若干恒星形成区的^12CO（J=1—0）与^13CO（J=1—0）观测

首次利用紫金山天文台青海观测站13.7m毫米波射电望远镜对若干分子云与恒星形成区的~(12)CO(J=1—0)和~(13)CO(J=1—0)分子辐射进行了观测,得到了各自中心位置的谱线轮廓。作为一个实例本文将介绍如何通过对分子云~(12)CO(J=1—0)和~(13)CO(J=1—0)谱线的综合分析与计算得到云中的物理参数。     

Beta decay of nuclides ~(56)Fe,~(62)Ni,~(64)Ni and ~(68)Ni in the crust of magnetars

By introducing the Dirac δ-function and Pauli exclusion principle in the presence of superstrong magnetic fields(SMFs), we investigate the influence of SMFs on beta decay and the change rates of electron fraction(CREF) of nuclides~(56)Fe,~(62)Ni,~(64)Ni and~(68)Ni in magnetars, which are powered by magnetic field energy. We find that the magnetic fields have a great influence on the beta decay rates, and the beta decay rates can decrease by more than six orders of magnitude in the presence of SMFs. The CREF also decreases by more than seven orders of magnitude in the presence of SMFs.     

Neutrino energy spectrum and electron capture of Nuclides~(56))Fe,~(56)Co,~(56)Ni,~(56)Mn,~(56)Cr and~(56)V in stellar interiors

Based on the shell-model Monte Carlo method and random phase approximation theory,the neutrino energy spectrum(NES) and the electron capture(EC) of56 Fe,56Co,56 Ni,56Mn,56 Cr and56V are investigated in presupernova surroundings.The results show that the EC rates are affected greatly at different densities and temperatures. The rates increase greatly and even exceed six orders of magnitude at lower temperature. On the other hand,the NES is very sensitive to stellar temperature and electron energy. The higher the temperature and the lower the electron energy,the larger the influence on NES is. For example,the maxima of NES in the ground state are 9.02,160,80,24.01,0.44,1.42 me c2for56 Fe,56Co,56 Ni,56Mn,56 Cr and56V respectively at ρ7 = 10.7,Ye = 0.45 and T9 = 15. Furthermore,the influence on NES due to EC for different nuclei has some otherness because of different Q0-values. For example,the spectrum of56 Co shows a double bump structure.     

同位素丰度比^12C／^13C与恒星演化及其核过程

近２０年中在银河系及河外星系中同位素丰度比＾１２Ｃ／＾１３Ｃ的毫米波及光学观测取得了一些结果,同位素丰度比＾１２Ｃ／＾１３Ｃ在研究恒星演化及其核过程方面具有重要意义,银河系中的＾１２Ｃ／＾１３Ｃ随银心距ＤＧＣ呈梯度分布,附近河外星系中明显较高的＾１２Ｃ／＾１３Ｃ表明银河系中心处于一个较为宁静的物理相,恒星中不同的＾１２Ｃ／＾１３Ｃ值则反映了各自不同的演化阶段,进一步高精度,大样本的观测将有助于人们     

~(87)Sr原子束的塞曼减速器磁场的研究

应用塞曼效应和多普勒冷却的理论,结合实验条件计算了87Sr原子束塞曼减速器的磁场.数值模拟给出了磁场线圈的层数、圈数、供电电流和其他参数,并据此制作了纺锤状线圈.测量结果表明,研制的纺锤状线圈的轴向磁场满足87Sr光晶格钟实验的要求.     

CO in the IUE spectrum of Comet Bradfield (1979l)

New identifications are reported of the fourth positive bands and Cameron bands of CO in the IUE satellite spectrum of Comet Bradfield (1979l). Although the predicted band intensities as well as the band identifications in Comet West (1976 VI) support the proposed assignments, VUV cometary spectra of higher resolution are necessary for conformation.     

CO interferometric observations of M1-92 (the minkowski's footprint)

We present high spatial resolution observations of the CO emission at 2.6mm in the protoplanetary nebula M1-92 (Minkowski's Footprint), obtained with the Plateau de Bure interferometer. The total mass corresponding to the CO measured intensity is estimated to be large, of about 0.1–0.2 solar masses. The cartography is particularly rich and revealing. From the measured position-velocity distribution of brightness, we conclude that a strong dynamical interaction between the AGB and post-AGB winds is present.     

Near-infrared imaging in H2 of molecular (CO) outflows from young stars

We have imaged several known molecular (CO) outflows in H₂ v=1-0 S(1) and wide-band K in order to identify the molecular shocks associated with the acceleration of ambient gas by outflows from young stars. We detected H₂ line emission in all the flows we observed: L 1157, VLA 1623, NGC 6334I, NGC 2264G, L 1641N and Haro 4-255. A comparison of the H₂ data with CO outflow maps strongly suggests that prompt entrainment near the head of a collimated jet probably is the dominant mechanism for producing the CO outflows in these sources.     

