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Diffuse interstellar absorption bands

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Science China(Physics,Mechanics & Astronomy) 2009年第4期52卷 489-501页

作者： XIANG FuYuan1,2,LIANG ShunLin2 & LI AiGen2,3 1 Faculty of Materials,Photoelectronics and Physics,Xiangtan University,Xiangtan 411105,China 2 Department of Physics and Astronomy,University of Missouri,Columbia,MO 65211,USA 3 Purple Mountain Observatory,Chinese Academy of Sciences,Nanjing 210008,China Faculty of Materials Photoelectronics and Physics Xiangtan University Xiangtan China Department of Physics and Astronomy University of Missouri Columbia USA Purple Mountain Observatory Chinese Academy of Sciences Nanjing China

The diffuse interstellar bands(DIBs) are a large number of absorption bands that are superposed on the interstellar extinction curve and are of interstellar origin. Since the discovery of the first two DIBs in the 1920s,the exact nature of DIBs still remains unclear. This article reviews the history of the detections of DIBs in the Milky Way and external galaxies,the major observational characteristics of DIBs,the correlations or anti-correlations among DIBs or between DIBs and other interstellar features(e.g. the prominent 2175 Angstrom extinction bump and the far-ultraviolet extinction rise),and the proposed candidate carriers. Whether they are also present in circumstellar environments is also discussed.

关键词： astrophysics interstellar matter interstellar extinction diffuse interstellar band circumstellar environment

“interstellar Express”:A Possible Successor to Voyagers

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Bulletin of the Chinese Academy of Sciences 2019年第4期33卷 226-229页

作者： SONG Jianlan 不详

Voyagers,the first and the only mission sent by human beings beyond the end of the solar wind,might be out of service in just several years.In the cosmos beyond 2025,very likely no artificial detector will be flying at the outer brim of the solar system.The interstellar Express,a mission proposed by CAS scientists,might come timely as a possible successor to fill in the gap.Unlike Voyagers,its detectors are expected to fly not only to the nose part of the heliosphere,but also the tail part and the altitude dimension.As planned in the shortterm stage of its three-step layout,the first two detectors will be launched by the end of 2025,if everything goes well.

关键词： USA Successor to Voyagers Express interstellar Express

The interstellar methanol masers and their environments

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Science China(Physics,Mechanics & Astronomy) 2003年第2期46卷 137-144页

作者：毛瑞青裴春传曾琴 Purple Mountain Observatory Chinese Academy of SciencesNanjing 210008China National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100012China Purple Mountain Observatory Chinese Academy of SciencesNanjing 210008China

To promote the understanding of massive star formation processes, we have studied the 6.6 GHz methanol (CH3OH) masers and their environments-- the dense cores and the outer regions of the molecular cloud. The physics of the CH3OH maser or the thermal emission formation region is studied by fitting the observational data of the 6.6 GHz 51-60 A+ and the 107 GHz 31-40 A+ CH3OH maser emission, using the radiative transfer calculations. The type II characteristics of the 6.6 GHz CH3OH maser are confirmed by the calculation results. A greater intensity of the radiation field leads to an increase in the peak intensity of the maser; however, high densities tend to turn off the maser. The calculation results show that to be a maser the 6.6 GHz CH3OH emission needs a radiation field of 150-300 K and a density not higher than 107cm-3, while the 107 GHz emission requires a radiation field of 210-300 K and a density not higher than 3×106 cm-3. The 6.6 GHz line is maser towards all six studied sources, while the 107 GHz line is maser towards Cep A only. Moreover, the former's intensity is much stronger than the latter. The radiative transfer calculations also indicate that the 6.6 GHz maser emission is so strong that the requirements of its formation (e.g. The radiation field, the density and the kinetic parameters) can only be satisfied at a certain stage of the processes of the massive star formation. Therefore it is often used as one of the most prominent tracers for the massive star formation regions. The calculation results of the simultaneous observations of (1,1) through (4,4) inversion lines of the ammonia (NH3) indicate that both the temperature and the density in the 6.6 GHz CH3OH maser formation regions are higher than that of the NH3 line formation regions. Furthermore, the common fact of |Vlsr(CO)| ＞ |Vlsr(NH3)| ＞ |Vlsr(CH3OH 6.6GHz maser)| in all six sources implies the ongoing developing trends of those gas flows driven by the masers.

关键词： methanol maser, massive star formation, interstellar molecular line.

New high-velocity bipolar outflows in S39 and IRAS 06306+0232

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Science China Mathematics 2002年第4期45卷 538-544页

作者：秦胜利吴月芳 Department of Astronomy Peking University Beijing China CAS-PKU Joint Beijing Astrophysics Center Beijing China

Mapping observations in 12CO J = 1 - 0 lines were made towards S39 and IRAS 06306+0232 with the 13.7 m radio telescope at Qinghai Station of Purple Mountain Observatory. The results showed that both of them have bipolar outflows. We have calculated the outflow parameters. The outflows have significantly more mass and higher mass loss rate than those from Iow mass YSOs. We also find that although the bolometric luminosities of the associated sources are large, the radiation pressure of wind is not sufficient to drive the observed outflows. There exist several stars of different evolve states in S39. It suggests that the star formation in S39 is in sequence, not in eruption.

关键词： interstellar medium, jets and outflows, star formation.

