共查询到20条相似文献，搜索用时 109 毫秒
1.
Denis Leahy 《中国天文和天体物理学报》2006,6(5)
Presented are new images of supernova remnants G114.3 0.3, G116.5 1.1 and G116.9 0.2 (CTB 1) at 408 MHz from the Canadian Galactic Plane Survey (CGPS). We also use the 1420 MHz images from the CGPS in a study of their 408-1420 MHz spectral indices. The flux densities at 408 MHz and 1420 MHz, corrected for flux densities from compact sources within the SNRs, are 12±6 Jy and 9.8±0.8 Jy for Gl 14.3 0.3,15.0±1.5 Jy and 10.6±0.6 Jy for G116.5 1.1, 15.0±1.5 Jy and 8.1±0.4 Jy for G116.9±0.2. The integrated flux density-based spectral indices (Sv∝v-α) areα=0.16±0.41, 0.28±0.09 and 0.49±0.09 for G114.3 0.3, G116.5 1.1 and G116.9 0.2, respectively. Their T-T plot-based spectral indices are 0.68±0.48, 0.28±0.15, and 0.48±0.04, in agreement with the integrated flux density-based spectral indices. New flux densities are derived at 2695 MHz which are significantly larger than previous values. The new 408, 1420 and 2695 MHz flux densities and published values at other frequencies, where images are not available, are fitted after correcting for contributions from compact sources, to derive their multi-frequency spectral indices. 相似文献
2.
利用中国科学院紫金山天文台德令哈观测站13．7米望远镜在IRAS 02232 6138方向进行了13CO,C18O,HCO 和N2H 的观测．随着探针分子的激发密度从13CO到N2H 逐渐增加, IRAS02232 6138云核的尺度从13CO的2．40 pc减小到N2H 的0．54pc,云核的维里质量从13CO的2．2×103M⊙减小到N2H 的5．1×102M⊙．研究发现,该方向区域内存在双极分子外流．对云核的空间密度结构用幂函数n(r)αr-α的形式进行拟合分析,得到α=2．3-1．2;随着探测密度的增加,该指数逐渐变平．分析得到, 13CO／C18O分子丰度比值为12．4±6．9,与暗云的11．8±5．9及大质量核的9．0-15．6值一致;N2H 丰度是3．5±2．5×10-10,与暗云核的1．0-5．0×10-10和大质量核的1．2-12．8×10-10值一致;HCO 丰度为0．9±0．5×10-9,接近大质量核的1．6-2．4×10-9值,没有发现HCO 丰度增长．结合IRAS数据,得到云核的光度质量比范围为37-163(L／M)⊙,由IRAS光度估计, IRAS 02232 6138方向云核内嵌埋的大约是一颗主序O7．5星． 相似文献
3.
F.C. Fehsenfeld 《Planetary and Space Science》1977,25(2):195-196
The reactions of atomic nitrogen with O+2 and atomic oxygen and atomic nitrogen with NO+· H2O and NO+2 have been measured at 296 K. The rate constants are reported and the implication of the measurements to atmospheric ion chemistry is discussed. 相似文献
4.
Bi-Qing For Elizabeth M. Green Gilles Fontaine Scott Shaw 《Astrophysics and Space Science》2010,328(1-2):87-90
In this paper, we report a rare reflection effect eclipsing sdB+dM binary, 2M?1533+3759. It is the seventh eclipsing sdB+dM binary that has been discovered to date. This system has an orbital period of 0.16177042 day and a velocity semi-amplitude of 71.1 km?s?1. Using a grid of zero-metallicity NLTE model atmospheres, we derived T eff=29250 K, log?g=5.58 and [He/H]=?2.37 from spectra taken near the reflection effection minimum. Lightcurve modeling resulted in a system mass ratio of 0.301 and an orbital inclination angle of 86.6°. The derived primary mass for 2M?1533+3759, 0.376±0.055 M ⊙, is significantly lower than the canonical mass (0.48 M ⊙) found for most previously investigated sdB stars. This implies an initial progenitor mass >1.8 M ⊙, at least a main sequence A star and perhaps even one massive enough to undergo non-degenerate helium ignition. 相似文献
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7.
