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1.
PHAI已在俄罗斯伊尔库茨克进行了一年半的观测,获得了1146组观测资料．根据这些观和资料编算出第一期光电等高仪星表。为了说明这期星表的情况,本文特将它与国内几本光电等高仪星表进行比较。  相似文献   

2.
A spectrum of a sunspot in the range of the Li I ?? 670.8 nm line and some lines of Ca I, Ti I, Al I, and Na I was measured. Observations were carried out with the TST-2 telescope of the Crimean astrophysical observatory on August 21, 1981. A model of the spot was calculated from the observed profiles of the Ca I, Ti I, Al I, and Na I lines. From the calculated model and the observed profile of the Li I ?? 670.8 nm line, the lithium abundance was estimated as log(N Li) = 0.78 (in the scale of logA(H)= 12.0).  相似文献   

3.
The aim of this paper is studying the relation between the coronal mass ejections (CMEs), and their associated solar flares. I used the CMEs data (obtained from CME catalogue) which observed by SOHO/LASCO, during the Solar Cycle 23rd (1996–2006), during this period I selected 12,433 CME records. Also I used the X-ray flares data which provided geostationary operational environmental satellite (GOES), during the same interval in the 1–8 Å GOES channel, the recorded flare events are 22,688. I filtered these CMEs and solar flare events to select 529 CME-Flare events. I found that there is a moderate relation between the solar flare fluxes and their associated CME energies, where R = 58 %. In addition I found that 61 % of the CME-Flare associated events ejected from the solar surface after the occurrence of the associated flare. Furthermore I found that the CME-Flare relation improved during the period of high solar activity. Finally, I examined the CME association rate as a function of flare longitude and I found that the CME association rate of the total 529 selected CME-Flare events are mostly disk-Flare events.  相似文献   

4.
The Beidou Navigation Satellite Demonstration System and Beidou Regional Satellite Navigation System are accomplished, and the Beidou Global Satellite Navigation System (BDS-3) is under construction. Nineteen networking satellites have been launched by the end of November 2018. To assess the new and old signals of new networking satellites, the data quality is analyzed from the observation noise and pseudo-range multipath two aspects based on the data of iGMAS stations from 18th to 28th May 2018. The accuracies of BDS-3/GPS combined orbit determinations with B1I/B3I and B1C/B2a are compared. The results show that the data quality of the new signal B2a is similar to that of B1I/B3I, and the data quality of B1C is slightly worse than that of B1I/B3I. Comparing the orbit and clock correction accuracies of overlapped arcs (48 hours), the results with B1C/B2a are slightly better than those with B1I/B3I. The averaged 3D position accuracies (3D RMSs) of precise orbit determinations with B1C/B2a and B1I/B3I are around 35 cm. The RMS values of clock corrections are less than 0.5 ns.  相似文献   

5.
Gireesh  G. V. S.  Kathiravan  C.  Barve  Indrajit V.  Ramesh  R. 《Solar physics》2021,296(8):1-45

This memoir is a summary of my early childhood, education, and research career at the Naval Research Laboratory (NRL) in Washington, DC. I describe my early interest in astronomy and how I wound up working in the fields of solar physics and X-ray-UV spectroscopy of high temperature plasmas. I describe some of my home life and other interests, my education at the University of Pittsburgh, and the various projects and management activities that I have been fortunate to work on at NRL. I have been blessed with being able to work at a first-class research laboratory populated by outstanding scientists. I am particularly blessed to have worked with my many friends and colleagues in the NRL Space Science Division. Perhaps I am most blessed by having had wonderful parents that gave me the interests I have in life and the passion to pursue them, and an outstanding wife that has been my partner through good and bad times for over 50 years. I am now retired but for three years I was a participant in the NRL Voluntary Emeritus Program (VEP). However, this memoir is a personal account, and not work done as a VEP.

