Observations of interstellar HOCO+: abundance enhancements toward the galactic center     

Minh YC  Irvine WM  Ziurys LM 《The Astrophysical journal》1988,334(1):175-181

A survey of the 4(04)-3(03) and 1(01)-0(00) transitions of HOCO+ has been made toward several molecular clouds. The HOCO+ molecule was not observed in any sources except Sgr B2 and Sgr A. The 5(05)-4(04) and 4(14)-3(13) transitions were also detected toward Sgr B2. The results indicate that gas phase CO2 is not a major carbon reservoir in typical molecular clouds. In Sgr B2, the HOCO+ antenna temperature exhibits a peak approximately 2' north of the Sgr B2 central position (Sgr B2[M]) and the 4(04)-3(03) line emission is extended over a approximately 10' x 10' region. The column density of HOCO+ at the northern peak in Sgr B2 is approximately 3 x 10(14) cm-2, and the fractional abundance relative to H2 > or = 3 x 10(-10), which is about 2 orders of magnitude greater than recent predictions of quiescent cloud ion-molecule chemistry.  相似文献   

Identification of the interstellar cyanomethyl radical (CH2CN) in the molecular clouds TMC-1 and Sagittarius B2     

Irvine WM  Friberg P  Hjalmarson A  Ishikawa S  Kaifu N  Kawaguchi K  Madden SC  Matthews HE  Ohishi M  Saito S  Suzuki H  Thaddeus P  Turner BE  Yamamoto S  Ziurys LM 《The Astrophysical journal》1988,334(2):L107-L111

We report the astronomical identification of the cyanomethyl radical, CH2CN, the heaviest nonlinear molecular radical to be identified in interstellar clouds. The complex fine and hyperfine structures of the lowest rotational transitions at about 20.12 and 40.24 GHz are resolved in TMC-1, where the abundance appears to be about 5 x 10(-9) relative to that of H2. This is significantly greater than the observed abundance of CH3CN (methyl cyanide) in TMC-1. In Sgr B2 the hyperfine structure is blended in the higher frequency transitions at 40, 80, and 100 GHz, although the spin-rotation doubling is clearly evident. Preliminary searches in other sources indicate that the distribution of CH2CN is similar to that for such carbon chain species as HC3N or C4H.  相似文献   

Variations in the HCN/HNC abundance ratio in the Orion molecular cloud     

Goldsmith PF  Irvine WM  Hjalmarson A  Elldér J 《The Astrophysical journal》1986,310(1):383-391

We have used observations of the rare isotopes of HCN and HNC to determine the relative abundance of these two chemical isomers along the central ridge of the Orion molecular cloud. The abundance ratio [HCN]/[HNC] decreases by more than an order of magnitude from the relatively warm plateau and hot core sources toward the KL nebula to the colder, more quiescent clouds to the north and south. Even in the cooler regions, however, the ratio is an order of magnitude larger than that found in previous investigations of cold dark clouds. We determine the kinetic temperature in the regions we have studied from new observations of methylacetylene (CH3CCH), together with other recent estimates of the gas temperature near KL. The results suggest that the warmer portions of the cloud are dominated by different chemical pathways than those in the general interstellar cloud material.  相似文献   

1991年度海冰预报年会在京召开     

刘纪元 《海洋预报》1991,(4)

1991年度海冰预报年会于1991年10月17日至19日在北京召开。国家海洋局、渤海石油公司、大港石油管理局、天津大学、大连理工大学等30个单位的50名代表出席了会议、会议由国家海洋环境预报中心陈克文处长主持;包澄澜副主任致开幕词,国家海洋局预报浮标处刘喜礼处长到会并讲了话。会议代表对1990年渤海冰情概况进行了分析总结;对1991年度冰情趋势及预报进行了预测和会商。会议中间还就海冰预报研究成果开展了学术交流;并根据海冰工作者的愿望,为促进海冰预报、科研工作的发展,成立了以徐继祖教授为主任委员的“中国海洋学会海冰专业委员会。  相似文献   

1994／1995年海冰预报会商及研讨会在北京召开     

王殿昌  刘纪元 《海洋预报》1995,(1)

１９９４／１９９５年海冰预报会商及研讨会在北京召开．１９９Ｖ１９９５年海冰预报会商会于１．９９４年１０月１９日在北京国家海洋环境预报中心召开。出席会议的有渤海石油公司，海军司令部气象中心，国家海洋环境监测中心，国家海洋局技术所，海洋环境预报中心以及海...  相似文献   

