl (91%), K (5%), KF (4%); RbCl (93%), Rb (4%), RbF (3%); CsCl (92%), CsF (6%), Cs (2%). Likewise the major halogen species and the percentage distribution of each halogen are NaF (88%), KF (10%), LiF (2%); NaCl (89%), KCl (11%); NaBr (89%), KBr (10%), Br (1%); NaI (61%), I (30%), KI (9%). We predict the major halogen condensates and their condensation temperatures at P=0.01 bar are NaF (1115 K), LiF (970 K); NaCl (1050 K), KCl (950 K); KBr (750 K), RbBr (730 K), CsBr (645 K); and solid I2 (200 K). We also model disequilibrium chemistry of the alkalis and halogens in the volcanic plume. Based on this work and our prior modeling for Na, K, and Cl in a volcanic plume, we predict the major loss processes for the alkali halide gases are photolysis and/or condensation onto grains. Their estimated photochemical lifetimes range from a few minutes for alkali iodides to a few hours for alkali fluorides. Condensation is apparently the only loss process for elemental iodine. On the basis of elemental abundances and photochemical lifetimes, we recommend searching for gaseous KCl, NaF, LiF, LiCl, RbF, RbCl, CsF, and CsCl around volcanic vents during eruptions. Based on abundance considerations and observations of brown dwarfs we also recommend a search of Io's extended atmosphere and the Io plasma torus for neutral and ionized Li, Cs, Rb, and F. 相似文献
15.
《中国天文和天体物理学报》2014,(9)
正Research in Astronomy and Astrophysics publishes original research papers and reviews 011 all liranchcs of astronoiriy and astrophysics.Reviews arc by invitation only.Important new results that require rapid publication can be submitted as a Letter(Letters must be restricted in length 相似文献
16.
Li Xin-nan Zhang Hai-ying Cui Xiang-qun Jiang Zi-bo Zheng Yi Liu Xing-tao Ni Hou-kun 《Chinese Astronomy and Astrophysics》2012
A special stressed annular polishing technique is proposed to mill the off-axis aspheric sub-mirrors of a large segmented mirror with an annular polishing machine. Based on the basic principle of stressed annular polishing technique, a set of special stressing mechanisms are designed to convert milling the aspheric surfaces of sub-mirrors with different off-axis distances into milling the spherical surfaces with identical radii of curvature, so that they can be pol- ished simultaneously on a continuous polishing machine. It took about contin- uous 40 hours to polish a scaled-down mirror of the planning Chinese Future Giant Telescope (CFGT) using this technique. This mirror has the 330 mm di- ameter, 3.6 m off-axis distance, and the 21.6 m radius of curvature, and its max- imum asphericity is 16 micron. The experiment shows that this method has a high effciency, suits batch manufacturing, especially the batch manufacturing of aspheric sub-mirrors of the segmented primary mirror of an extremely large aperture telescope. 相似文献
17.
Yehouda Enzel Rivka Amit Uri Dayan Onn Crouvi Ron Kahana Baruch Ziv David Sharon 《Global and Planetary Change》2008,60(3-4):165-192
Modern-day synoptic-scale eastern Mediterranean climatology provides a useful context to synthesize the diverse late Pleistocene (60–12 ka) paleohydrologic and paleoenvironmental indicators of past climatic conditions in the Levant and the deserts to its south and east. We first critically evaluate, extract, and summarize paleoenvironmental and paleohydrologic records. Then, we propose a framework of eastern Mediterranean atmospheric circulation features interacting with the morphology and location of the southeast Mediterranean coast. Together they strongly control the spatial distribution of rainfall and wind pattern. This cyclone–physiography interaction enforces the observed rainfall patterns by hampering rainfall generation south and southeast of the latitude of the north Sinai coast, currently at 31°15′.The proposed framework explains the much-increased rains in Lebanon and northern Israel and Jordan as deduced from pollen, rise and maintenance of Lake Lisan, and speleothem formation in areas currently arid and semiarid. The proposed framework also accounts for the southward and eastward transition into semiarid, arid, and hyperarid deserts as expressed in thick loess accumulation at the deserts' margins, dune migration from west to east in the Sinai and the western Negev, and the formation of hyperarid (< 80 mm yr− 1) gypsic–salic soils in the southern Negev and Sinai. Our climatic synthesis explains the hyperarid condition in the southern Negev, located only 200–250 km south of the much-increased rains in the north, probably reflecting a steeper rainfall gradient than the present-day gradient from the wetter Levant into its bordering southern and eastern deserts.At present, the rainiest winter seasons in Lebanon and northern and central Israel are associated with more frequent (+ 20%), deeper Cyprus Lows traversing the eastern Mediterranean at approximately the latitude of southern Turkey. Even these wettest years in northern Israel do not yield above average annual rainfall amounts in the hyperarid southern Negev. This region is mainly influenced by the Active Red Sea Troughs that produce only localized rains. The eastern Mediterranean Cyprus Lows also produce more dust storms and transport higher amounts of suspended dust to the loess area than any other atmospheric pattern. Concurrent rainfall and dust are essential to the late Pleistocene formation of the elongated thick loess zone along the desert northern margin. Even with existing dust storms, the lack of rain and very sparse vegetation account for the absence of late Pleistocene loess sequences from the southern Negev and the formation of hyperarid soils.When the north Sinai coast shifted 30–70 km northwest due to last glacial global sea level lowering, the newly exposed coastal areas supplied the sand and dust to these active eastern Mediterranean cyclones. This enforced the latitude of the northern boundary of the loess zone to be directly due east of the LGM shoreline. This shift of coast to the northwest inhibited rainfall in the southern Levant deserts and maintained their hyperaridity. Concurrently, frequent deep eastern Mediterranean Cyprus Lows were funneled along the northern Mediterranean increasing (probably doubling) the rains in central and northern Israel, Lebanon, southwestern Syria and northern Jordan. These storms and rains formed lakes, forests, and speleothems only a short distance north of the deserts in the southern Levant. 相似文献
18.
Philippe Stee 《Astrophysics and Space Science》2003,286(1-2):225-236
Interferometry in the visible provides milliarcsecond spatial resolution and thus has been used for studying the circumstellar
environment of active hot stars. In this paper I will illustrate how the visibility modulus and phase can be used to better
constrain the physics of Be disks through results from the VLA, the MkII and the GI2T interferometers. I will insist on the
importance and the potential of coupling high angular resolution with high spectral resolution to the study of Be shells.
Finally I will present a possible study of the circumstellar disk of Be stars using the VLTI.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
The central compact object for some gamma-ray bursts (GRBs) may be a strongly magnetized millisecond pulsar. It can inject energy to the outer shock of the GRB by through the magnetic dipole radiation, and therefore causes the shallow decay of the early afterglow. Recently, from a large number of GRB X-ray afterglows observed by Swift/XRT(X-ray telescope), it is revealed that many of them exhibit the shallow decay about 102∼104 s after the burst prompt emission. We have fitted the X-ray afterglow light curves of 11 GRBs by using the energy injection model of a magnetar with the rotation period in the millisecond order of magnitude. The obtained result shows the validity and universality of the magnetar energy injection model in explaining the shallow decay of afterglows, and simultaneously provides some constraints on the magnetic field strength and rotation period of the central magnetar. 相似文献