  相似文献   

6.
We study the properties of the He I 10830 (A) line in nine selected solar flares, using spectral data obtained with the Multi-channel Infrared Solar Spectrograph (MISS) at Purple Mountain Observatory (PMO) and photospheric images from the Michelson Doppler Imager (MD1) onboard the Solar and Heliospheric Observatory (SOHO). Our results indicate that, over an area of 3"- 8", the He I 10830 (A) line shows emission exceeding the continuum in nearby quiet region when the Geostationary Operations Environmental Satellite (GOES) X-ray class of the flare reaches a threshold value (C4.5). The He I 10830A line emission is detected only in the kernels of the Hα brightenings, but is not associated with the size of the flare. It is found that, whenever the He I 10830(A) line shows excess emission over the nearby continuum both the Hα and the Ca II 8542 (A) lines display enhanced intensities exceeding their preflare intensities. The He I 10830(A) line emission can occasionally extend into the umbra of the involved sunspot, which is inconsistent with previous studies. The weak com-ponent of He I 10830(A) line changes from emission to absorption earlier than does the main component. Our results favor the photoionization-reconnection mechanism for the excitation of the He I 10830(A) line.  相似文献   

7.
Abstract— We review the development of the I‐Xe technique and how its data are interpreted, and specify the best current practices. Individual mineral phases or components can yield interpretable trends in initial 129I/127I ratio, whereas whole‐rock I‐Xe ages are often hard to interpret because of the diversity of host phases, many of which are secondary. Varying standardizations in early work require caution; only samples calibrated against Shallowater enstatite or Bjurböle can contribute reliably to the emerging I‐Xe chronology of the early solar system. Although sparse, data for which I‐Xe and Mn‐Cr can be compared suggest that the two systems are concordant among ordinary chondrite samples. We derive a new age for the closure of the Shallowater enstatite standard of 4563.3 ± 0.4 Myr from the relationship between the I‐Xe and Pb‐Pb systems. This yields absolute I‐Xe ages and allows data from this and other systems to be tested by attempting to construct a common chronology of events in the early solar system. Absolute I‐Xe dates for aqueous and igneous processes are consistent with other systems. Consideration of the I‐Xe host phases in CAIs and dark inclusions demonstrates that here the chronometer records aqueous alteration of pre‐existing material. The ranges of chondrule ages deduced from the Al‐Mg and I‐Xe systems in Semarkona (LL3.0) and Chainpur (LL3.4) are consistent. Chainpur I‐Xe data exhibit a greater range of ages than Semarkona, possibly reflecting a greater degree of parent body processing. However individual chondrules show little or no evidence of such processing. Determining the host phase(s) responsible for high temperature correlations may resolve the issue.  相似文献   

8.
Abstract— The geologic history of Martian meteorite Allan Hills (ALH) 84001 is more complex than previously recognized, with evidence for four or five crater-forming impacts onto Mars. This history of repeated deformation and shock metamorphism appears to weaken some arguments that have been offered for and against the hypothesis of ancient Martian life in ALH 84001. Allan Hills 84001 formed originally from basaltic magma. Its first impact event (I1) is inferred from the deformation (D1) that produced the granular-textured bands (“crush zones”) that transect the original igneous fabric. Deformation D1 is characterized by intense shear and may represent excavation or rebound flow of rock beneath a large impact crater. An intense thermal metamorphism followed D1 and may be related to it. The next impact (I2) produced fractures, (Fr2) in which carbonate “pancakes” were deposited and produced feldspathic glass from some of the igneous feldspars and silica. After I2, carbonate pancakes and globules were deposited in Fr2 fractures and replaced feldspathic glass and possibly crystalline silicates. Next, feldspars, feldspathic glass, and possibly some carbonates were mobilized and melted in the third impact (I3). Microfaulting, intense fracturing, and shear are also associated with I3. In the fourth impact (I4), the rock was fractured and deformed without significant heating, which permitted remnant magnetization directions to vary across fracture surfaces. Finally, ALH 84001 was ejected from Mars in event I5, which could be identical to I4. This history of multiple impacts is consistent with the photogeology of the Martian highlands and may help resolve some apparent contradictions among recent results on ALH 84001. For example, the submicron rounded magnetite grains in the carbonate globules could be contemporaneous with carbonate deposition, whereas the elongate magnetite grains, epitaxial on carbonates, could be ascribed to vapor-phase deposition during I3.  相似文献   