2000年度海冰会商会在唐山市召开     

刘纪元 《海洋预报》2001,(1)

国家海洋环境预报中心于２０００年１１月６～７日在河北省唐山市主持召开了２０００年度海冰预测会商会。来自国家海洋局、海洋石油、海军等部门的领导、预报技术人员和科研、生产管理人员共３０多位代表出席了会议。会议对１９９９年度渤海及黄海北部冰情进行了总结。实测资料表明，１９９９年２月～２０００年３月渤海及黄海北部冰情为常年，局部海区较常年偏重。与会专家对２０００年１２月～２００１年３月渤海和黄海北部冰情趋势进行了预测与会商。专家们认为今冬明春渤海北部冰情为常年略重，渤海南部及黄海北部冰情为常年略轻。同时…  相似文献   

我国从今年起开始采用国际热带气旋名称和等级标准     

刘纪元 《海洋预报》1989,(1)

目前我国使用的台风名称和等级标准是历史上沿用下来的,与国际规定的标准不相一致。现经国务院同意,国家技术监督局和国家气象局共同决定,我国从1989年1月1日起在广播电视、报刊资料、航海海运、气象海洋业务中使用国际规定的热带气旋名称和等级标准。国际标准与我国现行标准的主要差异是:国际规定的热带风暴和强热带风暴,我国统称为台风;国际规定的台风,我国称为强台风。 我国采用国标热带气旋名称和等级标准后,将大大方便海上用户和国外用户,同时还有  相似文献   

Detection of a new interstellar molecular ion, H2COH+ (protonated formaldehyde)     

Ohishi M  Ishikawa SI  Amano T  Oka H  Irvine WM  Dickens JE  Ziurys LM  Apponi AJ 《The Astrophysical journal》1996,471(1):L61-L64

A new interstellar molecular ion, H2COH+ (protonated formaldehyde), has been detected toward Sgr B2, Orion KL, W51, and possibly in NGC 7538 and DR21(OH). Six transitions were detected in Sgr B2(M). The 1(1,0)-1(0,1) transition was detected in all sources listed above. Searches were also made toward the cold, dark clouds TMC-1 and L134N, Orion (3N, 1E), and a red giant, IRC + 10216, without success. The excitation temperatures of H2COH+ are calculated to be 60-110 K, and the column densities are on the order of 10(12)-10(14) cm-2 in Sgr B2, Orion KL, and W51. The fractional abundance of H2COH+ is on the order of 10(-11) to 10-(9), and the ratio of H2COH+ to H2CO is in the range 0.001-0.5 in these objects. The values in Orion KL seem to be consistent with the "early time" values of recent model calculations by Lee, Bettens, & Herbst, but they appear to be higher than the model values in Sgr B2 and W51 even if we take the large uncertainties of column densities of H2CO into account. We suggest production routes starting from CH3OH may play an important role in the formation of H2COH+.  相似文献   

Nitrogen sulfide in quiescent dark clouds     

McGonagle D  Irvine WM  Ohishi M 《The Astrophysical journal》1994,422(2):621-625

We report the first detection of interstellar nitrogen sulfide (NS) in cold dark clouds. Several components of the 2 pi 1/2, J = 3/2 --> 1/2 and J = 5/2 --> 3/2 transitions were observed in TMC-1 and L134N. The inferred column density for TMC-1 is NNS approximately 8 x 10(12)cm-2 toward the NH3 peak in that cloud, and in L134N is NNS approximately 3 x 10(12)cm-2 toward the position of peak NH3 emission. These values correspond to fractional abundances relative to molecular hydrogen of fNS approximately 8 x 10(-10) for TMC-1, and fNS approximately 6 x 10(-10) for L134N. The NS emission is extended along the TMC-1 ridge and is also extended in L134N. The measured abundances are significantly higher than those predicted by some recent gas phase ion-molecule models.  相似文献   

Chemical abundances in cold, dark interstellar clouds     

Irvine WM  Ohishi M  Kaifu N 《Icarus》1991,91(1):2-6

The Sun may well have formed in the type of interstellar cloud currently referred to as a cold, dark cloud. We present current tabulations of the totality of known interstellar molecules and of the subset which have been identified in cold clouds. Molecular abundances are given for two such clouds which show interesting chemical differences in spite of strong physical similarities, Taurus Molecular Cloud 1 (TMC-1) and Lynd's 134N (L134N, also referred to as L183). These regions may be at different evolutionary stages.  相似文献