Profile analysis of the (B-X) bands of CO+ in comet West

The calculated profile of (B ²⁺-X ²⁺) bands of CO⁺ based on resonance fluorescence process is shown to be in agreement with the observed profile for comet West.     

行星状星云中CO(1-0)谱线发射的新观测

利用紫金山天文台青海观测站１３．７ｍ射电望远镜,对５个行星状星云给出了新的谱线观测结果。其中行星状星云Ｍ１－８和Ｍ３－３已探测到ＣＯ（２－１）的发射,给出了它们的ＣＯ（１－０）观测结果;为曾进行过ＣＯ观测,但未探测到ＣＯ发射的行星状星云Ｍ１－１２、Ｍ２－４３和ＮＧＣ６５３７,第一次证认了它们的ＣＯ（１－０）发射。     

海尔—波普彗星的CO（J=1—0）谱线的观测

使用紫金山天文台青海观测站13．7米毫米波射电望远镜,于1996年12月10日至1997年1月2日和1997年3月25日至1997年4月4日对海尔－波普彗星的CO分子J＝1—0转动跃迁谱线（频率为115．27120GHz）进行了观测．观测谱线表明,CO分子相对于地心的速度比彗星整体相对于地心的速度要小些,即有蓝移现象．这反映了CO分子是由该彗星迎着太阳的面以一定的速度产生出来的．从观测谱线中还初步估算了该彗星CO分子的产生速率．     

The first CO(1-0) mapping of the globule IC 1396 W

Near-infrared observations indicate that three H₂ outflows and their driving sources are present in the globule IC 1396 W, where the existence of molecular outflows has also been suggested by some authors. We made the first CO(1-0) map of IC 1396 W, and found that its CO molecular cloud may consist of three physically distinct components with different velocities. We detected neither molecular outflows nor the dense cores associated with candidate driving sources. One possible reason is that CO(1-0) and its isotopes cannot trace high density gas, and another is that the beam of our observation is too large to observe them. The CO cloud may be one part of the natal molecular cloud of IC 1396 W, in the process of disrupting and blowing away. The CO cloud seems to be in the foreground of the H₂ outflows.     

Interstellar CO towards X Persei (HD 24534) – II. Two-component model

The observations made by the Goddard High Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope ( HST ) of molecular CO in absorbing gas towards X Persei are reported. The two-component statistical equilibrium model incorporating radiative excitation of CO by line emission at the same velocity that originates in nearby molecular clouds has been used to reproduce high-resolution GHRS spectra. Earlier analysis indicates that the cloud has a complex structure and at least a two-component model should be used to obtain accurate results. The spectra obtained from the International Ultraviolet Explorer ( IUE ) were used to complement GHRS data and constrain the space of possible solutions. The new oscillator strengths recommended by Eidelsberg et al. for A–X bands have been used. The results show that one of the components may be attributed to the Perseus OB2 molecular cloud, and the other component to an extension of the Taurus dark cloud. The total CO column density N (CO)=(1.0±0.2)×10¹⁶ cm⁻² has been determined. According to the results about 85 per cent of the observed CO belongs to an extension of the Taurus dark cloud. The CO radiation that originates in nearby molecular clouds may be the dominant excitation mechanism of the observed CO. The early results of ¹³CO line analysis indicate a ¹³CO/¹²CO ratio of about 40.     

Detection and evolution of the CO (Δv= 2) emission in Nova V2615 Ophiuchi (2007)

We present near-infrared (1–2.5 μm) spectroscopic and photometric results of Nova V2615 Ophiuchi which was discovered in outburst in 2007 March. Our observations span a period of ∼80 d starting from 2007 March 28 when the nova was at its maximum light. The evolution of the spectra is shown from the initial P Cygni phase to an emission-line phase and finally to a dust formation stage. The characteristics of the JHK spectra are very similar to those observed in a nova outburst occurring on a carbon–oxygen white dwarf. We analyse an observed line at 2.088 μm and suggest that it could be due to Fe  ii excited by Lyman α fluorescence. The highlight of the observations is the detection of the first overtone bands of carbon monoxide (CO) in the 2.29–2.40 μm region. The CO bands are modelled to estimate the temperature and mass of the emitting CO gas and also to place limits on the ¹²C/¹³C ratio. The CO bands are recorded over several epochs, thereby allowing a rare opportunity to study the evolution from a phase of constant strength through a stage when the CO is destroyed fairly rapidly. We compare the observed time-scales involved in the evolution of the CO emission and find a good agreement with model predictions that investigate the chemistry in a nova outflow during the early stages.     