9.
Plasma of electric arc discharges between composite Cu–W, Cu–Mo and Cu–Cr electrodes in argon flow and their spectra were studied by optical emission spectroscopy. Since values of oscillator strengths for W I, Mo I and Cr I presented in various sources are significantly different, selection of spectroscopic data for these elements (particularly oscillator strength) was expected to be useful for plasma diagnostics. The Boltzmann plot method was used as a tool for the selection of appropriate spectral lines and their spectroscopic data. The main result of the paper is W I, Mo I and Cr I spectral lines and spectroscopic data recommended for diagnostics of plasma with such metal impurities.  相似文献   

10.
Results of a spectral survey of molecular cores NGC 6334I and NGC 6334I(N) in a number of spectral intervals with widths of about 1000 MHz are presented. Observations were carried out with the SEST radiotelescope. Number of the intervals for NGC 6334I was 11. 209 spectral features were detected towards molecular core NGC 6334I, out of which 203 features were assigned to 25 species.Number of the intervals for NGC 6334I(N) was 6. They represent a subset of the intervals used for the NGC 6334I. The spectrum of NGC 6334I(N) appears to be considerably more poor with the features: 63 features were detected, out of which 55 were assigned to 13 species.Catalogues of assigned features for both sources are presented. They contain the notation of corresponding molecular transition, frequency, and the following observational data: integrated intensity, Vlsr velocity, FWHM and antenna temperature.  相似文献   

11.
Abstract— We have studied the I‐Xe system in chondrules and clasts from ordinary chondrites. Cristobalite‐bearing clasts from Parnallee (LL3.6) closed to Xe loss 1–4 Ma after Bjurböle. Feline (a feldspar‐ and nepheline‐rich clast also from Parnallee) closed at 7.04 ± 0.15 Ma. Two out of three chondrules from Parnallee that yielded well‐defined initial I ratios gave ages identical to Bjurböle's within error. A clast from Barwell (L6) has a well‐defined initial I ratio corresponding to closure 3.62 ± 0.60 Ma before Bjurböle. Partial disturbance and complete obliteration of the I‐Xe system by shock are revealed in clasts from Julesburg (L3.6) and Quenggouk (H4), respectively. Partial disturbance by shock is capable of generating anomalously high initial I ratios. In some cases, these could be misinterpreted, yielding erroneous ages. A macrochondrule from Isoulane‐n‐Amahar contains concentrations of I similar to “ordinary” chondrules but, unlike most ordinary chondrules, contains no radiogenic 129Xe. This requires resetting 50 Ma or more later than most chondrules. The earliest chondrule ages in the I‐Xe, Mn‐Cr, and Al‐Mg systems are in reasonable agreement. This, and the frequent lack of evidence for metamorphism capable of resetting the I‐Xe chronometer, leads us to conclude that (at least) the earliest chondrule I‐Xe ages represent formation. If so, chondrule formation took place at a time when sizeable parent bodies were present in the solar system.  相似文献   

12.
F. P. Keenan 《Solar physics》1988,116(2):279-284
R-matrix calculations of electron impact excitation rates in S vi are used to determine the theoretical temperature sensitive emission line ratios and which are found to be up to 30% larger than the earlier results of Flower and Nussbaumer. A comparison of the present data with solar observations from the Harvard S-055 spectrometer on board Skylab implies that the 944.5 Å transition may be blended with lines from species with relatively low ionization potentials, in contrast to the findings of Flower and Nussbaumer. The 712.8 Å transition may also be similarly blended.  相似文献   

