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1.
用国家台紫金山天文台13.7米望远镜的三谱线系统对23个有线翼特征的大质量恒星形成区进行了观测.获得了12个云核,发现其中5个具有外向流,2个有系统的速度变化,1个可能有塌缩,这些核的质量分布在9.4*10e2到2.2*10e5个太阳质量,氢分子密度从每立方厘米3.4*10e2到1.2*10e4.外向流的质量大于3.5个太阳质量,动能高于9*10e37焦耳,比低质量年轻星体附近的外向流大很多,每个核往往包含着几十个2mass源,其色指数和亮度各不相同,但最红的那个总是在IRAS源的误差椭圆内,可能就是IRAS源的对应体. 相似文献
2.
N. R. Troitsky L. E. Pirogov I. I. Zinchenko J. Yang 《Radiophysics and Quantum Electronics》2005,48(7):491-499
We present results of observations of 23 compact cores of molecular clouds associated with IRAS “ cold” infrared sources.
The observations were performed in the J = 1−0 line of the C18O molecule on a 13.7-meter radio telescope of the Purple Mountain Observatory, China. The C18O (J = 1−0) line was detected in the emission of 21 objects. Column densities of the C18O and H2 molecules towards the maximum of integral intensity of the C18O emission were estimated in the approximation of local thermodynamic equilibrium and amounted to (2.5–10.4) · 1015cm−2 and (1.5–6.1) · 1022 cm−2, respectively. The kinetic temperatures determined for these maxima from the CO lines vary from 14 to 45 K. For six objects,
whose mapping has been almost completed, the dimensions of the C18O emission regions are estimated to range from 0.5 to 1.2 pc. The masses of these objects lie in the range of (390–1750) M⊙ and are close to the estimates following from the virial theorem. The range of average densities of the objects is (0.3–1.4)
· 104 cm−3.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 7, pp. 553–562, July 2005. 相似文献
3.
《Comptes Rendus Physique》2012,13(1):5-13
Herschel is a spatial submillimetre observatory with spectroscopic and imaging capabilities covering the range from 55 to 671 μm (0.44 to 5.5 THz) partly explored for the first time here. With a primary mirror of 3.5 m, it is presently the largest telescope launched. Its primary targets are the cold dust, the light hydrides, with a special focus on H2O, and a few species of high interest like C+ and O2 in both our Galaxy and other galaxies. Its main focus is on star formation in all its possible aspects including cosmological metal enrichment evolution, statistics on prestellar cores or chemistry of protostar outflow terminal shocks to name only a few. We will describe the telescope and its three instruments, a selection of general results and we will focus on one typical case in greater detail, the observation of water in massive star forming regions. Herschel was launched in May 2009 and should function 3.5 years. 相似文献
4.
本文使用文献中的N2H+(1-0)、H13CO+(1-0)、HCN(1-0)和HN13C(1-0)谱线数据研究大质量恒星形成团块的化学性质和演化,发现H13CO+和HN13C的丰度受H2柱密度的影响. 由于从A阶段到B阶段这两个丰度的中值增加了近10倍,H13CO+和HN13C适合追踪大质量恒星形成团块的演化. 从A到B阶段四种分子丰度增长速度从高到低依次为H13CO+、HCN、HN13C、N2H+. 结果表明进行光学薄分子谱线的高分辨率观测对于研究大质量恒星形成团块的化学演化是必要的. 相似文献
5.
The ν3 fundamental band of H2CO (CH2 scissoring motion) has been studied by means of CO laser Stark spectroscopy and conventional infrared absorption spectroscopy. The primary aim of the work was to determine the dipole moment of H2CO in the v3 = 1 state, and the value determined was 2.3250 ± 0.0025 D. The spectrum was analyzed with the inclusion of the Coriolis interactions among ν3, ν4, and ν6 so that “true” rotational constants were determined for ν3; “effective” constants obtained by ignoring these interactions were also determined. The ν3 band origin was determined to be 1500.174 ± 0.002 cm?1. The H2CO spectrum was also used as a means of determining the frequencies of some 13C16O and 12C18O laser lines in the 1500 cm?1 region relative to 12C16O lines. 相似文献
6.
《中国科学:物理学 力学 天文学(英文版)》2010,(6)
Combining the 12CO(1-0),13CO(1-0),and C18O(1-0) data with IRAS four band data,we here estimate the physical parameters such as size,viral mass,and CO J=1-0 isotopic and infrared luminosities for 29 dense molecular clouds from two published CO samples. We further analyze the various correlations between CO J=1-0 isotopic luminosities and infrared luminosity(star formation rate,SFR) and discuss the relationships between the molecular gas tracers and SFR. The results show that 12CO(1-0),13CO(1-0) and C18O(1-0) luminosities have tight correlations with each other. CO J=1-0 isotopic luminosities and SFR show weak correlations with larger scatter than the HCN-IR correlations of 47 dense cores in the Galaxy and 65 external star-forming galaxies. This might be interpreted as that both the SFR and star formation efficiency are mainly determined by the molecular gas at high volume density rather than high column density. 相似文献
7.