High-velocity molecular outflows hear massive young stellar objects

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Science China Mathematics 1999年第7期42卷 732-738页

作者：吴月芳李月兴杨传义雷成明孙金江吕静韩溥 Beijing Astrophysics Center Beijing China Department of Geophysics Peking University Beijing China Shanghai Observatory Chinese Academy of Sciences Shanghai China Qinghai Station of Purple Mountain Observatory Chinese Academy of Sciences Qinghai China

By mapping the 12CO J=1—0 lines in IRAS 05391-0217, 06114+1745 and 06291+0421, three new high-velocity bipolar molecular outflows are found. Parameters of these outflows are derived, which suggest that they are massive and energetic outflows with total kinetic energies of about 1038 J and mass loss rates about 10-5 M⊙/a. The driving sources are identified by analyzing the positions, intensities and color temperatures of the associated infrared sources. These outflows are most likely driven by single sources which correspond to massive young stellar objects. In these regions H2O masers have been detected located near the embedded infrared sources, which indicates that their exciting mechanism may be correlated with that of the CO outflows. The relationship between the parameters of outflows and central sources shows that high-velocity outflow and thermal radiation of a star are two basic correlated but different features in the evolution of young stars.

关键词： interstellar molecule jet and outflow star formation.

The total column densities and fractional abundances of CH_3CN,CH_3OH,HCOOCH_3 and^(13)CS in W51 cores

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Science China(Physics,Mechanics & Astronomy) 2005年第2期48卷 158-167页

作者： PEI Chunchuan MA Hongjun ZENG Qin LI Bo Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China

We present interferometric observations of the W51 region at 2.7 mm and 3.3 mm with the Berkeley-Illinois-Maryland Association Array. The lines of CH3CN (J = 6 – 5, K = 0,1,2,3,4), CH3OH (15-2 ?151 E), HCOOCH3-A (71,6 – 61,5), HCOOCH3 -E (71,6 – 61,5) and 13CS (2-1) as well as the 2.7 mm continuum toward W51 have been observed. The derived total beam-averaged column densities NT and fractional abundances of CH3CN, CH3OH, HCOOCH3 and 13CS in W51 cores have been obtained.

关键词： massive star formation, interstellar molecular lines, column density, fractional abundance.

Plasma Blobs and Turbulence Impacting Magnetic Confinement(A Short Review)

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Journal of Energy and Power Engineering 2023年第1期17卷 1-10页

作者： Rahele Zadfathollah Seyed Kamal Mousavi Balgehshiri Ali Zamani Paydar Bahman Zohuri Department of Physics K.N.Toosi University of TechnologyTehranP.O.BOX 15875-4416Iran Physics and Energy Engineering Department Amirkabir University of TechnologyTehranIran Galaxy Advanced Engineering AlbuquerqueNew Mexico 87111United States of America

Space-based plasma(i.e.,a highly ionized gas or the fourth state of matter)blobs are isolated pockets of this highly ionized gas made up of charged particles.These blobs are believed to have a substantial impact on the structure and dynamics of the cosmos and can be seen in a variety of astronomical objects,including stars,galaxies,and the intergalactic medium.Some plasma blobs are connected to intense phenomena like magnetic reconnection,shock waves,and supernovae,while others may be the result of more passive processes like cooling and gravitational collapse.In both astrophysics and plasma physics,there is ongoing research on the characteristics and behavior of plasma blobs.This phenomenon has a very adverse effect on tokamak-based MCF(magnetic confinement fusion),which is the subject of this short review paper.

关键词： Plasma blobs plasma edge interstellar magnetic reconnection tokamak MCF

A submillimeter observation and study of star-forming regions

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Chinese Science Bulletin 2002年第1期47卷 16-21页

作者： JIANG Linhua, WU Yuefang & M. MillerDepartment of Astronomy, Peking University, Beijing 100871, China Chinese Academy of Sciences-Peking University Joint Beijing Astrophysics Center, Beijing 100871, China I. Physikalisches Institut, Zulpicher Str Department of Astronomy Peking University Beijing China Chinese Academy of Sciences-Peking University Joint Beijing Astrophysics Center Beijing China I. Physikalisches Institut Koeln 41 Germany

Using the 3-m radio telescope of KOSMA, we mapped 12CO (J = 3-2) lines for three molecular clouds, B35, S146 and TMC-2A. High-velocity molecular outflows are found in all these regions. The physical and dynamical pa-rameters of the outflows are derived, and their shapes and driving sources are analyzed. Contour maps of center veloci-ties show that the large scale systematic gradients exist in the three clouds. These observed motions are best explained by rotation after excluding the cause of outflows. Furthermore, in the core region of TMC-2A there is a velocity gradient in opposite direction from that of the large scale. It may be caused by magnetic braking. Finally, angular velocities of the clouds are calculated, and the effects of rotation against gravity and lowering the star-formation rate are also ana-lyzed.

关键词： dynamics of interstellar medium jets and outflows star formation.

An H_2O flare in GGD25

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Chinese Science Bulletin 2001年第1期46卷 35-39页

作者： XU Ye, ZHENG Xingwu JIANG Dongrong, ZHANG Fujun& YU Zhiyao1. Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China 2. Chinese National Observatories, Chinese Academy of Sciences, Beijing 100080, China 3. Department of Astronomy, Nanjing University, Nanjing 210093, China Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai China Chinese National Observatories Chinese Academy of Sciences Beijing China Department of Astronomy Nanjing University 210093 China

We report the observing results of a short time scale monitoring of the 22 GHz water maser emission in GGD25. A rapid water maser outburst with the time scales of 4 d has been detected, and the variations are accompanied by some changes in the line width. The time variations were probably caused by a collision pump which led to changes in the pump input.

关键词： interstellar masers (ISM) individual GGD25 masers.