13.
The northern section of the molecular cloud complex NGC 6334 has been mapped in the CO and CS spectral line emission and in continuum emission at a wavelength of 1300 μm. Our observations highlight the two dominant sources, I and I(N), and a host of weaker sources. NGC 6334 I is associated with a cometary ultracompact H  ii region and a hot, compact core ≤10 arcsec in size. Mid-infrared and CH3OH observations indicate that it is also associated with at least two protostellar sources, each of which may drive a molecular outflow. For region I we confirm the extreme high-velocity outflow first discovered by Bachiller & Cernicharo and find that it is very energetic with a mechanical luminosity of 390 L⊙. A dynamical age for the outflow is ∼3000 yr. We also find a weaker outflow originating from the vicinity of NGC 6334 I. In CO and CS this outflow is quite prominent to the north-west, but much less so on the eastern side of I, where there is very little molecular gas. Spectral survey data show a molecular environment at position I which is rich in methanol, methyl formate and dimethyl ether, with lines ranging in energy up to 900 K above the ground state. NGC 6334 I(N) is more dense than I, but cooler, and has none of the high-excitation lines observed toward I. I(N) also has an associated outflow, but it is less energetic than the outflow from I. The fully sampled continuum map shows a network of filaments, voids and cores, many of which are likely to be sites of star formation. A striking feature is a narrow, linear ridge which defines the western boundary. It is unclear if there is a connection between this filament and the many potential sites of star formation, or if the filament existed prior to the star formation activity.  相似文献   

14.
We present the results of a six-square-degree Pleiades survey in I and Z , which is photometrically complete to approximately I KP=19.2 ( I Cou=19.6 in the Pleiades). We remove non-cluster contamination on the basis of proper motions and infrared photometry, and present 339 candidate cluster members, 30 of which are fainter than I KP=17.5, and are thus strong brown-dwarf candidates.  相似文献   

15.
针对北斗二号(BeiDou-2) B1I&B2I标准双频无电离层伪距组合解算的共视比对结果中存在明显的噪声进而影响其短期稳定性的现象, 开展了在BeiDou-2和北斗三号(BeiDou-3)现有可用频率信号中选取最优双频组合的研究, 以期改善BeiDou的共视时间传递性能. 基于开发的CGGTTS (Common GNSS (Global Navigation Satellite System) Generic Time Transfer Standard)软件所生成的标准共视文件, 完成了中国科学院国家授时中心(NTSC)与捷克光电研究院(TP)之间GPS、Galileo、BeiDou-2 B1I&B2I及B1I&B3I和BeiDou-3 B1I&B3I及B1C&B2a双频无电离层伪距组合共视时间比对试验, 并用Vondark滤波对各双频组合的共视结果降噪处理, 通过计算滤波残差的RMS值来评估共视时间比对的精度. 结果表明, 利用BeiDou-3 B1C&B2a组合伪距值获得的共视时间比对结果噪声相对较小, 相比BeiDou-2 B1I&B2I、B1I&B3I和BeiDou-3 B1I&B3I组合的RMS (Root Mean Square)值分别提高约46%、52%和37%, 与GPS P1&P2组合的精度相当, 且与Galileo E1&E5a组合相差不大. BeiDou-3 B1C&B2a组合链路的短稳(< 1d)要优于BeiDou-2 B1I&B2I、B1I&B3I和BeiDou-3 B1I&B3I组合, 且与GPS P1&P2、Galileo E1&E5a组合的稳定性相当; 6条共视时间比对链路的中长稳(> 1d)基本一致.  相似文献   

16.
We have performed statistical equilibrium calculations for Ca I–Ca II, Ti I–Ti II, and Fe I–Fe II by taking into account the nonequilibrium line formation conditions (the non-LTE approach) in model atmospheres of giant stars with effective temperatures 4000 K ≤ T eff ≤ 5000 K and metal abundances ?4 ≤ [Fe/H] ≤ 0. The dependence of departures from LTE on atmospheric parameters has been analyzed. We present the non-LTE abundance corrections for 28 Ca I lines, 42 Ti I lines, 54 Ti II lines, and 262 Fe I lines and a three-dimensional interpolation code to obtain the non-LTE correction online for an individual line and specified atmospheric parameters.  相似文献   