Imad A. Ahmad 《Solar physics》1977,53(2):409-415
The intensity of the He+ 304 coronal line relative to the H0 1216 line, including the dominant contribution due to resonance scattering, is presented. All physical processes important in the corona are included. It is found that He+ 304 is a major contributor to the XUV corona, and that the sensitivity of the He+ 304/H0 1216 intensity ratio to coronal temperature is very weak, supporting the belief that this ratio is a good indicator of the coronal helium abundance. 相似文献
8.
Ju-Mei Yao Wei-Wei Zhu Pei Wang Di Li Ji-Guang Lu Fei-Fei Kou Ye-Zhao Yu Bo Peng FAST Collaboration 《天文和天体物理学研究(英文版)》2020,(5):175-180
In this paper,we present the Five-hundred-meter Aperture Spherical radio Telescope(FAST)observations of PSRs B1929+10 and B1842+14.Through analysis of the pulsars’scintillation pattern,we detected the known scintillation arc from PSR B1929+10 and two previously undetected scintillation arcs from B1842+14.We find that the B1929+10 arc’s curvature scales with observing frequency asη-∝ν-2.1±0.1 andη+∝ν-1.8±0.2,consistent with Arecibo results and the theoretical expectations ofη∝ν-2.From the arc curvature,we infer the scattering screen to be located at 0.20±0.02 kpc from the Earth,close to what was measured by RadioAstron at 324 MHz.From B1842+14,we find two scintillation arcs for the first time.The arcs’curvatures imply that they are caused by two scattering screens located at a distance of 0.3±0.2 kpc and 1.6±0.6 kpc from the Earth,respectively.The screen distance uncertainties mainly come from the uncertainty in pulsar’s dispersion measure(DM)-derived distance.We present these FAST scintillation observations and discuss the future prospect of FAST pulsar scintillation study. 相似文献
9.
The simplest, conventional, and original form of the circular restricted problem of three bodies is briefly described in sidereal and synodic systems using dimensional and non-dimensional variables. This dynamical system is generalized to n2 primary bodies (from n=2) with masses Mi, 1in, interacting with arbitrary force laws (instead of only gravitational forces). The number of bodies of small mass mMi not perturbing the primaries is increased from =1 to 1 where 1 and the minor bodies are allowed to interact with one another under arbitrary force laws. While the minor bodies (m) do not affect the motions of the primaries (Mi), the primaries influence the motions of the minor bodies with arbitrary force laws.For the case where n=2, 1, and only gravitational forces act on the system, an integral of the system is derived. It is shown that the energy integral of the general problem of N bodies and the Jacobian integral of the classical restricted problem of three bodies are limiting cases of this integral. The role of the integral in bounding the motion of the minor bodies is discussed. Several applications of this system are given. 相似文献
10.
E. P. Farina R. Falomo A. Treves R. Decarli J. Kotilainen R. Scarpa 《Astrophysics and Space Science》2013,345(1):199-202
We present optical spectroscopy of the nearest quasar pair listed in the 13th edition of the Véron-Cetty & Véron catalogue, i.e. the two quasars SDSS J15244+3032 and RXS J15244+3032 (redshift z≈0.27, angular separation Δθ≈7″, and line-of-sight velocity difference ΔV≈1900 km/s). This system would be an optimal candidate to investigate the mutual interaction of the host galaxies with ground based optical imaging and spectroscopy. However, new optical data demonstrate that RXS J15244+3032 is indeed a star of spectral type G. This paper includes data gathered with the Asiago 1.82 m telescope (Cima Ekar Observatory, Asiago, Italy). 相似文献
11.
The possible discovery of three new -ray pulsars PSR 0656+14, PSR 0950+08, and PSR 1822-09 (Ma, Lu, Yu, and Young, 1993) in data obtained with the COS-B experiment is reinvestigated using a refined technique for pulsar light curve analysis. The results of this study do not confirm the previously claimed -ray pulsar nature of any of these pulsars. Even when using the standard epoch folding technique in conjunction with energy-dependent acceptance cones, we do not detect pulsed -ray emission from these sources. We suspect that insufficient position accuracy is the cause for the discrepancy between our results and those of Maet al. (1993). We do not rule out that any one of the three candidates, or all of them, is in fact a -ray pulsar, but their spin properties must differ from those derived by Maet al. (1993). More work is needed to determine the correct high-energy properties of these three sources. 相似文献
12.
