Detection of abundant CO2 ice in the quiescent dark cloud medium toward Elias 16

被引:162
作者
Whittet, DCB [1 ]
Gerakines, PA
Tielens, AGGM
Adamson, AJ
Boogert, ACA
Chiar, JE
de Graauw, T
Ehrenfreund, P
Prusti, T
Schutte, WA
Vandenbussche, B
van Dishoeck, EF
机构
[1] Rensselaer Polytech Inst, Dept Phys Appl Phys & Astron, Troy, NY 12180 USA
[2] Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands
[3] Univ Cent Lancashire, Ctr Astrophys, Preston PR1 2HE, Lancs, England
[4] NASA, Ames Res Ctr, Moffett Field, CA 94035 USA
[5] Space Res Org Netherlands, NL-9700 AV Groningen, Netherlands
[6] Leiden Observ, NL-2300 RA Leiden, Netherlands
[7] ESA, Div Astrophys, ISO Sci Operat Ctr, Madrid 28080, Spain
[8] Univ Louvain, Inst Astron, B-3001 Heverlee, Belgium
基金
美国国家航空航天局;
关键词
dust; extinction; infrared; ISM; lines and bands; individual (Taurus Dark Cloud); molecules;
D O I
10.1086/311318
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We report the first detection of solid carbon dioxide (CO2) in quiescent regions of a dark cloud in the solar neighborhood, a result that has important implications for models of ice formation and evolution in the interstellar medium. The K-type field star Elias 16 was previously known to display solid-state absorption features of H2O and CO ices arising in the Taurus Dark Cloud. Our detection of the CO2 feature at 4.27 mu m in this line of sight implies a column density N(CO2) = 4.6(-0.6)(+1.3) x 10(17) cm(-2), equivalent to similar to 18% and 70% of the H2O and CO column densities, respectively. Comparison with laboratory data indicates that (unlike CO) the CO2 resides primarily in a polar (H2O-rich) component of the ices. CO2 is formed easily in the laboratory by the photolysis of ice mixtures containing CO2 but the detection toward Elias 16 indicates that CO2 formation can occur in dark clouds in the absence of a local embedded source of radiation. Possible alternative mechanisms for CO2 production include grain surface reactions and energetic processing driven by the interstellar radiation field or cosmic rays.
引用
收藏
页码:L159 / L163
页数:5
相关论文
共 44 条
[31]   EVIDENCE FOR CHEMICAL-PROCESSING OF PRECOMETARY ICY GRAINS IN CIRCUMSTELLAR ENVIRONMENTS OF PRE-MAIN-SEQUENCE STARS [J].
TEGLER, SC ;
WEINTRAUB, DA ;
RETTIG, TW ;
PENDLETON, YJ ;
WHITTET, DCB ;
KULESA, CA .
ASTROPHYSICAL JOURNAL, 1995, 439 (01) :279-287
[32]  
TIELENS AGG, 1997, IAU S, V178, P45
[33]   Circumstellar and interstellar synthesis of organic molecules [J].
Tielens, AGGM ;
Charnley, SB .
ORIGINS OF LIFE AND EVOLUTION OF BIOSPHERES, 1997, 27 (1-3) :23-51
[34]   INTERSTELLAR SOLID CO - POLAR AND NONPOLAR INTERSTELLAR ICES [J].
TIELENS, AGGM ;
TOKUNAGA, AT ;
GEBALLE, TR ;
BAAS, F .
ASTROPHYSICAL JOURNAL, 1991, 381 (01) :181-199
[35]  
TIELENS AGGM, 1982, ASTRON ASTROPHYS, V114, P245
[36]  
Valentijn EA, 1996, ASTRON ASTROPHYS, V315, pL60
[37]  
vanDishoeck EF, 1996, ASTRON ASTROPHYS, V315, pL349
[38]   SOLID CO IN THE TAURUS DARK CLOUDS [J].
WHITTET, DCB ;
LONGMORE, AJ ;
MCFADZEAN, AD .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1985, 216 (02) :P45-P50
[39]   Infrared spectroscopy of dust in the diffuse interstellar medium toward Cygnus OB2 No. 12 [J].
Whittet, DCB ;
Boogert, ACA ;
Gerakines, PA ;
Schutte, W ;
Tielens, AGGM ;
deGraauw, T ;
Prusti, T ;
vanDishoeck, EF ;
Wesselius, PR ;
Wright, CM .
ASTROPHYSICAL JOURNAL, 1997, 490 (02) :729-734
[40]   INTERSTELLAR ICE GRAINS IN THE TAURUS MOLECULAR CLOUDS [J].
WHITTET, DCB ;
BODE, MF ;
LONGMORE, AJ ;
BAINES, DWT ;
EVANS, A .
NATURE, 1983, 303 (5914) :218-221