Neutral Atomic Carbon in the Globules of the Helix | Zendy

Ken Young | Zendy; P. Cox | Zendy; P. J. Huggins | Zendy; T. Forveille | Zendy; R. Bachiller | Zendy

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Neutral Atomic Carbon in the Globules of the Helix

Author(s) -

Ken Young,

P. Cox,

P. J. Huggins,

T. Forveille,

R. Bachiller

Publication year - 1997

Publication title -

the astrophysical journal

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 2.376

H-Index - 489

eISSN - 1538-4357

pISSN - 0004-637X

DOI - 10.1086/310677

Subject(s) - photoionization , helix (gastropod) , envelope (radar) , carbon fibers , spectral line , chemistry , line (geometry) , atomic physics , physics , materials science , ionization , ion , astronomy , geometry , telecommunications , composite number , composite material , ecology , organic chemistry , snail , biology , radar , mathematics , computer science

We report detection of the 609u line of neutral atomic carbon in globules ofthe Helix nebula. The measurements were made towards the position of peak COemission. At the same position, we obtained high-quality CO(2-1) and 13CO(2-1)spectra and a 135" x 135" map in CO(2-1). The velocity distribution of CI showssix narrow (1 -> 2 km/sec) components which are associated with individualglobules traced in CO. The CI column densities are 0.5 -> 1.2 x 10^16/cm^2. CIis found to be a factor of ~6 more abundant than CO. Our estimate for the massof the neutral envelope is an order of magnitude larger than previousestimates. The large abundance of CI in the Helix can be understood as a resultof the gradual photoionisation of the molecular envelope by the central star'sradiation field.Comment: 5 pages, Latex, AAS macros, 3 EPS figures, to appear in Astrophysical Journal Letter

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