The eighth list of late-type stars of spectral classes M and C detected on the plates of the First Byurakan Spectral Sky Survey (FBS) in the zone +80 +90° is presented. Of the 79 objects detected, 67 are new discoveries (66 M stars and one carbon star); 16 objects are unidentified IRAS sources. The equatorial coordinates, spectral classes, and magnitudes are given.Translated fromAstrofizika, Vol. 39, No. 4, pp. 523–529, November, 1996. 相似文献
13.
对MSX红外暗云G79.2+0.38的11'×7'的区域范围进行了12CO(1-0)、13CO(1-0)和C18O(1-0)谱线的同时观测.观测到的两个C18O(1-0)谱线所界定的云核峰值分布分别对应MSX A波段的两块高消光区域.该区域的氢分子柱密度N(H2)-(5-12)×1022 cm-2,平均密度n-(3±1)×104cm-3.两块分子云核的13CO的线尺度分别是1.7和1.2 pc,而C18O的线尺度分别是1.2和0.6 pc,它们包含的质量为2×102-2×103M(?).分子云核的视向平均密度结构可用幂函数(?)(p)-p-0.34±0.02表征. 13CO和C18O的丰度和典型的光学暗云相比低了4至11倍,但是目前还没有证据表明13CO和C18O的相对丰度比X13/18随柱密度有显著变化. 相似文献
14.
The eleventh list of blue stellar objects in the second part of the First Byurakan Spectral Sky Survey (FBS) is presented. The list consists of 64 objects located in the region +80 +90° and 2h 08m a 20h 15m. The objects haveV magnitudes in the range 12.3–17.4 andB–V color indices in the range -0.55-+0.55. Of the 98 objects, 56 are newly discovered. Tentative classifications are given for 28 objects, of which there is one planetary nebula, 6 possible quasars, 15 possible white dwarfs, and 6 possible cataclysmic variables. Two of the latter are possibly novae having erupted at the epoch of exposure of the FBS plates in this region.Translated fromAstrofizika, Vol. 39, No. 4, pp. 531–540, November, 1996. 相似文献
15.
A. V. Raveendran 《Astrophysics and Space Science》1984,99(1-2):171-173
Photometry of the spectroscopic binary BD+25°2511 obtained during the 1981, 1982, and 1983 observing seasons shows that it is a variable with a period of about 3.5 days.Paper presented at the Lembang-Bamberg IAU Colloquium No. 80 on Double Stars: Physical Properties and Generic Relations, held at Bandung, Indonesia, 3–7 June, 1983. 相似文献
16.
J. S. B. Wyithe R. L. Webster E. L. Turner 《Monthly notices of the Royal Astronomical Society》2000,318(3):762-768
Microlensing in Q2237+0305 between 1985 and 1995 has been interpreted in two different ways. First, the observed variations can be explained through microlensing by stellar mass objects of a continuum source with dimensions significantly smaller than the microlens Einstein Radius ( 0 ), but consistent with that expected for thermal accretion discs . However, other studies have shown that models having sources as large as 5 0 can reproduce the observed variation . In this paper we present evidence in favour of a small source. Our approach uses the distribution of microlensed light-curve derivatives to place statistical limits (as a function of source size) on the number of microlens Einstein radii crossed by the source during the monitoring period. In contrast with previous analyses, our results are therefore not dependent on an assumed time-scale. Limits on the source size are obtained from two separate light-curve features. First, recently published monitoring data show large variations (0.81.5 mag) between image brightnesses over a period of 700 d or 15 per cent of the monitoring period. Secondly, the 1988 peak in the image A light curve had a duration that is a small fraction (0.02) of the monitoring period. Such rapid microlensing rises and short microlensing peaks only occur for small sources. We find that the observed large, rapid variation limits the source size to be <0.2 0 (95 per cent confidence). The width of the light-curve peak provides a stronger constraint of <0.025 0 (99 per cent confidence). The Einstein radius (projected into the source plane) of the average microlens mass m in Q2237+0305 is The interpretation that stars are responsible for microlensing in Q2237+0305 therefore results in limits on the continuum source size that are consistent with current accretion disc theory. 相似文献
17.