C.T. Fleaca I. Morjan F. Dumitrache L. Gavrila-Florescu A. Derory 《Applied Surface Science》2009,255(10):5386-5390
Two types of core-shell nanoparticles have been prepared by laser pyrolysis using Fe(CO)5 and C2H2 or [(CH3)3Si]2O as precursors and C2H4 as sensitizer. The first type (about 4 nm diameter) - produced by the decomposition of Fe(CO)5 in the presence of C2H4 and C2H2 - consists of Fe cores protected by graphenic layers. The second type (mean particle size of about 14 nm) consists also of Fe cores, yet covered by few nm thick γ-Fe2O3/porous polycarbosiloxane shells resulted from the [(CH3)3Si]2O decomposition and superficial oxidation after air exposure. The hysteresis loops suggest a room temperature superparamagnetic behavior of the Fe-C nanopowder and a weak ferromagnetic one for larger particles in the Fe-Fe2O3-polymer sample. Both types of nanoparticles were finally used as a catalyst for the carbon nanotube growth by seeding Si(100) substrates via drop-casting method. CNTs were grown by Hot-Filament Direct.Current PE CVD technique from C2H2 and H2 at 980 K. It is suggested that the increased density and orientation degree observed for the multiwall nanotubes grown from Fe-Fe2O3-polymer nanoparticles could be due to their magnetic behavior and surface composition. 相似文献
8.
This paper reports the assignment of the rotational spectra of the m = 0 and 1 states of 13CC5H6-H2O and C6H5D-H2O dimers. The m = 1 progression was not identified or assigned for both 13CC5H6-H2O and C6H5D-H2O in the earlier work, though for the symmetric isotopomers (C6H6-H2O/D2O/H218O), they were identified [H.S. Gutowsky, T. Emilsson, E. Arunan, J. Chem. Phys. 99 (1993) 4883]. The m = 1 transitions for 13CC5H6-H2O and C6H5D-H2O were split into two, unlike that of the parent C6H6-H2O isotopomer. The splitting varied, somewhat randomly, with quantum numbers J and K. The m = 0 lines of 13CC5H6-H2O had significant overlap with the m = 1 lines of the parent isotopomer, clouding proper assignment, and leading to an rms deviation of about 200 kHz in the earlier work. The general semi-rigid molecular Hamiltonian coupled to an internal rotor, described recently by Duan et al. [Y.B. Duan, H.M. Zhang, K. Takagi, J. Chem. Phys. 104 (1996) 3914], is used in this work to assign both m = 0 and 1 states of 13CC5H6-H2O and C6H5D-H2O dimers. Consequently, the m = 0 fits for 13CC5H6-H2O/D2O have an rms deviation of only 4/7 kHz, comparable to experimental uncertainties. The fits for m = 1 transitions for 13CC5H6-H2O and C6H5D-H2O dimers have an rms deviation of about 200 kHz. However, it is of the same order of magnitude as that of the m = 1 state of the parent C6H6-H2O dimer. The A rotational constants determined from the m = 0 fits for both 13CC5H6-H2O and 13CC5H6-D2O isotopomers are identical and very close to the C rotational constant for 13CC5H6. This provides a direct experimental determination for the C rotational constant of 13CC5H6, which has a negligible dipole moment. 相似文献
9.
The rotational spectra of formaldehyde, H212C16O and its isotopic species H213C16O, H212C18O, and H213C18O have been investigated in the ground vibrational state in the frequency region between 8 and 460 GHz. For most cases in which measurements of the a-type R- and Q-branch transitions already existed the accuracy of the line position has been improved to about 10 kHz. For H212C16O and H213C16O a large number of ΔKa = ±2 transitions were measured with similar accuracy. These new data when combined with all other available data and appropriate weightings lead to a set of ground state parameters which for the first time are compatible with infrared and ultraviolet data. The rotational constants (and 3σ standard deviations) obtained using Watson's A-reduced Hamiltonian are:
H212C16O | H213C16O | H212C18O | H213C18O | |
A/MHz | 281 970.572 (24) | 281 993.258(135) | 281 961.94 (39) | 281 985.00 (93) |
B/MHz | 38 836.0456(13) | 37 811.0887(25) | 36 904.1693(66) | 35 859.256(10) |
C/MHz | 34 002.2034(12) | 33 213.9790(25) | 32 511.5311(63) | 31 697.868(10) |