Mid‐infrared spectroscopy of refractory inclusions (CAIs) in CV and CO chondrites

Abstract— We present laboratory mid‐infrared absorption spectra (2.5 urn to 16.0 μm) of powdered calcium‐aluminum‐rich inclusions (CAIs) and matrix separated from the carbonaceous chondrites Allende (CV3.2), Vigarano (CV3.3), and Ornans (C03.3). Two groups of spectra with different features were found for the CAI: in the first group spectra are dominated by spinel, pyroxene, and sodalite ± nepheline, where main features occur at 9.3 μm, 10.3 μm, and 11.3 μm. In the second group, characteristic minerals are spinel and melilite with typical band maxima at 11.0 μm and 12.3 μm, and a broad feature between 14.0 μn and 15.0 μn. The position of the broad spinel feature probably depends on its iron content. Comparison of band positions in spectra from the CAI components to observed circumstellar emission spectra indicates the potential occurrence of CAI‐like material. Pyroxene‐ and spinel‐rich features could occur in spectra of dust around the Herbig Ae star HD104237, the T Tauri star Hen3‐600 and the post‐AGB star R Sge. Melilite‐ and spinel‐rich components possibly appear in the spectrum of HD 104237, Hen3‐600, 04187_1927, R Sge, and the planetary nebula Hb 12. There is also indication for a spinel component in dust from the Herbig Ae/Be star HD 179218. The spectra of the AGB stars R Cas and θ Aps show no features of CAl‐type spinel.     

Thermal model of water and CO activity of Comet C/1995 O1 (Hale-Bopp)

An investigation of the activity of Comet C/1995 O1 (Hale-Bopp) with a thermophysical nucleus model that does not rely on the existence of amorphous ice is presented. Our approach incorporates recent observations allowing to constrain important parameters that control cometary activity. The model accounts for heat conduction, heat advection, gas diffusion, sublimation, and condensation in a porous ice-dust matrix with moving boundaries. Erosion due to surface sublimation of water ice leads to a moving boundary. The movement of the boundary is modeled by applying a temperature remapping technique which allows us to account for the loss in the internal energy of the eroded surface material. These kind of problems are commonly referred to as Stefan problems. The model takes into account the diurnal rotation of the nucleus and seasonal effects due to the strong obliquity of Hale-Bopp as reported by Jorda et al. (Jorda, L., Rembor, K., Lecacheux, J., Colom, P., Colas, F., Frappa, E., Lara, L.M. [1997]. Earth Moon Planets 77, 167-180). Only bulk sublimation of water and CO ice are considered without further assumptions such as amorphous ices with certain amount of occluded CO gas. Confined and localized activity patterns are investigated following the reports of Lederer and Campins (Lederer, S.M., Campins, H. [2002]. Earth Moon Planets 90, 381-389) about the chemical heterogeneity of Hale-Bopp and of Bockelée-Morvan et al. (Bockelée-Morvan, D., Henry, F., Biver, N., Boissier, J., Colom, P., Crovisier, J., Despois, D., Moreno, R., Wink, J. [2009]. Astron. Astrophys. 505, 825-843) about a strong CO source at a latitude of 20°. The best fit to the observations of Biver et al. (Biver, N. et al. [2002]. Earth Moon Planets 90, 5-14) is obtained with a low thermal conductivity of 0.01 W m⁻¹ K⁻¹. This is in agreement with recent results of the Deep Impact mission to 9P/Tempel 1 (Groussin, O., A’Hearn, M.F., Li, J.-Y., Thomas, P.C., Sunshine, J.M., Lisse, C.M., Meech, K.J., Farnham, T.L., Feaga, L.M., Delamere, W.A. [2007]. Icarus 187, 16-25) and with previous thermal simulations (Kührt, E. [1999]. Space Sci. Rev. 90, 75-82). The water production curve matches the production rates well from −4 AU pre-perihelion to the outgoing leg while the model does not reproduce so well the water production beyond 4 AU pre-perihelion. The CO production curve is a good fit to the measurements of Biver et al. (2002) over the whole measured heliocentric range from −7 AU pre- to 15 AU post-perihelion.     

OMC--3的13CO(1--0)和C18O(1--0)分子辐射

利用紫金山天文台青海站的 １３．７ ｍ毫米波望远镜,对 Ｏｒｉｏｎ Ａ分子云中的 ＯＭＣ－３区域,进行了较高分辨率的１３ＣＯ（Ｊ＝１－０）和Ｃ１８Ｏ（Ｊ＝１－０）分子辐射的成图观测．给出了该分子云中１３ＣＯ和 Ｃ１８Ｏ云核分布的整体结构和平均物理参数．观测发现,该分子云的１３ＣＯ和 Ｃ１８Ｏ的云核中心分别与最年轻的天体－Ｃｌａｓｓ ０类源 ＭＭＳＩ, ＭＭＳ４,ＭＭＳ６和ＭＭＳ７,ＭＭＳ８;ＭＭＳ９成协．此外,通过分析ＯＭＣ－３整个区域的速度场结构,发现沿 Ｃ１８Ｏ和１３ＣＯ云核方向从南到北有一个～ １．７ｋｍ／ｓ的速度场梯度,而分子云的红、蓝移团块则分别趋于云的北部和南部．并对ＯＭＣ－３区的恒星形成特征进行了讨论．