S5 2007+777是一个典型的低峰值频率的蝎虎天体,该天体具有kpc尺度的X射线喷流,文献中利用模型估算的方法,得出X射线波段的多普勒因子达到13.0,从而喷流尺度可以达到Mpc量级.在此,搜集了有关S5 2007+777的欧洲甚长基线射电干涉网(European VLBI Network, EVN)高分辨率档案数据、美国甚长基线射电干涉网(Very Long Baseline Array, VLBA) 15 GHz观测数据等,研究了喷流的射电结构、亮温度、自行等方面的性质,发现该源的甚长基线干涉测量(Very Long Baseline Interferometry,VLBI)不同波段的喷流方向一致,但与文献中给出的kpc尺度的X射线喷流和甚大阵(Very Large Array, VLA)射电喷流方向存在一定的差异,说明该源的喷流辐射存在多普勒增亮效应.由VLBI观测得到的亮温度,估算了该源的射电多普勒因子的平均值及中值均为5.0,此值小于文献中X射线波段的多普勒因子,但与文献中利用其他方法得到的射电波段多普勒因子是一致的;另外,对多历元观测数据的拟合发现此源相同波段的各个成分在长历元上没有明显的自行,短历元上的自行甚至是视超光速运动.这可能是由低表面亮度成分中心位置的转移造成的.这同时也验证了之前估算的射电多普勒因子不是很大,小于X射线波段多普勒因子的结论.利用所得到的射电多普勒因子,发现该源具有较大尺度的本征射电喷流,可达到0.5 Mpc,由于这里使用的是均值,因此说明该源也有可能具有接近巨射电星系尺度的喷流. 相似文献
18.
张尔和 《中国天文和天体物理学报》1988,(4)
PG1030+590是最近发现的类新星食变星。我们首先给出该双星系统的高速光电测光结果及U、B、V和R光变曲线。通过利用激变变星的模型对观测结果进行分析,我们求得其物理和几何参数:白矮星子星质量M_1=0.83±0.22M_⊙,晚型星子星质量M_2=0.35±0.06M_⊙,晓型星子星半径R_2=0.37±0.08R_⊙以及轨道倾角i=81°±2°。我们还利用两种不同方法求出围绕白矮星的吸积盘的半径R_d≈0.32R_⊙,并把这个结果与密近双星中吸积盘半径的各理论模型进行了比较。 相似文献
19.
利用紫金山天文台青海观测站13.7 m毫米波望远镜对IRAS 23133 6050云核进行~(13)CO、C~(18)O、HCO (J=1-0)谱线观测.~(13)CO、C~(18)O、HCO 分子谱线辐射所对应的云核直径分别为4.0pc、2.1 pc、2.3 pc,质量分别为2.7×10~3M_⊙、0.9×10~3M_⊙、2.3×10~3M_⊙,气体平均密度分别为2.7×10~3 cm~(-3)、5.1×10~3 cm~(-3)、4.6×10~3cm~(-3).用幂律模型n(r)～~(-P)的形式分析了云核的密度分布,得到的指数p分别为1.75、1.56、1.48.分析发现,密度结构谱指数从云核的外部向内部逐渐变平坦.观测得到HCO~ 丰度为4.6×10~(-10),比暗云低一个数量级以上,比巨分子云也略低,而~(13)CO、C~(18)O的相对丰度比X_(13/18)为12.2,这与暗云11.8和巨分子云9.0～15.6的情况一致.该区域发现存在~(13)CO双极外流.由IRAS远红外光度和维里质量得到的光度质量比,分别为18.1,51.1、21.2. 相似文献
20.
The eighth list of blue stellar objects in the second part of the First Byurakan Spectral Sky Survey (FBS) is presented. The objects are located in the zone +65° +69° and 5
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15m
18
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05m.The list contains data on 98 blue stellar objects detected, of which 73 are previously unknown. A preliminary classification of the objects is given. The exact coordinates of the centers and the limiting magnitudes of the plates for this zone have been determined using the charts of the Palomar Sky Survey.Translated from Astrofizika, Vol. 37, No. 2, pp. 197–206, April–June, 1994.This work has been performed with financial support of the ESO C&EE fund (A-02-043). 相似文献