17.
Abstract— Iodine concentrations in small domains (～10 μm) of silicates and troilite (FeS) phases in three chondrules from the Semarkona (LL3) meteorite were determined by an ion microprobe. Independent determination of I content in some of these phases was accomplished by in situ laser probe mass spectrometric analysis of I-derived 128Xe in one of these neutron-irradiated chondrules. The ion microprobe data suggest low I content for olivines (20–45 ppb) and relatively higher values for pyroxene and glass (mesostasis) (40–160 ppb). The broad similarity in the measured I contents in pyroxenes in a porphyritic pyroxene chondrule by ion microprobe (42–138 ppb) and by laser probe (37–76 ppb) demonstrate the feasibility of in situ determination of I content in silicate phases via ion microprobe. The I contents in troilite measured by ion microprobe, however, are prone to uncertainty because of the lack of a sulfide standard. The ion microprobe data suggest I content of > 1 ppm in troilite, if the calibration from our silicate standard is used. However, the noble gas data suggest that the I content in troilite is comparable to that in silicates. We attribute this apparent discrepancy to an enhanced sputter ion yield of I from sulfides. Iodine-derived 129Xe excesses were observed in both pyroxene and troilite within this chondrule. The I-Xe model ages of these selected phases are consistent with the I-Xe studies of the bulk chondrule. The individual data points fall on or near the isochron obtained from the bulk chondrule, although all except the most radiogenic data point contain evidence of low-temperature uncorrelated iodine.  相似文献   

18.
In this work, I consider the logarithmic-corrected and the power-law corrected versions of the holographic dark energy (HDE) model in the non-flat FRW universe filled with a viscous Dark Energy (DE) interacting with Dark Matter (DM). I propose to replace the infra-red cut-off with the inverse of the Ricci scalar curvature R. I obtain the equation of state (EoS) parameter ω Λ , the deceleration parameter q and the evolution of energy density parameter $\varOmega_{D}'$ in the presence of interaction between DE and DM for both corrections. I study the correspondence of the logarithmic entropy corrected Ricci Dark Dnergy (LECRDE) and power-law entropy corrected Ricci Dark Energy (PLECRDE) models with the the Modified Chaplygin Gas (MCG) and some scalar fields including tachyon, K-essence, dilaton and quintessence. I also make comparisons with previous results.  相似文献   

19.
Abstract— I‐Xe analyses were carried out for chondrules and refractory inclusions from the two CV3 carbonaceous chondrites Mokoia and Vigarano (representing the oxidized and reduced subgroups, respectively). Although some degree of disturbance to the I‐Xe system is evident in all of the samples, evidence is preserved of aqueous alteration of CAIs in Mokoia 1 Myr later than the I‐Xe age of the Shallowater standard and of the alteration of a chondrule (V3) from Vigarano ～0.7 Myr later than Shallowater. Other chondrules in Mokoia and Vigarano experienced disturbance of the I‐Xe system millions of years later and, in the case of one Vigarano chondrule (VS1), complete resetting of the I‐Xe system after decay of essentially all 129I, corresponding to an age more than 80 Myr after Shallowater. Our interpretation is that accretion and processing to form the Mokoia and Vigarano parent bodies must have continued for at least 4 Myr and 80 Myr, respectively. The late age of a chondrule that shows no evidence for any aqueous alteration or significant thermal processing after its formation leads us to postulate the existence of an energetic chondrule‐forming mechanism at a time when nebular processes are not expected to be important.  相似文献   

20.
In this proceeding I present recent works dealing with magnetohydrodynamic (MHD) simulations describing resistive accretion disks continuously launching large-scale, self-collimated MHD jets. In particular, I discuss the physical conditions required to produce these outflows and the related numerical issues. As an illustration I also present axisymmetric MHD numerical simulations of such accretion-ejection engines, demonstrating the mechanism controlling these flows.  相似文献   

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